Conceptual Design of Bridges

Author Xiang Haifan, et al. Compiled by Xiang Haifan Xiao Rucheng, Xu Liping, Shi Xuefei Ge Yaojun, Wei Hongyi, Han Zhenyong Editor-in-Charge Shen Hongyan, Qu Yue

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Book Title: Conceptual Design of Bridges Author: Xiang Haifan, et al. Editor-in-Charge: Shen Hongyan, Qu Yue Originally Published By: China Communications Press Copyright © 2011 by China Communication Press Version No.: First Edition in June 2011 Printing No.: Firstly Printed in June 2011 Book No.: ISBN 978-7-114-08864-3 Cataloguing in Publication (CIP) Data Conceptual Design of Bridges / Edited by Shen Hongyan, Qu Yue – Beijing: China Communications Press, June 2011. Original ISBN 978-7-114-08864-3 I. bridge … II item … III Bridge Engineering - Design IV. U442. 5 Chinese version Library CIP (2011), No. 008931 All rights reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein. English Translated Version Printed in India in association with China Communication Press, No. 3 Waiguan Xiejie Street, Andingmenwai, Chao Yang District, Beijing (100011) ISBN: 978-93-5014-583-8 First Indian Edition: 2015 Published by: S.K. Kataria & Sons 4885/109, Prakash Mahal, Dr. Subhash Bhargav Lane, Near Delhi Medical Association, Daryaganj, New Delhi-110002 (INDIA) H.O. Opp. Clock Tower, Ludhiana (Pb.) Printed at Repro India Ltd., New Delhi (INDIA)

FOREWORD

After the 1952 adjustment, China’s Higher Education in Science and Technology basically inherited the former Soviet system, namely, establishing universities corresponding to industrial sections. Engineering Colleges were grouped into civil engineering, electrical and mechanical engineering, hydraulic engineering, chemicals, mining, aviation, geology, transportation and other colleges to meet the industrial needs for engineers and technicians. Arts and Sciences were combined into general university, resulting in the separation of engineering and Arts and Sciences, an unfavorable situation for engineering education. In the 1950s and 1960s, most engineering textbooks translated from the former Soviet Union. Those were teaching materials with practicality in mind, i.e., students were taught to design according to design specifications. Since the reform and opening up, department setup started to follow the discipline line and became to follow the international system, but the industry’s influence remained. In the new textbook “Bridge Project” published in 2004, all articles, chapters, sections arranged basically inherited the former Soviet Union old textbooks except some necessary changes under the new requirements. In the 2006 annual meeting of the International Bridge Engineering in Budapest, Professor M. Schlaich of the Department of Civil Engineering of the Technical University of Berlin published a report entitled “The challenge of education — conceptual and structural design,” at the General Assembly. He introduced ongoing civil engineering education reform at Berlin University, i.e. combining the steel materials department and concrete structures department into a new “conceptual and structural design” department, and the three full professors no longer taught “Steel Design”, “Design of Concrete Structures” according to the standard methods of analysis and design methods, instead, they taught conceptual design and structural design methods about all types of building materials according to the structure (bridges, tall buildings and space structures) to strengthen the cultivation of students’ innovative ideas and ability, not only the basic design skills. 2007 onwards, Bridge Engineering at Tongji University decided to open a new course “Concept Bridge Design” for graduate students in order to bring forward a new generation of bridge engineers with conceptual design capabilities to overcome the shortcoming in innovative ideas quality and aesthetic considerations in China’s bridge engineering. The course started in the Spring of 2008, first in the form of lectures given by several young professor in the division. 2008 summer, Professor Hoi Fan also joined the ranks of the course construction, participated in determining the teaching guideline, and coauthored with Professor Xiao Rucheng Chapter 1 Introduction; Chapter 2 Bridge Aesthetics and Design; Chief Engineer and Senior Engineer Professor Xu Liping and Professor Wei Hongyi at Bridge Design institute co-authored; Chapter 3 Basic Factors to be Considered in the Conceptual Design and Conceptual Design; Chapter 4 Analyzes Innovative Ideas; Professor Ge Yaojun Wrote; Chapter 5 Bridge Structural Disaster

Prevention and Durability, and Part of; Chapters 2 and 3; Professor Xiao Rucheng Wrote; Chapter 6 Bridge Structural System and its Key Mechanical Problems; Professor Shi Xuefei Wrote; Chapter 7 New Problems in Conceptual Design and Solutions; and Finally Conceptual Design Chapter 8 was rewitten by Tongji Urban Bridge Alumni, Tianjin Urban Construction Group Chief Engineer Professor Han Zhenyong, Senior Engineer. The book was validated by Professor Xiang Haifan before finalization. Recently, in the midst of the “Question of Qian,” we feel the urgency and the necessity of reform in engineering education in China. We hope that the publication of “the concept of bridge design” can bring inspiration and encouragement to Chinese students majoring in bridges sector as well as colleagues to overcome the deficiencies in China’s bridge design, to come out of misunderstanding, and to help the education of bridge engineering in Chinese Universities rid of the shackles of traditional materials and methods and to keep up with the international engineering education reform. We welcome all feedbacks, especially to the errors in the book, from colleagues bridge engineering for future amendment in the second edition in order to further improve this “Conceptual Bridge Design” and make it a compulsory textbooks for 21st century bridge engineers. Xiang Haifan February 2010

CONTENTS 1. INTRODUCTION 1.1 Overview of the Development of Modern Bridge (1660 to 1945) 1.1.1 Preliminary Period (1660-1765) 1.1.2 Progressive Era 1.1.3 Development Period I—The Born of Steel (1874-1945) 1.1.4 Development Period II—Steel Suspension Bridge (1883-1945) 1.1.5 Development Period III—Reinforced Concrete Bridge (1875-1945) 1.1.6 Summary 1.2 A Brief History of Modern Bridge (1945-2008) 1.2.1 Bridge Type and System Innovation 1.2.2 New Materials and Connection Technology 1.2.3 Innovative Structure Construction and Ancillary Equipment 1.2.4 Innovative Engineering Methods and Equipment 1.2.5 Innovation Theory and Analytical Methods 1.2.6 Summary 1.3 Achievements and Shortcomings of China Bridge Construction (1978 to 2008) 1.3.1 Introduction 1.3.2 Bridges the Rise of China in the 1980s 1.3.3 1990s China Bridge Takeoff 1.3.4 China Bridge at the Beginning of the 21st Century 1.3.5 Problems in Bridge Construction in China 1.4 Modern Bridge Engineering 1.4.1 Bridge Engineer’s Mission and Mandate 1.4.2 Research and Development of Bridge Project 1.4.3 Bridge-building in the Era of Knowledge Economy 1.5 Conceptual Design and Innovative Ideas 1.5.1 Conceptual Design Significance 1.5.2 Basic Principles of Conceptual Design 1.5.3 Definition of Innovation

1.5.4 Create Innovative Ideas 1.5.5 Tasks and Content of Conceptual Design 1.6 Chapter Summary Review Questions References

2. AESTHETIC BRIDGE DESIGN 2.1 Philosophical Foundation of Aesthetics 2.1.1 Philosophical Foundation of the West 2.1.2 Philosophical Foundation of the East 2.2 The Principles of Bridge Aesthetics 2.2.1 Diversity and Unity (Change and Unity) 2.2.2 Ratio and Symmetry 2.2.3 Balance and Harmony 2.2.4 Rhythm and Coordination 2.2.5 Innovations and Aesthetic Considerations in Conceptual Bridge Design 2.3 Success Stories in the World of Bridge Aesthetic Design—World’s Most Beautiful Bridges of the 20th Century 2.4 Success Stories in Chinese Aesthetic Design of Bridges 2.4.1 Nanjing Yangtze River Bridge (1968) 2.4.2 Fuzhou Wulongjiang Bridge (1971) 2.4.3 Nanpu Bridge (1991), Shanghai 2.4.4 Qiantang Bridge (1996) 2.4.5 Wanxian Chongqing Yangtze River Bridge (1997) 2.4.6 Jiangyin Yangtze River Bridge (1997) 2.4.7 Lupu Bridge (2003) 2.4.8 Nanjing Yangtze River Bridge (2004) 2.4.9 Su Tong Yangtze River Bridge (2008) 2.4.10 Zhoushan Island Project Xihoumen Bridge (2009) 2.5 China Bridge Aesthetics Design Problem Analysis 2.5.1 On the Rationality of Bridge Main Hole Span 2.5.2 Facade Layout Symmetry 2.5.3 The Side Holes Scales in Cable-stayed Bridge

2.5.4 The Arrangement of the Auxiliary Pier in Cable-stayed Bridge Side Span 2.5.5 Pyramid Select and Proportion 2.5.6 Asymmetric Single Tower Cable-stayed Bridge and Collaboration System 2.5.7 Arrangement of Side Span in Suspension 2.5.8 Proper Height of Main Beam Girder 2.6 Chapter Summary Review Questions References

3. BASIC FACTORS TO BE CONSIDERED IN THE CONCEPTUAL DESIGN 3.1 A Variety of Natural Conditions and Functional Requirements 3.1.1 Natural Conditions 3.1.2 Functionality 3.1.3 Landscape Requirements 3.2 Horizontal and Vertical Alignment and Hole Layouts 3.2.1 Layout of Bridge-axis and the Horizontal Alignment 3.2.2 Main Navigation Span Setting 3.2.3 Hole Layout 3.3 Applicability of Various Bridge Types and Bases 3.3.1 Bridge Type Evolution 3.3.2 The Type of Scope and Limits 3.3.3 Application Scope of the Basic Forms 3.4 Technical Factors Affecting Economic Indicators 3.4.1 Material and Economic Indicators of Bridge Types 3.4.2 General Layout of 2 Impact on Economic Indicators 3.4.3 General Layout of 3 Impact on Economic Indicators 3.4.4 Impact of General layout on Economic Indicators Review Questions References

4. CASE ANALYSIS OF INNOVATIVE IDEAS IN THE CONCEPTUAL DESIGN 4.1 The Bridge Scheme and General Layout Ideas

4.1.1 Tsing Ma Bridge in Hong Kong 4.1.2 Tsing Ma Bridge in Hong Kong 4.1.3 The Tsurumi Channel Bridge 4.2 Technical Innovation in the Bridge Program 4.2.1 Denmark Oresund Bridge-steel Truss Composite Girder 4.2.2 United States East Bridge of the San Francisco Bay Bridge Earthquakeresistant Tower 4.2.3 Chongqing New Shibanpo Bridge of Steel-concrete Composite Beams 4.2.4 Hangzhou Jiubao Bridge, Composite Arch Bridge 4.2.5 Uses of High Performance Steel and Concrete Composite Beam Bridge 4.3 Bridge Program Consideration of Landscape Requirement 4.3.1 Tsing Ma Bridge in Hong Kong 4.3.2 Shanghai Lupu Bridge 4.3.3 Chongqing Caiyuanba Bridge 4.4 Records Span the Right Concept 4.4.1 Denmark Great Belt Bridge 4.4.2 Japan Akashi Kaikyo Bridge 4.4.3 Luo River Bridge 4.4.4 Su Tong Yangtze River Bridge 4.5 Outstanding Structure Award-winning Bridge Profile 4.5.1 Switzerland Sunniberg Bridge 4.5.2 The Miho Museum Bridge 4.5.3 United Kingdom Gateshead Millennium Bridge 4.5.4 France Darius Milhaud Bridge Review Questions References

5. DISASTER PREVENTION AND DURABILITY OF BRIDGE STRUCTURES 5.1 Bridge Wind Resistant Design Philosophy 5.1.1 Wind and Bridge Wind-Resistance 5.1.2 Reduce the Static Wind Load 5.1.3 Reduce Wind-induced Vibration 5.1.4 Additional Control Measures

5.2 Bridge Wind Resistant Design Philosophy 5.2.1 Earthquake and Anti-seismic 5.2.2 Bridge Anti-Seismic Principles 5.2.3 Anti-seismic Design Success Stories 5.2.4 Common Seismic Mitigation and Isolation Measures 5.3 Bridge Wind-resistant Design Philosophy 5.3.1 Fortification Standard and Design Principles 5.3.2 Rational Selection of Bridge Site and Bridge Axis 5.3.3 Anti-ship Collision Design Success Stories 5.3.4 A Variety of Ship Collision Prevention Measures 5.4 Bridge Wind-resistant Design Philosophy 5.4.1 Structural Durability 5.4.2 Durability Design Principles 5.4.3 Structural Durability 5.4.4 Structural Durability Measures Review Questions References

6. BRIDGE STRUCTURE SYSTEM AND KEY MECHANICS QUESTIONS 6.1 Bridge Structural System 6.1.1 Bridge Structure System and its Classification 6.1.2 Evaluation Standards for Bridge System Quality 6.1.3 Mechanical Properties of Various Systems 6.1.4 System Innovation 6.2 Important Design Parameter Optimisation and Adjustment 6.2.1 Classification of Design Parameters of Bridge Structures 6.2.2 Effects of Design Parameters on Structure Loading 6.2.3 Design Parameter Optimization and Adjustment 6.3 Construction Method Selection and Safety Identification 6.3.1 The Construction Method of Bridge Structures 6.3.2 Relations between Construction Method and Structure Bearing 6.3.3 Selection of Construction Method

6.3.4 Construction Safety Identification 6.4 Estimation of Bridge Structure and Recognition of Advance 6.4.1 The Estimation Method of Bridge Structures 6.4.2 The Rational Scale of Conventional Bridge 6.4.3 Conventional Bridge Materials Index 6.4.4 Identifying Advances 6.5 Important Mechanical Calculation in Concept Design Phase 6.5.1 General Method for Structure Analysis 6.5.2 Strength Calculation 6.5.3 Rigidity and Stability Calculation 6.5.4 Dynamic Characteristics Calculation 6.6 Modeling Method 6.6.1 Method for Model Selection 6.6.2 Geometric Description 6.6.3 Materials and Sectional Properties 6.6.4 Boundary Conditions 6.6.5 Quality 6.6.6 Loads Review Questions References

7. SOLVING NEW PROBLEM IN THE CONCEPTUAL DESIGN 7.1 Technical Support of Realization of Innovative Design Ideas 7.2 Improvement of Structure and Properties of Structural Details 7.2.1 Innovation of Structural Details 7.2.2 Boundary Conditions Structure Meeting the Requirement of Different Force Requirements 7.2.3 Innovative Construction Composition 7.2.4 Structural Connections between Different Interface 7.2.5 Structural Measures to Mitigate Failure 7.2.6 Structural Measures Ensuring Structure Durability 7.3 Innovative Construction Method and Corresponding Equipment 7.3.1 Driving Force Behind Method of Innovation

7.3.2 New Technology of Bridge Erection Adapted to Special Requirements 7.3.3 Equipment of New Bridge Erection Technology 7.3.4 Detection Equipment for Bridge Erection 7.4 Applications of Advanced Materials and High-Tech 7.4.1 Application Requirements of New Materials and High-Tech 7.4.2 High Performance Steel (HPS) 7.4.3 High-performance Concrete (HPC) 7.4.4 Fiber Reinforced Polymer (FRP) 7.4.5 Role of IT Technology in Promoting Bridge-building 7.5 Choosing Research Topics in Complex Bridge Construction Work 7.5.1 The Purpose and Necessity of Research Project 7.5.2 Choosing Research Contents 7.5.3 Research Technique and Method Review Questions References

8. CONCEPTUAL DESIGN OF URBAN BRIDGE 8.1 The Concepts of Urban Bridges 8.1.1 The Definition of Urban Bridges 8.1.2 Historical Evolution of Urban Bridge 8.2 Conceptual Design of Urban Bridge—General Description 8.3 Conceptual Design of Urban Bridge—Structure and Engineering 8.3.1 Choice of Urban Bridge Style 8.3.3 Urban Bridge Structure Characteristics 8.4 Conceptual Design of Urban Bridge—Structure and Engineering—The Architectural Aesthetics 8.4.1 In Harmony with the Environment 8.4.2 Construction Techniques 8.4.3 Bridge Decoration 8.5 Conceptual Design of Urban Bridge—Structure Engineering in Combination with Architectural Aesthetics References

INTRODUCTION

1.1 OVERVIEW OF THE DEVELOPMENT OF MODERN BRIDGE (1660–1945) 1.1.1 Preliminary Period (1660~1765) Modern civil engineering went through the initial one hundred years (preliminary period, 1660 to 1765) over a period of 300 years from the 17th century to the mid-20th century. Italian Scholar Galileo Galilei (1564~1642), published a book “Dialogue on the Two New Scientific Theory” in 1638, and discussed the concept of mechanical properties and strength of the material, and then in 1660, the British State Scholar Robert Hooke (1635~1703), establish a relationship between stress and strain material (Hooke’s law), and in 1687, British Scholar Isaac Newton (1642~1727), suggested the three great laws on mechanics and they became the theoretical foundation of civil engineering. The French government established the first bridge ministry in 1715, and established the world’s first engineering college in 1747, as Paris bridge school. In 1765, before the British Industrial Revolution occurred, the French engineer Jean-Rodolphe (1708~1794), led the Paris bridge school to studied the stone arch pressure lines, and calculated the size of arch and pier using mechanical and material strength theory, and built many flat arch bridges (Fig. 1.1), bringing the stone arch bridge design in Europe to a high level. While the emergence of flat arch bridge in Europe was 1000 years later than China’s Sui Dynasty arch bridge (1765~1874), they were built on the basis of theory-derived scientific design.

Fig. 1.1 Pont de la Concorde in Paris, France.

1.1.2 Progressive Era The second period was the development of modern bridge from the British Industrial Revolution to the “Progressive Era” before the First World War (1765~1874), the metal

material gradually replaced in natural stone and wood as the main building material of the bridge. In 1779, the British engineer Abraham Darby III (1750~1790), designed and built the world’s first cast-iron arch bridge, the Coalbrookdale bridge. It was 30.65 m-span (Fig. 1.2) and also known as the end of the ancient bridges from first of modern times. Subsequently, the British engineer Thomas Telford (1757~1834), built more than a dozen larger span cast iron bridge, from which the most representative one was the Eaton Hall bridge (45.75 m-span) built in 1824. For the construction of multi-arch iron bridge, R. Stephenson (1803~1859), invented the Tied arch in 1849, this design spared the pier from the force generated by the arch and it established a new bridge type “Tied Arch Bridge”.

Fig. 1.2 English Coalbrookdale Bridge. At the same time, inspired by the Chinese Journey novels, England in the second half of the 18th century began to try to build Modern Suspension Bridges. The span gradually increased from the initial 70 ft (21.34 m), in early 19th century. The British engineer John & William Smith brothers designed and built the Dryburgh Abbey Bridge in Scotland with the main span of 260 ft (79.25 m). The bridge successfully used wrought iron rod eye as main cable. Then, in Wales and England several wrought iron rod suspension bridges were also be built, including the Union Bridge with the main span of 136.86 m built by the British engineer Sammel Brown in 1820. In 1826, British engineer Welsh Telford built the Menai Straits Bridge (Fig. 1.3) with the main span of 176.6 m (580 ft). The bridge still used the shots with wrought iron rod as eye cable, using stone pier and stone bridge approach, wooden planks laid on bridge surface. Unfortunately, the bridge was destroyed in 1839, by wind and rebuilt in 1940. Since then, wrought iron rod suspension bridge gradually spread to Europe and the Americas, and many suspension bridge in the range of 100~340 m were built in Austria, Hungary, Russia, the United States and South America, Brazil became important achievements of European and American Iron Bridge construction in the 19th Century. In 1850, the British engineer R. Stephenson built a giant (141 m-span) box girder bridge—the Britannia Bridge (Fig. 1.4) with pieces of wrought iron. Because wrought iron box girder bridge was too bulky. In 1857, German engineer H. Gerber under the

inspiration of cabin truss built a six-span (131 m) bridge spanning multiple lattice trusses. In 1864, the first cantilever truss girder bridge with hanging hole was built, with sub-span of 23.9 m + 37.9 m + 23.9 m. This quiet cantilever truss system with hanging hole is named Gai Erbo truss, because of its simple and clear stress analysis, soon it became popular in Europe and America and was a major bridge type of large-span railway bridge. For instance the 1859, Britain’s Albert Bridge has the main span of 138.6 m, the 1860 France’s Lu Zhate viaduct has a span of 55.125 m + 57.75 m + 49.125 m.

Fig. 1.3 Menai Straits Bridge.

Fig. 1.4 Britannia Bridge.

1.1.3 Development Period I—The Born of Steel (1874~1945) In 1874, the US replaced wrought iron with steel and built the first steel arch bridge, and opening a new era of large-span steel bridge construction. Since then, engineers have gradually abandoned cast iron and wrought iron and used steel for better performance, then bridge spans increased significantly. In 1890, the British built a 521.2 m-span Forth Bridge in England. The bridge used cantilever construction method and the pneumatic caisson on the basis, becoming a representative work of modern steel bridge (Fig. 1.5).

Fig. 1.5 England Forth Bridge. In 1909, the United States built the Queens bridge connecting New York Long Island and Manhattan Dayton across the East River, the bridge uses a cantilever truss, astride 143.17 m + 360.4 m + 192.15 m + 300 m + 140 m, and for the first time used of low-alloy steel (nickel-containing 3%), with the strength increased 40% than steel, thus greatly reducing the weight of the bridge. The Quebec bridge, Canada, with 548.78 m main span of the bridge, after experiencing two Cantilever Erection accident (the first due to the web instability of bar, and the second time crushed casting connector of the Hanging hole) was culminated in the 1918, and set the maximum span as a cantilever truss bridge. In 1869, moved to the United States, the German engineer Roebling family of three (father, son, daughter in law) began the construction of the Brooklyn Bridge (486 m-mainspan) in New York, and for the first used cold drawn steel wire rod eye-based cable in place of wrought iron. The bridge was completed in 1883, (Fig. 1.6), becoming a representing work of modern steel suspension bridge.

Fig. 1.6 Brooklyn Bridge in New York.

1.1.4 Development Period II—Steel Suspension Bridge (1883~1945) In early 20th century, the suspension bridge deflection theory established by Austrian engineer J. Melan in 1888, began to drew the attention of people. In 1912, Lithuanian engineer LS Moisseiff who had immigrated to New York was the first to designed with the deflection theory and built the Manhattan Bridge with success. Compared with the earlier Brooklyn Bridge (1883), and the Williamsburg Bridge (1903), and find out that the tower and main beams of Manhattan Bridge are more slender, that achieving better

economic efficiency. Since then, the deflection theory has been rapidly promoted, and between 1926 and 1940, multiple large-span suspension bridge, designed by or consulted with, were built by using the deflection theory in the United States, the notable ones are: 1. Benjamin Franklin Bridge (L = 533.75 m, 1926) 2. Ambassador Bridge (L = 564.3 m, 1929) 3. George Washington Bridge (L = 1067 m, 1931, Fig. 1.7) 4. Golden Gate Bridge (L = 1280 m, 1937, Fig. 1.8) 5. San Francisco Oakland Bay Bridge (L = 704 m, 1937) 6. Bronx-Whitestone Bridge (L = 701 m, 1939) Advantages of the deflection theory is that the use of gravity suspension stiffness reduced the bending stiffness of the bridge deck allows design engineers gradually abandoned bulky truss stiffening girder and used more economical plate girder bridge. With the reduced plate girder height and corresponding reduction of assumed bending moment, the safety of the bridge structure is ensured.

Fig. 1.7 George Washington Bridge. Built in 1940, Washington State Tacoma has a main span of 853 m and the width of the two-lane bridge is only 11.9 m, the height of plate girder stiffening beam 1.3 m. Due to the negligence of the deck torsional stiffness in the design and the deterioration of the aerodynamic performance, the bridge was destroyed by wind 4 months after its completion (Fig. 1.9). Thereafter, the suspension bridge stiffening beam resumed its previous hollow truss design which has better aerodynamic performance and become the basic form of a suspension bridge before the secondary world war.

Fig. 1.8 Golden Gate Bridge.

Fig. 1.9 Tacoma destroyed by wind.

1.1.5 Development Period III—Reinforced Concrete Bridge (1875~1945) In 1875, French engineer Joseph Monier built the first reinforced concrete footbridge Chazelet Bridge, with a span of 13.8 m and 4.25 m in width, which is a T-shaped bridge, a new bridge type transformed from the ceiling of house and the pre-cursor of reinforced concrete bridge. In 1877, French engineer Hennebique built a Steel Concrete footbridge (16 m-span and 4.0 m width), in 1898, he designed and built a reinforced concrete arch bridge (52.46 m span)—Chàtellerault Bridge. In 1890, Austrian engineer Milan (J. Melan) Push invented a construction method using stiffness frames as arch to cast reinforced concrete arch bridge, known as the Milan method which had increased the span of arch bridge to over 100 m. For the instance, Risorgimento Bridge, L = 100 m, 1911, Swiss Langwies Bridge, L= 100 m, 1914. The Swedish Sandö Bridge (Fig. 1.10), built in 1943, has 178.4 m in span and is a masterpiece of modern reinforced concrete arch bridge.

Fig. 1.10 Sweden Sando bridge. Back in 1886, Jackson was the first American engineer to be awarded a patent on prestress, in 1888, German engineer Doehring also obtained a patent in pre-stress application in the floor, but failed due to low value of steel pre-stress tendons as well as creep strain

and shrink losses of concrete. Success was not seen until 1928, when French engineer Freyssinet invented the conical anchor using a high-strength steel and high-strength concrete (1939). After World War II due to shortage of steel, the need for repairing bridges destroyed in the war led the rapid development of the pre-stressed concrete technology.

1.1.6 Summary Throughout the course of 300 year development of modern bridges: from the first phase (1660 to 1765), the theoretical foundation, to the second stage (1765~1874), cast iron bridge, (wrought) iron truss bridge and eye rod suspension, and the third phase (1874~1945), of steel (steel truss bridge, steel arch bridge and steel suspension bridge) and the subsequent emergence of reinforced concrete bridge. It can be said that the mainstream of modern bridge is steel bridge, including many railway bridges and urban bridge, with the representing landmark bridges being the Coalbrookdale iron bridge, Scotland Forth steel truss bridge, steel suspension bridge built in Brooklyn, New York, in the 1930s, and the representing modern bridges of the highest achievements being the George Washington Bridge, the Sydney bridge, the Golden Gate Bridge in San Francisco and Sweden Sandor bridge. The span of cast iron arch bridge increased from the initial 30.65 m in steel truss bridge to more than 500 m in steel truss cantilever bridge, and suspension bridge from less than 100 ft (30.48 m) of wrought iron rod suspension eye to the Brooklyn bridge of 468 m, and to Washington bridge which exceeds one kilometer, and the golden Gate bridge set a striking record of 1,280 m, all are remarkable achievement, results of the combination of wisdom and hard work of many bridges pioneers. The fifteen most outstanding modern bridge engineers (16th to 18th century birth) are: 1. Jean R. Perronet (1708~1794), (Fig. 1.11), Stone Arch Pressure Line; France. 2. Abraham Darby III (1750~1790), (Fig. 1.12), Cast Iron Arch Bridge; United Kingdom. 3. Thomas Telford (1757~1834), (Fig. 1.13), Cast Iron Arch and Eye Rod Suspension Bridge; United Kingdom. 4. John A. Roebling (1806~1869), (Fig. 1.14), the Brooklyn Bridge; Germany. 5. Gustave A. Eiffel (1832~1923), (Fig. 1.16), Cast Iron, Wrought Iron, Steel Arch Bridge; France. 6. Benjamin Baker (1840~1907), (Fig. 1.17), Forth Railway Bridge Truss; United Kingdom.

Fig. 1.11 J. R. Perronet

Fig. 1.12 A. Darby III

Fig. 1.13 T. Telford

Fig. 1.14 J.A. Roebling 7. Joseph Melan (1853~1941), (Fig. 1.18), Suspension Bridge, Bridge Construction Method of Milan; Australia. 8. John Bradfield (1867~1943), (Fig. 1.19), Sydney Arch; Australia. 9. Joseph B. Strauss (1870~1938), (Fig. 1.20), San Francisco Golden Gate Bridge; Switzerland. 10. Robert Maillart (1872~1940), (Fig. 1.21), Sarkisyan Valley Bridge; Switzerland. 11. Leon S. Moisseiff (1872~1943), (Fig. 1.22), the Manhattan Bridge; Lithuania. 12. Othmar H. Ammann (1879~1965), (Fig. 1.23), the George Washington Bridge; Switzerland. 13. E. Freyssinet (1879~1962), (Fig. 1.24), The Founder of pre-stressed Concrete; France. 14. Ralph Freeman (1880~1950), (Fig. 1.25), Sydney Arch; United Kingdom.

Fig. 1.15 J. Monier

Fig. 1.16 G.A. Eiffel

Fig. 1.17 B. Baker

Fig. 1.18 J. Melan

Fig. 1.19 J. Bradfield

Fig. 1.20 J.B. Strauss

Fig. 1.21 R. Maillart

Fig. 1.22 L.S. Moisseiff

Fig. 1.23 O.H. Ammann

Fig. 1.24 E. Freyssinet

Fig. 1.25 R. Freeman

1.2 A BRIEF HISTORY OF MODERN BRIDGE (1945~2008) In about 300 years from the mid-17th century to the mid-20th century, civil engineering completed evolution from the initial “foundation period” (1660~1765), to the “Progressive Era” (1765~1900), symbolised by the British Industrial Revolution, as well as the pre- and post-World War I period including the 30 years of great development or “Mature Period” (1900 to 1945), and started modern civil engineering characterised by the use of computer and IT technologies, corresponding to the development of modern bridge engineering. After the Second World War, the world has entered a relatively peaceful reconstruction era. After a period of post-war recovery, Europe and the United States started to implement highway construction and urbanization plans in the 1950s, and emerged many representing works of innovative technology for modern bridge engineering. Among them, the pre-stressing technology and related construction methods, the revival of cablestayed bridge and the invention of streamline flat steel box girder bridge, invented and created by famous engineers and scholars from France, Germany and the United Kingdom respectively, are three most important landmark achievements in post-war modern bridge engineering, these achievements greatly promoted the rapid advancement of modern bridge engineering. The following sections describe these innovative technologies.

1.2.1 Bridge Type and System Innovation 1. Cable-stayed Bridge, Germany Dischinger, Strömsund Bridge, Sweden (1956) (Fig. 1.26). 2. Cable-stayed Bridge with hanging hole concrete, Italy Morandi, Maracaibo Bridge, Venezuela (1962) (Fig. 1.27).

Fig. 1.26 Strömsund bridge, Sweden.

Fig. 1.27 Maracaibo Bridge, Venezuela. 3. X Arch Bridge, Leonhardt, Fehmarnsund Channel Bridge, Germany (1963) (Fig. 1.28). 4. Streamlined Box Girder Bridge, Gilbert Roberts, Severn Bridge, England (1966) (Fig. 1.29).

Fig. 1.28 Fehmarnsund Channel Bridge, England.

Fig. 1.29 Severn Bridge, England. 5. The secret cable system cable-stayed bridge, Homberg, Friedrich Ebert bridge, Germany (1967) (Fig. 1.30). 6. No wind bracing arch and cable-stayed bridge, using the stabilisation theory of non-orientedly conservative loadings effect, the Knie Rhine bridge, Germany (1969) (Fig. 1.31).

Fig. 1.30 Friedrich Ebert bridge, Germany.

Fig. 1.31 Knie Rhine bridge, Germany. 7. Mixing Deck Cable-stayed bridge, Leonhardt, Kurt Schumacher bridge, Germany 1971 (Fig. 1.32). 8. Sling Bridge, TY Lin International, Colorado Bridge, Costa Rica USA 1972, (Fig. 1.33).

Fig. 1.32 Kurt Schumacher Bridge, Germany.

Fig. 1.33 Colorado Bridge, Costa Rica. 9. Spine Girder bridge, American TY Lin International, San Francisco Airport Viaduct, 1973, (Fig. 1.34). 10. Inclined Cable Stayed bridge, Leonhardt, Köhlbrand bridge, Germany 1973, (Fig. 1.35).

Fig. 1.34 Airport Viaduct, San Francisco.

Fig. 1.35 Köhlbrand Bridge, Germany. 11. Single Cable Plane Concrete Cable-stayed bridge, Müller, Brottone bridge, France 1977, (Fig. 1.36). 12. Continuous Rigid Frame Bridge, Menn, Feigire Bridge, Switzerland 1979, (Fig. 1.37).

Fig. 1.36 Brottone bridge, France.

Fig. 1.37 Feigire Bridge, Switzerland. 13. Extradossed Bridge, Menn, Ganter Bridge, Switzerland 1980, (Fig. 1.38). 14. Cable-Rigid Cooperative System, the German company Leonhardt Svensson, E. Huntington Bridge, 1985, (Fig. 1.39).

Fig. 1.38 Ganter Bridge, Switzerland.

Fig. 1.39 E. Huntington Bridge, Germany. 15. Combined Girder bridge using Twists and turns steel as web plates, Maupre bridge, France 1987, (Fig. 1.40). 16. Cable-stayed bridge without Spine Girder, Calatrava, Alamillo bridge, Spain 1992, (Fig. 1.41).

Fig. 1.40 Maupre Bridge, France.

Fig. 1.41 Alamillo Bridge, Spain. 17. Cable-stayed Suspension system, British Flint-Neil company, Strait Bridge program, Bali, Indonesia 1997 (not yet built) (Fig. 1.42).

Fig. 1.42 Strait Bridge Renderings, Bali.

1.2.2 New Materials and Connection Technology 1. High-performance steel HPS-460-700-1100 (China Q345-370-420), 1950s to 1990s; Germany, and the United States. 2. High performance concrete HPC-80-100-130-150 (China C40-50-60), 1950s and 1990s; France, Germany, the United States and other countries. 3. High-strength bolts, United States, Germany and other countries, was used in the reinforcement of the Golden Gate bridge for the first time in 1951, (Fig. 1.43). 4. Of crude steel Dywidag anchor, DSL company, Worms Bridge, 1953; Germany (Fig. 1.44). 5. Lock-coil, the Thyssen company, used in early cable-stayed bridge, Strömsund Bridge, 1955, Germany (Fig. 1.45). 6. VSL clip anchor, VSL Company, 1958 Switzerland (Fig. 1.46). 7. Strand anchor group, Müller, Brottone Bridge, 1977, (Fig. 1.47); France. 8. HiAm chill casting Heading anchor, Leonhardt, Flehe Bridge, 1979, (Fig. 1.48), Germany.

Fig. 1.43 High-strength bolted connections.

Fig. 1.44 Crude steel anchor Dywidag.

Fig. 1.45 Enclosed cable.

Fig. 1.46 VSL clip anchor.

Fig. 1.47 Strand anchor group.

Fig. 1.48 HiAm chill casting Heading anchor. 9. PE sheath parallel finished steel wire rope, Nippon Steel Corporation, Meiko West Bridge, 1983, (Fig. 1.49). 10. FRP composites, 1970s to 1990s, (Fig. 1.50); Switzerland, Germany, the United States, Japan.

Fig. 1.49 Japan Meiko West Bridge.

Fig. 1.50 FRP composite materials. 11. Long stroke joints, Akashi Strait Bridge, 1970s to 1990s, (Fig. 1.51); Switzerland, Germany, Japan. 12. Carbon fiber reinforced plastic cables, in the 1990s, (Fig. 1.52); Switzerland, Japan.

Fig. 1.51 Long stroke joints.

Fig. 1.52 Carbon fiber reinforced plastic cables. 13. Combined structure of new shear device (PBL), Leonhardt, Germany Tsurumi Channel Bridge, 1994, (Fig. 1.53); Japan. 14. Ultra high strength steel, 1860~2000, MPa (China 1600~1770 MPa), Nippon Steel Corporation, Akashi Strait Bridge, 1998, (Fig. 1.54).

Fig. 1.53 Combined structure of new shear device.

Fig. 1.54 Ultra high strength steel.

1.2.3 Innovative Structure Construction and Ancillary Equipment 1. Anisotropic steel deck, Leonhardt, Koeln-Mannheim Bridge, 1948, (Fig. 1.55); Germany. 2. Large diameter bored pile foundation, Morandi, Italy Maracaibo bridge, Venezuela 1962, (Fig. 1.56).

Fig. 1.55 Anisotropic steel deck.

Fig. 1.56 Venezuela Maracaibo bridge. 3. Soft soil ground friction Anchorage, Small Kelp bridge, 1970, (Fig. 1.57); Denmark.

Fig. 1.57 Small kelp bridge. 4. Split box deck wind-proof structure, Brown, 1980s (Fig. 1.58); England.

Fig. 1.58 Split box deck wind-proof structure (dimensions in m). 5. Bridge longitudinal buffer device, 1990s, (Fig. 1.59); the United States, Britain. 6. The main cable de-humidification unit, Akashi Strait bridge, 1998. (Fig. 1.60); Japan. 7. Fully assembled three-way pre-stressed bridge, Müller, France JMI International, Thailand Bangkok Airport Viaduct, 1999, (Fig. 1.61). 8. Shock-isolation Foundation with Reinforced Soil, Combault, France RionAntirion Bridge, 2003, (Fig. 1.62); (Greece). 9. Shear Key Anti-seismic Tower, TY Lin International, Wendi Deng, the New San Francisco Bay bridge, 2007, (Fig. 1.63); US.

Fig. 1.59 Bridge longitudinal buffer device.

Fig. 1.60 Main cable de-humidification device.

Fig. 1.61 Fully assembled three-way pre-stressed bridge.

Fig. 1.62 Shock-isolation foundation with reinforced soil.

1.2.4 Innovative Engineering Methods and Equipment 1. Cantilever Casting Method, Finsterwalder, Worms Rhine Bridge, 1953 (Fig. 1.64); Germany.

Fig. 1.63 Shear key anti-seismic tower.

Fig. 1.64 Cantilever casting method. 2. The “backwards analysis” method in cable-stayed bridge construction control, Leonhardt, Theodor Heuss Bridge, 1957, (Fig. 1.65); Germany. 3. Incremental launching method, France, Leonhardt, Germany Agger Bridge, (Austria) 1959, (Fig. 1.66).

Fig. 1.65 Theodor Heuss bridge, Germany.

Fig. 1.66 Incremental launching method, France. 4. Movable formwork cast, Leverkusen Bridge, France, Germany 1959, (Fig. 1.67). 5. Movable carriage assembly France, Germany Wittfoht, Krahnenberg bridge, 1961, (Fig. 1.68).

Fig. 1.67 Movable formwork cast method.

Fig. 1.68 Movable carriage assembly. 6. Pre-cast segmental assembly with erecting machine, Müller, Oleron Viaduct, 1964, (Fig. 1.69); France. 7. The beam transport beam method, Sallingsund Bridge, 1978, (Fig. 1.70); Denmark.

Fig. 1.69 Pre-cast segmental assembly with erecting machine.

Fig. 1.70 Sallingsund bridge. 8. Front Light Cantilever casting method, Dames Point bridge, 1988 (Fig. 1.71); the United States. 9. The main cable PPWS method, South Bisan bridge, 1988 (Fig. 1.72); Japan.

Fig. 1.71 Front Light Cantilever casting method.

Fig. 1.72 Main cable PPWS method. 10. The integrated installation using large-scale floating crane, 9000t Big Swan floating cranes, Ele Song Strait Bridge, 2000, (Fig. 1.73); Denmark and Sweden joint construction. 11. Continuous cable-stayed bridge incremental launching construction, Virlogeux, Millau Bridges, 2004, (Fig. 1.74); France.

Fig. 1.73 The integrated installation using large-scale floating crane.

Fig. 1.74 Continuous cable-stayed bridge incremental launching construction.

1.2.5 Innovation Theory and Analytical Methods 1. Computer Technology and Finite Element Analysis Theory The world’s first computer “Aini A G” (ENIAC) (Fig. 1.75) was born in 1946, the world’s first PC arrived in 1981, the application of computer greatly promoted the progress of human civilization in 1943. Courant was the first who introduced the concept of unit; from 1945 to 1955, Argyris development the Structural Matrix Analysis; in 1956, Clough introduced the idea of structural matrix analysis into elasticity analysis and was the first to propose the “FEM” in the 1960s, which was gradually developed and perfected in the 1960s. A large number of mathematicians, mechanics and engineers had made important contributions in this area.

Fig. 1.75 World’s first computer “Eni Akbar”.

2. Bridge Design Analysis Software Development of the theory of finite element analysis and computer technology laid the foundation for the development of design and analysis software, and a number of large commercial software gradually emerged in the 1970s (Table 1.1), and the finite element analysis started its application in bridge design. Table 1.1 Well-known commercial finite element software. Name Ansys

Research Institute

First Release Main Developer

Swanson Analysis Systems, Inc

1970

Swanson

NASTRAN Mac-Neal Schwendler company

1970

MacNeal

SAP

University of California, Berkeley

1970

E.L. Wilson

TDV

Dorian Janjic & Partner GmbH company

1970

D. Janjic

ADINA

ADINA engineering company

1975

Bathe

ABAQUS

Hibbitt, Karison company

1979

Hibbitt

Lusas

Finite Element Analysis Company

1982

Paul Lyons

Midas

MIDAS IT company in

1989

–

3. Seismic Theory Early 20th century, the Great Kanto Earthquake of San Francisco and two disasters caused emphasis on structural anti-seismic research. Researches basic theory in earthquake, strong motion records, model test, analysis theory had been conducted in the engineering fields. Structural anti-seismic research started its rapid development period after 1940. In 1943, Biot published accelerated response spectrum deducted from actual seismic records; from 1950s to 1970s, scholars represented by Housner, Newmark and Clough of the United States and Muto of Japan laid the foundation of modern response spectrum antiseismic theory and carried out research on the dynamic response process of structural elastics and inelastic analysis; in the 1970s, Newmark, Park, Paulay put forward the concept of anti-seismic design ductility; in the mid-1990s, scholars from the United States and Japan proposed a performance-based anti-seismic design method.

4. Wind-proof Theory The wind destruction incidence of the Tacoma suspension bridge in 1940, which occurred at low wind speeds, triggered the beginning of comprehensive study of wind. Induced vibration and aeroelastic prelude theory concerning long-span bridge in the engineering field, and T. Von Karman and others of the USA conducted bridge model wind tunnel tests. Wind Theory Studied progressed and was perfected since the 1960s. Davenport of Canada proposed statistical mathematics approach in wind engineering research, solving creatively the problem of random buffeting and expressing the wind effect as an equivalent form of wind loads; Scanlan of the USA formed the bridge flutter theory and the shaking vibration theory; in the 1990s computed fluid dynamics made a significant progress in fluid dynamics, which is now able to solve the uniform flow, simple form, low Reynolds number numerical simulation computational problems.

5. Non-linear and Stability Theory In the end of the 19th century, scientists discovered that the linear theory of solid mechanics was not applicable in many cases and began the study of non-linear mechanical problems. In 1888, Melan of Austria was the first to propos deflection theory and applied it to suspension cable analysis; in mid-20th century, the theoretical foundation of nonlinear mechanics was Laid; in 1959, Newmark first proposed for solving non-linear dynamic problem using the Newmark-method; in early 1960s, Turner, Brotton and others began to publish research results solving problems concerning large displacement and initial stress. In late 1960s, the combination of finite element method with the computer gradually helped solve non-linear problems in engineering. On stability, Euler (L. Eular) in 1744 put forward the famous bar stable formula; Engesser and Karman of Canada proposed the tangent modulus theory and fold. Modulus operator theory respectively, based on a large number of observation that long lever exceeded the elastic limit before buckling. Since the 1980s, the space elastoplastic stability theory was gradually established based on a computer analysis.

6. Health Monitoring and Vibration Control Theory

In 1969, the paper by Lifshitz and Rotem were regarded as the first one illustrating the dynamic response of structural health monitoring and evaluation modern structural health monitoring concept; in 1987, Britain laid sensors on the 522 m three-span continuous steel box girder bridge Foyle to monitor the operational phase of the bridge under wind loads and vibration of the vehicle main beam deflection and strain response, the system is one of the first and complete health monitoring system ever installed. In the 1960s, linear systems theory and the progress of modern control theory laid a theoretical foundation for the structure of the active vibration control; in 1972 Yao Zhiping proposed the concept of civil engineering structural vibration control by combining with modern control theory and created a new phase of the study in structural vibration; in 1973 The Mass Damper (TMD) passive control style device was first installed on the CN Tower in Toronto, Canada; in 1989 Active Mass Damper (AMD) was first used in the Kyobashi building in Tokyo, Japan. Structure control evolved from passive control and active control theoretical research, and applied research phase of active control devices.

7. Coupled Vibration and Ship Collision Theory In early 20th century, Kirilov, Timoshenko, et al., carried out beam dynamic response studies regarding on constant force on the bridge, later A. Schalenkamp, Inglis, Bigggs et al., further studied the dynamic response of the bridge moving-mass and spring-mass model of the bridge, these studies were considered classical Axle System Vibration theory. After the 1960s, the gradual emergence of a wide range of applications and computer finite element theory, as well as the construction of high-speed railway in some countries in Western Europe, made the coupled vibration theory and test progressed rapidly, and modern computing Axle vibration model more refined, and the theoretical research advanced from plane to space, dynamic interaction and coupling relationship between axle to more in-depth research, analysis of the bridge-girder bridge advanced from bridge in the past to arch bridge, suspension bridge and other complex type. Research results have been applied to the design of high-speed railway bridges, as well as the formulation of the relevant provisions of the bridge specification. System research on vessel-bridge collision problem began in the 1980s, IABSE, AASHTO, Eurocode and other organizations or specification had developed a special design specifications or guidelines, a wide range of anti-collision facilities had also been implemented in more than a dozen large bridges, domestic or foreign. However, research in this area is not yet ripe, and the focus of research is on the aspects of design, protection policies, ship collision force calculation and design of protective equipment.

8. Durability Analysis Theory In 1960s to 1970s, the durability problem of concrete were found, and became the problem of the world. Holland in 1993, defined the durability as the following: under normal maintenance conditions, the use and the performance of material and structure does not exhibit a major change after a period of carrying capacity. It is generally defined in China as: the structure meets safety, functionality and appearance requirements by design requirements in the lifetime without reinforcement need or extra expenses. In recent years, the durability studies in materials research mainly concentrated in the corrosion problems due to carbonation of concrete and steel in the atmosphere in terms of

the main components, and on the performance of corroded reinforced concrete parts in terms of the components, and research methods such as survey and assessment in terms of structure. Research in this area is focused on durability analysis using computer numerical simulation system, durability test basis, lifespan-based concrete aspects of bridge design.

1.2.6 Summary Reviewing the 60 years of modern engineering development, many new bridge systems, new structures, new materials, new construction methods as well as the creation and invention of new theories and methods of analysis have made modern engineering completely different from the early modern engineering: the value of modern bridge engineering resides in the spirit of innovation. With the continuous upgrading of the emergence of new labour law and the corresponding construction equipment, bridge construction is also increasingly accurate, lightweight, automatic control, less reliance on manual operations, and the quality of the project better and more durable, continuously pushing the development of high performance materials. It can be said that the quality and durability of modern bridge engineering come from equipment innovation. Bridge engineer must strengthen quality concept, utilising advanced equipment to control and guarantee the quality, greatly reducing the reliance on manpower. Bridge engineer should also be continue to improve the aesthetic attainment, master the method of aesthetics design, promote cooperation with architects, design and create beautiful bridges to meet people’s aesthetic requirements of the bridge. Beautiful bridges do not rely on more money, but on balance and harmony of the most reasonable performance, most economical and most convenient structure construction. 25 internationally renowned modern bridge scholars and engineers are: 1. David Steinman (American, 1886~1961) (Fig. 1.76) • Main designers of the post-war suspension of the United States • Mackinac bridge, 1957 • Founder of Robinson & Steinman company 2. Franz Dischinger (1887~1953), Germany (Fig. 1.77) • Externally pre-stressed concrete bridge, 1936 • Modern bridge, 1956 • Concrete shrinkage and creep theory 3. Ulrich Finsterwalder (1897~1978), Germany (Fig. 1.78) • Hanging basket situ pre-stressed girder bridge construction method, 1950 • Pre-stressed concrete sling bridge, 1970 4. Gilbert Roberts (1899~1978), United Kingdom (Fig. 1.79) • British Freeman & Fox Chief Engineer • Forth road bridge, 1964 • Severn bridge, 1966 • Modern steel box girder bridge, 1966 • Humber bridge, 1981 5. Riccardo Morandi (1902~1989), Italy (Fig. 1.80) • Vertical rotation concrete arch bridge construction method, 1955

• V-shaped cantilever bridge pier, 1960 • Porous pre-stressed concrete cable-stayed bridge, 1962 6. Fritz Leonhardt (1907~1999), Germany (Fig. 1.81) • Anisotropic steel deck, 1948 • Construction Control “backwards analysis”, 1957 • Thrusting Method, 1959 • Wind-free bracing tower cable-stayed bridge, 1969 • Mixing deck bridge, 1971 • HiAm chill-cast Anchorage, 1979 7. G. Lohmer (1909~1981), Germany (Fig. 1.82) • First single tower cable-stayed bridge, designer of Severin bridge, Cologne, 1959 8. Hellmut Homberg (1909~1990), Germany (Fig. 1.83) • Closed cable system bridge, 1967 • Single cable plane cable-stayed bridge, 1967 9. Tung-Yen Lin (1912~2003), The United States (Fig. 1.84) • Pre-stressed Concrete Design Theory • Reverse Suspension bridge, 1972 • Spine girder bridge, 1973 10. Brandon Lee (1913~2005), China (Fig. 1.85) • Practical calculation method of suspension bridge, 1938 • Truss bridge deflection torsion theory, 1978 • Founder of Chinese independent construction of the bridge, from 1958 to 1990 11. Jean Müller (1925~2005), France (Fig. 1.86) • Pre-stressed concrete segmental construction, 1966 • Single cable plane pre-stressed concrete cable-stayed bridge, 1977 • The whole assembly floating crane construction, 1997 • Three-dimensional pre-stressed viaducts, 1999 • Single Cable Composite Beams Suspension bridge, 2000 12. William Brown (1928~2005), United Kingdom (Fig. 1.87) • Modern streamlined steel box girder bridge, 1966 • Split founder wind Deck (The above 12 have deceased) 13. Hans Wittfoht (1924 ~), Germany (Fig. 1.88) • Movable carriage assembly engineering methods, 1961 14. Christian Menn (1927 ~), Switzerland (Fig. 1.89) • Continuous rigid frame bridge, 1979 • Extradossed bridge, 1980 15. Ito (1930 ~), Japan (Fig. 1.90) • Contact bridge and chief adviser to Japan company 16. Jacques Mathivat (1932 ~), France (Fig. 1.91) • Extradosed board to pull the bridge (in vitro super reinforcement), 1990 17. Jörg Schlaich (1934 ~), Germany (Fig. 1.92) • Reinforced concrete truss simulation method, 1987 • Combined Deck bridge, 1993 • Multi-span cable-stayed bridge hybrid structure, 1998 • Footbridge Innovative ideas 18. N. Gimsing (1935 ~), Denmark (Fig. 1.93)

• Honorary Professor, Technical University of Denmark • Establish Gimsing & Madsen company • Great Belt Bridge consultants, (1998) • Öresund Bridge, 2000 19. Wendi (1938 ~), United States (Fig. 1.94) • Front-light Hanging Watering Act, 1988 • Shear key seismic Tower, 2007 20. Klaus Ostenfeld (1943 ~), Denmark (Fig. 1.95) • Great Belt Bridge, 1998 • Oresund Bridge, 2000 21. Jacques Combault (1943 ~), France (Fig. 1.96) • Reinforced soil isolated basis, 2003 22. Holger Svensson (1945 ~), Germany (Fig. 1.97) • Cable - Rigid cooperative system, 1985 23. Michel Virlogeux (1946 ~), France (Fig. 1.98) • Continuous push cable-stayed bridge construction, 2005 24. Peter Head (1947 ~), United Kingdom (Fig. 1.99) • Severn Bridge, the main span of 456 m bridge, 1996 • Hong Kong Kap Shui Mun Bridge, the 430 m- main-span railway bridge, 1997 25. Santiago Calatrava (1951 ~), Spain (Fig. 1.100) • Spineless cable-stayed bridge, 1992

Fig. 1.76 D. Steinman

Fig. 1.77 F Dischin er

Fig. 1.78 U. Finsterwalder

Fig. 1.79 G. Roberts

Fig. 1.80 R. Morandi

Fig. 1.81 F. Leonhardt

Fig. 1.82 G. Lohmer

Fig. 1.83 H. Homberg

Fig. 1.84 Tung-Yen Lin

Fig. 1.85 Brandon Lee

Fig. 1.86 J. Müller

Fig. 1.87 W. Brown

Fig. 1.88 H. Wittfoht

Fig. 1.89 C. Menn

Fig. 1.90 Ito

Fig. 1.91 J. Mathivat

Fig. 1.92 J. Schlaich

Fig. 1.93 N. Gimsing

Fig. 1.94 Wendi

Fig. 1.95 K. Ostenfeld

Fig. 1.96 J. Combault

Fig. 1.97 H. Svensson

Fig. 1.98 M. Virlogeu

Fig. 1.99 P. Head

Fig. 1.100 S. Calatrava Most of them have won awards from the International Association of Bridge and Structural Engineering (IABSE) of structural engineering and other international Awards: Germany 8, France 4, England 3, United States 3, 2 each for Denmark and Italy, 1 each for Switzerland, Spain, Japan and China.

1.3 ACHIEVEMENTS AND SHORTCOMINGS OF CHINA BRIDGE CONSTRUCTION (1978–2008) 1.3.1 Introduction Brilliant achievements of ancient Chinese bridge had played an important role in the history of world bridge development, as recognised by the world. The 18th century British Industrial Revolution created the modern science and technology, empowering Europe and the United States arrive to a new era of modern engineering. Opium war in the mid-1800s, resulted the already underdeveloped China beccoming a semi-colonial semi-closed country under imperialist aggression. Since then, the imperialist powers plundered the resources of China’s railway construction, the excavation of the mine, in the Jin-Pu, Ping-Han railway built by foreign engineers the Yellow River Bridge, in the early years of forced concessions (such as Shanghai, Guangzhou, Ningbo, etc.) Despite the construction of a number of bridges, the Yangtze River remained a natural moat. After the 1912, Revolution, Sun Yat-sen had planned transportation construction in China’s “Founding outline” in successive years but failed to materialise due to Warlord and long-term civil war. The construction of Hangzhou Qiantang River Bridge started in 1935, and was the first modern steel bridge design by a Chinese engineering, in just 30 months, in September 1937, it was inaugurated, the bridge is a Chinese History Monument. After the founding of new China, with the rise of the national economy, and transportation infrastructure and bridge construction started booming. In a first five-year plan to start building the first bridge of the Yangtze River — Wuhan Yangtze River Bridge, with the help of the former Soviet Union, using a new type of Column base and advanced manufacturing and erection steel beam techniques. In 1957, the 9-hole 128 m with a total length of 1155.5 m Wuhan Yangtze River Bridge was completed, laying the foundation for the development of modern large-span steel bridge and deep water foundation project. In 1968, Yangtze River Nanjing Bridge was design and constructed by our engineers. Compared with the Wuhan Yangtze River Bridge, Nanjing Yangtze River Bridge span increased to 160 m, using a continuous steel truss bridge taken off the stiffening of the third chord. Because of the complex geological conditions on the bridge site, the bridge is a milestone in the construction of the Yangtze river bridge. In the 1960s, due to the impact of three years of natural disasters, financial and steel are very scarce. China provincial highway departments had to develop low cost, less steel, with a variety of human resources, arch became popular during this period. In 1961, Yunnan Changhong broke the 100 m span stone arch bridge; Wuxi originated hyperbolic arch bridge; in 1968 the Henan bridge with a 150 m main span is to the best of this Large span type. At the same time, pre-stressed concrete technology also began to be used from the railway bridge to the road bridge, and 1964 saw the completion of the first pre-stressed concrete T-strap hanging hole rigid frame bridge with a main span of 50 m Henan—Five Ling Wei River Bridge.

Because of problems in curved arch bridge built on the soft soil, in early 1970s Lightweight construction of the reinforced concrete arch truss bridge suitable on soft ground was created, with the representing 75 m Zhejiang Ninghai bridge in 1976, and the 9 hole 50 m Henan Song County bridge. Meanwhile, in the Yunnan, Guangxi, Guizhou, Sichuan, south-west mountainous areas, the development of easy non-support construction of reinforced concrete box arch bridge were built, e.g., the 100 m Yibin, Sichuan Minjiang River Bridge (1973), the 116 m Yunnan Red Bridge (1974) and the 105 m Guangxi Laibin Bridge (1978). In 1972, due to the need to develop oil fields the Shandong Yellow River Highway Bridge is relatively rare steel bridge in China. Its main bridge is a 4-hole 112 m continuous steel truss bridge approach using porous 33 m pre-stressed concrete beams. Bored piles buried deep at a record 107 m. The bridge plays an important role in the development of China Steel Bridges. Western technology of cable-stayed bridge was introduced to China in the late 1960s, Shanghai and Chongqing research department began to build this new bridge, and in 1975 built the 54 m Shanghai new five bridge and 75.8 m Yunyang Tang River bridge in Sichuan. The completion of these two pioneer bridge is the harbinger of cable-stayed bridge in the 1980s, in China. In 1980, the 174 m largest domestic span pre-stressed concrete T-rigid frame bridge opened to traffic.

1.3.2 Bridges the Rise of China in the 1980s After the smashing of the “Gang of Four”, China has entered a new period of reform and opening up, bridge construction also ushered in a golden age. In 1981, the first railway pre-stressed concrete cable-stayed bridge with a main span of 96 m, Guangxi Laibin red water river bridge was opened to traffic. In 1981, at the National Conference held in Jinan experience on the construction of pre-stressed concrete cable-stayed bridge was reviewed. In 1982, the 220 m of Jinan Yellow River Bridge opened to traffic, it symbolises cable-stayed bridge in the country rapid growth in China. In 1982, the world’s largest rail span Slant Leg Rigid Frame — 176 m Shaanxi Ankang railway bridge in the country was completed, a major achievement of the railway bridge construction achieved in China. In the early 1980s, the Guangdong Province has attracted national attention around the bridge sector counterparts. To solve the Pearl Delta traffic barriers, many bridges were built. Among them, the 1984–90 m Rongqi bridge, which for the first time used 5000 kN floating crane overall erection of pre-fabricated beams and the simple support design. In 1988, Guangdong Panyu Luoxi Bridge of 180 m main span was built as prestressed concrete continuous rigid frame bridge. This is China’s large-span pre-stressed concrete beam bridge construction. For the development needs of the construction of Shandong oilfield, China’s first steeltower cable-stayed bridge deck and anisotropy type bridge, 288 m long Dongying Yellow

River Bridge was opened to traffic in 1987, the bridge’s cables used a New Generation of hot extrusion PE Parallel to the cable casing system (NWPS). In 1988, the 110 m off the coast of Guangdong Jiangmen bridge opened to traffic, it is the first short-term use of precast pre-stressed concrete cantilever erection of advanced construction of continuous beam bridge. Throughout the 1980s, the construction of cable-stayed bridge thrived in the country with the follows worth mentioning: 1. Guangdong Nanhai Jiujiang Bridge (1988), the main span 160 m, using floating cranes assembled piecemeal cantilever construction. 2. Chongqing Shimen Bridge (1988), the main span 230 m, was the longest cablestayed bridge cantilever construction. 3. Guangzhou Haiyin Bridge (1988), the main span 175 m, the bridge width of 35 m, was the widest single cable plane cable-stayed bridge. 4. Long Xiangjiang Jiangbei Bridge (1980), the main span 210 m, the first time the use of light hanging basket full section once before fulcrum suspended casting construction technology.

1.3.3 1990s China Bridge Takeoff After entering the 1990s, due to the rapid development of the national economy development and construction of Shanghai Pudong, bridge construction also expanded Shanghai Nanpu Bridge construction is an important opportunity, Shanghai Municipal House has invited Japanese companies to participate in the pre-design work. Upon the appeal from a professor at Tongji University in Shanghai, the then CPPCC Chairman of Shanghai Comrade Jiang Zemin decided to entrust Shanghai Nanpu Bridge to the cooperation in design and construction domestically, a self-building opportunities for scientific and technological progress achieved through practice. Of course, this is also a challenge as the state bridge sector realised the leap from the construction of more than 200 m span cable-stayed bridge to a main span of 423 m combination of cable-stayed bridge girder bridge. Shanghai Nanpu Bridge opened to traffic in 1991, and immediately after another span cable-stayed bridge, Shanghai Yangpu Bridge with main span of 602 m was erected in 1993. The successful construction of two cable-stayed bridges was greatly encouraged by the self-construction of the bridge counterparts large-span bridges of confidence and enthusiasm, setting off a national upsurge large-scale construction of the bridge in the 1990s. Cable-stayed bridge over 400 m include: 1. Hubei Yun County Hanjiang River Bridge, the main span of 414 m, 1993. 2. The Wuhan Yangtze River Bridge, the main span of 400 m, 1995. 3. Tongling Yangtze River Bridge, the main span of 432 m, 1995. 4. Chongqing Yangtze River Bridge, the main span of 444 m, 1995. 5. Shanghai Xuputaiqiao main span of 590 m, 1997. 6. Queshi Bridge, the main span of 518 m, 1998.

The successful construction of cable-stayed bridges encouraged China to build a bridge of modern suspension bridge. The 452 m of Shantou Bay Bridge is the first attempt, due to the more serious local air-sea corrosion, pre-stressed coagulation soil stiffening beams were used. Each main cable contains 110 shares of steel wires of 91 root 5 mm, with outside diameter up to 56 cm. The bridge was built in 1994. Guangdong Province in the construction of the Pearl River Expressway (GuangzhouShenzhen, Guangzhou-Zhuhai) had also begun planning the construction of Humen Bridge across the Pearl River. Several British experts were invited to help in bridge construction. When Professor Li Guohao lettered to the governor of Guangdong Province, Comrade Ye, strongly appealing for independent construction, and in return of Hong Kong on the eve of victory in 1997, built a Humen Pearl River Bridge with a main span of 888 m. This suspension bridge, Auxiliary Channel 270 m pre-stressed concrete continuous rigid frame bridge is another bridge in Chinese Milestone. In 1990s construction of the bridge has also made important progress. Since the steel supply has gradually abundant, application of steel concrete arch was introduced in China. This composite structure with easy installation and construction, the materials used by the reasonable economy, the ability to carry a big advantage. In 1990 Sichuan wangcang built the first 115 m main span concrete arch pipe. Later, in the decade built dozens of such bridge, such as Guangdong three main span of 200 m main span of 270 m Shanxi Bridge and three in Guangxi Shore Bridge. At the same time, bridge using the strength of the skeleton of reinforced concrete box arch has made development. Built in the late 1980s, the 200 m of Chongqing Fuling Wujiang River Bridge and the 240 m Sichuan Yibin Jinsha River bridge marched into a new type of steel pipe mixed Concrete arch skeleton, alike the 313 m Yongning Yongjiang Bridge. Using this technology the world’s longest span concrete arch with main span of 420 m, the Wanxian Chongqing Yangtze River Bridge, was built, another Monumental. In 1994, preparations for the long Jiangyin Yangtze River Bridge was started, cohesion of the Chinese people’s dream of several generations of the bridge, the first Chinese long span suspension bridge over 1000 m designed by the Chinese people. The North Shore has a huge caisson foundation anchorage and coagulation Dobashi tower construction company independently by China, the upper structure construction due to funding problems by the British company’s total contracting actually subcontract completed by Chinese companies. The 1385 m main span of Jiangyin Yangtze River Bridge opened to traffic in 1999, marking China with its bridge construction scale and speed of development as well as a variety of bridge-span charts at the forefront of the outstanding achievements in the world. It should be noted that before the reform and opening up, China bridge construction, particularly the large steel bridge construction was carried out by the Ministry of Railways Bridge Engineering Bureau. Chinese road level is not high, many major rivers still rely ferry connections. After 20 years of efforts, the Chinese public road transportation construction team has to grow up quickly, designed and built a bridge across the Yangtze river and its many deep water foundation. It can be said, in China’s contribution to the bridge construction, the provincial Ministry of Transportation and Communications Department of the design and construction team have occupied a very important position.

1.3.4 China Bridge at the Beginning of the 21st Century Chinese modern bridge made the last 20 years of the 20th century has made progress and achievement, and ready to build more ambitious Cross River Bridge Project. After the 1980s, “to learn and catch up” and 1990’s “track and improve the” two stages of development, China bridge community should enter a “innovative and go beyond” the new era in the early 2000s, through innovative design and construction achieve development in order to improve international competitiveness of Chinese bridge.

1. Large-span Cable-stayed Bridge and a Suspension Bridge Construction In 2000, China has built a main span of 618 m Wuhan white sandbar and the 312 m main span rail-cum cable-stayed bridge — Wuhu Yangtze River Bridge, the end of the bridge construction in the 20th century. Cable-stayed bridge has become the preferred bridge type for Yangtze River Bridge in Hubei, Anhui and Jiangsu provinces. Many cable-stayed bridge built simultaneously, on the Yangtze River. In planning Run Yang Yangtze River Highway Bridge, there are concerns among bridge engineers for China’s large span cablestayed bridge over 800 m. On the completion of the main span of 1385 m Jiangyin Yangtze River Bridge in 1999, on the decision to adopt a main span of 1490 m and greater span suspension bridge. In the 21st century, requires the construction of Stonecutters Bridge in Hong Kong, the ultra-km cable-stayed bridge, inspired by Chinese community participation in the design of bridge competition in the process also improves the impact of ultra-km cable-stayed bridge in confidence. Thus, in previous work Su Tong Bridge, tried using 1088 m main span cable-stayed bridge program, in order to avoid the difficulties suspension deep-water anchorage foundation construction.

(a) Nanjing Yangtze River Bridge (Fig. 1.101) Nanjing Yangtze River Bridge is the longest span cable-stayed bridge in China. Maximum span of the high tower, the longest cable and maximum width of the bridge is considered to be a huge challenge. If breaking scale did not meet applicable limits of existing technology, overcoming the obstacles set by technological innovation can be achieved through careful construction practice can obtain high-quality results. Nanjing Yangtze River Bridge Tower Pier using “composite foundation”, that the double-wall steel cofferdam, caps and bored pile group consisting of whole resistance ship collision force, in fact, the use of excessively large span has greatly reduced the chances of ship collision. Since the bridge’s small navigational clearance, compared with the first parallel Japanese Tatara Bridge tower, tower above the bridge deck height and total height ratio is too small, resulting in “Short leg” effect, the impact of the tower’s appearance. Long cables in full bridge closure after the emergence of a strong rain vibration, plus an interim decision on the cable after the suppression of the spiral wound vibration, this experience later provided an important basis for direct production of finished cable with spiral strips (Fig. 1.102).

Fig. 1.101 Nanjing Yangtze River Bridge.

Fig. 1.102 Nanjing Yangtze River Bridge Helix Cable. Long cantilever construction control in the Nanjing Yangtze River Bridge, the use of more advanced “neural network control technology” in cable force and elevation of dual control, achieved a higher closure accuracy. Orthotropic steel box girder bridge deck construction site with steel panels welded joints and U-shaped longitudinal ribs bolted form, is a new attempt and has promotional value. Finally, the steel deck pavement does not solve the problem long-term. Nanjing Yangtze River Bridge has introduced American epoxy asphalt concrete pavement technology through mechanical analysis and experimental research, improvements and equipment research and development to achieve a localisation formulations, excellent quality, and to fill the gap. After years of testing in summer and winter seasons, within the constraints of overloaded vehicles in good running condition of the bridge, has been applied in more than a dozen subsequent bridge.

(b) Yangzhou Yangtze River Highway Bridge (Fig. 1.103) When the main span of 1490 m of South Branch Runyang Yangtze River Highway Bridge was completed, it was the largest suspension bridge in China. In Runyang Yangtze River Highway Bridge construction, little difficulty superstructure on the basis of experience in building Jiangyin Yangtze River Bridge, the main Challenges from infrastructure projects. The 50 m deep north anchorage using embedded rock underground continuous wall (Fig. 1.104). Although underground continuous wall at the construction site is a mature technology, but for the huge plane size is 69 m × 50 m bridge foundation remains a

challenge. Construction side of the use of information technology in construction methods, a variety of information and continuous wall surrounding soil for real-time monitoring control and forward and inverse analysis to ensure that the basic construction of fast and safe.

Fig. 1.103 Runyang Yangtze River Highway Bridge.

Fig. 1.104 Runyang Yangtze River Highway Bridge underground continuous wall. North Anchorage (Elevation units: m; size unit: cm) Similarly, south anchorage freezing method technique is the traditional construction technique for mine shaft, but on the basis of the large size of bridges its use is a bold initiative with a huge risk. Construction by eliminating the danger, and finally succeeded. Bridge Tower Construction employed foreign template technology, which greatly improves the appearance and internal quality concrete progress has been made. As the The deck height is small, although the lateral wind loads can be reduced, also reduced the torsional rigidity and thus cannot meet the stability requirements. Construction of the first time the central buckle and central stabilising plate measures to solve this problem (Fig. 1.105). Bridge main cable corrosion was first introduced in Japan in dry air de-humidification, as a new technologies. In addition, the anchorage, foundation, tower, piers and and other concrete box girder bridge approach works have adopted the technique of fly ash added to improve the durability of the bridge is expected to ensure a lifespan of 100 years.

(c) Nanjing Yangtze River Bridge (Fig. 1.106) Nanjing Yangtze River Bridge has a chevron-shaped arc of the new tower. It should be acknowledged that this is inspired from the Stonecutters Bridge, the second top design in the Hong Kong international bridge competition. In order to speed up the construction speed, the bridge over the tower with steel was pre-manufactured, and brought down tower junction structure puzzle for steel-concrete segments. Eventually, opening on the the steel tower was opted and in-situ concrete and reinforced through the formation of PBL shear key was used as the main component load transfer (Fig. 1.107). After wind tunnel tests, rectangular-section steel tower cutaway was the best possible treatment to suppress the vibration of galloping and vortex. We can say that the south Beijing Tower Bridge is a creative design in steel bridge. Tower located at the depth of more than 40 m, imposing a greater risk to the traditional steel boxed construction, through careful organisation of the construction unit the foundation construction was completed successfully. High steel tower 215 m, it’s the introduction of a highly efficient air installation crane France, the smooth realisation of the seal top. Although the steel tower costs more than the average cost of the concrete tower, but won the construction speed in return.

Fig. 1.105 Runyang Yangtze River Highway Bridge in central stabilising plate.

Fig. 1.106 Nanjing Yangtze River Bridge Full-Bridge.

Fig. 1.107 Mixed Nanjing Yangtze River Bridge pylon connecting structure.

(d) Su Tong Bridge (Fig. 1.108) Su Tong Bridge (hereinafter referred to as Su Tong Bridge) is China’s first cable-stayed bridge over 1000 m. In the wide Yangtze River Downstream waters, both to meet the 100000t seagoing vessel’s navigation requirements, and to avoid the construction of water anchorage difficulties, it is necessary to adopt ultra large-span cable-stayed bridge.

Fig. 1.108 Su Tong Bridge Full-Bridge. The first is the deep water tower pier foundation. By comparison, it was decided to adopt large-scale construction grasp the larger group pile foundation. The 131 drilled shaft, 114 to 117 m long from 2.5 m to 2.8 m large diameter bored piles requires a lot of caps, steel boxed quality reaches 6000t, need to overcome many problems. Meanwhile, in order to prevent future erosion threatening the foundation, there was need for permanent erosion protection. Wind-proof and anti-seismic design was the center of the design phase of the Su Tong Yangtze River Bridge, focusing on issues considered, after the election and more than the program, using a combination of rigid and fluid viscous limit longitudinal restraint device, the introduction of American Taylor’s advanced liquid viscous dampers, and specially designed for the bridge with a limit (maximum limit force 10000 kN, maximum limit ± 750 mm) king damper so that strong winds and a strong earthquake, the bridge will not lead to large displacements occurred adversely affected by the force of the pylon, and endanger joints become span bridges important protection systems to ensure the safety of the bridge tower. Su Tong Bridge deck is wide, and the use of better stability of the oblique cable plane

layout makes wind stability guaranteed. In order to reduce wind load and lateral displacement of the deck small cable while preventing cable stormy wind-induced vibration and other vibration, Su Tong Bridge uses Japan’s advanced surface treatment technology with pits, as well as the cable side of the damper device. Meanwhile, largescale detailed high reynolds wind tunnel tests and studies to avoid adverse deck vibration. Installation of the 300 m high bridge tower construction and advanced overhead steel anchor box demanded efficient, safe, and secure the crane. Su Tong asked French bridge crane company for advanced reconstruction and transformation, making it suited for Su Tong Bridge. It also introduced advanced equipment and climbing formwork concrete pumping equipment. The 1990s advanced equipment to ensure that the bridge Tower’s safe, efficient, fast construction, to ensure the completion of the bridge towers quality. The construction of steel box girder bridge over 1000 m is a challenge. Because Su Tong Bridge Deck Normandy Bridge and Japan than in France Tatara Bridge should be wide, although the cantilever length increases, but instead a small wide-span ratio, so that the lateral stiffness of the construction phase is relatively large, and the side to windinduced vibration is reduced, which is more advantageous. In order to control the Su Tong Bridge Construction catch the world’s advanced level, construction workers using the “precise geometry control” advanced technology, command and construction general contractors invited to the British and Danish company. COWI company flourished as a consultant unit, with their advanced software to assist in the control, and achieved good results. In order to ensure the efficiency and accuracy of assembly, the introduction of the British Door Lang Company (DL Tech) advanced bridge crane, make up more than 500 meters cantilever erection smooth closure. In addition, the non-navigation arch of Su Tong Bridge for the first time uses the international advanced pre-stressed pre-cast segments and in vitro with cable technology, through the success of the practice, it has made significant progress, catch up with the world advanced level, became the pioneer in prestressed concrete continuous beam bridge. The demonstration project (Fig. 1.109). It can be said, Su Tong Bridge headquarters insisted independent construction, but does not exclude the developed countries to assist, so that bridge the technology used to achieve the international standard of the 1990s, and ensure the quality of the project to improve the efficiency, Made a lot of progress, has also been praised by foreign counterparts.

(e) Zhoushan Xihoumen Bridge (Fig. 1.110) Zhoushan island project in Xihoumen bridge with a main span 1650 m split three-span continuous box girder bridge. Xihoumen main navigation road water depth of 80 m, and the wind and waves, is the first international one officially started construction, the use of split large-span suspension bridge, in order to ensure the wind-proof stability of the bridge.

Fig. 1.109 Externally pre-stressed pre-cast segmental pre-cast yard Su Tong Yangtze River Bridge.

Fig. 1.110 Zhoushan Xihoumen Bridge Full-Bridge. Xihoumen Bridge’s main cable used ultra high strength steel, developed by Shanghai Baosteel, with reduced diameter of the main cable and the weight and thus saving rope clip accessories, anchorage size and lower cost base, reached the advanced level. Main cable construction used for the first time the Helicopter pilot rope traction over the sea, avoiding the risk of traditional methods may bring. Split deck design, manufacture and installation is the first attempt, the international community also can learn from the lack of experience in bridge hair exhibition in the history of the landmark (Fig. 1.111).

Fig. 1.111 Zhoushan Xihoumen Bridge split box section (dimensions: m).

2. The Construction of Large-span Steel Arch Bridge China’s steel arch bridge construction had long been lagging behind the Western countries. In the 1950s, Chinese steel arch bridge spanned no more than Hundred meters, such as the Jianghan bridge helped by the former Soviet Union in 1955, with a main span of the deck 87.37 m Beam Arch. Chengdu-Kunming railway built in 1966, to welcome water river bridge with a main span of 112 m Sophie just Truss Arch Combination. After the reform and opening up, Sichuan Province built the first span of 115 m of concrete pipe Tied Arch — wangcang East River bridge. This good economic indicators, the construction of the bridge-fast and easy to promote in the country, built in 2000, Guangzhou Yajisha main span has reached the 360 m, span. In the early 2000s, China began to try to build modern steel arch bridge with a span about 500 m, in order to change the backwardness aspect of the Chinese steel arch Bridge.

(a) Lupu Bridge (Fig. 1.112) Main span of 550 m of the Lupu Bridge is a world record-span steel arch bridge. Arch bridge spanning over a 300 m generally use hanging erection to reduce the arch truss and to decrease assembly weight, Lupu Bridge boldly used sloping arch box to obtain “basket handle arch” aesthetic styling. Roll stability from the analysis, the surface can be obtained in parallel arch enough to stabilise the security system, and in the arch sloping surface quality up to 480t of Ribs segments hanging fight, is indeed a huge challenge. Lupu Bridge Temporary work units using giant cranes and buckle cable systems, and through a lot of weights measures, and the introduction of foreign lifting equipment to overcome the difficulties and Ribs to closure. Shanghai’s large-span arch bridge on soft soil must be built strong balance Tied Arch Thrust. There are several systems in the construction to be converted and temporarily transferred to buckle cable tension level. Construction control of the whole process should be a very distinctive creative work (Fig. 1.113).

Fig. 1.112 Lupu Bridge Full-Bridge.

Fig. 1.113 Lupu Bridge construction plans. Arch Rib is a bluff body section, although the arch aerodynamic stability is very safe, but in a state of uniform flow wind tunnel test a strong vortex vibration rib was observed. While large urban turbulence intensity may inhibit the occurrence of vortex vibration, a hydrodynamic calculation method works best without affecting the aesthetics of “isolation membrane” pneumatic vibration suppression measures at a pre-set upper rib. The insulating film connecting device (Fig. 1.114), as the need to install the future. Moreover, in the vault at the sightseeing platform has played a part in the vortex vibration inhibition. After the completion of the bridge and from the effects of perspective, although it took some more steel and construction costs and the economic indicators are not good, it proved box arch over 500 m is feasible. Compared with the classical truss arch, boxshaped rib arch may be more modern.

Fig. 1.114 Lupu Bridge anti-vortex vibration isolation membrane.

Fig. 1.115 Caiyuanba Bridge.

(b) Caiyuanba Bridge (Fig. 1.115) Caiyuanba Highway Bridge is an upper and lower dual arch of urban rail transit designed By Chongqing Jiaotong Research and Design Institute and Tung-Yen Lin International companies design consortium, a Rigid steel-concrete composite Tied Arch of the new bridge system. Caiyuanba is a five cross-symmetrical arrangement consisting of a total length of 800 m including 420 m, 112 m and 88 m side spans. Main arch is inclined basket arch bridge following the use of concrete arch rib, compared with steel box deck above arch. Both the deck at the butt level and the formation of a hybrid structure. Orthotropic bridge deck using steel joist, the upper six-lane highway, the lower two-lane urban rail transportation. The Caiyuanba has a longitudinal separation system, which is divided into the cross tie rod and tie rod side span (Fig. 1.116), and anchorage independence in order to carry out the internal forces and linear adjustment and control.

Fig. 1.116 Separate Tied arrangement (A pair of symmetrical pre-stressed concrete continuous rigid frame + Tied hogging).

In terms of structural design, construction details Caiyuanba adopted many optimisation, such as steel box arch ribs and anchor construction boom, the department of 7 strand wire rod in vitro cable with PE jacket, Y-shaped rigid frame and mid-span the use of separate connecting Tied Tied shear key construction, steel box arch rib concrete rigid frame with a Y-shaped steel-concrete joint structure of PBL, as well as connecting structure side span joists and between the Y-shaped rigid frame and so on. Caiyuanba using a combination of structure, saving 13,000~15,000t of steel. Construction used the traditional day of hanging, hanging buckle cable and hybrid programs to fight portion of the stent, and a separate tied and active control technology for large-span arch bridge construction offers many worthwhile lessons learned.

(c) Chaotianmen Bridge (Fig. 1.117) Chaotianmen bridge located in the southeast end of the peninsula, famous pier Chaotianmen about 1.3 km downstream, was the main site of the six lines radiating outward things to fast main road, connecting the east Nan’an District, Chongqing and Guizhou Expressway Huangjuezhen Bay Interchange. The main span of the bridge is a record of 552 m, in the traditional continuous steel truss tied arch bridge. The upper deck of a double two-way six lanes and sidewalks on both sides, the total deck width 36 m; lower middle lane urban rail lines are arranged on both sides of each set aside a spare driveway.

Fig. 1.117 Chaotianmen Bridge. Span arrangement for the 190 m + 552 m + 190 m. Tied plane coincides with the plane of the main arch truss, force a clear, simple structure, easy construction. The bridge was opened to traffic at the end of 2007, not only to improve the traffic situation in the main city, has become the fast-track connection YuBeiOu, Jiangbei district and the South Bank area, and has important implications for social and economic development of Chongqing.

3. Cross-sea Engineering Construction Cross-sea bridge project began in the 1930s, with construction of the Bay Bridge (Bay Bridge), including a bridge across the mouth of the bay, most notably in 1937 when pushed San Francisco Bay, built in the mouth of the Golden Gate Bridge. The 1890 Bay Bridge, built in Scotland Forth can be said to herald the Bay Bridge. According to statistics, the world’s Bridge has built nearly 70 in more than ten countries, including Japan 18, US 18, Denmark 6, out the top three.

Japan and Denmark are two of the countries in the 1970s, began to connect homeland across the sea island project. Japan’s bridge as a starting point, the construction of the four-island project contact line; the small Danish island project kelp bridge construction started. In the end of the century with the completion of the two famous sea Belt Bridge (1997) and the Akashi Strait Bridge (1998), to achieve the ambitious island project plan while among the world powers of the bridge. In the 1970s, the world’s longest-linking project is 25 km Bahrain Island Narrows Bridge between Bahrain and Saudi Arabia by a French construction company. Bay Bridge construction in China began in the 20th century, the early 90s Shantou Bay Bridge and the new Hong Kong airport line island project in the three bridges, namely, Tsing Ma Bridge, Kap Shui Mun Bridge and Ting Kau Bridge. Since then, the Zhoushan island project has quietly started, gradually advancing to the mainland from the island of Zhoushan Islands Link. Other coastal cities, island project is also planned.

(a) Donghai Bridge (Fig. 1.118) China’s first cross-sea waters off the coast in the vast construction project was completed in 2005, in the East China Sea Bridge. The bridge connected by Nanhui District of Shanghai Yangshan Deepwater Port, full-length 32.5 km, at the mouth of Hangzhou Bay, Yellow Sea and East China Sea at the junction, is a landmark bridge, it’s built for the future of China across the sea projects, such as the Hangzhou Bay Bridge, the Hong KongZhuhai-Macao Bridge, as well as the planned Bohai Strait and Qiongzhou Strait project, providing valuable experience.

Fig. 1.118 Donghai Bridge. Donghai bridge builders face the harsh environment of the sea, the upper and lower portion of the structure are made of whole Erection of large pre-fabricated, equipped with a 2500t large floating crane. To ensure the service life of 100 years, the development of high performance concrete sea and various anti-corrosion measures to improve the durability of concrete in marine environment. In the waters of the construction GPS technology must be used, the construction of large storm-resistant construction platform, management also uses innovative ideas to ensure the smooth conduct of offshore construction. The two main navigation bridge Donghai Bridge, though not too long, but all using a combination of cable-stayed bridge girder bridge creative. Main channel bridge using a single cable plane and combined box girder bridge, with inverted Y-shaped pylons; stars Pearl Hill Bridge (Fig. 1.119) was combined with a parallel cable plane of the deck beams on the bridge tower using light beams steel crossbars. Since the main girder bridge using a

combination of full bridge deck pavement and a new uniform joints large container truck traffic provides a smooth, durable good driving conditions.

(b) Zhanjiang Gulf Bridge (Fig. 1.120) Opened to traffic by the end of 2006, Guangdong Zhanjiang Gulf Bridge, located in Zhanjiang City Maxie Bay, connecting East District, Zhanjiang Port is located on the international waterway 50,000 tons level. To save costs, and taking into account the ship out of port speed is constrained using cable-stayed main span of 480 m, in order to meet the 50,000 ton ocean-going vessel bound two-way navigation requirements.

Fig. 1.119 Stars Pearl Mountain Bridge.

Fig. 1.120 Zhanjiang Gulf Bridge. Although Zhanjiang Bay Bridge span is small, but in the design and construction process structure has many improvements made innovative efforts, especially in the antiship collision facilities and construct two cable-stayed bridge anchor, has made good results. Used to increase the “collision avoidance” high design costs, and to resist more than 8000t ship collision force will also greatly increase the cost basis of the span or set collision pier. Zhanjiang Gulf Bridge proposed a “flexible energy dissipation crash” scenario, in order to reduce ship collision force, only the cost of more than twenty million yuan (two main pier) is to achieve a “small hit is not bad, the hit repairable, big hit does not fall (pier no damage), the goal.” In a small bump process, so piers, ships and three collision facilities are protected, become a “three is not bad” crash facility.

Designed by Zhanjiang Gulf Bridge Steel Corporation and Shanghai Institute of Marine Research program was jointly developed by the outer pontoons, pontoon rope bull ring, the inner composition of the pontoon (Fig. 1.121), when subjected to ship collision, the bull ring absorption part of the ship collision force, while the bow goes to the side, along the outer pontoon slip away, thus changing the impact angle, reducing the ship collision force. This is a very creative achievements, the design of the future bridge crash will have an important role model. Cable was anchored to the steel box girder bridge, a methods now mostly used in the structural form of the anchor box. To simplify the structure, convenient construction, Zhanjiang Gulf Bridge envisaged commonly used in the I-beam anchor pull extended to the steel box girder structure success, through a detailed three-dimensional stress analysis and experimental research to prove the rationality of this anchoring structure advantages and ease of construction for future large-span steel box girder design provides a reference, but also an innovative sense of achievement (Fig. 1.122).

Fig. 1.121 Flexible anti-collision Devices Zhanjiang Gulf Bridge.

Fig. 1.122 Cable Anchor Way – Zhanjiang Gulf Bridge. In addition, Zhanjiang Bay Bridge tower design, the bridge approach movable formwork equipment and deck epoxy asphalt pavement aggregate localisation and other aspects of a number of technical improvements, become one of the technology demonstration project in Guangdong Province, China Communications Construction

quality engineering.

(c) Hangzhou Bay Bridge (Fig. 1.123) In the early 1990s, began planning the construction of Zhejiang Zhapu port connected by Hangzhou Bay, Cixi channel. Shanghai Tung-Yen Lin commissioned consultants Brandon newly established pre-feasibility study to compare a few possible direction, bridge type arrangement and form the basis of the line, and estimate the cost. Financing in the late 1990s, progress had been made, the former Ministry of Transportation Highway Planning and Design Institute completed a feasibility study report, the Ministry of Transportation (now renamed as the Ministry of Transport) approved the project, into the formal planning stage. Ningbo, Zhejiang Province organized a command, followed by Shanghai Donghai Bridge to start construction later in order to use heavy construction equipment and troops Donghai Bridge, drawing Donghai Bridge offshore construction experience.

Fig. 1.123 Hangzhou Bay Bridge. Hangzhou Bay Bridge is located in Hangzhou Bay, with a length of 36 km, the total length of the bridge over the East China Sea. Navigation bridge located two holes, North Navigable twin towers 448 m main span steel cable-stayed bridge with double cable planes, navigation standard 35000 t; South Navigable single cable plane is a single tower steel bridge, navigation standard 3 milliont. In addition to the North-South traffic openings, the remaining non-maritime shipping Span are continuous pre-stressed concrete box girder after 70 m simple support. Donghai bridge construction on some of the issues that appear, such as crack control of pre-fabricated pier wet joints, continuous box girder pre-fabrication and pre-tensioning technology, continuous box girder joints wet process so take a seat at the improvement measures (such as changes in marine concrete mix, increasing the protective layer and adding good ruth fibers, etc.), has made technological advances, hoping to solve the joint after the wet concrete cracking durability. For two nonnavigation bridge box girder construction heavy 200t, using design and manufacturing company from Germany, Italy advanced beam carrier, the precast beams moved into position by the hole to install, compared with the general adoption of mobile formwork situ process, improved quality. In addition, to improve the high wind environment lane bridge, the first large-scale use of wind barriers set up to achieve very good results. Hangzhou Bay Bridge was built in 2008, and synchronised Su Tong Yangtze River Bridge, realised with three trunk road across the Yangtze River Estuary and Hangzhou Bay, the two key projects, coastal Zhejiang and Fujian and Shanghai Zhucheng’s leading road transport more convenient, unobstructed.

(d) Zhoushan Island Project In the early 1990s, the development of economic Zhoushan and Ningbo had aspirations on Liandao bridge connecting the islands. At the time, stone is the company’s business owners, from Zhoushan, he is willing to make contributions to an island project planning and commission of Tongji road and traffic engineering, bridge engineering Zhoushan sent teachers togather the relevant information has been reconnaissance waters, completed the program and practicable route to meet the requirements of the bridge-navigation preliminary plan and estimate construction costs, but this proposal was shelved because conditions are not ripe. In the late 1990s, the city has determined to use its own financial resources, advance the Zhoushan Island and several nearby islands connected together, when conditions permit, and then connect Jintang Island, the progressive realisation and connecting Ningbo. In the 21st century, Zhoushan City has completed the three island project, built Taoyaomen Bridge, the island of Zhoushan Island and booklet fused, the last two remaining major sea project, namely, Xihoumen Bridge (Fig. 1.124) and across the waterway connecting Ningbo Jintang Bridge (Fig. 1.125).

Fig. 1.124 Xihoumen Bridge. The central government approved the construction of Shanghai Yangshan Deep water Port and Donghai Bridge to form the Shanghai Shipping Center. In this situation, Zhejiang Province and the Ministry of Transportation decided to use a deep water port in Zhoushan City resources, and Ningbo Beilun port in Hangzhou Bay south wing jointly build a large naval base, as the main access to the sea Zhejiang, Jiangxi and Fujian north north-west region, and echoes and Shanghai, East China together constitute an international shipping center in the Pacific Ocean in the West Bank.

Fig. 1.125 Jintang Bridge.

Xihoumen Bridge is suspension bridge spanning 1,650 m over the waterway with a depth of 80 m. As is located in typhoon-prone areas, the basic wind speed up to 44 m/s, requires flutter test wind speed 78 m/s, exceeding the limits of aerodynamic stability of the overall streamlined box girder could be achieved, and thus must be split slotted box girder cross-section. Additional stability is necessary when the central board to improve wind stability. Xihoumen Bridge has become China’s largest span when completed, and the first use of split deck suspension bridge. In 2006, construction of the main cable fairlead first traction over the sea using a helicopter to succeed, the whole bridge was completed in 2009, making the island of Zhoushan Jintang Island and connected. Jintang Bridge Engineering Zhoushan island project for the last one to be connected Jintang Island and the mainland. Originally planned to use the direct route across recently, due to the Strait of deep water, technically difficult, after the switch to a total length of 21 km, crossing the shallow water ashore in Zhenhai program. A 620 m using the main navigation span steel bridge, something the two auxiliary points navigable hole hole using a main span of 216 m of continuous rigid frame and 156 m main span continuous beam, and the rest were non-navigable approach for 60 m, 50 m and 30 m pre-stress concrete continuous beam. Jintang Bridge draws on the successful experience of the East China Sea Bridge and Hangzhou Bay Bridge, the total cost was 7.7 billion yuan, opened to traffic before the opening of Expo 2009 Shanghai, a century-old dream of Zhoushan people.

(e) HZMB Connection Works (2009-2016) Pearl river estuary Lingdingyang is the most important estuary, the Pearl river delta has four of the eight entrances to import Lingdingyang, bay mouth wide and 30 km, an area of 2000 km2. Lingdingyang east of Shenzhen, Shekou and Hong Kong, Zhuhai and Macao to the west, from the top of the Tiger Bay entrance Humen Bridge 65 km. With the rapid economic development of the Pearl river delta region, on both sides of the bay mouth began to consider the idea of the Lingdingyang bridge. Former Transportation Ministry organized design competition in 1993, collecting a number of domestic and international bridge-type program. A total length of 33 km, sixlane traffic, construction cost was estimated at about 16 billion yuan. December 1997 state approved a feasibility study of the project.

Fig. 1.126 HZMB location map. Due to the construction of the Disneyland on Lantau Island by the Hong Kong government, the Pearl of the West Bank cities to attract tourists; and the gaming industry in Macao also hopes to attract tourists to Hong Kong to Macau easy, so the Hong Kong Parliament rejected the Northern Line Lingdingyang ashore in Tuen Mun bridge program (I). Highway Planning and Design Institute Limited by HZMB Advance Work Coordination Group commissioned undertook a feasibility study on various proposed solutions by detailed comparison, recommended line position IIa (field stone Bay Northern Line - Beaconsfield / Pearl) and bridge and tunnel combination regimen. In December 2009, the preliminary design was completed and reviewed at several rounds of expert meetings, bridge and tunnel construction party decided to use a combination of programs (Fig. 1.126). The eastern section of the main channel by the immersed tube tunnel crossing, long 5.99 km. The western part of three auxiliary channel press the navigation requirements at different span cable-stayed bridge spans: from east to west, with a main span 458 m Green Island Channel Bridge; 2 × 258 m main span cablestayed bridge in the Three Pagodas — Direct Ship Channel Bridge jianghai; main span of 298 m Jiuzhou Channel Bridge. Bridge length of 22.9 km, a total investment of 34.72 billion yuan. The bridge was under construction by the end of 2009, was opened to traffic

in 2015.

(f) Qiongzhou Strait Project Qiongzhou Strait Tunnel State national lines is the southernmost project. In the early 1990s, the Guangdong Provincial Communications Department started a program of work, and invite international companies to do a preliminary exploration. According to the existing charts, geological, meteorological and hydrological data, preliminary planning a two-line position, namely, the Straits shortest median line bits and Nishiguchi line position. The former total length of 20 km, the average depth of 80 m, maximum depth of 160 m for avoiding the need to build multi-span 3000~5000 m suspension bridge; the latter a total length of 40 km, but the depth of only 40~45 m, can be a smaller span bridge or bridge and tunnel bonding scheme. In 1998, Guangdong Provincial Communications Department to allocated 83 million yuan in special funds, and Humen technology consulting firm was commissioned to carry out preliminary work of upto five years to complete a total of seven volumes of the 1.8 million word documents, technical standards, and natural conditions, navigation standards, traffic line position is preferred, conceptual design and environmental, technical and economic evaluation of bridge and tunnel scheme and so do a detailed study. After detailed research report comparing and preferred to avoid the basis of the midline 80 m water depth, recommended Strait Nishiguchi new line VII bit (Fig. 1.127), and recommend the most economical 2 × 800 m cable-stayed bridge with three towers programs. Auxiliary Channel Bridge north and south two 30,000ton ocean-going vessel traffic requirements, clear height of 50 m, 800 m each using hybrid cable-stayed bridge deck, the rest of the side holes available 250 m and 50 m continuous rigid frame composed of pre-stressed concrete continuous beam. Thus, taking the Strait Nishiguchi new full bridge VII line B program not only mature technology, but also the lowest cost, is an economically rational basis for competitive programs, feasibility studies for future projects provide a good technical foundation.

Fig. 1.127 Line position Qiongzhou Strait project comparison chart. Since 2008, the central government decided to expand the Yangpu Port in Hainan

Province, facing South-east Asia trade; in Wenchang construction of a new space launch base. For this reason, the requirements of the railway across the Channel to replace the current ferry transport, and decided to re-planning and preliminary studies Qiongzhou Strait project led by the Ministry of Railways. In February 2009, two (railway, transport) and provinces (Guangdong, Hainan) in Haikou, the first joint meeting was held to discuss the work to build a highway and railway. Joint Working Group proposed a variety of comparison program, overall, is currently working on preliminary investigations navigation area, traffic, geological exploration, hydrological and meteorological conditions are not sufficient to bridge deep water foundation and technical preparation immersed tunnel is not enough, as well as coordination problems between the Ministry of Railways and the Ministry of Transport, the need to have sometime to do the preliminary work consciously careful argumentation comparison, not hastily.

4. Participation and Cooperation of Foreign Companies After the reform and opening up, China’s bridge engineering counterparts in developed countries began to have contacts and exchanges. Visit abroad and participate in international conferences of university teachers, China Road and Bridge Corporation and the China Railway companies by overseas contracted projects, but also have a preliminary cooperation with foreign contractors. In exchange, we deeply felt and technical level of developed countries there is a big gap between the need to catch up, trying to learn the developed countries in the 1960s to 1970s, construction boom in the creation of many new technologies. Design units have introduced foreign advanced design software, and construction companies are buying a number of advanced equipment to replace the original inefficient outdated equipment. In the late 1980s, Shanghai Nanpu Bridge in self-construction process, invited the Chinese-American Mr. Deng Wenzhong as a design review and technical consultant for the Asian Development Bank successfully passed the review expert group played an important role. Guangdong Province, the first to open up, introduced advanced VSL clip anchor to the building of the Luoxi Bridge. Off the coast of bridge construction in Jiangmen by foreign investment in Japan Kumagai served by a contractor, and the use of advanced short precast segmental construction method and hanging fight. Shandong Province, bought Japanese PE sheath parallel finished wire rope in Dongying Yellow River Bridge construction. These technologies played as an important bridge between the model and guide during the progress and development of China. Since the 1990s, encouraged by the success of the Shanghai Nanpu Bridge and Yangpu Bridge independent construction, the provinces climax independent construction of the bridge, the provinces have begun to frequent visits abroad, while also inviting foreign well-known companies, such as the United States, Tung-Yen Lin (TY Lin) International Corporation, Japan’s growing up (Chodai), Germany’s Leonhardt companies such as consulting services. Anhui Tongling Bridge construction, Mr. Deng Wenzhong recommended cantilever construction of cable-stayed bridge in front fulcrum Light Hanging Basket; Queshi Bridge is used VSL strand group’s anchor cable system; some of the main cable construction used in Japan pioneered strand (PWS) working method. Some design and construction units are happy to invite some well-known outside consulting

company as some of the challenges, but also to buy some advanced equipment, such as Germany’s rig, Britain, Italy and France, cranes, movable formwork cast Norway, etc. Germany and Switzerland as well as large travel joints, vibration dampers and buffers as well as advanced construction pylon climb molds. On the software, the United States, Ansys, Korea Midas, TDV, Austria and the United Kingdom Lusas also introduced major software, major design institutes, independent design of the bridge to China has played an important role. In bridge construction boom in the late 20th century, some British companies such as Hong Kong Maosheng (Maunsell), Halcrow (Hacrow), Ao Weina (Orup) and Bandung (McDonald) and Denmark’s Cowi other well-known companies are in consulting services, sub-contracting tasks, the joint bid, case studies and other means, to participate in the design and construction of Chinese Bridge Cooperation of China’s development and progress of bridge played a very positive role. In addition, for some difficult problems to solve, such as steel deck from lack of pavement, through the introduction of epoxy asphalt American ChemCo’s patented technology has been resolved. Another example of fine cracks in the concrete, but also through the introduction of foreign fiber adding technology to overcome. It should be said, advanced technologies and successful experiences of developed countries is very helpful. In the 21st century, our country and outside the company’s cooperation has entered a mature stage. Some large-span bridges and sea project need to rely on large advanced equipment to ensure the project’s quality and durability, but cannot employing sea tactics and outdated equipment to complete. Some Bridge Engineering Command actively inviting foreign well-known companies as the site’s resident advisor on critical design and engineering methods were reviewed and checks, and also listed in the budget cost of purchasing advanced equipment in order to ensure the smooth progress of the project, such as Shanghai Donghai Bridge, Jiangsu Nanjing Yangtze River Bridge and Su Tong Bridge. We all recognise that the gap between China’s equipment manufacturing industry cannot solve the short-term, we also need time, through the efforts of independent innovation, to catch up with the level of equipment in developed countries. In some cities, domestic and international public tenders include foreign and domestic design companies have begun to design units, or through the establishment of China branch in the country registered a way to participate. Such as Guangzhou, Chongqing and Tianjin cities bridges bid by Mr. America Tung-Yen Lin Deng served as the international design. Some foreign companies have been gradually creative design accepted and appreciated for the Chinese community has also touched the bridge and inspiration. It should be said that this is a positive exchanges and cooperation for China’s development and progress of the bridge is very useful. The fifty years of development history of China’s modern bridge, in the first two Five Year Plan period (1953 to 1963), by 156 former Soviet Union aided engineering, quickly established the west since the 18th century industrial revolution two hundred the accumulated years of modern industrial system. In terms of bridges, aided by the former Soviet Union Wuhan Yangtze River Bridge, we have mastered the modern steel bridges, reinforced concrete and pre-stressed bridge of advanced technology, with a design and

construction team and several bridges factories. We can say that we have basically caught up with the pace of the world bridge project forward. Unfortunately, the “Cultural Revolution” made China’s economic on the verge of collapse, we completely missed the world in the 20th century, 60 to 70 years of postwar modern bridge technology booming golden age. When in 1979, the first batch of scholars and students to go abroad and see the Western Highway and the spectacle of urban modernisation, tremendous progress can only exclaim post-war modern bridge. We must study hard to catch up lost time to make it up as soon as possible. Fortunately, the Chinese bridge circles in the 1980s, after learning and catching up, in the 1990s, to track and improve both the development stage, and seize the opportunity to Shanghai Nanpu Bridge and Guangdong Humen Bridge construction, chose a learning foreign advanced technology, but do not give up the right of autonomy of independent road construction, and finally succeeded. We gradually catch up with the pace of the world of modern bridge forward, also won the international bridge industry peer recognition and praise, to become an international bridge an important member of the extended family.

1.3.5 Problems in Bridge Construction in China China bridge construction in the past 20 years has achieved tremendous progress and achievement, but in the face of the 21st century bridge engineering tasks and after entering the WTO counterparts in developed countries to compete in the Chinese market situation, we need to address the problems, and overcome as soon as these affect the competitiveness of the defects, ready to meet the challenge.

1. Design Innovation Design is the soul of the project, which largely determine the project’s quality, cost, construction difficulty and duration. Since the reform and opening up, although there have been a number of representatives of the excellent design of this era, but most designs there is a lack of innovation, poor economic indicators and the problems caused by poorly designed wasteful and unsafe bridge on the technical progress of the project with be adversely affected. Innovation should be the soul of design. However, we seem to lack an incentive mechanism used in the design of new structures, new materials and new processes. First, the design cycle is too short, too much to undertake the task, excessive pursuit of economic efficiency, the unit did not have enough time to make the design and optimisation of innovative thinking compared to imitation and plagiarism meet existing design. Secondly, the lack of truly fair and open competition system and strict design review and supervision system, but also the lack of creativity and economic indicators bad design passed and implemented. Finally, there is a look at the size of the awards at all levels of the project, not to pay attention to the tendency of design innovation and economic indicators, so that innovative ideas for design engineers tend to indifference. These are the causes for Chinese bridge design lacking creativity and poor economic indicators. Our bridge design has a bad tendency, the thicker text the better the design. However,

the most important design concept is very simple statement, did not say the reason clear choice programs. Foreign designs are limited to the number of pages of tender documents, tender design does not have to repeat basic information and requirements, the key is set forth innovative ideas and solutions approach, so that the file has distinct characteristics and persuasive. Foreign bridge design only do the bidding of construction tender design, equivalent to China’s preliminary design or technical design, the foundation of a large number of construction plans by the successful contractor based on business equipment and experience in the design upto complete the tender. Thus, the design department had sufficient time and energy to do the work of the design concept and technical innovation. There are even some smaller consulting engineer firm, specialising in doing the feasibility study and work program of the competition. This division of labour is very conducive to innovative design and construction of innovative technologies. We should change the current form of organisation to complete the design by the institute a full range of work from the feasibility study until the construction plans as soon as possible.

2. Engineering Quality Problems The speed of Chinese bridge construction often makes foreign counterparts “unbelievably” amazed. However, the haste of the design cycle and the construction period is not a good thing, it brings a lot of regret, leaving a lot of quality problems. Since the contract price is too low, even worse, even construction equipment purchase were not even included, construction contractors only lower than the fixed labour costs. In order not to lose money, they are forced to subcontract to low qualifications, lack of experienced engineering team to construction, so the layers of sub-contracting, the phenomenon is difficult to avoid cutting corners, eventually leading to poor quality of the project, undermines the engineering durability. In addition to the problem of technology, processes and qualifications on the Chinese market, there is still a material fake, shoddy problems. Cement, steel, pre-stressing equipment, templates and basic engineering materials have many quality problems, some even very serious. Although the construction supervision system, but there are still many loopholes and unhealthy, it is difficult to achieve a high degree of responsibility and strict supervision. Some Chinese-American counterparts during a visit to a Chinese bridge construction site, has repeatedly warned: “China’s bridge may require repair climax in less than 30 years”. This is contrary to our “long-term project, Quality First” slogan. “Corruption and waste is a great crime”, if our project is not durable, less than the design life requirements, which is a tremendous waste, we would have lost to future generations. China bridge construction engineering quality problems spread through the ChineseAmerican and Hong Kong counterparts, has affected the reputation of Chinese bridges become their “incredible” a satire of Chinese speed and annotations. We still have to promote the rational design cycle, reasonable duration and scientific attitude reasonable cost, and provide updates to the construction contractor equipment to improve the development of space technology, the complete elimination of layers of qualification reduced sub-contracting, resolutely resist shoddy materials and fraud, the implementation

of strict supervision. Only in this way can China bridges to high-quality brand internationally respected peers.

3. Bridge Aesthetic Issues Since the reform and opening up, China’s bridge construction at an unprecedented scale and speed to make the world wonder. But whether we are in a hurry to build a bridge gives a sense of beauty is a question worthy of reflection. Bridge is not only an important part of the transportation system, but also a landmark building. People want to praise uttered by the bridge at the time, enjoy the beauty. As a bridge engineer has the responsibility to pay attention to aesthetic value and landscape features in the design of the bridge, to meet people’s desire to watch. Foreign bridge engineers and architects have long-term cooperation, especially in a multi-program comparison of the conceptual design phase, aesthetic assessment of the bridge is often a very important factor. In some long-span bridges in the international design competition, aesthetic evaluation even more than the technical indicators become the decisive factor. In contrast, some of our bridge, since the design is not enough emphasis on aesthetics, the lack of participation and co-architect of various possible scenarios compare inadequate and often leave a lot of regret, such as giving a clumsy, dull and rough feeling and so on. In the past, our design principle was for the economy, and take care of appearance only when conditions permitted. As China’s economic strength, the concerns on the environment and landscape requirements are also rising. Aesthetic design of the bridge should become increasingly important principle, bridge engineers to constantly improve their aesthetic and artistic qualities, so that every bridge became landscaping, bringing joy to the people of art.

4. Economic Issues The costs of China bridge from the surface is lower than the cost of European countries, so give people create a false impression that the is the best interms of economy. Chinese bridge. However, after careful consideration the impression is not true. First, because of China’s low labour costs, many bridges have gathered a lot of sites of migrant workers, bridge equipment using relatively backward. Although the bridge can be built, and even record-breaking bridge, but often bring construction quality problems. While an investment is low, but if life is very short, the future costs of maintenance and reinforcement is very huge, from the viewpoint of the whole life is still very economical. Secondly, the bridge construction in China are often the first choice by the owners and design units, made by a scheme comparison, expert consultation meeting to discuss the decision by the final implementation plan. In economic comparison scheme will be some counterintuitive phenomena and man-made, even in order to meet the wishes of the owners and the total disregard of the economy, so uneconomical, weird, difficult construction program through false irrational economic indicators and not scientific “reasons” to be implemented. During the construction phase and then an additional budget to make the project economic principles useless. Again, an important indicator of the economy of a bridge is the amount of material per

square meter deck, attached great importance to this reflects the level of competitiveness and technology indicators in the international design competition. Because of China’s gap in the material industry, almost using the same kind of S345 steel bridge steel, concrete bridge most of the strength of the relatively low-level of C50 concrete, therefore, thicker steel plate and steel bridge in more varied, complex structure and bring welding process problems, concrete bridge also often seem relatively clumsy and obesity, the bridge will lead to increased costs. Finally, there is a problem in the choice of the bridge span. In addition to the bridge site topographic and geologic conditions unfavourable to cross the river to be a special project requirements, the country has a lot on Yangtze River in the blind pursuit of large span, even in the Xiangjiang River, a tributary branch of the Yangtze River Gan River and other inland waterways would have to build super-kilometer span bridge, which is very uneconomical.

1.4 MODERN BRIDGE ENGINEERING The end of World War II in 1945, marked the beginning of modern engineering to IT technology and computer applications characterised, so far we’ve gone through the first six years. From the previously described six years about 60 innovations of modern engineering can be seen, and before the war compared to modern bridge technology has made a huge progress, including high-performance materials, finite element method and computer software, construction method innovation and large-scale automation equipment and other aspects of construction, showing a more sophisticated modern bridge design, construction and more high quality and high efficiency, conservation and management of monitoring techniques are increasingly sophisticated. In the last decade of the 20th century, there are many international bridges are in 21st century conference theme. June 2006, the US Society of Civil Engineers (ASCE) held a “Future of Civil Engineering Summit” in Virginia Rand Youngstown City formed a prospect, “2025 Civil Engineering” report. The report calls for civil engineering counterparts around the world to work together to take action to create a more beautiful day for the early 21st century civil engineering. Bridge project is an important branch of civil engineering, if we can follow the stages of modern civil engineering that: From 1945 to 1980, period is the foundation of modern bridge engineering; 1980 to 2010, period is progress, creating the 1950s to 1970s, many of the new technology has been fully applied and developed in the late sprint cross-sea engineering and 20 years in large-span bridges; in 2010, the modern bridge project will be matured in the turning point of this development, we also need Looking to bridge engineers operational goals for the next 20 years and important mission.

1.4.1 Bridge Engineer’s Mission and Mandate “2025 Civil Engineering,” the report said: “Civil Engineers shoulders create a sustainable world and to improve the global quality of life sacred mission.” Therefore, “sustainable development” and “quality of life” is the 21st century, two important proposition, but also exposed the past 60 years the main issues and challenges faced. So the mission can be summarised as follows: 1. Bridge engineers are not only planners, designers and builders of the project, they should also be the lifetime operators and maintainers. 2. Bridge engineers should have the concept of sustainable development has become a protector of the natural environment and conservation of resources and energy advocates. 3. Bridge engineers should be involved in decision-making infrastructure, and construction of high quality and durable construction through continuous innovation, improve the quality of people’s lives become an active promoter. 4. Bridge engineer should become the project guardian against natural disasters, emergencies, accidents and other risks. 5. Finally, bridge engineers should also have team spirit and work ethic to become a model to resist all kinds of corruption performer.

1.4.2 Research and Development of Bridge Project To achieve the above mission and mandate, bridge engineering must rely on the latest achievements of science and technology development, and through ongoing research and development work, and constantly improving existing technologies to create and invent more advanced technology to overcome shortcomings and resolve new issues to meet the greater challenges of the 21st century. Research focused on the following five areas: 1. Improvement of material properties is an important driving force behind the continuous progress of the bridge project. Modern steel and concrete bridge engineering is still the main building materials. Over the past six decades, the development of the steel from S343 to S1100, the development of concrete from C30 to C150, has made substantial progress. A variety of high-strength lightweight composite materials and smart materials have been used in bridge engineering. In the foreseeable future, nanotechnology and biotechnology may become an important driving force of technological innovation in the 21st century, and continue to enter the field of bridge engineering applications, has become a new generation of building materials carriers. 2. IT technology and improvement of computer processing power and the corresponding structural analysis software continues to progress, will make increasingly refined bridge design, to create the conditions for the realisation of numerical simulation and the “Virtual Reality” (VR) technology. Therefore, to carry out research of advanced theories and methods of conceptual design of bridge engineering, structural design, construction control, health monitoring, management and other aspects of conservation and development of appropriate software and database technology is a very important area of research. 3. Intelligent monitoring devices (sensors, diagnostic monitors, portable computers) and inventions of large intelligent robot construction equipment, will enable the construction, management, monitoring, maintenance and repair work of the bridge and a series of on-site automation and remote management. Our industry is still relatively backward equipment, heavy construction equipment, advanced testing equipment and sophisticated sensors are dependent on imports, we should vigorously carry out research and development work in this field of hardware, and gradually increase its investment in this regard, to get rid of external dependence. 4. Natural disasters and terrorist threats put high risk to the future world. National Natural Science Foundation of China’s recently launched a major research program on “major projects power disaster” will help reduce risk and ensure the safety of people’s lives, but also improve important aspects of people’s quality of life. In addition, the study of risk assessment and improve the structural durability should be taken seriously in order to ensure the normal life of major projects. 5. Finally, norms and standards to reflect an important indicator of the level of nationbuilding. In the allowable stress method (1923~1963), after which the limit state law (1963~2003), developed countries have begun working to develop performancebased design specifications (Performance-Based Design Code) in order to improve the level of infrastructure construction. The development of this new design is based on a full life and sustainable development of the concept of performance-based

design codes and standards, should be one of the most important tasks in the early 2000s to keep up with trends in the world of civil engineering development.

1.4.3 Bridge-building in the Era of Knowledge Economy By the end of the 20th century, a new economic revolution quietly rose. In the 18th century Industrial Revolution two centuries later, with the information revolution as the core of the knowledge industry will bring a new era of human knowledge economy. Era of knowledge economy is essentially an intelligent and efficient era. The development of modern communications technology makes highly information-oriented society, but also to family life, office, factory production, transportation, construction, education and training, health care, national management and other activities can take advantage of visual communication networks and multimedia, “information superhighway” automated and intelligent. Human intelligence and computer networks combine to make the knowledge innovation has become the most valuable products, a mainstay of the economy and the core of various industries. Bridge construction in the era of knowledge economy will have the following characteristics: 1. In the planning and design phase of the bridge, people will use a highly developed computer-aided tools for effective rapid optimisation and simulation analysis, virtual reality application of technology so that the owners can be very realistic in advance to see the completion of the bridge after the appearance, function, and then simulate performance under earthquakes and typhoons, the impact on the environment and landscape day and night in order to decisions. 2. In the stage of manufacturing and erection of the bridge, people will use intelligent manufacturing systems complete the processing components in the plant, and then use the Global Positioning System (GPS) and remote control technology, thousands of miles away from the site outside the headquarters of the management and control of the bridge construction. 3. After the bridge is completed and delivered, by automatically monitoring and management system to ensure safe and proper operation of the bridge. Once a fault or damage, health diagnosis and expert system will automatically report the injury site and conservation countermeasures. In short, in the knowledge economy era bridge engineering and other industries will have the intelligence, information and remote automatic control features. A variety of intelligent building robots managed by computer software under the control of the commanding officers at headquarters, the completion of underwater and aerial work under field conditions, precisely as planned bridge construction, it will be a 21st century bridge engineering magnificent sight. By the end of 2007, the US National Academy of Engineering announced the approval by more than 50 experts in the “21st century 14 major engineering challenge project”, belonging to sustainable development, health, disaster prevention and improving the

quality of life in four areas. Which in addition to the health sector, and the remaining three are related and future bridge projects. Looking into the modern engineering in the next 20 years, we should be fully understand the mission of bridge engineers and tasks in materials, software, hardware (construction equipment and monitoring equipment), disaster prevention and re-double their efforts to a new generation of standardised five aspects, greet challenges across the sea and island project for building and sustainable development in line with the concept of the whole life of the 21st century, modern bridge engineering our contribution. Finally, it should be noted that the invention of plastic in 1907, one hundred years has gradually developed into a new family of materials. Metal and mineral products have been a large number of high performance fiber reinforced plastic composites and replaced in the field of electrical appliances, medical equipment, automotive, aviation, agriculture, machinery and equipment, etc., and has been infiltrated with cement and steel as the basic material of the modern civil construction. After the near future (probably in 20 to 30 years later), engineering plastics and composite materials instead of cement and steel will gradually become the protagonist of building materials, playing the role of a landmark, which will be modern civil engineering (engineering) into modern new era, and caused revolutionary changes in design theory, system configuration, connection technology and construction method and the like.

1.5 CONCEPTUAL DESIGN AND INNOVATIVE IDEAS Conceptual design is responsible for each project engineer given a mandate in the initial stages of brewing in the hearts of design ideas, but also the starting point for creative designers. In the past, civil engineering education in most countries in the world university professor of materials according to specifications at the different structural design. In the 21st century, many European countries have begun to recognise the need to train students’ innovative ideas, you must set up “concept design” new course. In order to catch up with this new trend, Tongji Bridge Engineering decided to open a “concept bridge design” course, hope that through this engineering education reform, strengthen innovation consciousness of young engineers from the bridge for China to bridge power.

1.5.1 Conceptual Design Significance Conceptual design is the core of engineering design, but also the entire design phase of the project the most important and the most difficult part, can be said that the soul of design. Conceptual design reflects the designer of the overall objectives of insight, ability to control the design task, and the ability in technological innovation, engineering thinking and integrated treatment and the like. The success or failure of a design task and depends heavily on the quality of its conceptual design, a mediocre concept design from the outset, the project decided at a disadvantage in the competition, even if the approval is also unlikely to succeed. Of course, a good conceptual design may also be due in the subsequent design phase aborted or not implemented destroyed the original idea. Conceptual design includes the “concept generation” and the “concept selection” in two stages. The concept generation is defined according to the needs arising from multiple objectives, targets and constraints to form a thought process all reasonable and feasible solutions. At this time, insight engineers is very important, this insight includes intuition, genius, inspiration, knowledge and experience, but also reflects the designer’s unique personality and style. From the “brainstorming” the generation of program should be “the more the better.” Therefore, we can mobilise the imagination and creativity of the design team, as much as possible to accept different personalities, different styles, different perspectives and emphasis of the design, to avoid missing some ingenious design concepts and ideas. Concept of choice is all possible options to evaluate and compare screened out a few excellent programs for analysis, research and detailed comparison in order to finalise an optimum conceptual design. In general, the conceptual design stage does not need to invest a lot of money and manpower, does not need too detailed calculations, especially to avoid using technical design and detail design methods to do conceptual design, and to focus on reflection and comparison, and with a small amount of text and a few pictures to express the designer’s ideas and creativity, outstanding personality and style that some different from the traditional, conventional and existing design highlights. In short, to demonstrate the

designer’s insight and creativity.

1.5.2 Basic Principles of Conceptual Design Foreign bridge design emphasises the 3E principle that the efficacy (efficiency), the economy (economy) and beautiful (elegance) are the three elements, this and “practical, economic, aesthetic care, where possible conditions,” the construction of the originally proposed guidelines are consistent. As China’s economic strength, people’s living standards improve, for aesthetic demands more attention, coupled with safety and quality problems occur frequently, the principles of engineering design was changed to “safe, suitable, economic, aesthetic.” This “character principle” has become the consensusbuilding system, appeared in many engineering design documents. It should be said, that the goal of safety and quality of construction of the main pre-requisite for the design, which is included in the design specifications of the various articles, the site is the design engineer must follow the law, that is designed according to specification requirements. As a basic principle of conceptual design, in addition to security, application, economic and aesthetic, construct ability should also be considered to guarantee the conservation of nature and life-use features durability. In recent years, for the sustainability of the project (sustainable engineering) saving resources and protecting the environment should be an important principle of the concept conceptual design to be considered. In short, the bridge concept design in the 21st century should meet the “safe, practical, economic, aesthetic, durable and environmentally friendly,” the six basic principles to reflect the spirit of conservation and environmental protection and sustainable development. And innovative ideas or creative (innovative or original idea) must run through the whole concept of the design process.

1.5.3 Definition of Innovation The concept of innovation was first used by Schumpeter (J. Schumpeter), published in 1912, “Theory of Economic Development” presented in a book. He will be lead to a qualitative change in the means of production and the development of the economy is defined as the occurrence of a new combination of “innovation”, while for small steps simply by adjusting production, although it also brings some amount of change or growth, but it cannot be called innovation. Visible innovation is a revolutionary tool that can cause things change. Innovation in technology should be a core technology for product innovation, rather than on the periphery of the secondary components or partial to make some adjustments and changes, which can only be described as an improvement. Thus, changes in qualitative or quantitative changes only, it should be important to define the criteria between innovation and improvement. China’s Eleventh Five-Year Plan put innovation into three levels, namely, original innovation, integrated innovation and the introduction of absorption and innovation.

Obviously, living in the highest level of the original innovation, it is the first (initiation) and original (origination). If science to discover (discovery) as the core technology is to the invention (invention) and creation (creation) as the core patent is a legal means to protect the original innovations, and “core technology” came from those with a patent the original innovations. About two later levels of “innovation”, in October 2008, at the Chinese Academy of Engineering President Xu stated in the speech, “to implement the scientific concept of development, building an innovative country”. “Integrated innovation” generally is overall an autonomy design driven by national needs, but the core components are often the best value for money to buy foreign products, assembly (integrated) up as high-speed rail EMU, regional aircraft, large tunnel excavator. “Introduction, digestion, absorption and re-innovation” is primarily a local improvement based on the imitation, such as home appliances and information industry, although some core components can be produced, but the poor performance, not durable (due to materials, production equipment, technology level gap), and some also purchase foreign patents components and software, pay high royalties, even if completely successful imitation, but the problem still exists levels of durability, which is the gap. Have a similar situation in China bridge construction of large mechanical equipment, such as drilling rigs, cranes and so on. Lower levels of generic success is not truly “independent research”, “completely independent intellectual property rights,” and some do not actually “complete”, and some overall design of the product is to ask foreigners to do with the high-priced purchase. Therefore, innovation must be realistic, to tell the truth, should not be exaggerate. Developed countries have a strong technological power innovation, invention patent them through continuous research and development arising, holds the industry’s core technology. They can stand on end, not only leading the development of science and technology, but also through the export of capital and technology from high-end low-end production leadership and command of developing countries. As Song Jian, former director of the Chinese Academy of Engineering, said: “Our only way out innovation, innovation in order to break the limit, to get rid of containment, withstood threats, only innovation can grasp out of containment inventions and intellectual property rights in order. equal access to international cooperation, “the former president of the Chinese Academy of Comrade Zhou Guangzhou also said:.” innovation must stand on the shoulders of giants, the “giant” is mastered the core technology, leading the developed technology. Therefore, we must first learn to be innovative application of the most advanced technology, this is a tough process to the forefront. If you want to further improve, it can only create new and better technology to replace the existing old technology, it is necessary “new channels”, “innovation.” At the early stage of reform and opening up, we introduced a lot of international cooperation through advanced technology and production equipment, but very little digestion difficult to re-innovation. Comrade Zhu Lilan, former director of the National Science and Technology Commission said: “The core technology is the soul of innovation, while the core technology cannot be bought.” So, to master the core technology, but also

to continue to move forward, we must have a stable R&D investment, the establishment of a high level of R&D team, and advance technical preparations for sometime, in order to obtain truly original innovation and core technology, otherwise it will be always lag behind. From concept bridge design point of view, the reform and opening up in the 1980s, in the study of innovation in many developed countries started in the design, there are some improvements. Since the 1990s, across the major rivers due to the need began to impact a variety of bridge-record span. To ensure the quality and improve efficiency, we have the introduction of foreign advanced construction equipment and design software, and also invited some well-known international companies to help do some of the technical difficulties of consulting services, has made great progress in technology, has also been international peer recognition and praise, can be said to have entered the advanced ranks. In the 21st century, some of the design and construction enterprises have gradually realised the importance of technological innovation, developed through research and development to continuously improve learning and experience in technology updates, have set up R&D team as a backup and technical support, it should be said that this is a great progress. Some people think, according to its nature and intensity innovation can be divided into breakthrough innovation and incremental innovation. The former brings a qualitative change in technology is a completely different old things revolutionary change, is an original and pioneering technology, such as modern bridge projects described above 60 years is about 60 original innovation, it makes modern bridge completely different from the modern bridge of epoch-making change. The incremental innovation is a partial improvement is based on the original replacement, such as a variety of new variants cablestayed bridge, thin cable becomes tight rope pyramid innovation, cable corrosion change, the same construction method equipment replacement and advancement. This improvement may occur dozens a year. Thus, innovation is original or groundbreaking, but is associated with the core technology. The rest should be called improvements or updates are local quantitative and improvements based on the original. In the introduction of absorption based on “re-innovation”, if not a breakthrough can only be a kind of “improvement.” The “integrated innovation” was more ambiguous and difficult to define. In short, the conceptual design of a project can have 1 to 2 real breakthrough innovations and technical improvements of 3 to 5 is a remarkable achievement, there can be a lot of innovations. Innovation in the “a” word is a creation (creation) of Italy, cannot arbitrarily labeled “innovative” label, but should have the support of patents, a qualitative change in the performance of the core technology mission to lead a new trend initiative.

1.5.4 Create Innovative Ideas President of the world-famous Tung-Yen Lin International, Inc. (TY Lin International), American Academy of Engineering, Chinese Academy of Engineering, Foreign Member Teng Wenzhong said on innovation: “A bridge engineer if you do not attempt in each design as much as possible to improve, then he did not do due to the obligation engineer.” “Visible, innovative ideas from the existing level of technology continues to be improved

motivation, that past achievements and satisfied with the desire to climb new heights.” When a series of quantitative improvements reached its limit, but it is difficult to solve the problem when it must be broken, namely, the need to create a new technology to replace old technology. At this time, there have been a qualitative change, an innovation was born. On bridge innovative, Mr. Deng Wenzhong said in his article “urban bridges innovation,” innovation can be simply defined as “meaningful improvement.” The socalled “meaningful” must add value, just to “different” and change, it makes no sense, cannot be considered “innovative.” “Modern bridge project six years,” cited about 60 major innovations of modern engineering, including innovative bridge type and systems, new materials and connection technology, innovation and structural construction and ancillary equipment, innovative engineering methods and equipment, and innovation theory and analysis methods in five areas. These are original and inventive, it should be listed as the first level of the original innovation. And a lot of bridge engineering innovation activities is Mr. Deng Wenzhong said “meaningful improvements” to make existing technology to get more value, they are “reflected in the improvement in function and reduce costs (economy), enhanced durability and aesthetic effect.” There is a form in the application of traditional concepts and methods of expanding its range of applications, because most of the original system and the beginning of innovative engineering methods are used for smaller spans, such expand or extend (expansion or extension) is also greatly promote the progress of the bridge, but also a creative achievement. To sum up, there innovative bridge is at three levels; original (origination) and invention, a meaningful improvement, as well as to expand the (extension) on the application of the prior art. We should have great respect for pioneering achievements, such as Shibanpo Bridge’s first hybrid continuous rigid frame bridge deck, the French Millau bridge’s first cable-stayed bridge continuously pushing construction. To encourage a large number of bridge engineers “meaningful improvement”, every new bridge will be able to do a better job than the previous one bridge to overcome the shortcomings and eliminate hidden dangers, step on a higher level. For the expansion of technology applications have certainly, but do not bother to pursue the span of, and should not be go barely expanding, wasteful, and thus give up on inventions to explore new and better technologies. Therefore, we must be “meaningful expansion”, which must be beneficial and add value. Specifically, to get more value in the structural performance, economical, convenient construction, increased durability and so on. For example, the caps do more deep foundation piles high the greater the number of most contention pile, size of the caps, but in a strong river erosion, or strong earthquake zone, or other aspects of the anti-ship collision, high-pile platform whether it is the best? Are there hidden dangers and risks? We must consider whether it makes sense to expand this, if there is a better solution, not to pursue meaningless expansion. Mr. Deng Wenzhong said: “Innovation comes from a question.” First ask why? This problem gives us the opportunity to challenge the conservative habits. Why only use the same old thing? Why should imitate, copy the original design? Why only someone did something we can do? The second question is why not? It gives us the opportunity to introduce new ideas and

breakthroughs constraints. Why not another way to do it? Why not try another material? Why cannot modify the old norms? Why not put anything else in the industry learn from the successful experience to solve our problems? The “Why not?” the problem is the core of innovative power, which lead us to be bold and innovative, play our greatest imaginative and creative, resulting in many new concepts and solutions, greatly improving the quality of conceptual design. The third question is “What if”? It allows us to be cautious and conservative, that is properly solve new problems arise because of the creative, so creative carried out, without a security risk. Some people say: “Innovation will increase the risk.” This is the traditionalist excuse is lazy in philosophy. For the result of innovation and the challenges and the way forward in what we need to do is overcome the difficulties, and it is part of the innovative ideas. Among the three questions of Innovative, the last one is the key to success. Mr. Deng Wenzhong stressed: “The project is a multi-program, so the engineer’s duty is to choose the most suitable solution.” Therefore, we must not meet in the conceptual design for “feasible”, and to the pursuit of “excellence” that all aspects of the requirements and conditions to find an optimal solution.

1.5.5 Tasks and Content of Conceptual Design As previously mentioned that the conceptual design is the soul of design, which showed the designer’s creativity, imagination, innovation and spirit of exploration. Imagination and conceived in the form of a bridge designer’s mind, in addition to meeting the basic functional requirements and mechanical properties, but also consider a variety of important factors. Designers experiences, lessons learned from the past and knowledge accumulation are the basis of his creativity in the conceptual design of the foundation. Mr. Ostenfeld K. President of the Danish company COWI Zhu Wen had described his experience in the conceptual design of major bridge projects, he said, “The bridge design is a multi-disciplinary working way (a multi-disciplinary approach), in addition to technology, but also there are many political, social, environmental and other common constraints final decision.” In the process of conceptual design (engineering feasibility and preliminary design phase), the engineer but also through more programs, select the optimal integrated solution from a number of viable options in order to ultimately reflect the “safe, practical, economic, aesthetic, durable and environmental protection,” six basic principles as follows: 1. Safety: In addition to the structure with excellent mechanical properties, but also contains withstand natural disasters, ship collision, anti-fire and other man-made disasters, other sporadic anti-risk capability and extreme (small probability events) as well as the case. 2. Function: Refers to satisfy the deck transportation, bridge navigation, and other

basic requirements for aviation bounding functions. 3. Economics: Refers to the cost in the whole life philosophy, conservation and management of the economy, as well as in the design of structures for durability, constructability, you can check, can take full account of the conservation of nature. 4. Esthetics: Conceptual design aesthetic considerations should include a variety of aesthetic requirements of the bridge structure as well as the coordination of the landscape and the surrounding environment (see Chapter 2). 5. Durability: Non-durable structures will be cause great waste and damage the reputation of Chinese bridge. Among them, promoting the use of high performance materials and the development of higher durability design standards will be China’s bridge in the future must focus on solving the issue. 6. Environment Protection: Core conserve natural resources and protect the environment, reduce CO2 emissions and the sustainable development of scientific concept of development, but also important challenges of the 21st century, the world faces. Infrastructure in resource consumption and CO2 emissions and energy are high proportion, must draw the attention of bridge engineering. The above six are important factors in decision-making and the right bridge design concept is the core mission, which must be fully demonstrated, in order to avoid a lack of creativity, mediocre, plagiarism, and grandiose, the blind pursuit of large span, weird the difficult construction, not durable, non-economic and unreasonable solutions by not rigorous “review” and is implemented, which greatly affect the progress of China’s bridge. Finally, the conceptual design of the content is generally divided into the following four steps: 1. Conceiving: Imagination, conceived plan, compare the selected creative process, but also the conceptual design is the most important step. 2. Modeling: On the idea of a structural program abstraction for analysis and calculations. But the conceptual design phase of analysis and calculation accuracy and technical design requirements are different, not the pursuit of precision, mainly to relatively program between, and for the next step to determine the size of the service, so approximate methods and means of empirical coefficients, etc., may be used. 3. Dimensioning: Is an estimate of the number of the main engineering and cost, including the application of high-performance materials and combinations of different materials used. 4. Detailing: For innovative systems, construction and improvement of traditional technologies meaningful, we must consider the relevant details of construction, so persuasive and creative programs, feasibility and security implementation. Chapter I to V of the book will be focus on the conceptual stage and Chapter VI on the key size selection and mechanical accounting, Chapter VII on the details from design through construction, application of innovative equipment and high-performance materials and advanced technology, sound conceptual design to solve new problems arise, that is, to solve Mr. Deng Wenzhong presented “What if” the third question, so that creativity can be achieved.

1.6 CHAPTER SUMMARY According to the seventh volume, the statistics, of Dr. Joseph Needham’s “Chinese History of Science and Technology”, China since about 4500 years BC to the 15th century, the year 3000 has contributed nearly 300 inventions, in many ways ahead of the world, including four great inventions and 26 are arranged in alphabetical important invention of the world-famous, there are pontoon (4th century BC) in bridge engineering, outrigger beam bridge (4th century AD), rope bridge (6th century AD), open shoulder Arch (610 AD Sui) and consistent wooden bridge (AD 1032 Song), etc. However, unfortunately, since the 16th century European Renaissance, China’s creative activity began to decline until the demise became the famous “Needham Question”: Why does not China modern science and technology to produce advanced why China cannot maintain the advantage and take the lead in creating? Industrial revolution happened and why China in the 19th century, the country was actually reduced bullying powers suffer ignorance and backwardness? Some with insight pointed out: China’s centralised authoritarian system of feudal society stifled the spirit of freedom of the Chinese people and the elite intellectuals had been attracted to a career via the imperial examination system and advocating obey the will of the emperor of a unified, thus weakening the inventions enthusiasm. Coupled with the complacency and lack of motivation to compete, eventually leading to a decline of nearly three hundred years of Chinese science and technology. We can say that this idea legacy still affects our younger generation of creativity. In commemoration of the founding of new China 60 years ago, we are at the historical turning point. After 30 years of reform and opening up efforts, Chinese bridge in the world community has kept up with the pace of modern bridge and entered into the international advanced level. However, we cannot be complacent, but to acknowledge gaps and weaknesses, our way in innovation. Only truly master the advanced core technology innovation in order to get rid of containment and control of the developed countries, in order to achieve the great re-juvenation of the Chinese nation. Premier Wen Jiabao’s recent speech at the University of Cambridge, said: “China to catch up with developed countries, there is a long-long way to go.” Articles of technical summaries are mostly straightforward but are lack description of the concepts like design and creative from foreign counterparts, instead emphasise more on size, such as the number of “difficult” and how “most” used words. In addition, many bridges are very similar, the lack of features and ideas, which is common in Chinese culture advocates, imitation and consistent, not to encourage negative reflecting the “maverick” consciousness, but also the technical progress of the taboo. The Chinese nation is nation of wisdom, China’s five thousand years of history and cultural heritage will be help us achieve revival. As long as we do not complacency, face inadequate and prudent, and through education reform, renewed the younger generation’s imagination and creativity, we will be able in the near future through innovation efforts, from bridge to bridge solidly Liang Daguo power.

REVIEW QUESTIONS 1. In 60 years of the development of modern bridges, unlike in developed countries has created many new bridges of modern technology, is widely used around the world, what do you think are the ten most influential technology? And compared these advanced technologies, China reform and opening up 30 years built a major bridge project, there are several technologies which have originality? 2. China’s achievements and progress in modern bridge is huge, compared to developed countries, but there are still gaps and weaknesses, what do you think the main reason? How to overcome these problems? 3. “Innovation” There are many different interpretations and positioning, which view you agree? Media propaganda in the “completely independent intellectual property rights” was, how should evaluate? 4. Are you on the “conceptual design,” meaning, principles, tasks and content of a new understanding? In the future design work in practice, how would you go to implement it?

REFERENCES [1] Yin Delan Wendi with Bridge — Chinese articles Beijing: Tsinghua University Press, 1988. [2] Brandon China Bridge Shanghai: Tongji University Press; Hong Kong: Hong Kong Building and City Press, 1993. [3] Square Mingkun Bridge Essay Beijing: China Railway Publishing House, 1997. [4] Modern Highway Bridges. Twentieth Century Blend of Major Scientific Achievements, 1998. [5] Meng Hoi Fan Bridges Twenty-first Century, Shanghai CAST: Shanghai Branch of the Altar, 1998. [6] Troitsky M.S. Conceptual Bridge Design//Bridge Engineering Handbook. CRC Press, 1999. [7] Of the Twentieth Century’s Greatest Engineering Achievements of Science and Technology Highway Articles. Chinese Academy of Engineering, 2001. [8] Klaus H Ostenfeld. Major Bridge Projects—A Multi Disciplinary Approach. IABSE Workshop Shanghai 2009-Recent Major Bridges, IABSE Reports, 2009 (95). [9] Hoi Fan, Hong Xuan Pan, Zhang History of the Holy City of China Bridge Shanghai: Tongji University Press, 2009.

AESTHETIC BRIDGE DESIGN

Efficiency, economy and elegance are considered to be the three elements of design guidelines since ancient Greece and its followed by the world engineers. China’s reform and opening up previously, due to the limited economic conditions, the only mention of the “practical, economic, possible conditions under proper care and beautiful” construction principles. In the 1990s, with the national strength, this principle has been changed to “safe, suitable, economic, aesthetic,” the eight-character principle, to secure a prominent position. Especially in urban bridge construction, bridge aesthetic requirements continue to increase, reflecting the demand for functional and aesthetic value of the landscape in the future to improve the lives of the bridge. Therefore, the aesthetic design of the bridge should be an important part of the concept of bridge design. As a bridge engineer, one has the responsibility to strengthen the aesthetic ideas in the initial stages of the design concept, engaging with beautiful ornamental bridges to meet people’s aspirations. Of course, aesthetic considerations should not violate the basic principles of technical safety, application and economy. Similarly, when according to technical and economical criteria options, nor should deviate from the target aesthetics.

2.1 PHILOSOPHICAL FOUNDATION OF AESTHETICS Unlike animals, humans are capable of thinking and manufacturing tools. In the tools era in the progress of human civilisation (from 2.5 million years ago to 50,000 years ago, Paleolithic and Neolithic from 50,000 years ago to 6,000 years ago), humans in order to survive and gradually get rid of the nascent, gregarious nest to acquisition-based primitive life, entered a hunting and fishing, animal husbandry, cooked and farming era, and the transition from a matriarchal society to a patriarchal society, the formation of association and the national society. In the course of evolution, humans are bound to ponder the nature of the moon and stars, thunder and lightning storm, biological growth, and reproductive senescence phenomena and human individual and social Relationships between groups, gradually gave birth to the original philosophy, which also includes Reflections on the United States. Mr. Tang Huancheng stated in his book “bridge philosophy of beauty,” a book mentioned in the introduction: “Bridge is a bridge aesthetic philosophy of beauty”, “height is not raised to understand philosophical aesthetics.” Therefore, learning bridge aesthetics will be certainly talk about the philosophical basis from aesthetics.

2.1.1 Philosophical Foundation of the West Western philosophy began in ancient Greece, 10th century BC to the 3rd century. When the 5th century BC, ancient Greece into the Golden Age, 331 BC, the Greek Alexander the Great conquered the ancient Persian empire. Development of ancient Greece’s industrial, commercial and seafaring culture and art and promote the prosperity of philosophy, there has been a number of far-reaching influence on Western civilisation philosopher. Of which the most famous are Pythagoras (Pythagoras, 582 BC to 500 years) (Fig. 2.1), Socrates (Socrates, 469 BC — 399 years) (Fig. 2.2), Plato (Plato BC 427~347 years) (Fig. 2.3), and Aristotle (Aristotle, 384 BC — 322 BC) (Fig. 2.4), et al. In ancient Greece, many natural phenomena did not have scientific explanation, but by virtue of the ancient Greek philosophers intuitively recognise the genius of nature does not change things are in motion in repose, resulting in the initial astronomy, meteorology, biology science and mathematics. Pythagoras that “things are harmonious whole number composed by the United States lies in the proper proportion and harmony numbers.” Socrates is considered “standard of beauty is a measure of the utility, useful to the United States, harmful to the ugly.” That is advocating social standards of beauty, or “functional beauty.” Western political philosophy of Plato as enlightening, as was the slave owners to establish a national democratic system and political philosophy, namely, human and social norms. In terms of aesthetics, he believes that “philosophy is all of this, is the origin of beauty, artistic beauty is a concept of beauty to share.” Aristotle is known as ancient Greece’s greatest philosophers and scientists, who, as an objective materialism representative, does not agree with his teacher Plato’s objective idealism “concept says,” and that “the essence of the concept of beauty is not called, and in a complete form of the object”, and “orderly, well-balanced and clear regarded as the formal beauty of the law that emphasises the beautify of form.”

Fig. 2.1 Pythagoras

Fig. 2.2 Socrates

Fig. 2.3 Plato

Fig. 2.4 Aristotle In 284 AD, ancient Greece was conquered by the Roman Empire and became part of the Eastern Roman Empire. In Roman times, the dominant theology and religion, God is exalted as the source of beauty. As the new Plato philosopher Plotinus (AD 204~270 years) (Fig. 2.5) stated that “God is the source of beauty.” St. Augustine (Augustine St,

AD 354~430 years) (Fig. 2.6) then said, “God is the root of all things beautiful.” AD 476, the Western Roman Empire was defeated by the Northern Germanic peoples, Europe entered a medieval feudal period, which is the knight and theocratic despotism period of upto one thousand years of the Dark Ages. Italian 15th century Italian Renaissance Alberti (Alberti) (Fig. 2.7) defined beauty as “the harmony of the parts,” and again to carry forward the ancient Greek philosopher Pythagoras’ aesthetic philosophy.

Fig. 2.5 Plotinus

Fig. 2.6 St. Augustine

Fig. 2.7 Alberti

The rise of western classical school in the 18th-century generated German idealist philosopher Baumgarten (1714~1762) (Part Fig. 2.8), Kant (1724~1804) (Fig. 2.9) and Hegel Seoul (Hegel, 1770~1831) (Fig. 2.10), as well as students of Kant Schopenhauer (1788~1860). Western materialistic philosophy school, there are British Burke (1729~1797), Diderot (1713~1784) (Fig. 2.11) and the 19th-century Russian revolutionary democrat Czerny Schiff Chomsky (1828~1889) (Fig. 2.12). Baumgarten is known as the father of Western aesthetics, his book in 1750, “Aesthetics”, a book advocating “Aesthetics is artistic beauty way to thinking, is beautiful art theory.” Kant believes that “the aesthetic nature of the representation of an object is something purely subjective aspects.” Hegel’s idealism has established a complete aesthetic system, he believes that “the concept of beauty is absolutely outside by the human mind into the sensual image that America is the concept of emotional show.”

Fig. 2.8 Baumgarten

Fig. 2.9 Kant

Fig. 2.10 Hegel

Fig. 2.11 Diderot If the German idealist philosophy is representative of the maintaining of a medieval theocratic feudal rule of conservative ideas, then British philosophers represented materialist aesthetic system represents the emerging bourgeoisie and the Industrial Revolution infancy, but also inherited and developed the ancient Greek philosophy simple materialism. Burke believes “things change a variety of reasons constitutes quality beauty.” Diderot is that “beauty is the thing itself attributes are present in our around them.” Chernyshevski is presented “Beauty is Life” famous thesis, he stressed the objectivity of beauty that the US cannot leave people and their activities independently exist. Before the 18th century industrial revolution, low productivity, science and technology was not developed. The majority of poor people cannot control their own destiny, but also the fear of divine nature, only in the hands of religious superstition and dreams afterlife transport. Imperial and theocratic religion and idealism also depend on the natural values and social values to maintain authoritarian rule. While a few pioneering scholars tend to materialism, but the force of a single potential thin, after all, cannot resist the ravages of the inquisition and oppression, such as the sufferings of Galileo (1564~1642) and Bruno (1548~1600). Controversy between Philosophical idealism and materialism existed for two thousand years, Engels (1820~1895) (Fig. 2.13) in the “Dialectics of Nature”, a book of contemporary natural science made great discoveries and important results summary philosophical idealism to materialism defeated the foundation, while drawing on the core of Hegel’s rational, and finally to establish a correct understanding of the nature of the unique way—materialist dialectics. Engels’ comrades, the great Marx (1818~1883) (Fig. 2.14) fought in the field of social sciences on behalf of the oppressed working class was to establish a dialectical materialist conception of history and Marxist doctrine, and on this basis the formation of an advanced Marxist aesthetic theory.

2.1.2 Philosophical Foundation of the East

Although China entered a bronze as a symbol of the slave society of the Xia Dynasty (2140 BC) nearly two thousand years later than in the West, but it had developed rapidly, after providers and Zhou have reached the heyday of the slave society, the “Book of Changes” yin and yang, gossip already pregnant with the simple philosophy. To the Spring and Autumn Period of the Eastern Zhou Dynasty (770 BC to 221 BC), Chinese society began the transition from slavery to feudalism, the emergence of contending ideological thinkers and cultural prosperity. Eastern philosophy whereby the originator, the most influential thinkers in when Confucianism and Taoism. Confucian, founder of the school of Confucius (551 BC to 479 BC) (Fig. 2.15) promoted virtue and music, mainly the pursuit of harmony and unity of man and society. Aesthetic concepts of Confucianism is “Zhiyong, head concept, Bede, Praising God,” stressed the practical beauty, shape beauty, moral beauty and spiritual beauty, namely, about beauty and ethical unity.

Fig. 2.12 Chernyshevski

Fig. 2.13 Engels

Fig. 2.14 Marx Laozi, founder of the Taoist school (about 600 BC to about 500 BC) (Fig. 2.16) advocated the road as the source of the universe, the main pursuit of unity and harmony of nature, to go in and change things opposition unity create beauty realm.

Fig. 2.15 Confucius

Fig. 2.16 Laozi Laozi’s thought inherited that from Huangdi and this is also referred to as “HuangLao.” Confucius followed Zongzhou, and the two are not inconsistent, but complementary A. Five Emperors era, society is relatively simple, and therefore is to explore the relationship between Taoism main-man and nature; the Shang and Zhou, the complex social conflicts, wars between slaveholders frequently, and therefore more concerned with the relationship between Confucianism and society. However, Taoism and Confucianism are that the universe is constantly moving and changing world, and recognise the opposition and unity of yin and yang. We can say that the ancient Chinese philosophy already has a simple Dialectics. Especially Taoism is full of original ideas materialist view of nature. Thus, the ancient Chinese aesthetic thought still shining wisdom charm. In summary, the Chinese culture respected “realistic”, “practice makes perfect”, “Practice is the sole criterion for testing truth” and so reflects the essence of materialism. And think things are in constant motion and change, recognise primary substance, also

admitted that the reaction of the spirit and initiative is the essence of dialectics, the two combine to form a contemporary outlook of materialist dialectics.

2.2 THE PRINCIPLES OF BRIDGE AESTHETICS Mr. Tang Huancheng (Fig. 2.17)’s “bridge beauty philosophy,” is a good summary of Eastern and Western philosophy based on the principles of the basic rules of bridge aesthetics. He particularly stressed: Any arts requires law as a rational guide, but to create works in practice cannot completely rely on the law, and to use their imagination and wisdom. Therefore, we need to know the law, as “the book calligraphy, painting tips, metrical poetry,” but cannot make it rigid and inflexible. Here are several laws of bridge aesthetics.

2.2.1 Diversity and Unity (Change and Unity) This is the first law of dialectical materialism aesthetics, because the world is diverse and unified. Chinese culture “and different” and “Heaven,” and the Greek Pythagoras thought “Harmony is a unified multi-hybrid” is a meaning, namely respect for diversity and change things, opposed to the monotony and uniform, but not chaotic, but to seek unity in diversity, and unity in seeking change. Mr. Tang Huancheng mentioned several times in his book the three unities are the most important attribute of beauty; the unity of emotional and rational, that feeling and consciousness of unity; unity of subjective and objective, namely, to harmonise the natural and human; form and content of unity, that unity of style and function. Germany’s famous bridges and aesthetic specialist Prof. Leonhardt (Leonhardt F) (Fig. 2.18) said in his monograph: “The US can change and similarities between the display, between the complex and orderly, and thereby be strengthened.” Visible, both complex changes, and orderly re-unification between non-identical and non-messy show rich level and content is giving to enjoy the beauty and soul stirring aesthetic essence. We create beautiful bridge following the aesthetic rules should be as beliefs in mind, and throughout the conceptual bridge design, which reflects the bridge design is the most important “innovation beauty.”

2.2.2 Ratio and Symmetry Pythagoras of the ancient Greece believed that “number is the nature of things,” “Beauty is harmony and proportion.” Here is the previously mentioned harmonious diversity and unity, while the proportion reflects the beauty of mathematics, or that an important proportion of US law. Plato also believes that “proportionate form is beautiful.” Medieval da Vinci (Fig. 2.19) also attaches great importance to the ratio, the proportion he believes not only in numbers but also in sound, quality, time, location being. The ratio is a relative number, the proportion of the United States may exhibit symmetry, adaptation, decent, presenting a “proportional beauty.” Leon Hart said: “We first respond to the proportion of objects that width to length ratio, high aspect ratio, or the ratio of the size and depth in the space between.” Grasp the concept of a variety of scales in bridge design an appropriate proportion between the very

important. Improper proportion will be give a feeling of deformity, weird, ugly and distorted image.

Fig. 2.17 Huancheng Tang

Fig. 2.18 Leonhardt

Fig. 2.19 Medieval Da Vinci Symmetry is not only a uniform and symmetrical, collectively, but also contains the right proportion, meaning decent match. Chinese Literary Arts pay attention to symmetry, such as the poetry of duality, couplet, buildings are arranged symmetrically around the central axis stress, gives a solemn, balance and beauty. Symmetry reflects the unity of the opposition and philosophy, that up and down, left and right, and echoes similar before and after, but not exactly similar. Strict symmetry represents dignified beauty, but can be too serious, strict and gives a dull feeling. Sometimes forcibly arranged in irregular environments symmetrical structure but will result in consequences clumsy and uncoordinated. In the terrain and the river bridge asymmetric-asymmetric arrangement but give people a kind of wisdom and coordinated beauty. Similarly, in the height of a small navigable waterway insist arranged oversized lower span of the bridge, will be lose the proportion of the beauty, people feel very depressed, and wasteful.

2.2.3 Balance and Harmony Bridges is a force-bearing structure, rather than a craft, and therefore must emphasise balance of forces. Its body shape to obey the laws of mechanics, gives a sense of security and stability. Also, handle the balance between security and economic, to “make the best use, rational distribution” to avoid waste. China put great emphasis on aesthetics of relative harmony and unity between two opposite features, such as rigid and soft, harmony with the movement of Yin and Yang and the actual situation, etc., between 4 opposites, reflecting a “harmonious beauty.” All arts are inseparable from the rigid, requiring there are just soft, firmness and flexibility. In the bridge, there are just beams with flexible and rigid arch flexible beam, the beam is also flexible with just the tower and the tower just soft beam. Another manifestation of rigid-soft is still and movement. In the plastic arts should behave out in a static, static in action, showing the movement changes, relaxation, advance

and retreat of harmony and unity. Yin and Yang was originally the collective sum of opposing faces, natural light and dark, cold and heat, fine buildings and rough, complex and simple, reflects a harmonious and orderly change between Yin and Yang. The essence of the actual situation of Chinese aesthetics is virtual and real, imaginary in reality, is the highest in a virtual realm of art, the creation of the bridge will be a great inspiration. In short, the structure should be the shape and design of various antagonistic relationship, such as security and economic balance and harmony, load and strength. Therefore, the bridge will be able to shape the beauty reflecting all aspects of balance and harmony between the various parts, namely, to find the most reasonable force system, most economical and most convenient arrangement structure construction technology to simultaneously showing the bridge. “Mechanics beauty,” “Balance of beauty” and “Harmonious beauty.”

2.2.4 Rhythm and Coordination Rhythm is at the heart of art, but also the focus of any art trauma and feelings. British engineer Faber stated in the “aesthetic concept of civil engineering design,”: “a structure to the beauty, there must be touching interest (excite interest), and attractive (charm)”. English “charm” of the term can be translated attractive word charm, magic, the equivalent of the Chinese “charm.” German professor Leon Hart said in the book “Bridge Aesthetics and Design,” bridge construction needs charm (reize), which is intended charm or rhythm. Chinese and foreign poetry should rhyme according to certain rules to reflect the change and repeat rhythm or regular, making it touching beauty, in order to achieve “character” or “charm” of the overall artistic charm. In the overall design of the bridge, in the main bridge and the parts, the main hole and side hole, superstructure and substructure, bridge and harmony with the surrounding environment (culture, geography, landscape), the goal is to find this rhythm and charm and to achieve seamless and “coordinated beauty”. In summary, the aesthetic design of the shape of the bridge is to make a bridge to reflect global and local innovation (change) United States, unified the beauty, the proportion of beauty, balance beauty, harmony and beauty, rhythm and coordination of the beauty, so the bridge in its life not only has the function of traffic, and can never get tired of its charm, gives a sense of beauty, when people through the bridge will be a beauty, physical and mental feeling of pleasure. As the American philosopher John Ruskin said: “When we build a project, not only for current use, should it become a future generations will thank us work.”

2.2.5 Innovations and Aesthetic Considerations in

Conceptual Bridge Design In section 1.5.4, it is has already cited Mr. Deng Wenzhong words:. “A bridge engineer if you do not attempt to make improvements in each design as much as possible, then he did not try to engineer bounden duty,” he did here said, “innovation”, but with the “improvements”, in fact, improved innovation was derived from the idea that does not repeat old, have been found for the problems and shortcomings of the past cannot repeat, but to be overcome to improve the existing technology, the constant development, has become a source of innovation. Innovative, safe, plus art is Deng’s design philosophy. Among them, the last of the “Art” is the concept of bridge design aesthetic considerations. He said, “Engineers should make this world more beautiful and proud”, “relative to the mediocre designs, people are more concerned about the appearance of the bridge, but also willing to pay more to keep their aesthetic appearance of the bridge is more durable, “and that” if there is a bridge engineer aesthetic accomplishment, slightly a little effort you can put a bridge made very beautiful. “he added,” progress is the accumulation of innovation. “Engineers must make every building we built through innovation, while ensuring the safety applies more economical and more beautiful. Leonhardt professor of Germany in his “bridge aesthetics and design” (Bridge Aesthetics and Design) introduces the creative process to bridge engineer of the creative process. 1. The design is based on a variety of information and completely digested in mind; 2. To understand the scope of application of various types of bridges and adept in the heart; 3. The original idea in the minds of possible solutions; 4. Lays out the first sketch, drawn in accordance with an appropriate proportion of the preliminary general arrangement and approximate size of each portion; 5. To continue the consider other possible scenarios for comparison; 6. The sketch on the wall of the programs they watch, and asked questions of peers and colleagues and critics to discuss the appropriate construction method; 7. The satisfaction of the draft can be drawn for a large proportion of the map, and to consider the structure and detail size; 8. Trying to think about it, were aesthetic considerations and treatment, and asked the architect as a consultant to carry aesthetic design and processing; 9. Construction engineer comments please select the appropriate engineering methods, or systems and structures for innovation, create new public law; 10. After much discussion and improvements can be selected for the program will be drawn into a clear drawing, counting and checking, checking the assumed size meets the requirements; 11. Rounds of calculations performed on the basis of this, modify the size, in order to achieve the most economical and reasonable layout of the indicators; 12. Through the production of models and photographs, from the perspective of each angle of the bridge to observe and judge the appearance of the bridge and its impact on the surrounding landscape, and examine the aesthetic effect.

While the above does not specifically emphasise the creative process of innovation and aesthetic considerations, but Professor Leonhardt who has created many new technologies bridge aesthetics master minds, innovative ideas should be run through the how to make in this creative process reflects their design work in front of the beauty talking about innovation, unified the beauty, the proportion of beauty, balance beauty, harmony and beauty, rhythm and coordination of the beauty, only through constant practice and compare to comprehend, the final contest results will be on your best judgement creative work.

2.3 SUCCESS STORIES IN THE WORLD OF BRIDGE AESTHETIC DESIGN—WORLD’S MOST BEAUTIFUL BRIDGES OF THE 20TH CENTURY In 1999, the British “Bridge Design and Engineering” magazine held a 20th century world’s most beautiful bridge contest. Magazine editorial department invited 30 internationally renowned bridge academics, engineers and architects, including the United States, Tung-Yen Lin and Deng, the German Schlaich J, French Virlogeux, Menn Switzerland and the United Kingdom Firth, Flint and Head, etc. Call for comments on the 20th century’s most beautiful bridges. Although tens of thousands of bridge built-in the 20th century, but in the end only 15 were nominated bridge, the top three receiving most of the votes are: 1. Salginatobel Bridge (Fig. 2.20) designed by Swiss engineer Maillart R. in 1930. This is a cross-valley sickle deck arch bridge. Architects said: “Walking on the bridge is a real spiritual enjoyment you and mountains, white clouds, blue sky so close, it constitutes a beautiful Alpine landscape.”, “All parts of the bridge are just right, impeccable. This is truly a combination of fine art and bridges.” 2. Golden Gate Bridge in San Francisco (Fig. 2.21) designed by American engineer J.B. Strauss in 1937, with Swiss engineer Amman (Fig. 2.23) as consultants. It’s comment: “It’s sleek, proportion, is the jewel in the bridge project, so that the designers of this century has been unable to go beyond.”

Fig. 2.20 Salginatobel bridge.

Fig. 2.21 Golden gate bridge.

3. The French engineer Jean Muller designed Brotonne Bridge (Fig. 2.22) in 1974. Although there are so many beautiful cable-stayed bridge in the world, but this is only the span of a single cable plane 320 m concrete cable-stayed bridge with its simple, clean, shape and hardness and softness coordination demeanor got the judges unanimously appreciated.

Fig. 2.22 Brotonne bridge. 4. Kirchleim Bridge Overpass (Fig. 2.23), Germany design by J. Schlaich in 1993. Streamlined shape and bending moment diagram of the bridge is similar to the body, gives a sense of strength. 5. Orly Bridge (Fig. 2.24), France design by E. Freyssinet in 1958. It is delicate and graceful curves gives a strong feeling.

Fig. 2.23 Kirchleim Bridge Overpass, Germany.

Fig. 2.24 Orly bridge, France. 6. First Bosporus Strait Bridge (Fig. 2.25), Turkey designed by the Freeman Foxand Partners Brown (William Brown), United Kingdom 1974. This design by the British Eurasian Bridge is an impressive building. 7. Sunniberg Bridge (Fig. 2.26), Switzerland designed by C. Mann in 1997. This is a beautiful rainbow, a boutique bridge building.

Fig. 2.25 First Bosporus Strait Bridge, Turkey.

Fig. 2.26 Sunniberg Bridge, Switzerland. 8. The French Normandy Bridge (Fig. 2.27), designed by M. Virlogeux in 1994. This cable-stayed bridge with a perfect coordination with local landscape. 9. Tatara Bridge (Fig. 2.28), Japan designed by Bridges Syndicalism in 1998. This is the maximum span cable-stayed bridge in the 20th century, with a mysterious oriental beauty.

Fig. 2.27 Normandy Bridge, France.

Fig. 2.28 Tatara Bridge in Japan. 10. Severinsbrücke (Fig. 2.29), Germany designed by C. Lohmer in 1959, the earliest single tower cable-stayed bridge, with simple and beautiful modeling, and shines with the Cologne Cathedral. 11. Ting Kau Bridge (Fig. 2.30), Hong Kong designed by Germany in 1998. The bridge is a masterpiece of hybrid structure, art and unified technology.

Fig. 2.29 Severin Bridge, Germany. 12. Ganter Bridge (Fig. 2.31), Switzerland designed by Mann in 1980. This is a real art surgical products, an innovative system. 13. Harbour Bridge (Fig. 2.32), Sydney designed by Brad Freeman and Fuerth in 1932. It brings the beauty of Arch from any angle. 14. Fehmarnsund Bridge (1963) (Fig. 2.33), Germany designed by F. Leonhardt. Beautiful basket arch bridge and cross the ramp boom gives the space a sense of stability. 15. Danish Great Belt Bridge (Fig. 2.34), COWI company Ostenfeld K Design (1997), This is not the longest span suspension bridge in the 20th century, but the unique design of the bridge towers and anchorages gives a deep impression. Among the above 15 are suspension bridges, Golden Gate bridge, Booz Poros Bridge, and Great Belt Bridge; 5 Stayed Bridges: Severin Bridge, Brooklyn Bridge, East Carolina, Normandy Bridge, Tatara Bridge and Ting Kau Bridge; 3 Arch Bridges; Sarkisyan Valley Bridge, Sydney Bridge, Fehmarn Belt Bridge; 4 plate pull bridge: Kish Beckham Bridge, Olin Bridge, Shengniboge bridge, Gan Patel Bridge.

Fig. 2.30 Ting Kau Bridge in Hong Kong.

Fig. 2.31 Gan Patel Bridge, Switzerland.

Fig. 2.32 Harbour Bridge, Sydney.

Fig. 2.33 Fehmarn Belt bridge, Germany. From the above the nationality of the bridge designer one can appreciate the country’s contribution to the aesthetics as well as the artistic accomplishment of the designer himself. Among them, four in Germany, Switzerland and France all three, England two, the United States, Denmark and Japan each one. It can be seen from this authoritative selection that span is not the most important factor. The top three winners were arch, hanging rope bridge and the bridge, but not the maximum span of this bridge type. Ranked fourth and the fifth are two overpass spans are 35 m and 53 m. World-known names of the bridge agree, “Do not bother to pursue the longest span.” Span should be meet navigable and natural topographic and geologic conditions determine the requirements, how the safety and under the premise of making a bridge designed to be more applicable economic, more beautiful is what we should strive for the ideal.

Fig. 2.34 Danish Great Belt Bridge. All the selected 15 bridges have a higher aesthetic and landscape value, convincingly. In appreciation of the process, we will realise the beauty of their innovations, the proportion of beauty, balance beauty, harmonious beauty, rhythm, coordination and harmonisation of the US America. As a learning object, let some aesthetic problems on the

domestic large-span bridges were cross-sectional analysis and find out some errors and gaps in order to strengthen our bridges in the future aesthetic considerations design.

2.4 SUCCESS STORIES IN CHINESE AESTHETIC DESIGN OF BRIDGES Although China has not been nominated for the bridge in the 20th century’s most beautiful bridge in the selection, but in many Chinese bridge also has aesthetic value was recognised by some bridges the public and industry experts. Here are 10 (arranged by the completion of age) in innovation and the United States, the proportion of the United States, the mechanical beauty, beauty and modeling aspects of successful examples of coordinated beauty.

2.4.1 Nanjing Yangtze River Bridge (1968) In 1959, China began the Sino-Soviet split and the journey of self-construction of the Yangtze River Bridge. Nanjing Yangtze River Bridge (Fig. 2.35) In addition there are many technological advances in the form of steel and foundation engineering aspects, the main span of 160 m of continuous steel truss used to increase the stiffness of the third string, aesthetically also received a magnificent appearance.

Fig. 2.35 Nanjing Yangtze River Bridge.

2.4.2 Fuzhou Wulongjiang Bridge (1971) Main Span of 144 m Fuzhou Wulongjiang Bridge (Fig. 2.36) was built in a difficult period of ten years of the Cultural Revolution was built in a record span pre-stressed concrete Tshaped rigid frame bridge. The bridge pier 45 holes, length 552.22 m. 55.5 m cantilever, with hanging hole 33 m, the roots of high 8.5 m, to middle reduced to 2 m, arc-shaped curve is very beautiful and appropriate proportions, is for aesthetic success.

Fig. 2.36 Fuzhou Wulongjiang Bridge.

2.4.3 Nanpu Bridge (1991), Shanghai

Under the impetus of the late president of Tongji University, Brandon Lee, Shanghai Nanpu Bridge (Fig. 2.37) pioneered the success of independent Chinese long-span bridge construction, the bridge uses Tongji proposed light weight, construction speed, more suitable Bond Beam deck Cable Stayed Bridge in Shanghai Soft and busy Huangpu river shipping channel conditions. The bridge tower, tall and beautiful, was hailed as the most beautiful cable-stayed Shanghai citizens.

2.4.4 Qiantang Bridge (1996) For W-shaped river channel, Hangzhou Qiantang River Bridge (Fig. 2.38) using the Southbank (Xiaoshan) and North Shore (Hangzhou) two single tower reasonably symmetrical arrangement of cable-stayed bridge, the central shoal is connected with a continuous beam. It is first domestic design to make use of kiloton single cable plane shape, yielding very simple and good aesthetic effect.

Fig. 2.37 Nanpu Bridge, Shanghai.

Fig. 2.38 Hangzhou Qiantang River Bridge.

2.4.5 Wanxian Chongqing Yangtze River Bridge (1997) Main span of 420 m Wanxian Yangtze River Bridge (Fig. 2.39) is the world’s largest span reinforced concrete arch bridge, with steel skeleton outsourcing Reinforced Concrete grade C-60 high performance concrete and advanced control technology built construction. The 1/5 span ratio is reasonable and beautiful, becoming an important landscape project upstream of the Yangtze river.

Fig. 2.39 Wanxian Chongqing Yangtze River Bridge.

Fig. 2.40 Jiangyin Yangtze River Bridge.

2.4.6 Jiangyin Yangtze River Bridge (1997) In 1385 m main span of Jiangyin Yangtze River Bridge (Fig. 2.40) is China’s first superkilometer suspension bridge. Carried out on the bridge tower aesthetic treatment, compared with other several suspension bridges, its tower line to beam size ratio is appropriate, and remains its attractive appearance and excellent quality a decade after use.

2.4.7 Lupu Bridge (2003) Main span of 550 m, the Lupu Bridge (Fig. 2.41) has a span of a world record in the steel arch bridge, but does not have the conventional parallel truss arch form, and the use of more aesthetic in basket-style box bearing rib arch. Due to the quality of the rib segments box reached 480t, in the face of the inclined arch Cantilevering is a huge challenge. While much of the construction costs of steel, and to overcome the difficulties of construction control, but the aesthetics point of view, than the box-shaped arch truss rib arch more modern. 2008, Lupu Bridge gained international bridge association’s outstanding architecture award.

Fig. 2.41 Lupu Bridge.

2.4.8 Nanjing Yangtze River Bridge (2004) Nanjing Yangtze River Bridge (Fig. 2.42) was the first use of “/\” shaped curve pylon cable-stayed bridge, the program may be the revelation of the international contest second stonecutters bridge in Hong Kong “Heaven” concept. Tower bridge following the adoption of concrete, steel deck above the tower to speed up the construction speed. Mixing tower joints using advanced shear construction, its magnificent pyramid-shaped tower is loved by the public.

Fig. 2.42 Nanjing Yangtze River Bridge.

2.4.9 Su Tong Yangtze River Bridge (2008) The world’s first ultra-km cable-stayed bridge, due to the large span bridge tower 300 m, with a stable and strong sense of inverted Y-shaped pylons are necessary. Total length of 6 km of horizontal and vertical curves arranged like a dragon across the wide Yangtze River, constitutes a beautiful breathtaking views, giving eternal beauty. Su Tong Bridge won the first place in the Bridges and structures Photo Contest 2009, held at the International bridge association.

Fig. 2.43 Su Tong Yangtze River Bridge.

2.4.10 Zhoushan Island Project Xihoumen Bridge (2009) Xihoumen Bridge (Fig. 2.44) is a suspension bridge with a main span of upto 1650 m, and is located in the region of strong typhoons, must be separated from the double deck box to meet the requirements of wind stability. On the pylons were aesthetic styling treatment, the first time this world with large-span suspension bridge split stance with its magnificent bridges become another milestone in China.

Fig. 2.44 Xihoumen bridge.

2.5 CHINA BRIDGE AESTHETICS DESIGN PROBLEM ANALYSIS 2.5.1 On the Rationality of Bridge Main Hole Span Main hole span of bridge is the most important aspect in long-span bridges scale, which determines the bridge type selection. Main hole (Navigable) navigation bridge span must first meet the requirements, taking into account the main pier anti-ship collision safety. China’s inland waterways is no clear uniform standard, they use a bridge deliberations, after the Ministry of Transport Water Transport Department to conduct feasibility studies depending on the circumstances at the bridge site fairways make case decisions. In this case, since the revetment work is limited to China waterway near the city zone, resulting in a large and stable enough swing waterway, plus there are still a large number of small vessels and large tugs hit pier accident, waterway sector is often calls for increasing the main span of the bridge to ensure navigation safety. There are also the owners in order to pursue “the span of the first”, indicating the use of excessive force span, which brought the ratio between the bridge across the main navigable height and disorders, but create a sense of oppression. The normal ration of main span (two-way navigation) to the navigable clear height falls between 15 m to 18 m, the maximum should not be exceed 20 m. An arrangement of two navigable holes (top and bottom rows of holes navigation), the main span and the clear height ratio should be 10 or less. However, there are many domestic large-span bridges have exceeded this proportion. Since the main crossing points is too large, so that cable-stayed bridge pylon height above deck and below deck height imbalance, especially when used in deck elevation elected at the legs of the gem-shaped pylon, it shows the lower part too short and tall enough to affect the aesthetics of the bridge tower shape. A Case Study of Nanjing Yangtze River Bridge, the bridge main span of 628 m, while the navigation bridge is only 24 m in height restricted Nanjing Bridge upstream, resulting ratio between the two is 26.2. Tower high above the deck for 150 m, above and below deck tower higher than 150/24 = 6.25, which creates the effect of short leg pylon gem type (Fig. 2.45), make cable-stayed bridge in overall lack of beauty. In contrast, the Shanghai Nanpu Bridge and Yangpu Bridge pylon shaped gem because there upright sense of proper proportion.

Fig. 2.45 Nanjing Yangtze River Bridge.

In the middle reaches of the Yangtze River (Wuhan–Nanjing section), in order to meet the requirements of navigable inland level (clear height 24 m), the use of cable-stayed bridges with the main span of 400~500 m is a reasonable choice for the economy. If the underlying low construction cost can also be used across 160~200 m of multi-beam bridge to meet up and down the rows of holes navigation. However, in the blind pursuit of largespan, but there have been some misguided thinking across a river 800~1000 m span cablestayed bridge, and even super-kilometer suspension bridge. At this point, span and bridge clearance height ratio much higher than the 20 : 1, even upto 50 : 1 entire deck “lying” on the water, completely lost beauty. Moreover, the cost is very expensive, and the adjacent smaller bridge span is also very coordinated. France, Greece, in the design of the Strait of Rion-Antirion bridge, in order to meet the requirements of 180000t of navigation, the use of multi-span cable-stayed bridge 560 m (Fig. 2.46). Between Denmark and Germany Fei Manen Channel Bridge, for the navigation 260,000t seagoing vessel, the recommended solution is multi-span 780 m double rail-cum Cable Stayed Bridge, bridge truss Composite Beam (Fig. 2.47), a solution worth learning.

Fig. 2.46 Rion-Antirion Channel Bridge, Greece.

Fig. 2.47 Fei Manen Channel Bridge.

2.5.2 Facade Layout Symmetry Arranged in accordance with the position of the main channel fairway hole layout principles is a quite natural layout. However, some owners prefer regardless of position in the water channel width symmetrically arranged, or even ask to move the channel by channel diversion works and dredging, which is very unreasonable. Facades of foreign long-span bridges are mostly arranged to determine the position of the main hole span and in accordance with channel centerline, while the edge of the hole

at the actual water depth and geological conditions are arranged left-right asymmetry (left and right edges of different pore size). As the water widens, it can also be arranged in a symmetrical side hole, plus about the length of different non-navigable water hole bridge, to form an asymmetric distribution holes in general, and to indicate to the navigation of the ship channel the water side of the actual bias location. Sometimes, you can also employ single tower cable-stayed bridge asymmetric arrangement or the use of collaborative systems to adapt to nature, and to achieve the purpose of the economic fabric of the hole. Take the design of a bridge to the program as an example [Fig. 2.48(a)], because the owners unreasonably required by the symmetrical arrangement of the water and had to increase the span of the main hole to 428 m, and the need to move the channel 46.5 m, in order to meet shipping requirements, navigable but still biased side of the main pier, increasing the risk of ship collision. Moreover, increasing the main hole is not conducive to the stability of the whole economy and arch bridges, but also increases the difficulty of construction. Instead, the use of asymmetric arrangement [Fig. 2.48(b)] not only conforms to the natural, to the economy and security in general, but also in the aesthetic point of view, a reasonable asymmetrical arrangement can also be presenting a beauty.

Fig. 2.48 Facade arrangement of a bridge (size unit: m) (a) Arranged symmetrically; (b) Are arranged asymmetrical.

2.5.3 The Side Holes Scales in Cable-stayed Bridge The ratio of side hole and central hole in the twin tower cable-stayed bridge is a question of the overall arrangement must focus consideration. According to earlier studies, Professor Leonhardt of Germany, in order to control the magnitude of stress tail cord to ensure its anti-fatigue properties, the tail rope must reserve sufficient internal forces of dead-load, live-load so that the positive and negative changes caused by the internal forces without causing too much stress amplitude. One important measure is appropriate to shorten the length of side spans of dead-load to increase the tail rope tension, and deadload and live-load than the smaller side span and is also smaller than the mid-span. At anchor when the ratio of maximum stress to minimum stress is under kac = 0. 4, relationship shown in Table 2.1 can be drawn from Fig. 2.49.

Domestic cable-stayed bridge, a strong side beams and pouring of concrete at the ends of the hole plus the weight of the transition are commonly used to to provide balance weights, there will be a mutation in the shape of the beam, affect the appearance. It is mostly used in foreign countries made a long pull anchor seat, anchor pier on the use of weight to balance the tail rope pull force, and set the continuous transition pore (transition span), the joints move to the rear end of the transition pore to optimize the structure at the anchor pier, as shown in Fig. 2.50.

Fig. 2.49 Beam stiffness affect the relationship between la/lm and p/g of (kac = 0. 4 time).

Fig. 2.50 End processing in cable-stayed bridge. Note: The solid line is ignoring curvature, shaded conditions included bending stiffness. Table 2.1 Effect of the beam stiffness on the la/lm and p/g ratio Deck type

Deck live-load, constant load ratio p/g

Side-span to cross-span ratio la/lm

Steel deck

0.4

0.35~0.39

Bond beam deck

0.2

0.40~0.45

PC deck

0.125

0.46~0.5

2.5.4 The Arrangement of the Auxiliary Pier in Cable-stayed

Bridge Side Span Whether applying auxiliary pier on the side span is an important issue to be considered in the preliminary design. If the side spans are in the water and often the same structure is used throughout the bridge deck, then an auxiliary pier is used mainly to resist high wind resistance cantilever construction phase, because the balance will-enable shimmy double cantilever, construction boom length frequency increases with a sharp decline, with a corresponding wind stability also decreased, but increased the amplitude of the cantilever end of construction very unfavourable. In the side span navigable meet the conditions required, you can set an auxiliary pier, in order to advance the fixed side of the cantilever, the formation of a single cantilever construction better stability. When the side spans are arranged on the shore, you can use the mixing deck approach, that edge may be more economical PC across the deck and arranged a number of shoreside pier, so that the force to meet the high beam simply supported beam construction phase state requirements, and with the cross-beam of high co-herence. Side span of the pier can be uniformly arranged [such as France Normandy bridge, Fig. 2.51(a)], can also be arranged unevenly, across the river to the shore that is gradually decreasing cross direction, in order to achieve a sense of rhythm aesthetic [such as Hong Kong Ngong Shuen Island Bridge, Fig. 2.51(b)].

Fig. 2.51 Arrangement of shore side span in cable-stayed bridge pier aid (size unit: m) (a) Nommandy bridge; (b) Stonecutters bridge.

2.5.5 Pyramid Select and Proportion Pylon cable-stayed bridge is an important factor in the landscape, we must attach great importance to the proportion of its shape and size, and the latter more important. The tower of built bridges can be summarized as follows: 1. Gantry towers parallel to the surface of the cable and H-shaped towers (vertical

column and diagonal column). 2. A-shaped ramp tower cable plane, inverted Y-shaped towers, as well as the legs to form a bridge following gem-shaped pylons. 3. Single column towers wit single cable plane of (Stonecutters Bridge in Hong Kong), and after additional cable plane cable-stayed to ramp-shaped tower mixed gems (such as the Ting Kau Bridge in Hong Kong).

Fig. 2.52 Various cable-stayed bridge tower. Various pyramids as shown in Fig. 2.52. In these tower designs pay special attention to the two proportional: 1. Height of tower above the deck to bridge width ratio H2/B. 2. The deck height and full-tower high ratio H1/H. High tower cable-stayed bridge deck above the main span L and economy than H2/L ≈ 0.2~0.25. As most of the domestic requirements of six-lane bridge deck width, namely, B ≥ 30 m. If you wish to H2/B upto 4 or more, to make sense of the pyramid there is upright, the main span of L must satisfy the requirements of the following formula:

Obviously, cable-stayed bridge with span less than 500 m, if the bridge width is more than 30 m, the ratio of H2/B is not good enough, the pyramid will be look chunky and not beautiful. Navigation bridge deck clearance height determines the deck height H1, if they wish a H/H1 ratio less than 4, the main span of L should satisfy the requirements of the following formula:

Thus the follows are deducted:

As mentioned earlier, such as the Nanjing Yangtze River Bridge, the bridge height less than 30 m, main span of 628 m, is inappropriate and unnecessary in the navigation. Under the bridge span is too large to make the legs after Chantha than the total height of the tower is too small, resulting in poor aesthetics short legs. Similarly, Su Tong Bridge’s main span of 1088 m, but insufficient headroom under the bridge 60 m, such as the use of the legs of the proportion of gem-shaped pylons are not good enough, do not use inverted Y-shaped legs of the tower is more beautiful, is the right choice. Hong Kong’s Stonecutters Bridge’s main span is 1018 m, bidding plans such as single column bridge pylon tower, A-shaped towers, inverted Y-shaped towers all avoided the imbalance problem caused by legs. In addition to Nanjing Bridge, the Yueyang Dongting Lake Bridge, white sandbar Bridge and Runyang Bridge Auxiliary Channel Bridge also used gem-shaped pylon legs, the height of its deck following a high percentage of the total column and are small, giving a sense of short legs, affecting the aesthetics of the bridge tower. Each of the bridge are the result of the irrational pursuit of large-span. Only when the main span to navigable headroom maintain proper proportions, can sleek pylon be achieved.

2.5.6 Asymmetric Single Tower Cable-stayed Bridge and Collaboration System Bend in the river at a mainstream bank often tend to form asymmetric riverbed section. In this case the use of asymmetric single tower cable-stayed bridge is more appropriate, such as Germany Rhine Flehe bridge (Fig. 2.53). Shoal in the side span can be arranged into a small cross, and the use of PC deck, while the steel bridge across the river, forming a very economical and easy mixing deck construction.

Fig. 2.53 Flehe German Rhine bridge. The First single tower cable-stayed bridge using the collaboration system was the United States East Huntington Bridge (Fig. 2.54). Since the river side of the bridge approach across multi-span continuous form beams, cantilevered and then use the relative

access cable-stayed bridge formed a collaborative system. In order to make use of the side beams and double cable-stayed bridge deck and use a central box girder continuous girder bridge can smooth docking, you must set a transitional period, so that the bridge structure is more complex, which is a drawback collaborative system. Our Zhaobaoshan Bridge has a similar topography, also used the transition period with a single tower cable-stayed bridge and the bridge connecting structure of the cooperative system. Although the cable-stayed bridge cantilever bridge construction, due to improper control of the emergence of the web and the bottom of the box girder section crush accident, but after the removal and repair damage zones and construction control method has been adjusted and pre-stressed arranged after successfully built a bridge. Clearly, as long as the design and construction handled properly, this cooperative system with single tower cable-stayed bridge in the special terrain is very appropriate.

Fig. 2.54 US East Huntington bridge.

2.5.7 Arrangement of Side Span in Suspension Suspension currently uses the vertical arrangement of double cable plane (large-span suspension bridge there may be cases of three cable plane or spatial cable plane), and therefore is not appropriate pyramid changes, mostly using gantry bridge tower, the only difference is the number of beams. The main problem is in the main span to determine how the terrain conditions appropriately furnished by side span. When the side span to cross the water and the long, hanging on the main cable is necessary to form a three-span continuous deck. Such as pylons already ashore, direct access to the main cable anchorage, but with the formation of small independent single-span suspension bridge span bridge approach. When the crossstrait situation is not the same, while there may be side span continuous deck, while the asymmetric arrangement of small independent cross, and even using some of the suspension, a small cross-section independent special arrangement, not in order to construct and calculate the simple use of unreasonable symmetrical arrangement. Typical arrangement of side span suspension bridge shown in Fig. 2.55.

Fig. 2.55 Suspension facade arrangement (dimensions: m) (a) Tsing Ma Bridge in Hong Kong; (b) Dragon Bridge, Hong Kong.

2.5.8 Proper Height of Main Beam Girder Girder suspension and cable-stayed bridge girder selection is an important issue in the conceptual design factors to be considered are the following two aspects.

1. Coordination between the Main Bridge and the Height of Bridge Approach Main Girder Suspension bridges with large span or cable-stayed bridge with Facade layout span on both sides of the main bridge should be accompanied by a certain length of bridge approach. Approach bridge type usually choose economic aperture as 50 ~ 70 m of small and medium-span continuous beam or a simply supported beam, high beam is 2.5~3 m deep. In order to make the entire bridge deck has a uniform height of the sides in order to achieve a coherent aesthetic, the height of the main bridge deck and bridge approach should be close to the height of the main beam, avoid large jumps.

2. Meet the Wind-proof Requirements of Large Span Bridge From the perspective of wind stability, suspension and cable-stayed bridge on the main beam height requirements are different. Most mining suspension with parallel straight cable plane, this time mainly depends on the main girder high torsional stiffness and provide corresponding torsional frequency, and therefore the main beam height should not be too small. As the Danish Great Belt bridge final selection 4.5 m high beam depth with aspect ratio of B & h main beam = = ≤ 7, to obtain enough to twist and twist frequency ratio. Run Yang Yangtze Bridge using high beam is small, although the lateral wind loads can be reduced, but the twist frequency is low, so that lack of stability, and finally had additional central stabilising plate to meet the wind requirements. Long Span

Bridge is generally used oblique arrangement of cable plane. At this time, due to the oblique cable plane (structural measures) provide a good torsional capability, high beam girder can be small as much as possible, through a wider aspect ratio to reduce wind resistance and vortex shedding. Such as the use of parallel cable planes and even a central single cable plane cable-stayed bridge, you still need to consider the main beam should have sufficient height and torsional rigidity. When using separate double box and slotted central section (aerodynamic measures), the main beam height can be chosen to be as small as possible, because the separation tank has provided sufficient aerodynamic stability.

2.6 CHAPTER SUMMARY Bridge aesthetics philosophy is that every bridge engineer must have the basic literacy. We designed the bridge in addition to the life of each period to maintain the excellent quality of service, you must also give the user the enjoyment of beauty, that bridge not only have traffic function, but also has aesthetic and landscape value. Famous bridge in the world are beautiful, and beautiful bridge will get more protection, will be more durable. With the improvement of people’s living standards, people will continue to require strengthening of bridge aesthetics, and even willing to increase a certain percentage of the cost of programs to choose more beautiful, but not the most economical solution. However, the appearance does not necessarily rely on more money, but through innovative efforts to find the ratio of the structure, balance and harmony, tend to force the most reasonable performance, most economical and most convenient structure construction, but also can be the most beautiful bridge. Well-known foreign design companies have a high bridge engineer aesthetic qualities, but also to establish long-term cooperative relationship with the architect, the whole concept of the design process in constant communication and discussion, to seek technical and artistic coordination and harmonisation. Chinese bridge design profession shows inadequate attention to aesthetics, and the lack of participation and collaboration of architects, and sometimes there is interference and misconceptions affect homeowners, there have been some flaw in violation of aesthetic principles and mistakes, hoping to learn a lesson, to overcome this deficiency, and constantly improve the level of Chinese aesthetics of the bridge.

REVIEW QUESTIONS 1. Fundamentals bridge aesthetics to evaluate the bridge you are familiar with China and the world’s most beautiful bridges and make a comparison, talk about your feelings. 2. What is your evaluation and learning experience for the German professor Leon Hart of the creative process? 3. Successful examples of your Chinese aesthetic design of the bridge and there is a problem any different opinions or supplementary examples.

REFERENCES [1] Engels, Dialectics of Nature Beijing: People’s Publishing House, 1956. [2] Huancheng Tang Bridge Beauty Philosophy Taipei: Plain Bookstore, 1994. [3] Leonhardt Bridges Architecture and Modeling Beijing: China Communications Press, 1988. [4] Yin Delan Wendi Articles with Bridge—China Beijing: Tsinghua University Press, 1988. [5] Ito school. Bridge Shape. Japan Maruzen, 1998. [6] Troitsky M.S. Aesthetic Requirement / / Bridge Engineering Handbook. CRC Press, 1999. [7] Hoi Fan. Aesthetic bridge thinking. Science, 2002, 54 (10). [8] Cai ytterbium Bridge Building bridges Yizhu dream—Taipei: Technology Books, 2003. [9] Xu Fengyun, Chen Derong Aesthetic Principle Bridges Beijing: China Communications Press, 2007.

BASIC FACTORS TO BE CONSIDERED IN THE CONCEPTUAL DESIGN

The basic concept of the design factors that should be considered include other natural conditions, function and various bridge type and basis of suitability and investment. Natural conditions is an objective at the bridge site, not to change the will of the designer, we have through research, collect and test analysis to fully understand and fully grasp it. Extensive research, such as the river regime, must be at the bridge site over the years of hydrological data, the reaction riverbed erosion and siltation, the deep channel stability, etc., over the years bathymetry and tidal information, etc., to make sub-holes are arranged to meet the riverbed underwater environment the laws of nature, laws of nature without destroying hydrology, but also to ensure the structural safety of the bridge. Conversely, if the destruction of the hydrological environment, leading to a lot of erosion and siltation, causing riverbed changes, deep grooves change, will be affect shipping, affect bridge safety. Therefore, through full study, understanding and digesting the results of the rational use of the thematic biography bridge natural conditions, the concept can be scientifically designed to meet these natural conditions, a basic safety requirement for conceptual design. Functional orientation must be subject to the objective requirements of engineering construction and road construction, urban construction, transportation construction and shipping master planning regulatory documents. Determine the functions to meet the functional requirements, including bridges flat, vertical alignment design, layout, and other section shall meet the requirements of the traffic feature, set the main navigation and sub-hole layout should meet the requirements of the shipping function, the applicability of the concept design of the basic requirements. A variety of bridge type and applicability is one of the bases of the professional knowledge, only more learning, more accumulation, in order to ensure the creation of the designer has a scientific basis and foundation of all kinds of bridge type has its history, characteristics and stress the applicability of the concept is designed to meet the scientific laws, can only local conditions and constant innovation. Economy is a basic requirements of designers from the state, conceptual design must comply with reasonable requests economy. Rational innovation economy is the real technical innovation, meaningful innovation. To understand the evolution of technical suitability, as well as the scope of the various forms of bridge-variety basis, and know how to use economic point of concept selection. This is the conceptual design of technological innovation and economic rationality of the basic requirements.

3.1 A VARIETY OF NATURAL CONDITIONS AND FUNCTIONAL REQUIREMENTS Collection of natural conditions and functional planning and other basic information are done mostly through the professional sector or industry department in the form of research reports and raw data for statistical analysis and inference, through a certain review or approval procedures provided for bridge designers its use. Of course, the study of these thematic information itself requires a certain period, so that the work is often synchronised with the design phase, a phased approach. Such as engineering feasibility study stage, you need to geophysical and geological data for individual drill hole data available to the preliminary design phase requires Chukan geological reports, construction design phase of the project requires detailed geological survey data reports. Conceptual design must submit the appropriate depth of these basic data requirements for the outcome, as the basis of the information or documents conceptual design, of course, it does not need as much detail as the preliminary design and construction design, comprehensive, but require accurate, able to seize the natural conditions or functional orientation characteristics, difficulties and points. Natural conditions and functions of the conceptual design is the first step, and it is an important step.

3.1.1 Natural Conditions Natural conditions include river regime, hydrology, climate meteorology, topography, geology water quality, environmental and earthquakes, this section describes each of these bridge conditions at the same time, by engineering examples illustrate how to analyse, use of the information, how to make the conceptual design for to meet these basic conditions. These data used in the conceptual design phase generally has two aspects: on the one hand, the understanding of these materials on the basis of digestion, to seize their core elements and control conditions, the formation of the embryonic form of our ideas and layout; the second aspect, calculation and analysis (macro and control) for general and key components, verification and adjustment of previous ideas and arrangements. As for the geological data, you first need based on geological data and other relevant data to form the basis for discussion and conceptual design and form the basis of this kind of basic size, construction methods and key technologies controlling data, followed by application of geological information related to the macroparameters to checking the feasibility of the basic program.

1. River Regime In the river dynamics, river regime is defined as a plane posture rivers, including the mainstream lines, waterlines and flat morphology (e.g., branch road, corners, edges beach, the heart of the beach, riverbank, floodplain) posed and surface phenomena is about the form of the elements of assembly, sometimes referred to as the basic river flow potential. In addition, there are also pointed out that the definition of river is river flow situation and development trend of the plane. Include: changes in the distribution and trend of river flow

dynamic axis position, direction, and the bay, shoreline and sandbars, beaches and other heart. Evolution of river bed is a branch derived from the research and practice of river regulation process by engineering and technical personnel and technology workers from a broad riverbed evolution out of pure research to a separate branch of the flow plane change. Therefore, the river regime change is the interaction of water and sediment and bed boundary conditions, the results of mutual influence. The main factors influencing the evolution of river generally include the following three aspects: 1. Water and sediment conditions: mainly refers to the total amount and the process of entering the water and sediment downstream. 2. River border: mainly refers to accommodate the main features and parameters and constraints river border movement of water. 3. Project boundary: mainly refers to the case of other works by the stream length, arranged in the form, size and spacing between the upper and lower engineering convergence as well as engineering. Overall, the main concern when choosing the bridge site is about how over the years in the area of the riverbed mechanical action of the water, the main river channel, waterway and other elements of the situation, determine the extent of the impact the stability of the natural elements, and after the bridge on these basic conditions. River regime also inflience the location of navigable hole layout and thus plays a decisive role. Example 3.1. Taizhou Yangtze River Road Bridge over election. Reach for the comparison of Zhenjiang Yangtze river bridge site from the existing shoreline conditions and planning, as well as the stability of river areas, identified three possible positions, namely, Wing Chau North, South Wing Chau Bridge eight bits. Fig. 3.1 Taizhou Yangtze River Highway Bridge segment total plane. Wing Chau Pak channel on the right bank of the water turning red top position, the downstream heart bypass beach area, look left and right support thalweg still swing within a certain range from years of data analysis, but the range is limited, cross-sectional area over the water, river width, average depth change is limited. 1998 more after the changes tend to be small, river regime basically stable. Fig. 3.2 shows a cross-sectional Wing Chau North Bridge bits. Wing Island South Corridor is wide and shallow riverbed, was typical W-shaped, central to the heart of the beach, the main features of evolution: Heart on the beach above mentioned diversion point decline occurred when the heart beach plane position is not stable enough, about thalweg appears limited swing (over 200 meters), the river regime is relatively stable. Fig. 3.3 shows a cross-sectional Wing Chau South Bridge bits. Eight bridge has wide and shallow river channel, deep grooves stickers right, Ushaped cross-section, the deep grooves on both sides of the development of this position closely with upstream over the hearts of Boat Harbour Beach, while the confluence point

of the lateral movement of a large (500 m), 1998 years later, and have put on the right. Beach and river regime by heart day Xingzhou greater impact. Fig. 3.4 is eight bits Bridge cross-section.

Fig. 3.1 Total flat section of the river bridge site.

Fig. 3.2 Wing Chau North Bridge bit section.

Fig. 3.3 Wing Chau South Bridge bit section. Riverbed evolution analysis; Taiping Island left branch (Oe) three elected positions than from the perspective of both fluvial Guojiangtongdao basic macro with the construction of river conditions. After comprehensive comparison believe, Wing Chau Pak channel section of river conditions macro better.

Fig. 3.4 Eight bits Bridge section.

2. Hydrologic That is flow, flow, water quality, tidal, wave and other basic information on the maximum and minimum navigable water level, of bridge site area and needed for bridge design, constant level, the design frequency of flood level, wave height, wave power, etc., design parameters. According to “General Specification for Highway Bridge Design” (JTG D60-2004), freeway, highway design flood frequency Bridge 1/300, 1/100 Bridge. The pier is located in the water, the water pressure should be calculated, and so the role of wave forces on piers, bridge tower. Example 3.2 Wuhan White Sandbar Bridge. Wuhan White Sandbar Bridge is City Master Plan linking the north and south sides of another traffic arteries, the Hankou hydrological station, 11.1 km downstream, during which the Han river to import, according to statistics, the average annual flow of the Han river accounts for about 6% Hankou station, average annual sediment load accounted for 10.8% Hankou station, therefore, Hankou hydrological station sediment eigenvalues basically reflects the bridge site reaches of run-off and sediment conditions. Table of hydrology, sediment characteristics Hankou station value Tables 3.1. Table 3.1 Hydrology, sediment characteristics Hankou station value tables (table elevation Wusong elevation).

Water level (m)

The maximum value & the minimum value Value Date (Year, Value Date (Year, Average Statistical max month. day) min month. day) years year (Years) 29.73 1954/8/18 10.08 1865/2/4 19.16 1865~1991

Flow rate (m3/s)

76100

1954/8/4

2930

1865/2/4

579

1964

2.67

1954

4.26

0.772

1966

0.273

1954

0.611 1953~1991

Item

Annual sediment load (one hundred million t) The annual average sediment concentration (kg/m3)

23438 1865~1991 1953~1991

From the run-off and sediment from the Hankou station statistics, Hankou station to

sediment run-off during the year mainly concentrated in the flood season in October, 73.3% of its accounts for the year runoff, sediment accounts for the year 84%, more sediment than to focus on the flood water. Wuhan river flood control standard shows, according to the Yangtze river flood control planning, once in a century flood contained within dikes and flood diversion area upstream of the joint use of the standard range of defense, while the water level in Wuhan dike designed for the highest level measured in 1954, 27.64 m (Yellow Sea elevation, the same below), therefore, the use of bridge design water level with the corresponding values of 27.99 m, the design flow using the value of 1954 Hankou station measured maximum flow rate 76100 m3/s minus the Hanjiang river flows into the sink after 73380 m3/s. Highest navigable water level used is the 20-year flood peak of 26.25 m, the minimum guaranteed rate of navigable water level of 99% using the low water level 10.21 m.

3. Weather and Climate Meteorological refers to the atmosphere of hot and cold, wet and dry, the general term for the wind, clouds, rain, fog, snow, frost, lightning, and other physical phenomena and physical processes. Meteorological observation projects have air temperature, humidity, temperature, wind direction, wind speed, precipitation, sunshine, barometric pressure, weather phenomena. Climate refers to a region-specific integrated weather for many years, the so-called unique weather conditions refers to the average weather conditions in both years, including the area in individual years the emergence of some extreme weather conditions, is an area of cold, warm, dry wet weather conditions and other basic features of a comprehensive reflection. Various statistics of meteorological factors (temperature, precipitation, wind, etc.) (mean, maximum, probability, etc.) is the fundamental basis for the expression of the climate. Determine the parameters and design based on meteorological data directly relevant to the study of climate. Basic design wind speed in bridge area (m/s), is according to the Department of flat open ground, 10 m high from the ground, the return period of 100 years 10 min, average, maximum wind speed calculated and determined; when the lack of wind speed observations bridge area, v10 can norms “national basic wind speed map and weather stations across the country the basic wind speed and basic wind pressure value” of the relevant data and the use of the field after investigation and verification. Construction stage of the design wind speed is multiplied by the wind speed according to different return periods return period factor, such as the return period of 5 years, the return period is 0.84 coefficient of 0.78,10 year, when construction of the bridge over the surface structure of less than 3 years, may be not less than 5 years return period wind; when the construction period of more than three years or a bridge located typhoon-prone areas, we can use a moderate increase than the actual wind conditions return period factor. According to bridges and culverts specifications, calculate the role of bridge structures caused due to a uniform temperature deformation or constraint applied, the structure should be restrained when the temperature begins to consider the role of the effect of the

highest and lowest effective temperature. Maximum and minimum standard value of the effective temperature of the structure is calculated according to the local calendar highest or lowest average daily temperature average daily temperature, such as for steel deck bridge, with temperatures between 20~45ºC, its effective temperature standard value = 38 + (Tt – 20)/2.00; the temperature is between (2~50ºC), the effective temperature of the standard value = –1.48 + Tt / 0.91. Such as the lack of actual survey data, the value adopted by the specification table. According to the environmental conditions in which the durability of bridge design is performed, specification of the environmental atmosphere is grouped into four environmental categories: (i) class is warm or cold regions, and non-aggressive contact with water or soil; (ii) class is cold regions of the atmosphere use of de-icing salt environments, coastal environments; (iii) class is the marine environment; (iv) class is subject to aggressive substances affect the environment. Example 3.3. Hangzhou Bay Bridge. Hangzhou Bay is located in the eastern coast of China, the sub-tropical monsoon climate zone, monsoon significantly, the annual four seasons, mild climate, humid, and rainy. Meteorological elements characteristic bridge area values can be analysed based on the series of Cixi weather weather stations and bridge the north shore of Pinghu south bank from 1954 to 2000, measured data, the results shown in Table 3.2. Table 3.2 Meteorological eigenvalues bridge area exemplar project Pinghu Cixi. Item

Air temperature

Extreme maximum temperature (°C)

38.4

Chee creek 39.1

Extreme minimum temperature (°C)

–10.6

–9.3

The annual average temperature (°C)

15.8

16.2

The average temperature in the coldest month (January) (°C)

3.7

4.1

The average temperature in the hottest month (July) (d)

28.2

28.3

≥ 35ºC average number of days (d)

5.4

14.7

≤ 0ºC average number of days (d)

40

28.9

Average annual precipitation (mm)

1220.3

1294.6

The maximum monthly precipitation (mm)

468.3 (June)

569.3 (June)

≥ 50 mm annual precipitation days (d)

2.7

2.7

The longest continuous precipitation days (d)

20

19

The maximum wind speed (m/s)

20.3

22.6

Maximum wind speed (m/s)

32.2

31.9

Precipitation

Pinghu

Wind

Fog Day (d)

Often wind

SE

ESE

Strong wind

NW

NW

≥ 8 winds number of days (d)

16.3

11.1

Typhoon affect

5~11

5~11

The annual average number of typhoons

2.56

2.56

57

67

35.6

21.5

82

81

56

58

32.1

36.6

15

17

Years up The annual average

Relative humidity Annual average (%) Thunderstorm days (d)

Years up The annual average

Snow depth (cm) Maximum

Severe weathers affecting the Hangzhou bay area are mainly typhoons, tornadoes, thunderstorms, strong cold air, fog, heavy rain, etc. These severe weather has some effect on the construction and operation of the bridge, need to be considered.

4. The Topography Topography mainly refers to the terrain and location of surface morphology, including natural and artificial surface features, including the feature, the ups and downs of the state of the surface. Its natural form can be divided into mountains, hills, plains and basins. Example 3.4. Hangzhou Bay Bridge. Hangzhou bay is located in the Yangtze river in the landscape, river plain area north of Zhejiang plain area, is composed of coastal and lake sediment accumulation formed environment, low and flat, the general elevation of 2~7.5 m, many in the region, Wu Tong, dense river network. Near the bridge site can be divided into land, beaches and waters of the three geomorphic units. 1. Land: Across the Hangzhou bay is a vast plain terrain, flat, local monadnock distribution. 2. Beaches: Beaches across the Hangzhou bay has developed, with silty sand and silty floodplain dominated under the tide, is a tidal flat topography. North Shore beaches narrow to shore erosion mainly south coast beaches, said three north shallows to silting based. 3. Sea: Under the strong trend of Hangzhou bay, the main role of the formation of the trend and the trend of the ridge notching two landforms. Example 3.5. Su Tong Bridge. It was known from October 2001, underwater topographic maps that the main channel bridge bit of Su Tong Bridge has a steep slope on the right side, in the south of the main

pier on both sides to be selected around each 200~300 m slope of 2.5% to 4% zone relatively slow, and the bridge upstream position –40 m deep trench distance of about 500 m, obviously this bridge than the engineering feasibility study stage main pier south axis to optimize more favorable position, shown in Fig. 3.5. Figure 3.6 June 2003 schematic cross section measured bridge axis, the distance between the levee is about 6250 m. Main channel was “V” shape, a bit south coast, –10 m contour covering waters width 1970 m, –20 m contour covering waters width 1170 m, the deepest point elevation of about –32.7 m, the north-south main tower location situation bed elevation are about –15 m and –26 m; clip groove in the main channel south of the main channel and clip groove center distance of about 1700 m; clip was bowl-shaped groove, width of 430 m, a bottom surface elevation of about –10 m .

5. Geology Geology refers to the nature and characteristics of the earth. Mainly refers to the earth’s material composition, structure, construction, development and history, including the Earth’s spheres of differentiation, physical properties, chemical properties, rock properties, mineral composition, rock formations and output state, the contact relationship between the Earth history of structural development, biological evolutionary history, the history of climate change, as well as the status and distribution of occurrence of mineral resources.

Fig. 3.5 River bed topographic maps near the South Main tower.

Fig. 3.6 Axle shaft section.

These data are obtained by geological and geophysical exploration drilling. Geophysical map identify: geological structure (fracture location, size, fragmentation width, occurrence, nature, etc.), poor geological phenomena, the bridge near the axis of the underwater terrain, cover thickness, bedrock depth, lithology and so on. Given soil, bedrock material through mechanical parameters of the standard penetration test, soil testing, rock testing. These data are used for the designer to select pier bit bearing stratum and construction methods. Example 3.6. SuTong Bridge. Bridge site area bridge site area is divided into 22 engineering geological layers based on geological strata expose era, genetic type, lithology, and burying their physical and mechanical characteristics, each layer is mainly characterised as follows. Holocene (Q4) is divided into four layers (1~4 layers): one for the north side of the upper layer of silt loam or silt clip, sub-divided into three sub-layers; two for the south bank of the upper layer of clayey “crusty layer”; 3 layers of silty loam or silt south side of the upper mezzanine, divided into two sub-layers; 4 layers for the bottom of loam or silt loam with inter-bedded. Upper Pleistocene (Q3) is divided into four layers (5–8 layers): five layers of siltbased, local clayey, is divided into three sub-layers; 6 layers of coarse sand. Pebbly, local sand, was divided into two sub-layers; 7 layers of fine sand, silt; eight layers sandwiched coarse pebbly silty sand, clay sandwiched lens-shaped sub-divided three sub-layers. Pleistocene (Q2) is divided into 6 layers (9 to 14 layers), lithology powder, sand layer, clayey soil. Lower Pleistocene (Q1), on the third line (N) at 200 m above the roof depth, roughly divided into eight engineering geological layer (15 to 22 layers). 16 to 22 projects for the Lower Pleistocene geological formations and the Upper Tertiary sediments, sand next to the main folder Pleistocene clay, on the third line for the semi-cemented like clay, sandbased, bottom to expose the basalt. Table 3.3 Quaternary stratigraphy profile. Table 3.3 Quaternary stratigraphy exemplar. Department

Quaternary

System

Codenamed

Jane Main lithological thickness (m) 3.000

—

In general, each bridge has a span of its most affordable. Under or over this affordable economical range, although it is possible to build, but is often not economical or technical difficulties on the other indicator. Therefore, should in principle within the scope of the economic alternative to competing programs. Main span of 200 m bridge PC continuous girder bridges, PC continuous rigid frame bridge with continuous beam bridge, arch bridge of concrete-filled steel tube and steel, steel box arch bridge and PC cable-stayed bridge (Tower) options and comparisons. Main span of 500 m bridge steel box arch bridge, a steel truss arch bridge, PC cable-stayed bridge, girder cable-stayed bridge options and comparisons. Generally, 700 m should choose a lighter steel deck pavement of bridge deck cable-stayed bridge cable-stayed bridge. However, due to China’s truck out of control, durability of steel deck pavement has not been properly resolved, paving damage cannot be repaired in a timely manner would cause fatigue crack of the orthotropic steel bridge deck, affecting the durability of steel deck. Because this improved performance more reliable structural steel deck and extend use of composite girder cable-stayed bridge is worthy of consideration. Cable-stayed bridge spanning breakthrough kilometers, its economic scope upto 1200 m, 1400 m, plus, stiffness, cable-stayed bridge cable replacement, and does not require anchorage advantages will be an advantage in competition and suspension bridges, thus forced back toward the larger span of suspension bridge. Can even be envisaged within the span of 1500~2000 m, cable-stayed and suspension cable system may be able to anchor construction easily made of low stiffness and suspension bridge and further to 2000 m back down. According to the development trend of seagoing vessels, the seventh generation of container ships has reached 400,000 tons, high vertical clearance requirement is above 70 m. In order to adapt to existing port bridge navigation standard, larger seagoing vessels would limit height, and continue to grow in width and length show vertical clearance width will increase accordingly, but will not increase without limit. We shall continuously improve the lower foundation in deep water technology and economic level, across the span of a bridge linking the island and the Taiwan Strait in the future limit at the level of around 3500 m to improve bridge competitiveness of the beams for the tunnel option. Because as the bridge span increases, and its cost will rise rapidly, in the face of increasingly sophisticated tunnel DAO technical and economic indicators, the bridge will be difficult to compete and tunnel scheme.

Finally, it is to be noted that, from the perspective of the development trend of ship navigation (see Table 3.9) and is currently navigable routes less than 300,000 tons road hole bound navigation time, 2 holes 750 m of multi-tower cable-stayed bridge has been able to meet the requirements, such as being designed by Germany and Denmark carries upto 260,000t of Fei Manen Strait between ocean liners, 34 Tower cable-stayed bridge across 780 m more economic plan would eventually overcome the large-span (5) suspension bridge even for the future potential of a 500,000 ton lane, 2 × 1500 m navigation requirements can also be used more competitive multi-tower cable-stayed bridge scheme, so as to avoid deep water anchorage difficulties. Furthermore, programmes are more likely to meet the rail cable-stayed bridge for two stiffness requirements for bridge, especially the advantages of cable can be replaced, durability and total lifecycle cost of the cable-stayed bridge suspension bridge better than the suspension bridge. In short, the km over the span of bridge type selection of cable-stayed bridges should be given priority, and caution on suspension bridge. Unless faced with water deeper than 100 m and a wide channel, which span more than 1500 m, you must use consecutive TRANS2000 m (5) suspension bridge At this point, such as Sham Shui Po anchorage must be addressed through research and development, anti-sliding at the tower of the main cable, and rigidity of customs key technical problems and also had to face the strong competition of the tunnel option. Denmark and Germany between instances of the Fehmarn Belt Bridge is an important revelation: in order to meet 260,000t sea navigation ask, after thorough investigation and analysis of ship collision risk, recommending three-span bridge program is a four tower 780 m of truss composite beam cable-stayed bridge, who gave up on large cross-(2000 m) ICP-suspension bridge, to stay competitive on the tunnel option. Since most of the tonnage of the ships below 300,000t, ultra large ocean liners were just a few of the more than 300,000t. Even if you want to ask at full speed, “freedom of navigation” porous 1~200 m have been 300,000t to meet the shipping requirements (see previous Table 3.9), occasionally there are a few more than 300,000t of ultra large ocean liners pass through, deceleration can be used by “constrained navigation”. In this way, 1200 m long-span cable-stayed bridge is the most competitive Cross-Sea Bridge. Cablestayed bridges stiffness, wind resistance performance is good, cables can be replaced, and avoid deep water anchorage of suspension bridge and across the main cable saddles of suspension bridge tower problems such as skid-resistance, not only economy better than suspension bridges, but also has the competitive advantage of the tunnel option. Therefore, in addition to 5 km-width Super Sham Shui Po (100 m) strait-tower suspension bridge spans must be used (for example, Italy Messina Strait Bridge), the water is wide (20 km) Strait Bridge should be give priority to the economic rational scheme of cable-stayed bridge, rather than blindly span breakthroughs, not economical for large-span suspension bridge scheme and loss of competitiveness in tunnels.

3.3.3 Application Scope of the Basic Forms Bridge foundation construction technology for development along with the evolution of the bridge structure, and construction equipment improved, as well as bridge builders design concept and idea development.

In General, the current main types of rigid spread foundation of bridge foundations, piles and column bases, the caisson and bell-shaped bases, sink box foundation and piles, pipe, bell formed the basis of open caisson, a combination of foundation, where the oldest and most commonly used in amounts foundation is the biggest pile, then caisson foundation. Pneumatic caisson construction of foundation for security and other reasons, this technology in Japan has become less application, instead, auto pneumatic caisson foundations in the early 1990, of the 20th century, the medium-term, fundamental developments are mainly tubular column base combined base and bell-shaped bases and foundation; late in the 1990, of the 20th century, forms the basis of many other bridges to build, such as locking steel pipe pile, column bases, underground continuous wall of double tubular column foundation bearing platform, and so on. At present, with the needs of the sea-cross bridge construction and advances in construction technology, pre-cast or overall basis set show prospect, which is similar to the offshore drilling platform design and construction of ultra deep foundation also received wide attention and research engineer. In bridge foundation design, must consider the feasibility of bridge structural system and construction as well as depth, geology, hydrology and environment many bridges, such as the natural conditions by analysing and comparing the foundation type selection. Natural conditions of the bridge is the underlying type determinants of choice. For the depth of water is less than 5 m and have exposed bedrock, rigid spread foundation is the preferred type for depth of 5~50 m range bridges, piles, tubes and caisson is the underlying type of the applicable, in which 5~20 m depth, domestic construction technology quite mature; at a water depth of 50~70 m base, the construction is very difficult, more suitable for installation of pre-fabricated construction of sinking well foundation and bell-shaped base, in this regard, there are many success stories abroad; for a water depth larger than 70 m basis, whether in the basic shape type selection and appropriate construction technology is a challenge, may adopt similar forms the basis of offshore platforms. For the foundation through the overburden thickness, steel piles and pipe buried near 50 m; 100 m bored pile to soil; open caisson of fitness appropriate range of 35~50 m, maximum 100 m locking steel pipe pile 35~50 m soil depth is more appropriate based on the underlying type. For bridge site geology, such as thick in the river gravel layers greater than 10 m, driven piles, pipe foundation, locking construction of steel pipe pile foundations have difficult issues. If structural basis, ground and river areas are required to have the ability to resist horizontal force, inclined pile foundation, Shen Jing Ji bases are a good choice. All in all, a variety of bridge Foundation respectively, to adapt to different geological conditions and environmental factors, at the location of the bridge superstructure of requirements and load characteristics, and so on. the following three general forms the basis of modern times, appeared after the war forms the basis of modern and 1990s, there were two forms the basis for the development of three new categories based on their structural characteristics and fit as described in condition.

1. Basis of Three Commonly Used Forms Various types of pile foundation and caisson, caisson foundation is the foundation of modern forms, respectively, below their technical features and development, applicable conditions, as well as typical examples.

(a) Foundation Pile foundation of bridge deep water Foundation is the most commonly used and forms the basis of the most economical. Pile foundations are so versatile, versatility, working mechanism varied, so piles are often based on the material, the degree of impact on soil, construction, construction method and load conditions as well as the relative position of the CAP, were classified. Table 3.12 lists components of poles. Table 3.12 Post classification. Classification Materials

Types of pole Stakes, steel piles, reinforced concrete piles pre-stressed concrete piles, composite pile.

Set status piles

Straight, sloping piles.

Construction method Sinking piles, piles, stir in situ soil, Pile the forces

Friction piles (pure friction piles, pile end bearing friction) piles (piles pure friction piles).

Location of caps

Elevated pile foundation pile, low pile caps pile.

Relationship pile and Non- pile, rock-socketed pile. bedrock Compared with open caisson and caisson foundations, in most cases, the foundation has the following advantages: needed to sink into the depth of pile sinking well, small caisson sinking depth required; when the caisson, depths of caissons and piles are equal, pile of material about than the caisson, caisson foundation 40%~60% less material. Therefore, the cost than the caisson, caisson pile foundation; however, along with the advantages and disadvantage is: pile foundation stiffness ratio of open caisson, caisson foundation of small, especially in the case of velocity, scour depth, diameter scour depth increases as it grows, so that its advantages are gradually reduced. Pile the generally applicable conditions are: 1. Low strength and compressibility of the soil covering, or for other such as the ice heaving soil or expansive soil. 2. Unstable soil, and under it in the appropriate depth when there are good supporting layer of soil can be used as in the quake zone, soil covering is liquid. 3. Soil, under which a vibration-resistant stability of soil when Pier Foundation under horizontal force you want about surface soil covering the punching. 4. Brushing effect of large have higher requirements for settlement of bridge

Foundation. 5. Specific site conditions and construction feasibility on pile foundation design options need attention: For sinking piles, RC, PC, PHC pile suitable water depth is 20~30 m, permeable overburden thickness upto about 35 m, mass for the saturated fine sand, clay, sand and gravel; compared to the steel pile and pile type mentioned above, as long as the construction equipment available, which adapt to water depth, covering a wide range of thickness but 10 cm over gravel layer, containing a lot of the strata of rocks or other obstructions, the types of sinking piles are suitable for. Similarly, when the surrounding pipelines or dilapidated houses, are sensitive to soil compaction effect, there is no suitable use of soil compaction effect of sinking pile foundation. Bored pile than sinking piles, piles can be penetrate the hard gravel, cobble and Boulder, also available through the complex geological conditions cave, construction equipment, simple, no squeezing effect, construction noise and vibration, suitable depth and depth greater. Among which the rotary drill hole pile’s suitable water depth upto about 30 m, depth is more than 100 m; impact drill hole pile adjustment suitable water depth and reach the hole is slightly decreased, but you can use a variety of ground conditions, especially in karst areas, would be a plus application of bored pile. Considering pile bearing capacity of end-bearing pile applied in soft soil surface is not very thick, but for hard soil layer in the lower part of the case; brush pile applied in soft soil surface with a thick, with moderate compressibility of the soil layer in the lower part, and hard soil depth in a lot of situations. For low pile foundation and high pile bearing platform of choice depends on the depth and ease of construction, typically in the floodplain, or shallow water sets the low-pile pile foundation. High-pile bearing platform of design should be noted for the underside and navigable relationships to protect the pile from influence of ship collision. In addition, from the point of use, helical pile than a vertical pile has a strong ability to resist horizontal force, may ship impact, waves beats and seismic effects used on the bridge. At present, some latest piling barge equipped with a plug piling upto more than 82 m. Inclination of ±18.5° increased pile capacity; but in the bored pile construction tilt, limited capacity of domestic equipment, generally only achieved approximately 5° of inclination sloping pile. In contrast, foreign construction equipment more capable, diameters can be carried out 1.5 m, 40 m length, tilt 1 : 4 bored pile construction, while form 3 in diameter. 5 m expanded diameter. At present, the pile foundation construction technology is very mature, large pile foundation success stories, too many (as in bridge bored maximum diameter pile has reached 4 m Su Tong bridge main pylon pile foundation composed of 131 diameter 2.5~2.8 m, 124 m bored pile), Has very good economic effect of piles, on many occasions would be preferred. Pile foundation design, there are two points it is worth mentioning: firstly, pile foundation of bridge in the country at present some bias in the application of the project, seems to be “without piling without foundation” tendencies. However, in a busy shipping channel, bridge with earthquake requirements, whether with high-pile

foundation bearing platform appropriate is questionable; second, the bridge pile foundation bearing platform structures are often designed as a solid structure, under the force of the quake, the high-pile piled foundation piles due to pile more and more bent, resulting in not meizoseismal bridge’s pile foundation design of seismic control. Thus, measures that could be considered reduced quality in the design, such as the design of hollow pile cap, set at an angle to reduce small-cap area. Example 3.17. Donghai bridge in Shanghai. Starting Luchao port in Shanghai Nanhui Donghai bridge across Hangzhou Bay in northern waters, and Shengsi in Zhejiang Province small rocky islands of ocean mountain Island, is about 31 km, is the first offshore sea-crossing bridge. Main forms of continuous beam bridge structure (construction method) and the cable-stayed bridge, sub-structure for pile foundations (PHC pipe pile foundations, steel pipe pile foundations). Seen from the geological conditions, typical geological layer from top to bottom to grey-brown mud, black-gray silty clay, gray clay, four-story gray-green, sadly, 1 layer of grass and yellow sand silt clay silt, sadly 2 layer of dust and grass-gray silty (Foundation pile the bearing layer), hydrological conditions and average tidal range 2.75~3.20 m the maximum velocity of 2.4 m/s, wave height of 3.45 m (NNE) and 2.15 m (SE). Considering the tide, tide, wave, wind influence of hydrologic conditions on construction jobs, as well as the corrosion of sea water on the pile problems in the design of the original, non-navigable spans of all foundations set to pile in low pier area high intensity, the compactness of concrete, Cl-penetration resistance performance is good and relatively cheap cost of PHC pipe pile (1200 mm), by vertical piles and piles of pile combination (Fig. 3.78 for 70 m to bridge abutment pile layout and structure). According to the stage of the actual pile of design changes to adjust the pile, the vast majority of the pile into a steel pipe piles. The main reasons are the following several points. 1. Bridge sea tide, tide, wave, wind, fog and hydrometeorological conditions affecting the stability of the pile driver, resulting in the missed hammering and thus pile crushing. 2. The bridge pile foundation bearing stratum of soil top elevation is generally high, and layers thick, and with high sand content in the soil, for Low compression compacted soil, and SPT blow counts, and not conducive to PHC pipe pile sinking. 3. PHC pipe pile tip large section, resulting in large amount of soil compaction and resistance, is not conducive to the pile sunk. Although construction of the additional the steel pile shoes, helped sink the effect is not obvious. In the PHC pipe pile through low compressibility of compacted soil layer is not enough. 4. PHC pipe pile with low cost, good corrosion resistance advantages, but the fighting ability of PHC pipe pile steel pipe piles is poor, and when the hammer more often, when penetration is smaller, it tube pile easily damaged.

Fig. 3.78 Cap structure and pile layout schematic (size: m) (a) platform façade structure; (b) pile layout. 5. Pile hammer equipment capacity and length of PHC pipe piles, pile weight and the pile bearing capacity of an uncoordinated, can’t be “Heavy hammers tapping” the pile requirements. Construction of pile foundations of Donghai bridge practice experience is: the choice of pile foundation of bridge pier foundation should be take full account of environmental conditions the influence of high strength, torsional behavior of the pile should be chosen well, hitting resistance capacity of steel pipe pile; offshore waters affected by seabed scour and deposition, wave impact differs from the geological structure of the continental shelf seabed geological structure, the design should fully analyse soils and bearing capacity force of bridge pile foundation in offshore waters, and upon the request of both vertical and horizontal bearing capacity; whether the waters off the coast with PHC pipe pile foundations, should be based on comparison and selection of foundation conditions were reasonable, to control the construction of the total number of blow and penetration, in order to ensure piling process the pile structural integrity and durability of structures using. Example 3.18. United States, San Francisco-Oakland Bay Bridge. United States—San Francisco-Oakland Bay Bridge East span bridge is a double-deck all 10 lanes of large-span bridge, with a total 4 km, full-bridge into self-anchored suspension bridges and viaducts on the sea, on both sides of the approach spans four parts of wiring, substructure for the pile foundation. Foundation design of one of the most characteristic is the use of inclined pile foundation of high-pile, pile structures in multi-cell box shaped steel frame filled with concrete, being a concrete-filled steel tube. From the perspective of geological condition of the bridge, river bed under the soil distribution varies widely, on main bridge tower is located in relatively shallow bedrock slopes. Most other foundations located deep in the mud layer. Oakland Bay Bridge East span bridge located in the strong earthquake, seismic risk can cause two major geological fault lines of Sandy Bridge site 12 km and 25 km only. Requests by two fortification level for aseismic design (normal use and safety features of earthquake). First piers of the viaduct by sea 50 m high bridge pier foundation (Fig. 3.79) as an example, the pier is located deep in the slime layer shang, pile high 6.5 m, water 2 m,

constructed in the form of box-shaped steel frame filled with concrete, to fight for concrete shrinkage, creep and deformation caused by temperature and reduce the cracks. Foundation due to earthquake deformation and the size of the cap, and cap set of 6, diameter 2.5 m, length about slope respectively, 1 : 8, 1 : 12100 m, pile of steel pipe piles. Design wall thickness along the pile of steel pipe pile long range, range from 51~68 mm, mainly based on bending bearing capacity of piles, ductile, corrosion and “scored” based meter. Within the upper two-thirds length of steel pipe filled with concrete, in order to ensure the transfer of load from the combination between concrete-filled steel tubular pipe, steel pipe pile (a concrete filled area) welded onto the inner wall of shear studs, bottom weld shear ring plate. Fig. 3.79 shows the plane and elevation of pile-raft foundation and steel pipe pile elevations. Construction sequence was: Mencke MHU 1700 hammer for pile foundation construction and pre-fabricated pile floating and sinking in place, through the internal steel frame system pile with steel pipe piles and pier reinforcement of internal connections, and then fill high strength concrete and light-weight concrete, finally setting collision bezel facilities.

Fig. 3.79 Elevation plan of the piled-raft foundation and steel pipe pile elevations (unit: mm).

(b) The Open Caisson Foundation Caisson is the underlying type of an application has a long history, the earliest documented’s caisson at around 5 m tall wooden caisson (1738), but by the time limit of construction technology, the caisson were unable to penetrate deep enough to resist the erosion of soil layer in a long time not used, replaced by a pneumatic caisson foundation. Until the early 20th century, sink well technique to large gauge die use, especially in deep water Foundation, such as the United States Oakland Bay Bridge (1936), depth of 32 m, covering layer thickness of 54.7 m, floating caisson, position suction sink, base depth is 73.28 m. Now, with the large hoisting, transporting construction equipment located and seabed drilling-and-blasting and cleaning floor leveling, pre-casting and installation of open caisson as the main deep water Foundation has been used many times in real cases of cross-Sea Bridge project. Characteristic of sunk shaft foundation embedded depth can be large, high integrity and good stability, can withstand large vertical loads and water flat load; open caisson foundation and construction of cofferdam retaining and retaining structures, the

construction process is not complicated. The open caisson foundation disadvantage is that during a long, fine sand and silt soil in the hole pumping prone quicksand phenomenon, caused the caisson tilt; under the open caisson sunk in the process of large boulders, rock or the bottom surface of the trunk tilted too much, will bring to the construction of certain difficulties. Table 3.13 lists part of the caisson classification form. Table 3.13 Caisson classification. Classification

Types of pole Steel open caisson

Materials

Concrete, reinforced concrete caisson Ferro-cement thin-walled open caisson

Sinking support measures Production methods

Air curtain in open caisson Mud lubricated sleeve caisson Cast-in situ sinking open caisson Floating open caisson

Based on the principle of reasonable strength, construction may, generally in the following circumstances can the open caisson foundation. 1. Load larger, while the extent of allowable bearing capacity of foundation soil on the surface, spread foundation excavation work, and support difficult, but under a certain depth (8~30 m under the surface) have good bearing layer using caisson foundation comparing with other deep foundations, while economically reasonable. 2. II in the mountainous river, although better soil properties, but erosion, or have a larger river pebbles and inconveniences pile foundation construction. 3. The surface relatively flat and covered with thin layers of rock, but the river deeper, using construction cofferdam for spread foundation when you are in trouble. 4. In depth, wave height, tidal rush of cross-Sea bridge project as a basis for precasting and installation settings. Example 3.19. Air curtain open caisson of the. North anchor foundation of Jiangyin Yangtze River Bridge Jiangyin Yangtze River Bridge superstructure loads to Anchorage’s main function was effectively the main cable 64000 kN forces to the foundation, and horizontal displacement control within the allowed range; based on geological conditions of anchorage zone of overburden depth 77.6~85.6 m, Clayey and sand layers, respectively (I), fine sand layer (II), and clay layer (III), fine sand, or gravelly sand layers in (IV), can be used as bearing stratum II and IV layers, depth of 30 m and 60 m, form the basis of comparison for diaphragm walls and sinking. For underground continuous wall construction broke up and makes the construction is not a global stress after forming the basis structures to withstand the anchoring structure outside great water pressure, and at that time the excavation of the underground continuous wall construction experience 40 m integrated in all circumstances, the last anchor foundation of choosing sinking.

Jiangyin Yangtze River Bridge anchorage (Fig. 3.80) sunk well of length 69 m, width 51 m, high 58 m, was the world’s largest caisson. To ensure smooth caisson sinking, elaboration of the general construction plan for non-wood production for the land, repeatedly sinking, sinking method according to the specific conditions of drained and undrained sink combination, and auxiliary air curtains help heavy under water concrete.

(c) Pneumatic Caisson Foundation Difference between pneumatic caisson and caisson foundation lies in its section at the end of a top cover and top cover plate installed on the well pipes and airlocks construction Studios. About a century before and during the early 19th century, pneumatic caisson is a major basic types of bridges. Later because of the size of worker safety issues, this structure except in Japan has been less used outside. Caisson’s great advantage is to eliminate stagnant water in the basement, the staff can enter the bottom box Interior to implement barrier removal, substrate Inspection Department. And other construction work, for a variety of complex geological and hydrological conditions, basic quality more reliable; main drawback is construction complex equipment and high construction costs, there are safety issues such as protection of workers into the enclosure.

Fig. 3.80 The Jiangyin Yangtze River Bridge North anchoring sunk shaft foundation of air curtain structure (unit: cm). To address safety problems, currently Japan auto pneumatic caisson base was developed. Mechanised mining system in order remote control excavator operations, minimise artificial the caisson and improves the safety of construction to automatically

control information management system and testing caisson sinking. When deep water foundation of bridge to be built-in the large permeability of soil containing difficult obstacles, or base required special treatment situations, sinking could not sink, caissons can be used.

2. After World War II a Modern Basic Form In the 1950, of the 20th century, the first Wuhan Yangtze River Bridge and successfully applied to tubular column base, forms the basis of pipe string and its combinations with other base (such as the caisson) were further developed.

(a) The Column Base String based on the built-in 1953, at the Wuhan Yangtze River Bridge, the first of a new foundation forms. In Wuhan Yangtze River Bridge, the first and the actual use of tubular column base due mainly under the influence of hydrological and geological: bridge-bit depth upto 40 m, the maximum water level fluctuation between 19 m and high level long enough; the river bottom overburden soil to sand, bedrock surface is undulating, scope of bridge pier foundation rock surface height difference upto 5~6 m, under the influence of erosion and cover may be washed away some pier is at the rock for toxic gases. Or detrimental to security and bedrock caisson caisson construction falls bed stability, such as limiting the use of open caisson and caisson. Moreover, the effect of negative pile anchor badly and stability. By various analysis and comparison, final adopted by 35 number of pile, diameter 1. 55 m depth 2~7 m string consisting of rock-socketed pile foundation. At present, the development of pipe pile foundations: the Nanjing Yangtze River Bridge will be reinforced concrete pipe column instead of pre-stressed reinforced concrete tubing diameter grew to 3.6 m in Nanchang Gan River Bridge, further developed to 5 in diameter 5.8 m. In other countries, the former Soviet Union, Japan and the Europe and the United States began to use tubular column foundation, and in terms of construction methods and equipment have increased and improved, among them, Japan on the expansion of this type of foundation, improving the most powerful, the Yokohama Bay Bridge tubular column foundation (3.81) tubing diameter 10.0 m. Even more important is the base string by the scope of River Development Foundation in deep water to the big wind, wave and tide rush hammer and ice-melting impact larger deep water foundation. Tubular column base with large diameters or small diameter open caisson foundation of pile foundations of main difference between column base of the pipe string is socketed rock. Its main features are: take column base embedded in the rock and pillars embedded rigid CAP reduced the free length of columns and improves the overall foundation stiffness of second string forces comprising primarily pre-fabricated wall (reinforced concrete, pre-stressed concrete or steel) bear, when up by a tube filled with concrete or reinforced concrete.

Fig. 3.81 Pipe pile foundation of Yokohama Bay Bridge (unit: mm). Pipe column base materials can be divided into reinforced concrete pipe, pre-stressing force concrete tube, steel tube column, according to the cap position low string based, high pile bearing platform management foundation. Tube base can be used for deep water, tidal influence, the rock face rugged riverbed without coating or overlay is very thick, are suitable used to close clay and all kinds of rock, soil, and through caves, boulders supported on dense soil layers or fresh high on a rock. String base not too applies to regions with serious geological defects, such as crushing or serious fault loose areas. In general, within sunk pile appropriate range of application pile foundation tubing can be used. Example 3.20. Wuhan Changjiang river second bridge piers, 8th: steel-pipe column base. Wuhan Yangtze 8th pier continuous rigid frame bridge with intermediate activities supporting pier. Construction during flood period the maximum velocity of about 1 m/s, deep ~ 25 m, the geology is complex, covering layer thickness 23~27 m top to bottom is silty and fine sand in layers and 0.2 ~ 0.3 m thick round gravel rock surface elevation about –21.5 m, under which the conglomerate fully strong weathered and weak weathered and conglomerate fracture zone. 8th original design for double-wall steel cofferdam for pier foundation bored pile foundation bearing platform, but taking into account the adverse geological conditions, the cofferdam resistance water area is large and has little depth, a structure may vary depending on local soil erosion is difficult to guarantee stability. Comprehensive comparison of select high pile steel pipe column base (Fig. 3.82). The foundation a total of 12 pieces of steel pipe column, column inner diameter of 2.2 m, wall thickness 14 mm, long 49.5 m; hole diameter 1.8 m, drilling deep 14.5~28.5 m double-wall steel cofferdam for outer diameter of 20.6 m, thickness 0.6 m, the level 22.05 m.

Fig. 3.82 Sketch of infrastructure (unit: cm). Foundation construction, set-provides orientation of steel tubular column with steel surrounding cage, inserting steel pipe column into the rock surface, steel pipe column cover mix concrete tube and begin drilling and pouring concrete, all string after the construction is completed, dismantle the steel surrounding cage, lifting and sinking waterproof cofferdams, cofferdam sealing concrete pouring pumping building cap. Example 3.21. Canton Railway Zhaoqing Xijiang Bridge: double tubular column foundation bearing platform (Fig. 3.83). Double cap tube on the base is made up of pile caps, pipe columns, consisting of rocksocketed pile and bored pile under, which is different from the column increase foundation located under the cap role to reduce the length of string. Canton Railway 5 × 144 m of continuous steel trussed girder of Zhaoqing Xijiang bridge, 4th pier is located in the main channel of the Xijiang river in water, double-pile tube CAP, tube on the pillar base is made up of columns, consisting of rock-socketed pile and bored pile under. Foundation design construction is mainly because: base location for extrusion cement limestone bedrock, single axial compressive ultimate strength of more than 400 MPa, has good bearing capacity; the bedrock overburden soil is coarse and gravelly sand, its thickness increase change hydrological impacts reduction between 10~13 m. When designing a high water level, local scour of the riverbed extends to rock face, which added the length of the string, resulting in column design of bottom bending stress exceeds allowable limits design; from a construction point of view, the pier depth (depth of water into the rock face at 38 m) covering layer and shallow, it tube column’s position in the construction process and security deposit issue. Therefore, in the design of foundations, taking into account the structural strength to the full load of rock-socketed pile-supported piers, do not consider pile cap itself load-bearing function. The cap role only to decrease the string length to meet the lateral stiffness of the structure, no basement

drill subjected to bending moment in order to avoid the inadequacy of rocks in tectonic. All in all, cap is set to replace the eroded under overburden foundation provides embedding functions more effectively.

Fig. 3.83 Double cap tubular column foundation (Size: m).

(b) Composite Foundation In depth very deep and very thick cover or case with complicated geological conditions, and because of their limited capacity, could not be a single foundation sinking when the desired depth is reached, can take two different forms the basis, build a bridge to use the relay to Sham Shui Po, usually called this combination forms the basis for the foundation. Typical combination is based on the caisson with bored piles, pipe, bell-shaped bases, combined to form the foundation. While considering the construction of temporary facilities, and another double-wall steel cofferdam in combination with piles, pipe forming foundation. Example 3.22. Of main bridge of Nanjing Yangtze River Bridge, 2nd pier and open caisson and tubular column foundation (3.84).

Fig. 3.84 Main bridge of Nanjing Yangtze River Bridge, 2nd Pier and open caisson and tubular column foundation Schematic (unit: cm) (a) sunk shaft with steel Tubular column foundation structure; (b) level of caisson and Cap hinge. Hydrogeological conditions along the pier located at the depth of about 30 m, covering layer thickness of about 40 m, scour the riverbed of 23 m, based on the technical conditions to adopt the single string base have difficulties or caisson foundation. From the caisson and string combinations to form the basis of, it tube embedded within the bedrock of the lower end of the column, top embedded in the pile of concrete, concrete caisson bottom sealing and capping the connection string into integer steel can be used as a guide frame and cofferdam in construction of open caisson, is part of the permanent structure,

enhances the rigidity of the base.

3. In the 1990 of the 20th Century has two Basic Forms of New Development Owing to the harsh water conditions, construction time and quality are difficult to ensure, on the other hand, pre-casting and installation needed for transport, cranes and other equipment and technology to further mature, large pre-cast foundation in deep water or floating installation process as a whole has developed rapidly. As early as 1939, United States pioneered the Bell foundation in recent years, there have been new developments and applications. Similarly, underground continuous wall foundation originated in the 1950, of the 20th century in Europe, alongwith the dredging machinery and technology development, is another forms the basis of the recently developed rapidly.

(a) Install Pre-cast and Pre-fabricated Base (Basis Set) Pre-cast and pre-fabricated installation base (also known as the basis set) on the basic form is divided into two kinds: pre-fabricated caissons, this forms the basis in Japan and the United Kingdom, and Denmark have been used; another is a bell-shaped base, United States, and Japan, and Canada are also used. Japan as early as 1988, built North and South of great Seto bridge 6 based at sea, using the float in place, direct placement the whole foundation of open caisson foundation, followed by pre-cast caisson applied gradually, such as built in 1991, United Kingdom Thames Dartford-steel cable-stayed bridge over the river, which was completed in 1998. Denmark great belt Strait to the East, Nishihashi and completed the same year Japan Akashi Strait Bridge has adopted this basic form. Clock-based initiative in United States in 1939, on the Yubotuoma River Bridge, at present, the United States, and Japan, and Canada, and Denmark countries, have been used in the construction of deep water foundation of bridge foundation form. Bell-shaped base compared with the sinking, in addition to structural shape differences, main difference: sinking in place construction of open caisson is a permanent bearing structure, is a bell-shaped base in construction of thin shell structure, can be described as waterproof cofferdam concrete construction forms, is non-wing long structures only become final only upon completion of cast in place concrete permanent load bearing structure. Technical characteristics are the basis of Bell: first base and part of the pier on the shore of shape steel plates for welded steel or reinforced concrete, a bell-shaped thin-shell pre-stressed pre-cast concrete box, and then place this box lifting in total sound foundations or piles on it. Then, the pouring of concrete of pile caps and pier at the same time, make it into a whole. (Fig. 3.85) The United States in 1959, St. Mary Stewarthaiwaer bridge built in combination with steel piles forming the basis of Bell-shaped base.

Fig. 3.85 American St. Mary Stewart iron bridge built-in Haiwa on the basis of Bellshaped pile. The clock on the pile-foundation this simple base with less construction materials, construction methods, construction speed the advantages, but its biggest drawback is the high technical requirements for construction. In addition, by Yu Zhong-Foundation for main tower of large span bridge, Pier foundations, foundation load capacity, high requirements for foundations, built directly on the basis of sometimes requires the rock stone ground. In use, bell-shaped foundation and caisson resemblance, namely, pre-fabricated loading method and applied to sea-spanning bridge construction. Example 3.23. Canada Federal bridge Bell Foundation. In 1997 completion of Canada Federal bridge across the Northumberland Strait, for 44 holes of main spans of pre-stressed concrete box girder of long span 250 m, in order to meet the conditions for offshore operations, it, bell-shaped pier foundation and upper structure are all using pre-fabricated components, factory pre-fabricated on shore, use large gondolas for installation on site. Bell-shaped base (Fig. 3.86) basal diameter of 22 m, based on height to the depth of 10~35 m vary within a range, base made cone-shaped platform at the top, with the pier closed. Construction used large floating hanging bellshaped base lifting sinking into place, then piers pre-cast foundation crane-mounted directly into the top of the cone-shaped platform, through the pre-stressed structures both as a single entity. Example 3.24. Greece Rion-Antirion Bridge: “reinforced earth base isolation”. Greece bridge of Rion-Antirion bridge in highly exceptional circumstances, environmental factors, depth of greater than 2500 m length range more than 65 m, steep on both sides of the sea bed, accompanied by strong seismic activity (recurrence period of 2000 the maximum peak acceleration 1.2 g) and the tectonic movement (Fig. 3.87). Gulf shipping request, ship impact force for 180000 t/16 section (section 1 = 1 nautical mile/h = 1.852 km/h); geological factors (Fig. 3.88), bedrock depth of the bridge over 500 m, under the sea-bed soil order are as follows: (a) 4~7 m non-stickiness gravel, (b) rather unstable

sand, silty sand and silty clay layer, free (c) 30 m is a homogeneous layer of silty clay or clay, for the typical soft ground. A 20 m liquefaction of deep layer is on the north shore. The bridge main controlling factors on the seismic safety of the design. Apart from the upper structure selects five outside the floating structural system of cable-stayed bridge span continuous, in the sub-structure of the processing, diameter 2 m, deep steel pipe piles with 7 of 25~30 m~8 m the spacing of soil and solid, covered with sand, gravel and crushed stone pile top 3 m thick composed of sand-gravel cushion forming class “Composite Foundation”, which is located on 90 m in diameter formed box foundation for the sliding of the “reinforced earth base isolation” (reinforced soil foundation) (Fig. 3.89).

Fig. 3.86 Canada Northumberland Strait Bridge Bell Set the base (size: m).

Fig. 3.87

Fig. 3.88 (Size: m).

Fig. 3.89 Rion-Antirion Bridge: “reinforced earth base isolation”, Greece.

(b) Underground Continuous Wall Underground pile bent diaphragm wall type, slot type, pre-cast and many other structures and modular forms, but should be used in bridge foundation structure is mainly made of grooved-section. In bridge construction in China, the transport sector application starts when the construction of the Guangdong Humen bridge and research in anchorage of runyang Yangtze river highway bridge in Jiangsu, was also adopted. At present, underground continuous wall of most developed countries are Japan, has accumulated over 15 million m2 of underground continuous wall built, among other things is in the application of bridge deep water foundation. Its main construction in two ways: one is the cofferdam built island in the water, and then in the above the underground continuous wall construction. Another is used as waterproofing and resistance of underground continuous wall cofferdam of earth pressure in the surrounding excavation work within the Weir, arrived at the design elevation in situ perfusion deep like a caisson foundation. Example 3.25. Japan Aomori bridge main pylon Pier foundations of main span (Fig. 3.90). Japan-Aomori bridge-tower cable-stayed bridge across the 240 m, through to the caisson, shaft, locking pipe piles and pile with large diameter diaphragm wall under programmes such as comparison, selected underground continuous wall for its infrastructure. Also according to the ground conditions, focus on the basis of support, on the large flat area (20.5 m × 30 m) and shallow (45 m only), small surface area (12 m × 30

m) and the deep (85 m) two schemes make choices and, finally, according to characteristics, economic and reasonable structure, construction easier and used the flat shallow scheme. Also used a similar lock in construction (with gaps of steel tubes and steel plugs) the new connector.

Fig. 3.90 Aomori diaphragm tower foundation of pylon pier of the bridge division of the element and the construction sequence (size: m).

3.4 TECHNICAL FACTORS AFFECTING ECONOMIC INDICATORS Since entering the 21st century, due to the low carbon economy and sustainable development, the whole-life design philosophy of attention to bridge design follow the “safe, suitable, economical, beautiful, durable and environmentally friendly” six principles has become a consensus among members. However, with the Chinese classics increase of economic development and national investment, the economic principles of bridges in China seem to get overlooked. Some economic and unreasonable large-span program, often due to the owner’s “over-ambitious” was used and designers blind pursuit of largespan bridge, technicians mistakenly, that span’s breakthrough was “innovation” is the world leading level of realisation and, to that end, will take a doubled price, and even cause serious imbalance (span/height ratio), and evil in the vastly disproportionate to the adjacent bridge. We should encourage the adoption of innovative effort to reach the best mechanical properties, the reasonable constructional details and the most convenient construction technology, but also the most cost effective and aesthetically pleasing bridges, thereby enhancing the reputation and competitiveness of China’s bridges. Projects of product conceptual design phase the idea choice, you need to consider many factors, economics is one of the most important factors. Different bridge-type has a different economic and technical indicators, and indicators changes alongwith changes in the condition of building the bridge. Therefore, for special set the conditions of bridges, project selection to choose the economic programmes are needed; for a specific bridge, spans of different layouts, section, tower shape, structure, and will be also demonstrate different economics; construction will affect programme of the economy; with basis in particular deep water foundation account for a higher proportion of the total investment, so concept of selection is based an important task in the design stage.

3.4.1 Material and Economic Indicators of Bridge Types Bridges are an important indicator of economic deck material consumption per square metre, attaches great importance to this international design contest reflect the indicators of competitiveness and technology. Due to gaps in the materials industries, our bridge material grades is relative backwardness. Design of steel box girder, Europe and the United States, using the HPS460 (Europe)-HPS480 (United States) BHS500 (Japan), high performance steel, even at high stress areas with a small amount of local HPS560 and HPS690 to reduce thickness board, simplifying construction and manufacturing difficulties. An S345 steel used mostly in China, but of different thickness steel plate welders arts and inconvenience, it is also very economical. In terms of concrete structure, China has mostly C50, and foreign high-performance HPC80 has been commercialised. Thus, our concrete bridges tend to be relatively clumsy and “fat”, but outside the concrete bridge is much more slender and light (smaller dimensions, wall thickness is thinner), concrete is also greatly reduced, there is a clear gap. Suspension bridge’s more expensive, a long construction period, regardless of the cross-river project in the lower reaches of the Yangtze river, coastal sea island drive and

cross in the mountains of West-Central Valley Project, the priority should be relatively economical and cable-stayed bridge cable can be replaced or suspension bridge scheme. Full justification must be provided for suspension must be used, and is not to replace the main cable control rot should be dealt with seriously, in order to ensure the durability of their lifecycle. Not only the pursuit of span by ignoring economic principles when choosing suspension bridge schemes. Same bridge conditions, different layout structure and span of the bridge material indicators, economic indicators are different and, therefore, economy of bridge type alternatives tend to be conceptual design scheme selection of the most important considerations. Example 3.26. Of Taizhou Yangtze River Bridge. Taizhou Changjiang bridge preliminary design phase for a total of six economic analysis and comparison of the design, as shown in table 3.14. Table 3.14 Six programmes cost comparison Engineering

Dual-tower cablestayed bridge with main span of 980 m

Projects Length Construction- Index Cost Equal (m) installation (RMB/ (10,000 length costs (10,000 m2) Yuan) construction Yuan) costs (USD) Main 1860 213864 33818 Approach 3580 52180 4485 334638 347922

Main span of 980 m uneven-tower cablestayed bridge

Main

1690

198131

34481

Approach 3840

57057

4572 321295

Main span of 1328 m of three-span suspension bridge

Main

2400

232476

28490

Approach 3450

50576

4511 355544

Main span of 1280 m of three-span suspension bridge

Main

2350

226795

28385

Approach 3520

51240

4479 349359

Main span of 2 × 1080 Main 2160 m of three-span Approach 4880 suspension bridge

213410

29059

73175

4614 359887

Main span of 2 × 950 m of three-tower suspension bridge

1900

198561

30737

Approach 5160

78646

4690 348354

Main

333841

365466

359117

360051

348354

Example 3.27. Su Tong bridge preliminary design phase bridge type selection. 1. Tower cable-stayed main span span is determined as 1088 m, take 500 m side spans, two auxiliary piers, taking into account the auxiliary channel, khunj uplink channel requirements, the span arrangement for 100 m + 100 m + 300 m + 1088 m + 300 m +

100 m + 100 m. 2. With a total length of 2088 m continues taking into account location, south anchorage on the main channel and navigation channels between shoals, north of anchorage on the north side of the main channel the 8 m terrain around, considering the main channel and the secondary channel is set in the bridge main span that are required in the span of about 1510 m, mining with a three-span suspension, integrated structure factors, take 453 m + 1510 m + 453 m = 2416 m cloth across the way. 3. South anchorage in a dedicated channel on the South Shore levee between the shoals, north of anchorage on the north side of the main channel is –5 m elevation close, considering the main channel and the secondary channel is set within the main span, dedicated lanes set up in the South Shore, and the use of three-span crane, Heald structure factors, take 938 m + 2010 m + 938 m = 3886 m cloth across the way. Investment estimation: full-bridge cable stayed bridge with a main span of 1088 m programme a total investment of 59.0 Yuan, suspension bridge with a main span of 1510 m programme bridge, a total investment of 68.300 million Yuan, 2010 m programme full bridge suspension bridge main span with a total investment of 82.200 million Yuan. Main span of 1510 m cable bridge program investment than cable stayed bridge with a main span of 1088 m price 9.300 million Yuan, a main span of 2010 m scheme of suspension bridge main span 1 088 m cable-stayed bridge scheme investments increased by 23.200 million Yuan, the cable stayed bridge with a main span of 1088 m programme of investment in the province. Example 3.28. Qingdao Bay Bridge. Qingdao haiwan bridge across Jiaozhou Bay connected with the main city and Huangdao of Qingdao and auxiliary city city of large bridges, railway bridge project surveying and designing Institute in the feasibility study report of the bridge, ferries and two bay bridge under different conditions of bridges examined a number of long-span suspension bridge scheme. According to traffic under the bridge function, combined with topography and geology and other natural conditions, respectively, on the ferry’s bridge and the bay bridge overall layout. (a) The ferry bridge—Bridge Program (Fig. 3.91). East side features two large holes meet the requirements of port channel and the central fairway, Lee of nonnavigable spans of sand ridges area in central pier or contact the bridge in the middle, with waters on the west side or edge of the cay set in shallow water anchor pier based on cay on the west side of port channel setting in the middle of longspan cable-stayed bridge.

Fig. 3.91 Qingdao Bay ferry bridge scheme selection (size: m). Prepared a programme of three tower suspension bridge, spans the composition 350 m + 1200 m + 1200 m + 350 m, central tower of 250 m, two 160 m tower. Main cable resulting from the unilateral load in order to overcome the huge levels of tension vertically using a main tower-like structure, this class bridge-both at home and abroad, there is no large instances. Option II for suspension bridge with two hand decorate, share a bi-directional anchoring, anchoring the main cable. Span consists of 350 m + 950 m + 350 m + 350 m + 950 m + 350 m. Similar bridge main span in the world for the first time. Option III for a two-seat hybrid cable-stayed bridge joint layout, steel box girder of cable-stayed main span and side spans of pre-stressed concrete box girder span constitute 330 m + 950 m + 330 m + 330 m + 950 m + 330 m. The main span of the bridge is also a world record. (b) The ferry bridge—Bridge Program (Fig. 3.92). Each bridge main span across the central deep water shipping. Depth on both sides of the main tower is about 25 m, anchor set in near-shore shallow water district. Programme I of three tower suspension bridge, spans the composition 646 m + 1652 m + 646 m, central tower of 250 m, two RC master 255 m tower. The main span of the bridge at the first bridge of its kind in the world. Programme II of three-span continuous steel box girder of suspension bridge, spans the composition 652 m + 1832 m + 652 m, RC primary 265 m tower. Programme III is a three-span suspending cable-stayed hybrid structure, spans the composition 592 m + 1832 m + 592 m. The bridge world the first. (c) Number of Major Works: Corresponding to the above-mentioned scheme, number of main bridge of the main projects as shown in tables 3.15 and 3.16. Table 3.15 Ferry and bridge engineering quantity comparison. Project three-tower

Suspension bridge

Suspension bridge with two of 950 m

Two 950 m of cablestayed bridge

Cable wire (t)

22550

19080

11050

Steel box beams (t)

46000

49300

51000

Tower

63700

36200

92000

Foundation

117600

134200

160000

Main tower of concrete (m3)

Fig. 3.92 Qingdao Bay ferry bridge scheme selection (size: m). Table 3.16 Ferry and bridge engineering quantity comparison. Main Span 1652 m suspension bridge 30400

Main span 1832 m suspension bridge 36800

Main span 1832 m cable-stayed suspension 25400

Steel box beams (t)

39900

44400

41800

Main tower of Tower concrete (m3) Foundation

75600

88900

108700

126500

141300

142340

Anchorage

151000

167300

125000

Foundation

111199

99400

120560

Item Cable wire (t)

Anchorage concrete (m3)

3.4.2 General Layout of 2 Impact on Economic Indicators General features include size, the presence of deep-water foundation, the main beam with long span cross-section tower of forms and materials, shapes and materials, economic and technical indicators of the whole bridge, so mastering its general laws, contribute to overall layout phase fully into account in programme economy, the economy took the first step for the programme, and a decisive step because the bridge and the overall layout of

the economy is controlling factors of the economy of the entire programme, once the bridge and determine the layout and is difficult to reduce costs, only partially, a small amount of to optimise and reduce costs. At present, long-span cable-stayed bridge has exceeded kilometers, and there is development potential in the range of 1200 m-span entirely from anchor angle laqiao of the economy will be significantly better than suspension bridges. Also, rigidity and windresistant stability of multi-span cable-stayed bridge and construction are superior to many suspension bridge. For example, France designed by Greece Rion-Antirion bridge, depth of 65 m, and is located in an earthquake zone, navigable sea of 180,000t round, 560 m said that a very economical and reasonable scheme and new cable-stayed bridge of reinforced soil-isolated foundation, does not adopt a more cross-suspension bridge Such as Germany and Denmark Marne Strait bridge between (Fehmarnsund Bridge) programme selection spans 780 m of cable-stayed bridge to meet 200,000t navigation requirements for seagoing vessels, is the most economical Cross-Sea project, for the lower reaches of the Yangtze River in China Cross-River project and the southeast coast of the island-sea link project has provided an important reference.

(a) The Span Arrangement Increased span, avoid water foundation, also may choose to a conceptual design of economical and reasonable. Example 3.29. The Yangpu bridge, the bridge river main channel on the East Coast, East of main pier is located on the shore, West pier would be located on land, shore or in the water, which can be three-span arrangement, as shown in Table 3.17. Table 3.17 Yangpu bridge piers plans comparison. Models Main pier location

A B Two piers Proprietor pier on land, are on land west main pier at the shore

C Proprietor pier on land, in the water main pier west

Main span (m)

602

580

520

Lower structural costs/ total cost

19%

27.5%

35.5%

N

N + 1 470

N + 640

Total cost (10,000 yuan)

Plan A: Two main piers are located on land, main span is 602 m; Plan B: East main piers located onshore, west side main piers located in the original terminal location, half water, half on the ground, the main span size is 580 m; Plan C: East main piers located onshore, west of main piers in the water, main span 520 m. These three scenarios, such as plan a main pier foundation construction cost for 1.0, and the shore, the proportion of the cost of in-water pier foundations 1.0 : 2. 1 : 3.3, directly affect the total cost of the bridge. Although cost is directly related to the size and span of the superstructure, the greater the span the more expensive. But because the cost

of land based and water based differences, resulting in long span 602 m model a total cost than span B, 520 m and span C, 580 m programmes were reduced to 6.4 million Yuan and 14.7 million dollars.

(b) Deep-water Foundation Large-scale deep-water foundation of costly, risky, directly affects the economic effects. To allow for lower construction cost comparison, from several cable-stayed bridge in engineering, expressed in a lower construction cost and percentage of total cost. 400~600 m span cable-stayed bridges: main piers located on the shore of the Nanpu bridge and Yangpu bridge, the geological conditions of main piers located in shallow water or in low water level for onshore construction when the Chongqing Yangtze river, lower construction cost of cable-stayed bridge with a total cost of 19%~22%. When pier located in good geological and topographic conditions, lower structural costs will be lower, such as Jialing river of Shimen bridge lower construction cost total 16.4%. When the main piers located in the water when the sub-structure cost total cost ratio with the hydrological, geological, topographical and change, general 30%~40%. In normal circumstances, decreases with long span, lower structural costs as percentage of total cost goes rising trend.

(c) Master Girder Forms and Materials Girder bridge is a PC an intermediate form between the steel deck and the deck, its weight is about 300 kN/m, and PC bridge (500 kN/m) and the steel bridge (150 kN/m). Accordingly, in the cable-stayed bridge with a large scope of application (l = 200 ~1000 m), three decks have the advantage of the most economical and reasonable range respectively. (i) PC Bridge (for l =200~500 m) When the length of the cantilever exceeds 250 m, the heavier deck will expose the weaknesses of PC. To reduce weight, need thinning of box girder wall thickness, and thus increase the stress level in the construction phase, plus required pre-load stress against the live load of tensile stress in the future. As control construction quality problems of improper or, Ningbo Zhaobaoshan bridge appears as “attending” the passive situation, and even lead to crushing accidents. (ii) The Girder Bridge (for L = 400~700 m) Girder bridge due to covered with pre-cast concrete bridge decks, deck asphalt pavement conditions and perhaps the PC Liang Yi achieve, especially at high temperature region of steel deck pavement technology is still a problem case, selection of combined beam can avoid later concerns. Composed of composite girder with steel girders and beams beam line, manufacturing and installation is very convenient, high-strength bolt connection can be used, the construction convenient, low cost than steel box girders. In the cable-stayed bridge under 700 m, as long as the inclined plane of the cables, the open knot beams already has plenty of wind resistance, such as the main cross 605 m Fuzhou Minjiang river bridge is a successful example. Although knot deck is heavier than steel box girder deck, cable steel and base quantity increase, but the broad economic indicator is still better than steel box girder well and are worth considering.

(iii) Steel Box Girder Deck (for L = 700~1200 m) 700 m should select light weight cable-stayed bridge of steel deck. Suzhou-Nantong Yangtze river bridge, studies have shown that, when used plane and six-lane closed rectangular box girder flyover, then its critical wind velocity of more than 100 m/s, to meet the world’s most wind in areas prone to wind-resistance requirements. If the side span of cable-stayed bridge has landed, you can choose the side span PC bridge, main span steel bridge deck mixed forms, rigidity and wind-resistant stability of bridges will also be further improved. Example 3.30. Main navigation span of Donghai bridge bridge program. Design of main navigation span of Donghai bridge, for double tower double cable plane, twin single-cable-plane cable-stayed bridge with steel box girder of concrete box girder, twin and single cable plane cable-stayed bridge with box girder, double tower double cable plane cable-stayed bridge I-girder cable-stayed bridge with four programmes were compared, as shown in Table 3.18. Its span arrangement are as follows: 94 m + 111 m + 420 m + 111 m + 94 m, per square meter economic indicators were 23680, 19500, 20940 and 21180. 2% higher than the concrete box girder of steel box girders, both were higher than the combined beam 13% and 12%. Table 3.18 Donghai bridge main navigation span scheme selection. Serial Scheme name number 1. Double tower double cable plane cable-stayed bridge with steel box girder

Jian fei Relative (10,000 yuan) relationship 64849 1.13

2.

Towers and single-cable-plane of concrete box girder of cable-stayed bridge

53411

0.93

3.

Double tower single-cable-plane combined box beam cable-stayed bridge

57366

1.00

4.

Double tower double cable plane I-girder cablestayed bridge with

58012

1.01

Example 3.31. Jiaojiang bridge main span 480 m girder structure of the program as a whole process of idea generation, is in a great deal of information based on the collection, analysis, test design based on the results of the various concepts, through the concept of choice, eventually forming the half-closed steel box set beams, a new concept of composite beams. During the main girder of pre-stressed concrete box girders, I-beams, fully enclosed steel beam combination beams, box-girder beams, fully enclosed and semienclosed steel box composite beam of steel box composite beam test design and estimating the investment results are shown in Table 3.19. Table 3.19 Cable-stayed bridge of main girder structure scheme design. Name of main girder structure construction

Jian fei (100,000,000 yuan)

Relative relationship

Concrete beam

Side of the main beam pre-stressed concrete beam

5.80

0.88

Full steel girder

Fully enclosed steel box girder

7.49

1.13

—

—

Composite box-girder beam

6.52

0.99

Fully enclosed steel box girders of the steel beam

6.88

1.04

Semi-enclosed steel box girders of the steel beam

6.88

1.04

I-shaped edge girder composite beam Composite beam

Example 3.32. Completed in 1986, Canada Annacis bridge main span 465 m of composite beam cable-stayed bridge, two main towers, respectively located in shallow waters on both sides of the river channel and filling sand foundation construction connected with the bank. According to the proposal (programme for process tuliang coagulation, option two for composite beams) results: the economic performance of composite beams with more advantages than the concrete beams, laminated beams has a cost about 20% lower. Example 3.33. Completed in 1984, Spain Luna bridge main span of 440 m pre-stressed concrete double tower, double cable plane cable-stayed bridge main span across the water reservoir of 50 m reservoir bottom gravel overburden thickness of 17 m layer, the bedrock is limestone. Two main tower located on the shore. In early 1980, the design, and made 22 of the ICP for main girder of steel girders, concrete beams are superimposed demonstrate the beam, came to the conclusion that: a concrete beam construction cost. Example 3.34. In accordance with China’s Anhui Province, preliminary design, detailed comparisons of Anqing Yangtze river bridge: the main span of 500 m steel cost about 124% of the concrete cable-stayed bridge. Based on domestic economic conditions, 500 m within the main span concrete cable-stayed bridge has a considerable competitive edge.

(d) The Tower Type and Material Different tower types with the same material, and its cost is different. For the same type, using different materials, and its cost are also different. Generally speaking, steel tower of the most expensive, and its cost is 2.5~3 times. Example 3.35. Su Tong bridge tower-shaped materials and different economic comparison Fig. 3.93 for the design of each tower-shaped landscape scheme optimised selection of landscape renderings.

Fig. 3.93 Three tower schemes (a) Inverted y-shaped tower (b) Diamond-shaped towers; (c) A-shaped tower. Table 3.20 comparison of different engineering and construction of the tower. Because the one tower anchor area separation of two towers, tower space is relatively small, and steel-anchor-box anchorage, other towers of steel anchor box and circumferential prestressed programmes carried out analysis and comparison. As can be seen from the table in the use of steel-anchor-box anchorage of the same mode, inverted y-shaped towers than the diamond-shaped tower JI, Jian province about 1 of 5 million Yuan. When using circumferential pre-stressed, diamond-shaped tower with a-shaped tower cost basically the same, and inverted y-shaped towers the most economical. Example 3.36. Su Tong bridge tower-shaped materials and different economic comparison in the preliminary design stages, the tower of reinforced concrete, steel, steelconcrete combined the three schemes are the same depth of research and compared. Tower: The tower height is 297.7 m lower pylon column for ministers at the end of 15 m, wide 8 m, wall thickness 1.5 m chang 8 m, anchor, 8 m wide, wall thickness 1.2 m. Cable tower: The tower height is 297.7 m lower pylon column for ministers at the end of 15 m, 8 m wide, steel plate thickness 40 mm; head of anchor 8 m, width 8 m, plate thickness 38 mm. Steel-concrete composite pylon tower: The tower height is 297.7 m lower pylon column at the base length of 15 m, width 8 m, wall thickness 1.5 m, anchorage area is steel structure, length 8 m, width 8 m, plate thickness 38 mm. (Note: in the selection of materials section, cross Tower Bridge to the × direction longitudinal to size for top of tower 8 m × 8 m, bottom of tower 8 m × 15 m, and eventually selected the top size 9 m × 8 m, 8 m × 15 m at the end of vary, and coagulation tusuota cable uses a section of steel anchor box. Tower project number and cost comparison of different materials are shown in Table 3.20. Table 3.20 Tower of quantities and construction fees (all bridges). Materials

Inverted Diamond

A-shaped

Inverted Y-shape Diamond shape

Y-shape (Steel box) 51002

shape (Steel box) 56410

Bars (t)

12308

Ordinary steel (A3) (t)

Concrete (m3)

(Circumferential (Circumferential (Circumferential prestressed) pre-stressed) pre-stressed) 57519

52321

59533

13636

13821

12638

14417

3808

4226

4258

3914

4475

Anchor box of steel (Q345) (t)

1800

1800

Strand (t)

374

456

530

550

632

Anchors (set)

864

1008

1616

1712

1856

Construction fee (10,000 yuan)

18338

19823

16947

15545

17732

Constructioninstallation ratio

1

1.081

0.924

0.848

0.967

Table 3.21 Tower project number and cost comparison of different materials. Project Concrete (m3)

Concrete pylon 50318

Steel tower 3036

Combined tower 44032

302

—

208

Bars (t)

12226

304

8146

Steel (t)

5988

32738

8638

Construction fee (RMB)

18617

58888

27553

1

3.163

1.480

Strand (t)

Construction-installation ratio

Note: Tower engineering to scheme comparison of early value, little different from the final design recommendations. As can be seen, towers of concrete, steel towers, tower of steel-concrete composite construction cost ratios of about 1 : 3.163 : 1.480. Example 3.37. Taizhou Tabgtze River Bridge Tower of steel tower with concrete tower concrete structure of the tower two, a steel tower of a scheme is shown in Table 3.22. Table 3.22 Side tower plan comparison. Tower plan

Tower scheme one

Tower scheme two

Tower number three

Scenarios description Construction costs (10,000 yuan), Cost ratio Comparison Conclusion

Concrete tower: Concrete tower: a concrete light ktype concrete beams beam crossing with a steel cross Programme web portfolio

Steel towers: a k-cross beam scheme

9180.51

8926.76

24066.94

1

0.97

2.62

Scheme Recommendations

Scheme Comparison

Scheme Comparison

Analysis according to Table 3.22, steel tower cost concrete tower 2.6 times, therefore, finally, concrete tower scheme as a recommendation. Example 3.38. Tower of Jiaojiang bridge scheme comparison. Scenario comparison and selection of design after several rounds of tower, tower concentration in bud form, on a diamond-shaped and Vase-shaped, as shown in Fig. 3.94. According to the consultants, observations on the three towers has done to further optimisation. Table 3.23 is a three-tower design renderings and the material quantity, cost comparison.

Fig. 3.94 Three tower schemes (a) diamond-shaped tower; (b) bud-shaped tower; (c) a vase-shaped tower. Table 3.23 Comparison of three-towers-jiaojiang bridge. Tower-shaped Quantity (m3, a single Suo Taji) Construction fee (10,000 yuan) (based on full bridge two meter) Construction installation ratio

Diamondshaped about 10683

Flower bud Vaseshape shaped about 13386

about 13101

19718.6

22008.9

21848.4

1

1.12

1.11

Recommended solutions

recommendation selection

selection

By comparison, diamond-shaped tower construction cost, construction technology, vertical small frontal area, clear, and thus finally this scheme was adopted.

3.4.3 General Layout of 3 Impact on Economic Indicators Based programmes had a great influence on the bridge in economic indicators, especially deep water foundation, tend to invest in full-bridge 30%~40%, and greater risk of deep water foundation construction, often concerns the success or failure of the bridge. Therefore, a good concept based gage foundation (including the method of its construction) must have the construction risk, duration can be controlled and economical characteristics, and economic design of the foundation is also one of the highlights of the whole design. Example 3.39. Tower of Taizhou Changjiang River Bridge pile foundation and caisson scheme comparison. Rounded rectangular open caisson well plane size is 58.2 m × 44.1 m, fillet radius 7.95 m, to facilitate suction soil sinks, layout of open caisson for the 12 × 12.7 m × 12.7 m large hole. Because of sinking depth deep, surrounding wells is set to round end shape, Arch formed to resist water pressure, in order to facilitate sinking, in arch has a diameter of 1.0 m water hole. Use rounded rectangular open caisson (Fig. 3.95), the pier scour elevation –19.27 m, scour elevation 59.57 m, caisson bearing layer selection-68.88 m gravel sand layer. Taking into account the erosion and changes affecting the river, sinking bottom elevation production –70.00 m, in order to prevent the ship hit the tower, top of sinking well exposed above the highest navigable water, elevation to + 6.0 m, open caisson high 76 m.

Fig. 3.95 Three-tower suspension bridge towers in rectangular open caisson solution (unit: mm). Main tower of bored piles with 118 root f3.1 m/2.8 m bored piles (steel pipe diameter 3.1 m), as shown in Fig. 3.96. Friction piles, plum blossom decorate bottom of pile height –110 m, 106 m bottom of pile bearing stratum for gravelly sand. Caps shuttle shape, flat feet inch is 87.4 m × 67 m. Cap above the highest navigable the cap crest + 6 m, cap 10 m, sealing concrete thickness 2.5 m to prevent the ship impact pile, lateral sealing concrete along the cap end of a local thickening. Table 3.24 shows bridge caisson and scheme of bored pile works.

Fig. 3.96 Tower suspension bridge pile foundation program (unit: mm). Comprehensive comparison of the recommended solutions based on open caisson. Example 3.40. Tower of Jiaojiang bridge scheme comparison. According to geological data were furnished with the friction pile and pile embedded

in rock, as shown in Figs. 3.97, 3.98. Friction piles with 2.5 m pile diameter, 48 numbers of pile of length 108 m. Variable diameter rock-socketed piles and pile diameter from 2.9 m change to 2.6 m, 24 numbers of pile at North Tower with an average length of about 115 m, the South Tower, with an average length of about 135 m. By calculation, allowable value of axial compressive bearing capacity of single pile of 68230 kN, pile total lateral resistance of 8049kN (12%), the total lateral resistance of rock-socketed segment 22393 kN (33%), the total resistance is 37789 kN (55%). Table 3.24 Caisson drilling pile schemes. Project Concrete (m3) Project volume

Programme drilled 100725

Caisson pile 155972

Bars (t)

3929

23037.5

Steel (t)

5376

19880

31543.85

49850.81 (the sinking ratio 1.58)

28

27

Construction costs (10,000 yuan), Duration (months)

Total 60 m of open caisson (Fig. 3.99), elevation –55.17 m, top height + 4.83 m Caisson Song Festival 15 m steel concrete caisson, the remaining segments for 45 m high concrete open caisson concrete strength class C35 underwater, cutting edge of plate wall 16 mm and the remaining wall thickness of steel segment 8 mm, concrete wall thickness of 1.2 m, 8 mm steel shell concrete wall insulation thickness. The bearing layer containing clay roundstone (4-2), the fa0 = 320 kPa. Three basic scenarios shown in Table 3.25. Table 3.25 Side tower plan comparison. Type of foundation Flat size (m)

Embedded rock pile Friction pile foundation Sunk shaft foundation foundation Raft was hexagonal, 45.2 × Cap was hexagonal, 57.7 Round-ended, 23.4 × 32.6 56 × 32

Total height (m) Average length 125m, Average length of 108m, variable diameter 2.9 m → diameter 2.5 m, 3 m + 5 2.6 m, Cap thickness 6.0 m m = 8 m Cap thickness

60

Settlement (mm) Except piles of rocksocketed pile compression no

Settlement since has entered the highly weathered rock formations, sink

Very small reduction 244 (bridge later 98)

Full bridge cable 50532 tower foundation concrete (m3)

76996

78371

Recommended solutions

Selection

Selection

Recommendation

Fig. 3.97 Pipe pile foundation of Yokohama Bay Bridge (unit: mm).

Fig. 3.98 Main pile foundation of Yokohama Bay Bridge (unit: mm).

3.4.4 Impact of General layout on Economic Indicators Investments in construction methods directly related to the bridge, under normal circumstances, a certain bridge engineering, construction companies are often will be based on its own experience and equipment, choosing the most economical solution construction in order to gain the maximum profit, and owners tend to focus on duration, project quality, and capital investment. An excellent construction enterprise must be able to fully take into account a variety of factors, construction innovation, advanced equipment, security technology, advanced management of quality, technology, construction and profit in a win-win. Construction itself, closely related to design and construction method, a design may have a number of options for construction method of construction experts in special studies of needs and optimal construction method. In many cases, the design is more specific (past construction method can not be applied), or construction requirements are

relatively harsh (a similar construction method where did not have the conditions imposed), concept design must take into account specific construction methods.

Fig. 3.99 Caisson Foundation scheme (unit: mm). Example 3.41. Construction of Yajisha bridge scheme selection. Traditional construction method of arch bridge cable erection method, brackets and so on, but as the bridge span increases, construction equipment and temporary facilities costs rising sharply, long duration and high cost disadvantages, and there in the upper section assembly, welding quality guarantee. Yajisha bridge will have a span of 360 m, vector 76 m, using traditional construction methods, in terms of possibilities and an economic rationality, it is not desirable. Combination of bridge and bridge of Yajisha bridge features of open space and convenient sea transport across the Taiwan Strait, of main arch installation puts forward three lifting, such as Kapyong turn whole floating, vertical construction program. 1. The three stage lifting scheme. To meet the requirements of navigation, the main arch was divided into three segments, segment of each side is 70 m, the field is 204 m. Both segments separately in bridge erection bracket assembly, middle 204 m Yaji group after a spell on the sand, slip into barges floating transported to the bridge, vertical lift in place closing (Fig. 3.100). 2. The whole floating programme. The programme overall float to the main arch span of 344 m bridge installed, in order to reduce work on the water (Fig. 3.101). By sliding the track moved to arch the whole barge, submerged barges, each 120 m long,

30 m wide, mass 15000t. 3. The kapyong turn vertical programmes. Considering the condition of bridge site open space on both sides and reduce Spider-man, the main arch rib-installation production kapyong turn vertical construction scheme, quality of vertical rotation 2058t, horizontal rotation quality as 13865t, horizontal rotation quality as the largest Fig. 3.102.

Fig. 3.100 Three stage lifting scheme (unit: mm).

Fig. 3.101 Whole floating scheme (unit: mm).

Fig. 3.102 Kapyong turn vertical programmes.

4. The Scheme Selection (i) Three lifting and rotation programme various operating conditions calculations are to

meet the design requirements, it is technically feasible. Three stage lifting scheme of arch bracket assembled on the bridge, bridge alignment easier to control, middle section of main arch by temporary tie rod alignment adjust shape, while keeping the structure system transformation is more complicated. Swing construction programmes take full advantage of the side arches and across half an arch formation self balancing system, large diameter loop ensures that the balance is in the rotary process, enough of the factor of safety against overturning and adjustment buckle Suo Lali, can make the side arches and a main arch during the rotation process in an optimal stress state, but using high-precision synchronous lifting technique. Whole floating hoisting transport Fulcrum 53 m vault of 88 m transport system for variable structure, risk is too big. And because of inadequate treatment, bridge caused a number of residual stress in the cross section is too large, has obvious flaws in the technology. (ii) Three stage lifting scheme of peacetime construction influences on waterway is small, but because the waterway favour south, scaffolding and construction trestle occupied main channel waters and waterways, department continues expanding to the north, and set emergency turn-around bridge upstream and downstream areas, and smaller ships waiting parking area, in the interest of navigational safety. Middle section of main arch floating, positioning, lifting both construction procedures need to cover, such as homework, in order to ensure Hong Kong normal production, requires two 24 h completed within a climatic ebb and, unable to carry out continuous operation. Erection scheme of main arch assembled on shore, changed a lot of Spider-man for the ground operation. Because the clearance under the main arch much greater than the design navigation clearance, in the process without cover, Swivel, to minimise the impacts on waterway. (iii) Three hoisting assembly bracket and lifting scaffolding upto 60 m, a larger amount of material, temporarily tied several times adjustable the entire, complex operation. Due to the side effects of supports on channel, it is necessary to widen the waterway, while deeper draught barges required for floating van surrounding waters for dredging, and aerial operations required compensation for the shipping sector, incurred large costs and difficult to estimate. Swing construction programme despite an increase of some agreed temporary works, and rotation construction requires high-precision synchronous lifting equipment, but less uncertainty, project cost control. (iv) Three stage lifting scheme can be of rotation programme and processes work in parallel, can shorten the duration. Comprehensive comparison, swivel construction plan is safe and reliable, with minimal impact on waterway, short duration, economy, experts demonstrated many times, review determined to implement the programme. Swing construction successfully completed on October 24, 1999. Example 3.42. Anchor block of Taizhou Changjiang River Bridge construction method of comparison with economy.

Fig. 3.103 Diagram of anchor structure (North anchor) (unit: cm) (a) side facade; (b) plane. Rectangular open caisson foundation programmes: general arrangement to reduce the overturning moment, anchoring, anchoring base with eccentric reset hole in the back filling grouting in rock ballast, so that more uniform stress under dead load. Due to the supporting layer of silty sand North Coast as far South Bank is deeply buried, so North anchorage of caisson sizes larger than south anchorage. Sinking plane dimension of north anchor with 52.0 m × 58.8 m sink caisson depth 57 m, floor 1610.8 m × 12.5 m borehole; the South anchor with 50.0 m × 56.8 m, open caisson high 51 m, layout of open caisson for the 16 × 10.3 m × 12.0 m large hole. Section wall thickness at the end of 2.15 m, the

remaining wall thickness 2.0 m, wall thickness 1.6 m sink hole section of 10 m for concrete-filled steel and the remaining section of reinforced concrete. Sealing concrete 10 m, covers an average thickness of 5 m. Steel Q235 steel, concrete C30, sealing concrete water C30, C40 manhole cover concrete. Knot frame as shown in Figs. 3.103, 3.104.

Fig. 3.104 Diagram of anchor structure (North anchor) (unit: cm).

Underground continuous wall base surface can be arranged into rectangles and circles in two scenarios. While working with a circular cross-section in construction of underground continuous wall of reasonable strength, but due to anchor the bottom section is rectangular, round base with rectangular cross-section does not match the anchorage, rounded volume large, uneconomic. Underground continuous wall of rectangular layout is very compact, and longitudinal stiffness, reasonable force as a whole, the composite diaphragm wall foundation considers only rectangular plan.

Fig. 3.105 Of north anchor underground continuous wall chart (unit: cm) (a) I-I profile; (b) floor plan. North anchor underground continuous wall foundation: its structure and open caisson structure the same size as north anchor wall anchorage to the substrate 29 m, structure is shown in Fig. 3.105.

Design according to the comparison (Table 3.26), featured rectangular open caisson foundation programme. Table 3.26 Underground continuous wall of sink well and plan comparison table (North of anchorage, for example). Project

Project volume

Rectangular open caisson Scheme 84092

Rectangular diaphragm wall scheme 107780

Bars (t)

4449

7 953

Steel (t)

1223

771

22

26

Concrete (m3)

Duration (months)

REVIEW QUESTIONS 1. Related to climate and meteorological data analysis what are the basic parameters in which designers can use? And brief usage. 2. Please tell us your main factors on bridge site selection. 3. The brief span several main span of the bridge economy and limit. 4. Would you please talk about the advantages and disadvantages of self-anchored suspension? 5. Briefly mix based on applicable conditions. 6. Select landscape when you tell us what type of bridge requirements and control investment relationship.

REFERENCES [1] The sea sails. Conceptual Design of Large-span Bridge Problems//proceedings of the 16th National Conference on bridges. Beijing: China Communications Press, 2004. [2] Ocean sail. Reflection on Chinese Economic Problems of Bridge. Bridge, 2010. 4. [3] Haifan, et al. Introduction to Civil Engineering. Beijing: People’s Communications Press, 2007. [4] The Lei Junqing, Zheng Mingzhu, Xu Gongyi. Suspension Bridge Design. Beijing: People’s Communications Press, 2002. [5] Shao Changyu, Lu Yongcheng. Technical Characteristics of Shanghai Changjiang River Bridge//proceedings of the 17th National Conference on bridges. Beijing: people’s China Communications Press, 2006. [6] In Highway Planning and Design Institute, et al. preliminary design of SuzhouNantong Yangtze River Bridge project across the river. 2002.11. [7] Jiangsu Provincial Highway Traffic Planning and Design Institute etc. Taizhou Yangtze River Highway Bridge Crossing the River Bridge Project Preliminary Design, 2006.10. [8] The Research Institute of Tongji University Architectural Design (Group) Co., Ltd. Jiaojiang bridge preliminary design and wiring engineering. 2008. [9] Dou Wenjun. The Choice of Large-span Cable-stayed Bridge Main Pier Location. 1994 International Symposium of the Conference of the cable-stayed bridge. [10] Yin Haohui. Construction Scheme of Main Arch of Guangzhou Yajisha Bridge Option. Guangdong Highway Transportation, 1999 (4). [11] He Zonghua. Urban Light Rail Transit Engineering Design Guides. Beijing: China Architecture and Building Press, 1993. [12] Yi Lunxiong, Gao Zongyu. New Record of High Speed Railway Bridge—Bridge of Nanjing Dashengguan. The bridge, 2009 (4). [13] The People’s Republic of China Industry Standards. CJJ 69-95 Technical Specifications of Urban Pedestrian Overcrossing and Underpass. Beijing: China Building Press, 1995. [14] The People’s Republic of China Industry Standards. JTG D60-2004 General Specification for Design of Highway Bridges and Culverts. Beijing: people’s Traffic Publisher, 2004. [15] The People’s Republic of China industry standards. CJJ 11-93 City Bridge Design Standards. Beijing: China Architecture and Building Publishing, 1993. [16] The People’s Republic of China Industry Standards. TB 10002. 1-2005 of Railway Bridge and Culvert Design Specifications. Beijing: China Railway Publisher, 2005. [17] In Shanghai Municipal Engineering Construction Standard. DGJ-08-109 Code for

Design of Urban Rail Transit in 2004. [18] Anton Peterson, Zhang Jinping. Cross-channel Challenge—Northern and Longspan Bridges in the World. The Bridge, 2009 (5).

CASE ANALYSIS OF INNOVATIVE IDEAS IN THE CONCEPTUAL DESIGN

Conceptual design is based on “safety, utility, economy and beauty, durability and protection” principle in order to bridge engineering and related disciplines knowledge and practical experience on the basis of (large bridges in particular requires a multidisciplinary approach), with technical innovation as the goal, make suitable natural conditions, to meet with functional design. Concept design is the soul of design. Due to the condition of building the bridge is different, it is impossible to copy others ‘outstanding design achievements, however, we can learn people managed to design thinking, grasp its essence, together, become a rich source of our conceptual design. Learning, research the innovative ideas and design concepts, as well as successful experience is learning to concept design, innovative ideas important ways. For this reason, this chapter from the following view descriptions, analyse the successful conception of philosophy and its distinctive design. 1. The bridge scheme and general layout ideas. Bridge scheme refers to all kinds of bridge the conception and selection, overall including the layout and facades the span and cross-section layout, etc., containing the main navigation span settings, side spans, towers, piers and girders and other major structures, study on the structure and support system, and so on. It is the overall layout considerations and decision-making of conceptual design for structure, concept design fully reflects the basis and guarantee of six design principles. 2. Technical innovation in the bridge program. Mr. Man-Chung Tang, a bridge engineer said, if you do not try to in the design of each as much as possible to improve, then it does not fulfill the obligation of the engineer. Natural conditions and the functional requirements of each bridge vary, provided through research and ideas, creating groundbreaking technology solutions and become a technology of conceptual design flash points of light, is technological innovation. A bridge program, the pursuit of 1~2 innovative ideas, worthy of our bridge technicians work more efforts and re-double their diligence. 3. Bridge program consideration of landscape. Comparison and selection of bridge schemes conceived and is based on the principles of economical and suitable for all bridge programme should be accord with aesthetic principles. For the city an important bridge to living in the city (region) demand for landscape designers will be become an important factor in order to fully meet the needs of landscape functions. This would need to be designed to rely on wisdom find a balance point of six design principles and purpose. 4. Records span the right concept: Maximum span of each bridge there is a current record, there are also bridges performance and its limitation span of the current material properties (see Chapter 3, Section 3.3.2), and they are developing and

changing. It is very important task is to establish the overall layout of main navigation span, a record span the overall layout of the very important task is to identify the main navigation span, a record span of the bridge is the idea of the outcome of the overall layout of a “special cases”, it’s “special” is made up of natural conditions (including geology, topography and water depth, etc.) and shipping capability request form. Conceptual breakthrough long-span bridge to record programmes, in particular, we would like to emphasise the application of economic principles and, establish a correct idea of philosophy. Finally won the outstanding structure award will systematically introduce other bridge (other award-winning bridge in this chapter, or its he is introduced in the section), in order to facilitate the reader to fully understand and absorb their design philosophy.

4.1 THE BRIDGE SCHEME AND GENERAL LAYOUT IDEAS Many factors affecting the bridge scheme and general layout, such as a river, hydrology, meteorology, topography, geology, climate, environment, construction conditions and high aviation limited, port terminals, landscapes, and so on. In considering how under these restrictive conditions, structure think economy, construction convenient bridge scheme and layout, we need to have the boldness and innovation capacity. Here are a few conceived scheme and general layout of the bridge phase of successful experiences.

4.1.1 Tsing Ma Bridge in Hong Kong Design Idea: According to the topographical differences on both sides and side of Tsing Yi Road interchange arrangement requested by asymmetric cross, cross-and Ma Wan side of tower two-span suspension bridges that span suspension concept is also the longest clear span of road-railway suspension bridge. Referring to the benefits of stiffening truss Liang Hang lane Central ventilation and closed box section of wind-resistant high effectiveness and low drag co-efficient of potential, proposes streamlined cladding of stainless steel with double girder design and enclosed double box girder of the central slots combines concepts.

1. Selection of Bridge Schemes Feasibility studies began in 1978, in detail a series of programmes linking North Shore city, and Ma Wan. In order to reach across the Strait, using bridges, sunk pipe tunnel and into the tunnel of the three programmes and carry out economic and technological to demonstrate and compare three scenarios-building costs were 1.45, 1.44 and 1.75 billion HK$. Three programmes for across the straits from the design and construction, maintenance and operation costs, limit traffic adaptability, flexibility, ring shipping of environmental impact and vulnerability assessment in every respect. From view point of numbers alone, drilling has been ruled out of the tunnel, which cost significantly more than the other two programmes, construction issues, as far as the bridge, under normal weather conditions, its construction speed faster than alternatives the Czech Republic, especially the sunk pipe tunnel, since the tunnel dug with the shop, but also to make some previous discussions and leak-plus works. But under severe weather conditions, its building efficiency and far exceeds that of other programmes, because it is outside the scope of architecture is separated from outside, so it is not affected by weather and environmental influences. Moreover, the suspension bridge finished, due to strong winds by reducing its transport efficiency. In terms of flexibility, drawbridge can be said to be the fastest growing one, because it consists of the original four-line development to after eight lines, both proceed from the bridge itself, just at the right place in building more roads would have been enough, but the other two programmes, the need to increase the lane, you must be build a new tunnel and, therefore, in terms of cost and time, and should bridge the economy. Last used

Suspension Bridge.

2. Overall Layout Tsing Ma Bridge’s main span the width of navigation under the bridge, here to hang a width of 1200 m, east of the bridge tower was built on the shore, while the West Tower was built-in where the water is relatively shallow, and therefore decided to bridge the most economical main span of 1377 m, 2160 m (Fig. 4.1).

Fig. 4.1 Facade layout (size: m). Six-lane separated from the upper deck of the bridge layout is bi-directional roads, lower level is a double-track railway lines and two single-lane closures highway. Side of Tsing Yi Island, steep terrain, severe restrictions on the new highway interchange, 3rd. As the shore the water is very deep, route plan calls for starting with the main line at Lane approach roads from the bridge tower. Depth on the shore of Tsing Yi Island and tower was built on the shore, highway interchange lines prevented the side span suspension bridges programme, approach supported by four hollow reinforced concrete piers consisting of 72 m long-span, and equipped with overhead lines between Anchorage and later cable. Ma Wan side towers built near an undersea Continental Shelf offshore 350 m, towers built around an anti-ship collision strike protection of Islands, this is final 1377 m inter-and 355 m in Ma Wan sidespan suspension bridge with two spans of the arrangement. East pylon foundation of reinforced concrete spread foundation, each tower foundation for long 27 m wide, 19 m, 7 m, based on coagulation direct placement 7 m deep in the rock pit, the top surface flush with the bank, for offshore reasons, based with steel rods were painted epoxy resin layer to prevent corrosion. Near Ma Wan Island is based on the tower consists of two 28 m long, 20 m width and 16 m high fabricated steel made of reinforced concrete caissons. When first put in the water of the seabed surface blasting out of rough stone floors, finishing, the tug towed the caisson to the foundation office, add water, sinking, sinking it to the design height. Depth here is about 10 m, a caisson concrete, forming a giant bridge tower foundations. Four weeks plus a stone layer and caisson breakwater, forming an artificial island, to protect the tower structure is to damaged of vessels. Fig. 4.2 shows the photos of Tsing Ma Bridge in Hong Kong.

Fig. 4.2 Tsing Ma Bridge in Hong Kong.

3. Study of Bridge Structure Since in the 1940, of the 20th century since the Tacoma Narrows Bridge was destroyed by the wind and aerodynamics research shows that surfaces of suspension bridge benefits of stiffening truss carriageway with central ventilation, this form of ventilation has been reflected in the forth road bridge in Scotland. However, other studies have also shown that closed box section of wind-resistant efficacy and resistance co-efficient is low. Immediately after the Forth Bridge Design England, Severn Bridge has a main span of similar, stiffening girder box-section is used. Nasty windy climate, the Tsing Ma Bridge requires optimal aerodynamic efficiency, so the composite study on the forth bridge severn bridge and the main potential benefits of performance. The Tsing Ma Bridge, the last of the double box-section truss stiffening structure and non-structure edge deck units, streamlined appearance, providing upper and lower longitudinal ventilation, to increase stability. Original design, only road and rail link to the airport, and container berths on Lantau will go through the Tsing Ma Bridge, the latter this passage has also been preserved, for the bad weather. This round-the-clock capability through the lower aerodynamic performance good stainless steel case cover rail and two road lanes to reach. Section includes two final 6.3 m high longitudinal trusses, 30 m, which supports lane cross interaction of orthotropic deck plate provides flexural rigidity, hollow horizontal framework supported above the longitudinal diagonal bracing trusses, stiffening Liang Hang lane components together. Non-structure 1.5 mm stainless steel baffle plate edge of the shell surface, upper deck dual carriageway between 3.5 m wide vertical vents spaced railway mainly within the box, located in the central 12 m vertical vents on either side are two hidden highway lanes (Fig. 4.3).

Fig. 4.3 Facade layout (size: m). Aerodynamic testing bridge models to monitor the different arrangement of ventilation when the size, position, and orientation of the edge detail bridge surface performance. To change the upper and lower ventilation effects separately, while the upper vent width from 9.4 m reduction to 2 m, remain satisfied with the critical wind speed and amplitude of the Eddy current divergence decreases. When the width of the lower ventilation changes, discovered eddy flow divergence amplitudes decrease, needs on both sides of the tracks have a short closed length. In both cases, come to a totally closed ventilation can lead to a sharp decline in critical wind velocity of conclusions.

Fig. 4.4 Section space renderings. Cross-section aerodynamic testing to prove there is no divergent oscillation which measurement of swirl diverging oscillations. This is what happens when wind speed is low, the amplitude size and frequency is acceptable. Due to the lack of actual Typhoon air flow pattern near the center of information, so the bridge is at risk. Wind deck performance is in a horizontal tilt of ± 7.5º to 5° determination. But there should be emphasized under test only, in order to understand the section in wind acts include a larger point of view, and does not reflect a projected bridge site conditions. Fig. 4.4 shows section space renderings.

4.1.2 Tsing Ma Bridge in Hong Kong

Design idea: according to the terrain and waterway conditions, selected from among more than three-tower cable-stayed bridge scheme, which does not use more than more expensive rigid tower design, instead of using stable cable and plug in the cable tower of steel anchor box and beam, transverse cable, steel-concrete composite beams with combined structure, such as a series of distinctive design and construction. Ting Kau Bridge is the 3rd most important part of the route, the bridge tunnel in north main line of country park, across the Rambler Channel South Tsing Yi and Lantau Link and can be provide the North-West New Territories to the Chek Lap Kok new airport, Kowloon and Hong Kong Island’s convenient channel. Bridge navigation headroom requirement is 240 m wide, high 62 m channel. If there is a Tower located in the Strait, plus ship collision protection system to guarantee total tonnage of vessels of upto 220000 DWT without disturbing the fairway to the piers. 250 m continues minimum width of the anti-collision facilities a safe distance so that the minimum span between the towers of 300 m, and headroom is limited to the bridge towers higher than 220 m, since Hong Kong is often affected by Typhoon, bridge design for 3s gusts of 200-year flood event for 300 km/h. Survey results show that at Ting Kau coast, fine grained porphyritic granite are in the land of 2~3 m, in Rambler Channel seabed stratigraphic layers for marine sediments, rock and alluvium of the original soil, 26 m thick layer of marine sediments of raw soil from under the very soft composed of weathered volcanic Tuff and granite of Tsing Yi Island, waterway center maximum depth of 25 m.

1. Tower Cable Stayed Bridge with Three Spans (Main Span of 420 m) In order to facilitate the project bid, the Government commissioned a consultant engineer to do a feasibility design, bridge-like facade decorated for 140 m + 420 m + 140 m tower cable stayed bridge with three spans (Fig. 4.5), pylons as folding legs h-shaped, PC box girder bridge is a single room, beam 6 m, a tower pier is located shore of Tsing Yi Island, while another pylon located on an artificial island in the Strait.

Fig. 4.5 Twin towers three-span cable-stayed bridge scheme (unit: m).

2. Single-span Suspension Bridge This design for the cross-river, the advantage is avoiding built piers in the channel, eliminating the expensive ship collision with protective facilities built, elevation layout for 140 m + 900 m + 140 m suspension bridge (Fig. 4.6), the bridge beams with vertical bars of pure-warren truss-free, total thickness 5 m, plus stainless steel streamlined oval veneered on both sides, so as to reduce wind resistance. Main beam is provided by two main truss elements, because of its resistance to torsion enormous stiffness, deck light,

construction is easy. 220 m, a-pylon could increase the torsional stability of the tower itself, or cancellation in addition to the traditional design for main cables of suspension bridge caused by reversing the effect, two steel cables diameter of 77 cm, near bridge main span towers one-fourth midspan, two main cable connected form for single cable form, thus increasing torsional stiffness and reduced the main cables of the bridge tower of torque, would count as a new design. However, after the review believes that this is the most expensive option.

Fig. 4.6 Single-span suspension bridge scheme (unit: m).

3. Dual-Tower Cable Stayed Bridge with three Spans (Main Span of 900 m) This is the programme instead of cable-stayed bridge of single span suspension bridge above, and 146 m + 900 m + 146 m of main tower of three-span double cable plane cablestayed the bridge (Fig. 4.7), the two 146 m there are two auxiliary side of pier, bridge towers as a tilted h-shaped deck for the inverted trapezoid, add beam in steel box girder of main span is 5 m high, plus streamlined cladding on both sides, while the side span for 5 m PC four-cell box girder, increased to reduce the upward tension caused by its main span. Cable adopts France Normandy galvanised steel wire beams design concepts in parallel, in order to facilitate installation and maintenance. This disadvantage is the main span and side spans quite uneven, pull upward at the side spans have a great foundation special handling.

Fig. 4.7 Twin towers three-span cable-stayed bridge scheme (unit: m).

4. Three-tower Cable-stayed Bridge Bridge-like facade decorated for 136 m + 450 m + 450 m + 136 m a four-span cablestayed bridge with three towers (Fig. 4.8), on either side across a auxiliary piers. This programme compared with the 900 m cable-stayed bridge, except in the middle of adding a Rambler towers and cables volume is nearly cut in half. Bridge tower in the middle of the sea-bed, happens to have a prominent landforms, natural location used to emplace

bridges pier. PC girder of 5 m high six-cell box girder, with a balance of on-site pouring concrete in construction law, construction of main girder at speeds up to daily 1 m. All in all, programmes in terms of aesthetic, economic, construction, construction and construction costs than other programmes a plus. This programme and final programme is very similar.

Fig. 4.8 Twin towers three-span cable-stayed bridge scheme (unit: m). In January 1994, the department chose seven qualified companies to carry out the “design and construction” methods of bidding, according to owners of existing designs, bidders to present their design and cost. Through the commercial and technical assessment, the lowest bidders won. Finally, successful programs at 17. HK $ 3.8 billion.

Fig. 4.9 Elevation of Ting Kau Bridge layout (size: m). Ting Kau Bridge is a four-span continuous steel-concrete composite girder cablestayed bridge with three towers, its span into 127 m + 448 m + 475 m + 127 m, with a total length 1177 m, see Fig. 4.9. This design feature is the tower of the bridge structure, long circular section concrete column is used, while in the horizontal steel structure and cable to be widened, forming width necessary for supporting girders. Main girder of the bridge into a trough steel plate welded open sections of the steel beams. Steel channel beam height 1500 mm, flange on the top surface lay 250 mm thick pre-fabricated reinforced concrete bridge deck. Steel channel beam and deck are separated by 19 mm of high strength bolt (STUD) combined. Girder steel Liang Quangao 1750 mm.

Fig. 4.10 Ting Kau Bridge. As a four-span cable-stayed bridge with three towers, the central tower, designers turned away abandoned a costly programme of rigid towers, and using an additional Tower is stable approach to stiffness of the central tower of the cable required. Stable cable on each side a total of 4, is located in between two sets of main beam 5.8 m free range, stable cable bolted to the top of the tower at the top of steel anchor box, anchored at the bottom to set two group on the anchor beams between girders. Fig. 4.10 shows the photos of Tsing Ma Bridge in Hong Kong. Tower from Tower Pier of the bridge to the top since the Central Suo Tagao 157.35 m, the towers of each side is 129.35 m (Ting Kau coast) and 120.35 m (Tsing Yi coast). Towers are long circular reinforced concrete column section, central main pylon for 10 m (portrait) × 5 m (horizontal), towers on either side are the 8 m (portrait) × 5 m (landscape). In the soffit, towers and tower columns of horizontal steel beams, bracing, transverse cable composed of steel structural scaffold tower widens to a total width of 50 m. Two groups respectively in Suo Tachu is supported on the steel supporting frame for main girder of steel beam (Fig. 4.11).

Fig. 4.11 Layout and structure of tower (size: m) (a) Main tower column cross section; (b) Main pylon; (c) Tower. Tower anchorage of cable-stayed, the bridge used in concrete pagoda design of lateral

anchorage of column of steel anchor box, this can be obligate omitted in the tower body, casting anchor link, on the installation of steel anchor box for cable, stretching and provides jobs platform, especially for four-cable-plane cable-stayed bridge of this bridge, this design shows more advantages (Fig. 4.12), as shown in Fig. 4.13 construction photos.

Fig. 4.12 Cable-Tower anchor structure.

Fig. 4.13 Construction photos.

4.1.3 The Tsurumi Channel Bridge Design idea: according to the main and auxiliary channel and channel dimension as well as the request of the two bridges is arranged in parallel without auxiliary piers the maximum span single cable plane cable-stayed bridge concept and increasing tower height to improve rigidity and horizontal cable between the taliang and resistance to improve the force. Condition of building the bridge: Bridge, effective road width of 29 m, containing wind up 38 m; main channel of 450 m × 49 m, auxiliary lanes on both sides 200 m × 25 m air; deep 12 m, two parallel bridges in urban planning, which 49.75 m; flutter testing wind of

74.4 m/s; seismic intensity = 7.8~8.2 level. According to the channel required, cross-cross 510 m, side 254 m. Due to the 1 : 2 of side, cross-ratio, span and cannot be located within the secondary pier, side live load deflection in particular, in order to reduce the load reduce cable stress and deflection, and require an increase in tower height, dominated the economic height of the tower across a span of 0.2~0.25, the bridge takes 0.25, so the height from the base of the tower is 180 m at the top (Fig. 4.14).

Fig. 4.14 Elevation of Ting Kau Bridge layout (size: m). Two bridges is arranged in parallel so that cables may appear chaotic complex, and finally decided to adopt the single-cable-stayed bridge. Flat steel box girders, box office, beam height 4 m (Fig. 4.15). Because of single cable plane cable-stayed bridge of torsional stiffness for double rope bridge with only one-fifth, which is parallel to the bridge, likely at low wind speed chatter and the center barrier needs to be increased to raise the bridge when wind resistance. Tower Vase-shaped, lower pylon column size to take in, in appearance to increase tower base using pneumatic caisson construction, more than the cofferdam relief and not enough spacing between the two bridges tower is less than 3 m (Fig. 4.15). Tower height, wind loads, the rigidity of main beam and longitudinal beam with horizontal elastic rope and spiral damper main beam elastic joint between the tower and reduced beam longitudinal and horizontal cable in seismic stability (Fig. 4.16 & 4.17). Home about 250 m3 concrete ballast beam placement.

Fig. 4.15 Tsurumi channel bridge girders and tower (unit: mm).

Fig. 4.16 Tower and a horizontal cable connection structure.

Fig. 4.17 Propeller type damping device.

4.2 TECHNICAL INNOVATION IN THE BRIDGE PROGRAM Concept scheme requires in-depth study and understanding of the natural conditions and function, through repeated thinking, constantly changes, and more comparison and selection, to form the technical improvements and technical innovations of design works. Innovation in technical innovation requires designers to establish a correct concept, rejection of plagiarism, not content to imitate, not blind pursuit of “firsts” and “best”. Reflections on innovation from the. As elaborated in chapter 1th, the innovative three ask (Why? Why not? What if?) Is shabby, establishing new forms of reasonable and prudent technology trilogy. Following the introduction of composite structure bridge also experienced such innovation development process, since entering the 21st century, by in concrete bridge and the problems of orthotropic steel bridge decks and disease continue to be found to make composite structures has been in Europe and America States and Japan bridge area recognition and application, the technology has been further research and development. Explain some of the best technical innovations in the bridge program and its results.

4.2.1 Denmark Oresund Bridge—Steel Truss Composite Girder Design Ideas: as one of the largest composite structure with long span bridge, a good representation of the composite structure bridges the past half century development. The bridge with double-deck structure, upper level concrete slab width 25 m, directly supported by the two main truss top chord. Because common cizongliang in the steel bridge and beams are omitted here. The Oresund bridge, concrete’s role is not only to vehicle load transfer to the main truss, also increase the transverse stability, and form part of a closed frame. The closed frame is from the lower box-shaped diagonal steel beams, truss and steel truss, on holding between chords composed of concrete. Oresund bridge with a total length of 8 km, is likely to be the largest composite structure bridge, but it may be surpassed by the Feynman Strait Bridge. The bridge between the Taiwan Strait continues to approach spans with a total length of about 16km. (Referenced above Denmark Professor Ji Muxin as SEI Volume 20, Number 2, 2010 composite construction album write introduction.) Full 16 km Oresund Cross-Sea project, made up of three parts, of which 7.8 km bridge, 4 km road on the island, 3.8 km cross harbour tunnel and the coast extends to 0.4 km, connecting Denmark Copenhagen and Sweden’s third-largest city of Malmo, in Started in 1995, was completed in July 2000. Layout 140 m + 160 m + 490 m + 160 m + 140 m = 1090 m main channel bridge of long-span, steel truss composite girder rail for two use double-deck, upper level is a 4-lane

highway, the lower level is double-line railway bridge navigation clearance of 57 m. Main tower is an h-shaped bridge tower stayed-cable of the harp-shaped parallel cable (Fig. 4.18).

Fig. 4.18 The Oresund Bridge.

Fig. 4.19 Railway concrete channel beam construction. Of stiffening girder steel truss composite girder, upper transverse post-tensioning prestressed concrete bridge deck, the lower level is concrete channel beam (Fig. 4.19) combined with the steel structure as a whole, thereby reducing rail noise, improve overall strength, across the trusses transverse forms a seal closed steel box. Truss rod’s angle of about 30° and 60°, inclination can match the cable inclination angle, pull cable anchor solid lies on the same outrigger truss diagonal angle. For hollow rectangular bar full of steel truss girder welding, rod is equipped with de-humidification system to improve the durability of trusses (Fig. 4.20 and 4.21). Steel structure by using S420 (EN10113) steel plate thickness for the primary span railway bridge from the center underside of the 9 mm to pylon joints webs 50 mm.

Fig. 4.20 Main bridge steel truss composite girder section (unit: mm).

Fig. 4.21 Bridge approach steel truss composite girder (unit: mm). Manufacture of steel truss composite beams (Fig. 4.22) and pouring of the concrete deck slab is in Spain. Beam segment length 140 m, 7,000t, contains upper concrete deck and lower deck railway concrete channel beam, use flat-bottomed barges transported to the bridge site, dabeiertexiqiao Swan, crane ship (lifting capacity up to 8700t, raising 70 m) lifted onto a pier (Fig. 4.23).

Fig. 4.22 Main bridge steel truss girder manufacturing. Also and with the same height of stiffened girder of approach spans and structural steel truss composite continuous beams, each hole span 140 m, truss an angle of 45°, each truss element length is 24 m, on both sides of the bottom chord at every 24 m in the node are connected by beams (Fig. 4.21). With the same hoisting the hole.

Fig. 4.23 Steel box beam hoisting.

4.2.2 United States East Bridge of the San Francisco Bay Bridge Earthquake-resistant Tower Design Ideas: In the landscape need only cylindrical tower of limiting conditions, move closer to the gate-tower two towers, beam cut short, the door translate the beam flexural yielding shear yielding seismic energy consumption, forming a vertical pylon under strong earthquake remain elastic seismic single tower concept. In the mid 1930s, the construction of the San Francisco-Oakland Bay Bridge, 12.8 km, is the longest in the world at the time, high technical level of the bridge, still to the main line of the East Bay of the San Francisco peninsula, heavy traffic, daily traffic nearly 280,000 vehicles. Design earthquake force is small, the east bridge (steel truss bridge) in 1989, at 7 on the Richter scale. 1 partial collapse during an earthquake, so that construction of the new East Bay Bridge to replace the existing bridge, 3.6 km. New deck 25 m wide in each direction, including 5 lanes and a light railway. Side of the bridge there are wide and 4.8 M sidewalk, taking into account the 1500 year return period earthquake. Final implementation plan “Self-anchored suspension bridge” system with a main span of 385 m, side 180 m. General prevailing notion that, at such a high intensity earthquake area, bridge-tower should be. In this way, the beams of the tower under earthquake to earthquake energy consumed can form a plastic hinge, making vertical pylon remains elastic. Thus, single tower was considered unsuitable for the main unit of the bridge, as it is not a statically indeterminate structure. During the preliminary design, the gantry tower and a single tower with different types of studies were carried out (Fig. 4.24). According to the calculation a single tower can be meet current seismic design requirements, but the towers is not a statically indeterminate structure, once the plastic deformation will be lead to destruction, so that this type is not appropriate. However, despite these concerns, still the appearance of single tower exclusive.

Fig. 4.24 Gate bridge tower scheme selection.

Designers draw bridge towers and research how to make it look more like a single tower. Move closer to the two towers, beam will be cut short; after beam cut short, just not in bending yield but caved in under the cut. Designers and ask, why not just make it just under the shear yield? If it doesn’t look like the usual tower bends bend, but the shear yield how? If multiple towers closer together, the tower look like a single tower structure (Fig. 4.25).

Fig. 4.25 Twin tower column in shear connection bridge. Thus, an innovative single-tower scheme surfaced water surface. Results indicate that this structure under earthquake action loaded with good performance, as shown in Fig. 4.26. In facts it is more excellent than conventional gantry tower on, for now we can according to the different needs between the two towers position increased shear, which can significantly increase number of statically indeterminate jiaqiaota (Fig. 4.27). Final design of the bridge tower 160 m tower made up of 4 columns, along the high shear joints, tower of steel box-section column 3 m interval of diaphragms as shear connection. Not across the anchor at the top of the main cable saddles on. Cap 6.5 m support 13 diameter 2.5 m. On 5 m of steel pipe piles, pile filled in pouring concrete, pileNET, 20 m, embedded in rock.

Fig. 4.26 Earthquake-resistant tower concept

Fig. 4.27 Tower column shear (size unit: mm). In addition to the pylon design, the other components of the bridge also has many unique features. Cable diameter of main channel bridge of two 0.78 m, East (385 m), anchoring the east pier of beam, wire saddles for bridge box girders, and designed to be removable, to balance out the two main cable of cable is bad. West (180 m), surrounded by two separate saddles of the main cable in the west on the pier, both saddle fixed on the west pier, west pier design a pre-stressed cap beam, its quality can be balanced bridge span asymmetry of dead load forces on the west pier, also used to bear the west pier and two main cables at the time of operation and earthquake loads them different saddle stress. Superstructure for two with orthotropic deck plate of steel box girder and suspenders on the load distribution in the box girder, box girder with wide 10 m, 2.5 m, 30 m interval of the transom connection, the 72 m cross beams bear suspender transverse load, ensuring two box loads, is the overall effect of wind and earthquake loads. Hanger rod located at the outside of the two boxes to form two spatial cable plane.

4.2.3 Chongqing New Shibanpo Bridge of Steel-concrete Composite Beams Design: Design this a world record span box girder bridge, by introducing 108 m steel box girder in the middle of the main span steel box beam segment implements technical and economic possibilities. Steel box girder is 1000 m and raw materials produced by the Department of Wuhan in Chongqing. It has been designed to barge in the form through the three Gorges dam was towed to Chongqing from Wuhan, placed in the main cross raised into position below. Old shibanpo bridge was built-in 1981, the new bridge parallel to the old bridge is located in the upper reaches of the old bridge. Two bridge-centerline distance between 25 m, old bridge the bridge width is 21 m, Shinbashi bridge width is 19 m. Spacing between the two bridge deck is 5 m. After extensive research, shipping sector must be removed between two main piers, the main span of 330 m, as shown in Fig. 4.28.

1. Design Philosophy Taking into account the advantages of concrete and steel is light weight, ultimately chose

the hybrid structure—the main span of the bridge in the middle used steel box girder and the rest using conventional concrete. 800 mm thick concrete slab under pressure, C60 is approximately equal to 100 mm thickness and yield stress of steel plates for 345 MPa compression capability, the latter is the most commonly used steel in China. However, thick concrete slabs construction easier than plates. Therefore, close to the pier girder using concrete makes more sense. The middle part of the main span steel, steel can be thinner, reducing weight and thus reduce the mid-span bending moments, more valuable. Light mix concrete weigh about 60% of conventional concrete. Used across the middle weight about conventional concrete box girder of steel box girder of 30%. If using span definition, equivalent to all the ordinary concrete beam, and at the end have the same moment of consolidation the needed span. Reduced weight for intermediate beam, calculations show that when they span the middle one-third with steel box beam, 330 m hybrid girder span is equivalent of 269 m.

Fig. 4.28 Span layout of the the old and the new Shibanpo bridge (size: m) Select steel box beam segment length the second consideration is the recommended construction method design, entire segments of steel box girders on factory production, to barge onto the scene, integral hoisting, such operations are limited. In addition, the factory is located in the three Gorges dam downstream, dam ship lock length limits the size of steel box girder. After careful study, decided to adopt the middle length of the steel box girder 103 m. Total length of steel box beam segment also includes 2 at each end. 5 m transition section, total length is 108 m, weighing about 1400t. Ultimate new shibanpo bridge as shown in Fig. 4.29. In addition to the main span steel box beam segment in the Middle, and the remaining parts are made of conventional concrete.

Fig. 4.29 Composition of the hybrid girder. Bridge District the highest water levels can be higher than the minimum water level of Yangtze River 38 m, so high water flow may be imposed on the pier is great lateral forces.

Although Foundation located in solid rock, in order to increase the ability to resist lateral loads, set ø2.5 m and ø2.0 m short pile of pile diameter Dig-hole pile is necessary. Standard cross-section of the bridge to direct Web box girder sections. Bottom width 9 m, total width of the roof is 19 m, each flanking margin-width 5 m (Fig. 4.30). Inside the box girder of main span of 330 m, installed a 4 section 27 units of externally pre-stressed steel stranded wire. If necessary, by adjusting these steels twisted deformation of steel box girders of the stress correction.

2. Steel Box Beam Transport and Hoisting Steel box girder is 1000 m and raw materials produced by the Department of Wuhan in Chongqing. It was designed as a form of barge, two temporarily closed. Through the three Gorges dam was towed to Chongqing from Wuhan (Fig. 4.31). And then turn 90°, below crane placed in the main cross-promotion in place. First to be hoisting the transition part, hoisting one at a time. Lifting these 2.5 m not very long beam interferes with voyage. Lifting 103 m of box girder sections must be completed at 12 h in order to minimise interference with shipping on the Yangtze River (Fig. 4.32). Actually lifting only had less than 5 h, but after segmental box girder erection in place and fixed with more time.

Fig. 4.30 Concrete box girder and steel box girder of cross-section (unit: mm).

Fig. 4.31 Steel box girder as a barge to transport.

Fig. 4.32 Transition and hoisting of steel box girder.

4.2.4 Hangzhou Jiubao Bridge, Composite Arch Bridge Design: Hangzhou jiubao bridge is 1855 m, is an all composite construction of large bridges crossing the river. Non-channel and main channel bridge approach respectively, using a combination of large-span continuous arch bridges and composite continuous boxgirder bridge, arch bridge with box beam using multi-point synchronising incremental launching construction. When incremental launching construction of bridge approach, 85 m-span without a temporary Pier; incremental launching construction of the main bridge, 210 m span and only 1 temporary pier.

1. Bridge Type Design Main channel bridge 3 × 210 m of continuous composite arch bridge main span, covering the entire scope of grooved swing and be able to less than 1000 DWT river-trade vessel navigable depth requirements. Using V-shape piers of main bridge piers, piers contour line along the main arched the line, in order to achieve better visual effects, V-shaped piers and girders are actually separated, set bearing (Fig. 4.33). The upper structure using beam-arch composite system, consists of a steel-concrete composite structure bridge deck and steel arch structure for supporting long-span 188 m + 22 m + 188 m + 22 m + 188 m of continuous structures. Main Pier Foundation of bored piles in a 16 diameter of 2 m. Map of main bridge of Fig. 4.34 bridge steel girder segment diagram.

Fig. 4.33 The rendering of main bridge.

Fig. 4.34 Schematic drawing of main bridge deck girder segment. In order to reduce the impact on river hydrology, requiring non-waterway bridge rate increased span and reduce the Foundation block water as much as possible. Although using long-span PC continuous box girder of 85 m, DUN sub-division scheme, can meet the requirements, but within this span composite box girder is not only economic competitiveness, and the whole structure form of continuous composite box girder, combining substructure, base size the decrease, you can be minimise the effects of the bridge on the river. In addition, the composite box girder by incremental launching construction of steel girders, without need to set temporary piers in the River, compared with conventional cantilever casting of PC box girder structure, symmetry of traditional

structures and construction method, create the conditions for improving project quality and reduced impact on the environment.

2. Push Technology and Equipment Main channel bridge construction in accordance with the general programmes, and the erection in the water a lot of brackets, deck and the arch structure installation. So violently on the tidal bore of Qiantang River and Riverbed region, is not only costly but large workloads, high safety and quality risks. Based on careful analysis of environmental and structural characteristics of the construction and judgement, design innovation by incremental launching construction method. This design idea construction is now in construction on the water to the shore, not only from the river in a large number of temporary piers and supports, reduce construction and shipping on the environment interference, also avoids the high risks and difficulties in assembling the arch rib on the water, in addition, all steel construction on shore, in order to improve project quality creating optimum conditions. Non-channel and main channel bridge incremental launching construction of bridge, as opposed to domestic common or dragging the slip on the beam at the point of method of conventional beam methods often need to be strengthened to meet the pusher and stability requirements of local, this will be result in costs far higher than for steel beam strengthened by increased costs for new launching technology and equipment. For this reason, design and raise sound tow equipment and technology, as well as synchronise and balance control technology, mechanical safety assurance structure reliable, make incremental launching construction which can be implemented without the steel beams were strengthened. It aims to promote the progress of construction technology of thrusting, and groups composite structure bridges the total cost of the most economical; current progress indicates that not only meets the expectations, as well as incremental launching construction technology technology and equipment is a key technology of composite box-girder bridge with access to sound economic one. Main channel bridge construction in general can be divided into two parts of steel structures and bridge decks. Includes deck girder and steel arch of steel structures, beam using multi-point synchronising incremental launching construction. When pushing scattered in various piers (including the temporary pier) device the lifting, advance, apart from the bridge and bridge piers, but each across 3 main span 1 temporary piers, set 3 temporary pier at the collector. When pushing in the between deck girder and Arch ribs with provisional pole in order to push joint force. Completed per assembly 1 hole top 1 hole until all 3 holes pushing into place, as shown in Fig. 4.35 and 4.36. Decking prefabricated, cross-wise into 3 pieces, a small beam for segmentation and vertical 4.25 m distance between steel beam section. Steel push is complete, according to the design the prescribed order, stretching booms and removing temporary arch bars, the laying of prefabricated bridge deck poured joint concrete, completed construction.

Fig. 4.35 First hole of main thrusting.

Fig. 4.36 Third hole of main thrusting. Incremental launching construction of arch bridge and 210 m span and only 1 temporary pier, is a new attempt. Composite arch bridge removal after the deck, load capacity compared to its weight of steel structure with a larger available space. By steel arch rib of steel vertical between temporary bars, can effectively play an overall carrying capacity of steel structures, both technical and economic features the advantage and competitiveness.

4.2.5 Uses of High Performance Steel and Concrete Composite Beam Bridge Design Ideas: High-strength steels and ultra high performance fibre reinforced concrete slab design of new beams. using S460, S690 grade of steel can reduce the weight of the superstructure, steel weight decreased to 40%, reducing the total weight of the superstructure about 25%. Bridges composed of three 95 m + 130 m + 95 m, a bridge deck total width 21.5 m, the four-lane design. Main span span is France to construct the maximum span composite beams.

1. Structure with a Partial S690 Table 4.1 shows the distribution of steel bridge structures. Support near and Central main span uses steel grade S690, because decks will be fully used to provide cross sectional resistance. Panels in both vertical and horizontal prestressed, appear to resist the serviceability limit state consumer pressure condition. Table 4.1 Steel girder structure distribution. Support positions

Segment length (m)

70

16

18

16

21

38

21

16

18

16

70

Top flange thickness (mm): S460

30

35

40

40

35

30

35

40

40

35

30

Bottom flange thickness (mm)

35

45

60

40

40

40

40

40

60

45

35

Lower flange of steel grade

S460 S460 S690 S460 S460 S690 S460 S460 S690 S460 S460

Web thickness (mm): S460

20

22

22

22

20

18

20

22

22

22

20

2. The Ultra-high Performance Fiber Reinforced Concrete (UHPFRC) Board material is used in ultra high performance fibre reinforced concrete. This content of high strength steel fiber concrete 200 kg/m3, 20 mm long, 0.3 mm thick no need to configure bar, under pressure of 150 MPa. This concrete slab inspired by France national project of MIKTI ribbed plate 1 (Fig. 4.37). In this project, 12 m wide, for ease of transport transmission and divide it into 2.5 m wide units. Vertical and horizontal ribs Center spacing is 0.6 m. Deck plate total thickness 0.38 m, by 0.33 m rib height and 0.05 m plate high mix. Ribbed bottom width of 0.07 m, ribbed top plate width of 0.10 m.

Fig. 4.37 France MIKTI Engineering (LCPC in laboratory tests). In this project, due to the four-lane design, board width is very large. Deck width is 21.5 m, located on each side of the bridge 2. The 0% cross slope. Main beam distance 14.3 m, deck cantilever on each side long 3.6 m. Pre-fabricated section 21.5 m, width 2.5 m. MIKTI bridge panels meet these constraints by increasing the height of the ribs. MIKTI total 0 from the symmetry axis. 615 m line changes to free edges 0.4 m contains 0.05 m high tickness. Other dimensions: ribs at the bottom width of 0.07 m tension stranded wire is necessary, ribbed top width of 0.10 m, thickness 0.05 m, these have been local frictional MIKTI project laboratory test for success. Bridge deck cross section as shown in Fig. 4.38, and Fig. 4.39 shows the main beam dimension detail.

Fig. 4.38 Bridge deck cross-section (size: m).

Fig. 4.39 High-performance fiber-reinforced concrete for main girder of transverse profiles (size: m). In order to resist lateral bending moment throughout each deck width set 5 rib T15S internal pre-stressed steel twisted pair (Fig. 4.38 and 4.39), which has two steel stranded wire is not pulled to the outside cantilever sections (Fig. 4.38). In the longitudinal direction, set 30 12T15S steel beams and supports 1.2 m high tension, provided in the board 14.3 MPa forever compressive stress. In under serviceability limit state at any time, can resist pressure suppression effect.

3. The Construction Phase Similar to the bridge construction and pre-fabricated units, and appropriate modifications based on longitudinal pre-stressing requirements. Construction stages: installation of steel girders, 2.5 m, 21.5 m wide deck plate element installed, vertical tensioning of prestressed, concrete slabs and steel-bonded frame connection (through the hinged joints of concrete slab has been poured coupling), internal support tension, eventually installed nonstructural facilities. It is worth note that surface layer thickness of 60 mm and normal strength concrete slab to prevent cracking at the supports have to be located 110 mm.

4. Weight and Cost Comparison Actual price list according to steel structures, structural steel for weight savings of 40%, equivalent to 25% cost reduced. In contrast, for in the bridge deck, and more expensive than traditional high-performance fiber-reinforced concrete slabs. Taking into account the cost of the entire structure, such as fruit prices for high performance deck template be borne jointly by several bridges, high performance bridge will be a very competitive bridge. Use of high performance materials such as high strength S460 steels and S690, as well as high-performance fiber-reinforced concrete in this area out of steel and for optimal performance of the concrete structure. European norm is likely to lead to more use of combined beam bridge design. In this emphasis state awareness times, vigorously promote material savings, particularly for steel piers, concrete savings of foundation. This concrete slab context, contains more high-performance fiber-reinforced concrete cement, with regard to the environment is more harmonious. High Performance Concrete slab (HPC), is

available as an option in the future will require further study.

4.3 BRIDGE PROGRAM CONSIDERATION OF LANDSCAPE REQUIREMENT Landscape in a way that is also a functional requirement in modern cities, a bridge in addition to the opening of the meeting, pedestrians and shipping requirements, but should be also meet the requirements of viewing, giving the viewer a pleasant effect, giving the viewer with beautiful enjoyment. Landscape of bridges, both historical, cultural and geographical influences the viewer’s subjective requirements also have an aesthetic method then, consistent with the environmental condition of objective requirements. Programme is to meet the requirements of landscape bridges both organically together in order to structure and shape in response to these requests.

4.3.1 Tsing Ma Bridge in Hong Kong Design thinking: Through the competition and technology, beautiful selection of judges the judges, elected by chic, the iconic round chimney type pylons, steel box beams and concrete mixing split-beam cable-stayed bridge scheme. Stonecutters Bridge Hong Kong Nineth main part of the route between Tsing Yi and Cheung Sha Wan, bridge across the 900 m wide with heavy traffic rambler in the Kwai Chung container terminal, main span will be more than 1000 m. Bridge is the most prominent part of the whole project, and will be become a major landmark of a metropolis like Hong Kong. To this end, the Hong Kong S.A.R. the Highways Department for the first time hosted a international design competitions, for the Stonecutters Bridge, the landmark bridge provides concept design. This two-stage bridge design contest in November 1999, formally opens, the Highways Department through the application of bridge design teams and units prepare participants to maximise design record and the team’s experience of bridge engineers and architects, the examining choose the 16 design teams, inviting them to participate in the first phase of the competition. 16 teams by a total of 64 separate companies and the designers, and the team’s governing body came from mainland China, Finland, and France, and Germany, China, Hong Kong S.A.R., Japan the, Norway and the United Kingdom and the United States. In the first stage of the game, there are 21 design team submitted two proposals, there are 5 teams to submit a programme for a total of 27 design schemes. Of which: 22 for cable-stayed bridges, 2 suspension bridge and 3 collaboration system for cable-stayed and suspension bridge. Participation in the first stage of the programme, in terms of both concept and focus there is a big difference. Cable-stayed bridges programme, traditional inverted y-shape, such as A-and H-shaped towers, there is also a new chimney, Y-, X-, or horn-shaped and so on. Cable aspects also vary, from single to four. Steel box beams have adopted a more traditional single-box design, also has adopted a more innovative dual box design and central slot of box girders, avoided the traditional h-bridge tower of suspension bridge design-to take a special a-shaped or Y-shaped bridge towers, cable arrangement is also

very special, cable-stayed and suspension system programme mixed the two newer concepts of design, and the self-form of anchor, but so is more complicated (see Fig. 4.40).

Fig. 4.40 Collection of various forms of bridge tower. Two review committees in accordance with a pre-determined rating criteria were assessed. First by the technical evaluation committee scores, the programme must reaches a certain level and then to the beautiful Review Committee score. After two review committees to phase one design scoring the Highways Department has selected five outstanding programmes, and programme arrangements participants optimise and submit more detailed information on the second-order games paragraphs. Five into the second phase of design for cable-stayed bridge scheme with a main span from 1000 m to 1019 m, full-bridge with a total length 1600 m, the five designs are distinctive (Fig. 4.41).

Fig. 4.41 Five renderings (a) Programme a; (b) Second plan; (c) Scenario three; (d) Programme IV; (e) Programme five. Option one is a a-pylon cable-stayed bridge, a main span of 1017 m, 292 m and 321 m, respectively, with a total length 1630 m. Cable layout as a semi-scalloped, stiffening girder side span and near the main span of the bridge tower 52 m part is a concrete box girders, parts for double-box steel box girders. Top of the tower is a steel core surrounded by stainless steel cladding. Overall, the programme in the on the design and construction is a traditional programme. Scenario two is an inverted Y-shaped towers of cable-stayed bridge. Its main span is 1000 m, TRANS-300 m, full-bridge a total length of 1600 m. Cable distribution and connect as a semi-scalloped girders on either side, each pair of cables in the middle by a deflector cable banded into a anchored to a tower. Girders and pylons in recent 100 m part of the tower as a single entity. Stiffening girder side span in concrete box girder in main span 800 m is a steel box girders of the central authorities. In addition to the arrangement of the cables out, which is a traditional design. Scenario three is a funnel-shaped pylon of cable-stayed bridge, upper part of the bridge tower 112. 5 m is a steel structure under the portion is this concrete slab Bridge’s main span is 1018 m, TRANS-298 m, respectively. Full-bridge has a total length of 1, 616 m, cable with half a pie cable layout as a semi-scalloped, stiffening girder side span and near the main span of the bridge tower 24 m part is a concrete box girders, with box-beam,

double-box steel beam by beam together. Overall, the programme both in design and construction for a new beam scheme scenario four is a h-pylon cable-stayed bridge, tower when stiffening girder above cross-bar with no. The main span of the bridge is 1001 m, full-bridge has a total length of 3001 m, cable with half a pie cable distribution as a semiscalloped in two vertical planes. Full-bridge are made of steel box girders, joined in a steel box girders of side span in concrete to increase the dead load weight to balance the main span. Due to the tower from the bridge extra high without beams, both in design and construction of the programme seems to be rather special. Option one is a a-pylon cable-stayed bridge, a main span of 1019 m, 280 m and 321 m, respectively, with a total length 307 m, the bridge has a total length of 1616 m for cable distribution in a fan-shaped manner, on the anchorage of steel anchor box in the tower the upper set, add beam supported by pylons in the vertical and lateral directions. Stiffening girder side span and near Tower Bridge main span portion of the 89 m and 95 m are concrete box girder and the rest for steel box girder of main span, as a whole, this programme in terms of design and construction is a traditional beam. Scheme judges voted the Championship programme as the number three, Championship consists of the Halcrow Group Ltd (United Kingdom), Flint and neill Partnership (United Kingdom), Dissing + Weitling (Denmark) and the Shanghai municipal engineering design and Research Institute (China), consisting of design team submissions. Second place for plan v, third place for scenario four, while option one and option two is named honorable mention.

4.3.2 Shanghai Lupu Bridge Design ideas: As last crossed the Huangpu river of Shanghai Lupu bridge, Nanpu bridge and Yangpu bridge built two oblique after laqiao, the all-welded steel structure deck box arch bridge in programmes in cable-stayed bridges, suspension bridges, and many scheme selection of the successful bidder, such as this becomes especially landmark buildings of the Expo in Shanghai. On the Huangpu river of Shanghai Lupu bridge. Span 550 m, across the river. Lupu bridge is not only a means of transport, it should be not only embody the cultural landscape, and reflect modern achievements of science and technology. Possible schemes for cable-stayed bridge, suspension bridge, arch. In 1999, Shanghai Lupu bridge was open for bidding, Arch programmes successful. For the arch bridge, and at domestic level: 420 m span of the Wanxian Changjiang River Bridge was built-in 1997, concrete arch bridge (Fig. 4.42). Thrust was too large but concrete arch bridge, it should not be built on soft soil foundation in Shanghai.

Fig. 4.42 Yiling Yangtze River Bridge. At the international level: are trussed arch 500 m arch bridge forms in the past, the rod and much smaller. Built-in 1977 United States new River Gorge Bridge with a main span of 518 m (Fig. 4.43). Completed in 1932, Australia Sydney Cove bridge with a main span of 503 m (Fig. 4.44).

Fig. 4.43 New River Gorge Bridge. Truss arch bridges originated in the 1930, of the 20th century, is lifting capacity constrained components lighter and more. In recent years, lifting capacity upto 500t, rapid development of field welding of steel structures, designed to adapt to the trends Widget perfecting of welded box structure design, component makes a great little steel indicators-economic, fast construction, clean lines. Decisions adopted and welded steel box arch bridge of Lupu, modeling simple, span of 550 m, the world’s largest span arch bridge, is one of the landmark buildings of the Expo in Shanghai. To increase lateral stability, simplified structure, Lupu bridge main arch are basket type spatial structure form (Fig. 4.45).

Fig. 4.44 The Bay of Sydney bridge.

Fig. 4.45 Shanghai Lupu Bridge. Lupu bridge structure span of 550 m, the ratio of height to span 1 : 5.5, arching cross section width 5 m, Arch cross-section height of 6~9 m, vertical clearance high 46 m. Through tied arch bridge of the Lupu bridge, on both sides of the main span between end cross beam arrangement of 16 horizontal cables to balance across the arch of nearly 200,000 kN of thrust. Horizontal cables upto 761 m, dangenlasuo upto 110T (4.46).

Fig. 4.46 Structure system. In order to ensure the structural safety of each steel beam can be replaced for operational maneuverability, including 8 within the box girder, 8 piece set on the deck. Even on the deck 8 was accidentally damaged, box 8 roots can keep the structure in the limit State and doesn’t collapse, easy to repair (Fig. 4.47).

Fig. 4.47 Shanghai Lupu bridge cross-section. Integrated construction technology of rigid-frame bridges and cable-stayed and suspension bridge construction of this bridge. 1. Based on construction technique of rigid frame bridge with form a triangular system (Fig. 4.48). 2. Construction method of cable-stayed bridges, installing main arch (Fig. 4.48). 3. The introduction of cat the Tao to install extra long, heavy levels of suspension bridge cables, 16 levels of cable for preformed parallel wire strands, long 761 m, 110t, cable diameter is 18 cm (4.49). 4. Combined with the characteristics of Lupu bridge structure, the construction units responsible for the research and design of bridge girder erecting equipment with independent intellectual property rights: a main arch deck crane of crane and Arch (Fig. 4.49). 5. The successful implementation of field welding quality control of steel structure.

6. The closure measures: end bolting an end weld, closure temperature of 20ºC, cooling closure supplemented with small amounts of incremental launching method of external forces. Fig. 4.50 shows the hanging and closing main arch bridge construction photos.

Fig. 4.48 Triangular systems and installing main arch construction photos.

Fig. 4.49 Installing the horizontal rope and arch crane construction photos.

Fig. 4.50 Shows the hanging and closing main arch bridge construction photos.

4.3.3 Chongqing Caiyuanba Bridge Design ideas: Want to build a beautiful arch bridge, according to the double-layer traffic, navigation, appearance and other general requirements, combined with the shape landforms was studied for deck, middle deck and lower deck arch bridge, and concludes with a Y-shaped rigid-frame structure and tied-arch composite box-shaped arch bridge, the arch of a new system. When beginning the design of caiyuanba bridge, we have a wish: I hope that this new bridge is an arch bridge, a special drift light arch bridge. Caiyuanba bridge is located in yuzhong peninsula south of caiyuanba connected

yuzhong and South Bank. Bridge is a two-tier structure, upper deck has 6 traffic lanes and two-sided sidewalk, the lower level consists of a two-line light rail lanes. In order to satisfy clearance requirements of light rail track, height of the beam 11 m. Due to the requirements for navigation on the Yangtze river, the span of the bridge was identified as 420 m. First of all, designers think girder truss structure should be to make light rail passengers can enjoy the scenery of Yangtze river. While if the box girder of 11 m, that appears to be very bulky, and the use of truss structures do not need to think about the ventilation of the lower deck design. Arch bridges can be divided into thrust and thrust two. True arch was thrust, caiyuanba bridge location, geology condition good, can withstand greater thrust. But if directly by the foundation under horizontal thrust arch had to be very low, unable to meet the requirements of navigation. Thrust free arch bridge is a tied arch. It could be a deck, middle deck and lower deck. Navigation requirements are met before side note, deck-type arch of the bridge will be squished, force structure requirements are not met. Through-arch bridge, since all deck arch it looks so heavy, unable to meet aesthetic requirements. So choose a deck arch bridge. In this place, the main span southern tip of home bias, high and low water levels vary greatly. In order to avoid rib struck by ships, designers had to arch slightly improved on, using pre-stressed concrete sub-structure, to achieve high impact resistant capacity. Arch is the main backbone of arch, arch main is the bar, must take into account the vertical and lateral stability. In terms of vertical, due to lower deformation of light rail has more stringent requirements on bridge structure must be very strong, as limits distortion. Fortunately, light rail length is shorter, only partially affected. Girder is a 11 m high trusses, stiffness, this arch stiffness requirements can be reduced. In bridge design, because the hangers at different elongation under load is limited, and inspection when you calculate the stability of arch bridge with vertical, can broadly be superimposing the rigidity of beam and arch stiffness. So, if the beam stiffness large arch stiffness can be small. Because the arch is mainly influenced by pressure bars, box-section truss work. In terms of appearance, if the main beams and arches are truss bridge shape look too heavy, not enough light, Chongqing Yangtze river scenery and pretty disturbed. Chongqing is a city beautiful mountain city, her beauty lies in her pretty face. So, between the steel box arch and steel pipe truss arch, chose the more slender, 2 m wide and 4 m high steel box arch (Figs. 4.51 and 4.52). Lateral stability of arch must rely on horizontal poles to ensure its stability. However, for aesthetic reasons, struts must be slender, passers-by looked without any sense of clutter and closed, according to the local stability of arch rib request, decided to use 6 transverse bracing and for overall coordination, these transverse braces are box section. Eventually introduced the steel-concrete composite rigid frame structure and tied-arch bridge, a new bridge structure of main bridge of Chongqing caiyuanba Yangtze river Bridge structural system. Bridge across 420 m and 112 m and 88 m in a symmetrical distribution of side span and side spans. The main bridge with a total length 800 m (Fig.

4.53). In the main bearing structure design of prestressed concrete “Y” shaped steel box tied arch bridge of rigid frame with basket combinations to improve the main structure spanning ability. On this basis, additional vertical side pier bowstring-cable, main body of the bridge (rigid frames and the main arch) forces and lines adjustment and control of configuration space (Fig. 4.54).

Fig. 4.51 Steel box arch vision effect.

Fig. 4.52 Steel pipe truss arch vision effect.

Fig. 4.53 Caiyuanba Yangtze River Bridge photos.

Fig. 4.54 A symmetrical pair of pre-stressed concrete continuous rigid frame + tie bar arch. Orthotropic deck truss beam integral node of the design has evolved and matured, the basis of high-strength bolts and thick plate welding technique above, in the first manufactured using festive design, large, hanging festive carriage, large sections of the design idea, aimed at quality and construction units to provide more space for duration of protection (Fig. 4.55).

Fig. 4.55 Segmentation and segment plates hanging on the deck gestured. Orthotropic bridge decks in combination with steel truss beam efficiency of increasing combination truss suare, hang the level of increased fertiliser speed, better ensuring the construction quality. But also design, manufacture, construction, poses new challenges and problems. At the level of designing new issues need to be addressed include: orthotropic bridge deck joint role with the truss top chord; truss top chord decking and decking construction details of the connection of the primary and secondary beams; derrickcomposite-bottom chord truss beam-tilt hanging rod-lower design and construction of track beam design. Making programmatic and technological design problems more, which mainly include: modular truss beams cross-decking of the opposite sex basic unit of blockmaking; composite truss beams decking manufacturing base unit connection types of the opposite sex; composite truss beams deck deformation control technique of the opposite sex; composite truss beam monolithic gusset for a variety of manufacturing processes combined large segments of truss beam overall assembly solutions and precision control technology.

4.4 RECORDS SPAN THE RIGHT CONCEPT Records of the bridge span, because of their construction methods and equipment problems to be solved, design theory and innovative structural problems and a series of problem, which is an enormous challenge for bridge engineers and technicians in order to bridge technology and contribute to the development of global attention. With the development of transportation and technology, record bridge span and constantly being refreshed. First of all, span breakthroughs must be necessary and reasonable. Such as shipping requirements, topographic and geologic conditions and the depth of need when large-span, is necessary and reasonable, such a large span matches the height of layout and navigation, coordinated with the terrain, which is economically reasonable, on the landscape is beautiful. Conversely, blind pursuit of long-span breakthrough, will be only lead to the construction of wind insurance and investment wasted. As the navigation requirements are not high, and bridge spans golden times wider than the waterway NET, causing the span high bridge disproportionately so that both investment and reflects the landscape. Bridge design of six principles did not require the designer to pursue breakthroughs of the span and number of “first” and “most”. Despite all the bridges now span the span of the record have yet to reach a viable limit, but we cannot only for the pursuit of span first without regard to economic principles. Therefore, bridge engineer must put their creativity into innovation, quality and aesthetics three aspects, while also attaches great importance to economic indicators, and strive to build a high quality, durable and beautiful bridges, to benefit the people. Secondly, there must be a breakthrough in the span of its scientific and technical soundness. Span to break, there is bound to run into problems not encountered bridge, however, whether these issues have a clear understanding of whether there is a clear solution, it is related to this breakthrough is feasible, whether scientific, whether conservative issues. Such as the main Japanese Tatara Bridge cross because of topography, geology and navigation conditions set for 890 m, then Japan has been completed and the name of the Hong Kong Central Bridge 590 m, the French 856 m Normandy Bridge began construction on this basis, in order to grasp the main span from original level increased to 500~600 m after 890 m of cable-stayed bridge structural properties (e.g., member forces and natural frequency, etc.), how much change, and this change is the size and span linear or non-linear relationship, specifically on the 500 m, 890 m, 1400 m and 2000 m four kinds of main hole span studied compared. Thirdly, a span of breakthrough of technical progress and technical innovation is a real “world record”, that is, with the development of new technologies, record refresh, it has its indelible in the history of bridges “historical status”. If just span development, the size of the cross breakthroughs do not have or lack of skill “gold content”, it’s hard to become the technical level of “world record”. Quoting Mr. Man-Chung Tang “Record spans (Civil Engineering, March 2010)” as described in the article view points: construction of record-breaking bridge not only builtin a record-breaking, additional costs it takes to break the record must be able to bring value, if it is not, we are wasting taxpayers money.

Of course, competition is that people are born with the designed bridge record warmth is not declining. However, in our efforts to before you record, be sure to carefully consider the cost of the project and the resulting value. We must also take into account that records will be maintained how long. Today, due to the bridge span records regularly being broken, so it’s best to spend our energies and creativity on the construction quality better rather than bigger bridges with long span. Though several years after the Golden Gate bridge would lose record-holder status, but there is still like to visit it because it is the rare beauty of the structure.

4.4.1 Denmark Great Belt Bridge Design ideas: Feasibility phase proposed main span cable stayed bridge with a main span of 1204 m and 916 m, and a main span of 1448 m and 1688 m programme of suspension bridges, and through surveys of shipping conditions and shipping analog, found that the superstructure of small-span bridge cost savings far sub-structure and underwater protection measures cost little. Finally decided to adopt the main span is 1624 m suspension bridge, bridge design incorporates a mix concrete spandrel frame light anchor, using buffer to reduce dynamic displacements of girder of suspension bridge, the new design ideas. Denmark’s Great Belt suspension bridge links the is land of Zealand and the Philippines because of the Great Belt East Bridge Road project, the project includes 8 km tunnel, 6.8 km East Bridge and Highway 6.6 km west parallel road and rail bridge. In 1987, when you do design scenario, East bridge has made of cable-stayed and suspension bridge scheme 1416 m and 780 m. It is clear that 780 m main span cablestayed bridge with large span cable-stayed bridges are built or under construction were many (In 1986, Canada built 465 m Annacis bridge), and the main span is 1416 m suspension bridge was built-in 1981, by United Kingdom Permanent Bill (Humber) River Bridge, 6 m, be first in the world, and technology across more secure. In 1989, however, shipping conditions of survey research shows that 780 m of span is not enough. Feasibility and design stage, presented four different spans of programmes, namely, the main span cable-stayed bridge with a main span of 1204 m and 916 m, suspension bridge with a main span of 1448 m and 1688 m programme. When the construction of cable-stayed bridge, the greatest difficulties were encountered during the construction phase. Cantilever length of cable-stayed main span of 1200 m free 600 m, to meet the phase stability of the cantilever bridge widened to 6 m. In addition, through the shipping conditions of further investigations, in particular by shipping simulation found that costs of superstructure of small-span bridge substructure and underwater protection measures for savings is far more cost. Therefore, Dong finally decided to adopt the main span of the bridge is 1624 m, and sides of three-span suspension bridge scheme over 535 m (Fig. 4.56). The anchorage of the bridge design incorporates a new shape form, because commonly used desktop gravity bridge anchorage of suspension bridge with a great body product,

this suspension bridge and the rest of the incongruous contrast to the slender member. So in the design of this bridge anchorage, after careful research and decided to anchor is designed by concrete spandrel frame of main cable in anchorage and a bearing vertical piers of the bridge (Fig. 4.57).

Fig. 4.56 Denmark big bear-suspension bridge scheme (size: m). Anchoring in 10 m deep built in relatively shallow water, noted in the bidding plan, these vital water component can be used in the sea by doing construction or after a temporary cofferdam construction on the wharf. In order to prevent the ship collision, anchoring two artificial islands built on both sides.

Fig. 4.57 Big bear special triangles anchorage of suspension bridge (size: m). Bridges in anchorage and 2 parallel hydraulic buffers installed between beam limiting device, as shown in Fig. 4.58, which is the driving force locked and static limit of two functional combination of devices. Power lock function Master Liang Zongqiao by car, wind-induced vibration the impact movement, adjust lock speed control value at 0.01~2 mm/s range, power lock power 5 mn of each device; static limit functionality limits the main beam does not meet the temperature slowly displacement displacement occurs, whose value is controlled within ± 900 mm and regulation section 200 mm, satisfy the range of ±1 000 mm expansion joints, 15 mm static limit, if there is no vertical limit device, beam displacement will be 1800 mm. The buffer by Italy FIP Industriale s.p. In 1995~1997 year for design and production, in autumn 1997 to install.

Fig. 4.58 Hydraulic damping device.

4.4.2 Japan Akashi Kaikyo Bridge Design ideas: Studies to fit them into the four foundations, particularly the 3P Pier (the main pier of the Awaji side) design criteria very tough. 1900 m, 1950 m, 2000 m, 2050 m, 2100 m, corresponding to the different main span superstructure fine contrast. In order to ensure the edges, across more than 0.5 m and each side span at 25 m intervals. For comparison with a focus on the wind resistance, vibration characteristics, stability, duration and cost, and difficulty of construction. Japan Honshu Shikoku contact line Akashi Kaikyo Bridge Kobe·Naruto online, bridges total length for 960 m + 1991 m + 960 m = 3911 m bridge 110 m the deepest waters, the maximum velocity is 4.5 m/s Akashi Kaikyo Bridge’s steel consumption is: stiffening truss sections 90000t of 60000t of steel for cable, Tower of steel consumption 50000 t, full bridge amounted to 200000t, substructure concrete approximately 1250000 m3. The construction of the bridge from May 1988 to May 1998.

1. Selection of Bridge In 1967, Japan Society of Civil Engineers (JSCE) featured vertical rock-water line as the choice of Honshu-Shikoku bridges route. In this design, was selected as the pier’s two shallow: one extending from the side of Kobe’s “Takaiso” another is 40 m depth of ocean elevations “Gazitajo”, as shown in Fig. 4.59. Distance between the two sides since this line exceeds 5 km, so the main span of the bridge will be set upto 1500 m in both sides of the main span and two side spans of about 700 m. In 1970, Honshu-Shikoku Bridge Authority (HSBA) was established, found that before the two main Pier “Takaiso” and “Gazitajo” the geographical condition is flawed. In addition, including wind tunnel testing of a large number of studies have confirmed that suspension limitation span of the bridge is about 1800 m. Study Maiko-Matsuho these facts led directly to the start line in this scenario, the main bridge across 4 km apart on both sides of the Akashi Strait’s narrowest width. Proposed road-rail combined bridge span arrangement for 890 m + 1780 m + 890 m, it sets the main pier at the depth of 40~50 m on the ground.

Fig. 4.59 Selection of bridge.

2. Highway Bridge In June 1981, due to the deterioration of financial and political influence on Japan national railways re-structuring impact HSBA bridge study programme in place of a highwayrailway dual-purpose bridge. HSBA conducted a number of studies, including design, construction, price estimates, the construction period and the feasibility of collecting tolls and so on. Raised road bridge (890 m + 1780 m + 890 m) combined bridge the economic feasibility of the same. Programme of highway-railway dual-purpose bridge construction costs are relatively high, although the railway bridge section to only 41% of the cost, on the other hand, its bridge section has to bear the full cost (Fig. 4.60). In August 1985, the building and land Bureau, Transport Department has concluded from the report: Akashi Kaikyo Bridge Highway should be used.

3. Study on Optimal Span Alone, when the highway bridge program was established, compared with the combined bridge, which have greater freedom in the design. Combined bridge design, the 3 P Pier (Awaji side Pier) is extremely difficult, the trick is by 1800 m may limit the span for sure, this problem can also be solved by increasing the span. For optimal span arrangement, conducted the following research.

(a) Based on Location (Fig. 4.60) Before selection of combined bridge piers based on studies to fit them into the four foundations.

Fig. 4.60 Planning and development programme’s overall layout (size: m). 1A: If the bridge is not set up on the shore, the depth will increase sharply after the more than –7 m, so changes of the mooring dolphins will be subject to limit. If 1 A fallback, its range at best no more than 110 m, so as not to affect the 2nd route and Maiko Park. 2P: the original terrain is perfectly flat, Akashi strata of geographical conditions and no significant change. But beyond this point. In the Harbour a sudden drop observed. If the superstructure of 2 P backward will be increase the cost of 2 P in both directions therefore changes are unfavourable. Back through the coast of Awaji side if location, depth and tidal flow rates will be eased, and bearing layer, stratum in Kobe become slightly lighter. In addition, piers and navigation the hole edge distance would increase, this will be increase navigation safety at construction and completion. Thus to proper conclusion can be drawn: 3 P position back. 4A: because more close to the coast of Awaji, 4 A supporting layer of granite to go lighter, 4 A’s design and construction Much easier, especially when 280 m is moved from a previous location. However, moving above 300 m would be undesirable, because the Mainland would be affected. So, in conclusion: upto 4 a backward 300 m.

(b) The Upper Structure 1900 m, 1950 m, 2000 m, 2050 m, 2100 m, corresponding to the different main span superstructure ratio. In order to ensure the edges, across more than 0.5, and each side span at 25 m intervals. For comparison with a focus on the wind resistance, vibration characteristics, stability, duration and cost, and difficulty of construction. Some of these conclusions are as follows. Compared with previous programmes Span I, 780 m, deformation and vibration is not much changed. In the span, you can use the width is 14.0 to 35 m. The truss stiffening girder of 5 m to ensure that it will have sufficient wind stability. Three parts, from the perspective of project cost and duration, optimal span should be

2000 m.

4. Final Scheme Side span to main span ratio of 1 : 2, primarily on the basis: (a) by comparing different span Division, when the ratio was used, the package, (b) includes upper and lower total project cost structure, the most economic and second least impact on navigation, (c) for the design and construction of large-span cantilever bridges has accumulated sufficient technique. The Main Cable: Allowable stress of previous suspension bridge cable 1600 MPa tensile strength divided by 2.5, a safety factor equal to 640 MPa newly developed 1800 MPa strength of steel wire cable tension due to live load is only quarter of cable tension 8%, the safety factor is 2.2, the allowable stress of upto 820 MPa. Due to the improvement of strength of steel cables, towers, making out stone bridge tower height reduced to 30 m. The Steel Pylon and Foundation: Tower high above the sea level is about 300 m, given the tower during construction or during operation due to wind effects may cause vibration, wind tunnel tests were carried out. After wind tunnel testing by selected section shape of the tower. In addition, by at the top sets the attenuation of vibration damping device, tower wind stability is greatly improved. Pylon foundations of circular caisson of diameter of 80 m, high 65 m. Choose the caisson is mainly adapted to ocean climate conditions under, But also can be prevent the current impacts and erosion. First in a factory making steel caisson foundation, launched by a shipyard, and shipped to the construction site, and then anchor position, sink, pouring concrete. From the tower to the base of the largest vertical force to 125000t (Fig. 4.61).

Fig. 4.61 Pylon foundations (left), and the tower of general plan (right) (size: m) Note: the 3P in the underlying data. Stiffened Truss: The choice of stiffening truss section to, respectively, of the modern United Kingdom genre of box a streamlined cross-section and classical truss sections are analyzed and compared. Design standards, self-excited vibration critical wind speed for 73 m/s above. Wind tunnel test knowledge box girder section self-excited vibration critical wind speed of about 60 m/s. In the other hand, the select the main beam as shown in Fig. 4.62 section wind-resistant stability to meet the above conditions, trussed girder is economical, convenient construction and so on.

Fig. 4.62 Stiffening truss (size: m). Anchorage: Akashi Kaikyo Bridge line force of about 1200000 kN, because suspension bridges on both sides of topographical and geological conditions are so Kobe side 1A (Fig. 4.63) and Awaji side 4 two anchor the shape and size of a completely different.

Fig. 4.63 Anchorage (1A) (size: m).

Fig. 4.64 Three-span suspension bridge scheme (size: m).

4.4.3 Luo River Bridge Design idea: According to technical reserves and engineering experience in suspension bridges and cable-stayed bridge scheme selection made after the 890 m cross cable-stayed bridge scheme; design further research of the hybrid girder cable-stayed bridge with side elastic connection between the cross-ratio, cable-stayed bridge in taliang problems using large lifting steel beams and tower construction method. Japan Mr bridge at the Honshu Shikoku contact bridge Onomichi—Jzs line, it is a connected Islands and ruins island Sea 4-lane bridges. 1973 the planned programme of the bridge was built as a traditional-style steel truss stiffening girder-Three-span suspension bridge, long-span 300 m + 890 m + 300 m (Fig. 4.64). Beginning in 1987, the above plan was re-assessed. As in the 1980, of the 20th century, Japan has been through the construction of a large number of steel cable-stayed bridge (such as a primary port west across the 405 m bridge, 420 m Black Stone Island Bridge and Rock Island Bridge, East of 460 m Yokohama Bay Bridge, 485 m bridge, 510 m Tsurumi channel bridge in Kobe, as well as 590 m of Meiko Central bridge, and so on), of large-span cable-stayed bridges have accumulated certain experience, plus France 856 m main span of Normandy began construction of the bridge, in order to capture maximum of long-span cable-stayed bridges in the world title, it decided in 1990, to change the design, such as 270 m + 890 m + 320 m three-span steel cable-stayed bridge as shown in Figs. 4.65 & 4.66 main girder section.

Fig. 4.65 Three-span steel-concrete composite cable-stayed bridge (size: m). Compared with the original proposal under the now programme, instead of cablestayed bridges can be also avoid programmes island shore main cables of suspension bridges anchor large excavation and the damage to the original natural environment, windresistant and have certain cost advantages.

Fig. 4.66 The main beam section (size: m). The bridge across the main span due to topography, geology and navigation bar such relationships as 890 m. But in order to master the main span from the original 500~600 m levels increased to 890 m, on cable-stayed bridge of knots frame properties (such as stress and natural frequency components, etc.) how much big changes, and this change is linear with the span size closed systems will also be non-linear relationships, so the 500 m, 890 m, 1400 m and 2000 m studies comparing the four-hole span. Research shows that the main spans of 890 m structure characteristics generally similar to the 500 m found no divergence of non-linear phenomena. Due to the topography of this bridge the two side spans respectively disposed in 270 m (Island side) and 320 m (the junior side of the island), due to this ratio of side and main span of 270/890 = 1/3, 320/890 = 1/2.8. Both ratios were relatively too far small consequence on dead load bottom pivot negative reaction and pylon moments are too large. To that end, by calculating the comparison study additional auxiliary piers and side spans between the end point to the secondary pier counterweight additional options, as shown in Table 4.2. Based on the results settings to the auxiliary piers and balanced programme on structural characteristics are improved considerably. And 1.1 and 2.1 and 2.2 compared to span mode is basically the same, so this bridge eventually decide on the island uses the 1.1 schema, junior island side 2.1 schema. Table 4.2 Side layout. Island junior 1-0

Schema

Island side 2-0

1-1

2-1

1-2

2-2

Schema

Fig. 4.67 Tower at the high-performance rubber bearing. Has studied and compared four kinds of support plans: (a) suspensions department of, (b) elastic fixed to the twin towers, (c) is completely seated in the twin towers about, (d) fixed to one end of the beam. Suspension system in vertical wind turbines will greatly increase the bottom under bending moment, and beam the nodal displacements ± 10.18 m high, thus first are discarded. Secondly, give up programme is completely fixed to the twin towers, because this programme is warming girder longitudinal forces caused by the most, higher than those of other programmes about one-third. Fixed on one end of the main beam programmes generally are with elastic fixation to the twin towers program similar, but the former is rendered to a non-while the latter is superior to the former in this respect, and therefore programme of tower elastic fixation (Fig. 4.67). Fig. 4.68 shows construction and installation are shown in the photos.

Fig. 4.68 Construction photos (a) Talianglian; (b) Using fixed jib type cranes in the tower to install pylons; (c) Balancing assemble the main beam; (d) Through a direct method of the girder for the increase Extension Assembly.

4.4.4 Su Tong Yangtze River Bridge Design idea: According to the broad river bridge located in 8 km, a 50,000 ton container

ship bi-directional navigation and overlay thickness 300 m condition research on cablestayed bridge, suspension bridges and cable-stayed suspension system and other programmes, finalization of the main span is 1088 m cable-stayed bridge. Study on design of bridge pile foundation stability, nonlinear effects, for large span cable-stayed bridge cable vibration, wind-resistant stability and taliang connected system and a series of technical problems. Control of Su Tong Changjiang bridge and the main factors affecting the main channel bridge of long-span has the following several points. 1. The Su Tong bridge navigable river and seagoing vessels, vessel density, is the busiest waterway of Yangtze river. Navigation of the Khumbu reset should be deep water, shallow water shallow and porous navigation principle, setting up a two side navigation, main navigation span, a special pass air holes and a flood channel. Main navigation channel press the single-hole bi-directional navigation standard for design, navigation the clearance width of not less than 891 m main navigation span both side edges of holes according to the single-hole single navigation standard for design, navigation the clearance width of not less than 220 m. 2. According to the evolution of river bed and river regime analysis reports, deep main channel at the location of the bridge is 300~350 m the swing range and cross-path selection and arrangement should take into account the deep history and possible future of the varied sites to fit the bridge waterways may have been a fan wall swing needs, provide greater adjustment for the channel space. 3. By 2~3 km formed in the upper reaches of the Yangtze river on a bridge axis curve, the channel also set it, so span should be selected to navigation there is a course adjustment of surplus, for the safe navigation of ships, piers, collision avoidance benefit. 4. Bridge site at –20 m isobath width 1000 m, –10 m isobath width 2000 m, the main channel of the bridge should be covered by deep water, provide better conditions for navigation, and to minimise the number of deep water pier, in order to reduce the difficulty of construction. 5. Structure from the channel farther collision probability is small, the ship impact force is smaller. Therefore, there is a navigation NET paused in order to reduce the probability of main structure of ship impact to ensure structural safety. 6. The main tower base side must exist within the flow area, range about 50~70 m and flow velocity variations in the district difference gradient is large, once the ship enters orbit around the flow velocity, hit the pier accident-prone, for navigation and the safety of navigation is not lee and the voyage should be avoided. Therefore, the main span of the selection should ensure clear width than unilateral navigable surplus of about 50~70 m, in order to avoid the area around the stream. Under the control and influence factors of main channel bridge of Su Tong bridge main span should at least meet the following requirements: (a) Navigation clear width requirements: not less than 891 m; (b) The tower base and facilities against dash size: according to the design plan, flanked by a total of 55~85 m;

(c) Navigation clear width Fully considered of main importance, in order to ensure its better navigation conditions under any circumstances, taking into account the cable tower foundation flow around a sphere of influence on the side size: unilateral 50~70 m gauge, flanked by a total of 100~140 m. Comprehensive consideration of, main span of span fetch 1088 m. For construction of Su Tong Yangtze River Bridge conditions, combined with the current level of actual bridge construction at home and abroad, research and proposes four main bridge type scheme (Fig. 4.69).

Fig. 4.69 Chart of main bridge layout (size unit: cm). 1. A main span of 1088 m tower cable-stayed bridge scheme, side spans two auxiliary piers, span arrangement for: 100 m + 100 m + 278 m + 1088 m + 278 m + 100 m + 100 m = 2044 m. 2. Main span cable-stayed bridge with three towers of 650 m programmes, set up an auxiliary piers, span arrangement as follows: 96 m + 164 m + 2 × 650 m + 164 m + 96 m = 1820 m. 3. Suspension bridge with a main span of 1510 m of the twin towers three-span suspension programmes span arrangement as follows: 453 m + 1510 m + 453 m = 2416 m. 4. A main span of 1510 m cable-stayed-suspension bridges programme, span arrangement as follows: 120 m + 188 m + 1510 m + 188 m + 120 m = 2126 m Rough

layout of main bridge type is shown in Fig. 4.69. Main span suspension bridge has been completed and the maximum span at 1385 m and 1991 m, building 1510 m suspension bridge, its mature superstructure design and construction experience, adaptability of the navigation better. But because of Su Tong Yangtze River Bridge, the river width wide, deeply buried basement bearing layer of soft, so anchor foundation not only can put in the water, and the scale is huge, a number of deep water foundation leads construction difficulties, long duration, higher construction cost, South anchor foundation on the local river still needs further research. In addition, its poor wind resistance capacity and wind-resistant safety. Investment estimation shows that suspension bridge with a main span of 1510 m project cost than main span 1088 m hightower cable-stayed bridge scheme of about 900 million dollars. For main span of 1510 m cable-stayed-suspension bridges program study showed that large-span cable-stayed-suspension bridges building is technically possible, but now spans more than 500 m there is no engineering, due to the complex can take design and construction experience, the technology is immature. Compare with comparable suspension bridges, due to poor geological conditions at the bridge, anchor Ikari is still quite large and put into construction equipment and its technical superiority not obvious. Because the main span cable-stayed bridge with three towers of 650 m scheme in Sham Shui Po to set up more large structure, adaptability to shipping and poor ability to prevent ships extremely prejudicial impact, impact on the river as well. And it spans the size of three towers cable-stayed bridge is also first in the world, also has a great deal of difficulty in their technology. Tower cable-stayed bridge, Japan in 1999, opened the Tatara bridge span had reached 890 m, main span built in 1995, was more than 856 m of France in Normandy bridge, a main span in the world at that time-span the largest cable-stayed bridge, construction of a cable stayed bridge with a main span of 1000 m international technology matures. Su Tong bridge main span of 1088 m tower cable-stayed bridge scheme, because of the relatively few large structures in Sham Shui Po, had met with main span two-way channel width summation the main channel the possible range of oscillation, influence on the river is relatively small, project cost is reasonable. After workers stage a bridge program and the study on key technology of bridge, consolidate the views of the experts, you can come to the conclusion that: According to the requirements and characteristics of building of Su Tong bridge, a main span of 1088 m tower cable-stayed bridge scheme, although the deposit certain technical difficulties, there are lots of research on the key technologies needed to be deepened, but according to the current level of bridges and the practice, by deepening the study and the necessary scientific experiments and absorbing international advanced technology, in the design, construction, materials, equipment, management of works are feasible, technical problems can be solved.

4.5 OUTSTANDING STRUCTURE AWARD-WINNING BRIDGE PROFILE International Association for Bridge and Structural Engineering (IABSE) since 2000 to establish Outstanding Structure Award in recognition of the most significant (remarkable), the most innovative, one of the most creative or both wise and exciting (stimulating) the new structure, but does not pursue maximum span or height. Outstanding structure award by the awards from application projects for the year, the Committee selected one to three bridges or structures in the outstanding works of the project, from 2000 to 2009 in 10 years, has comments on 20 projects have been selected, including 11 in structural engineering and 9 in bridge engineering 2008 Shanghai lupu as the first Chinese project won the outstanding structure award. Bridge conceptual design below introduces one of 4 bridges.

4.5.1 Switzerland Sunniberg Bridge 1. Special Conditions of Bridge Design More than 20 years ago, Switzerland the Government envisaged building a highway in the Alps regions, because the line would will have an impact on the environment and encountered strong opposition, more consideration of environmental factors on the basis of the number of the original design was amendments, thereby making lines most of the tunnels. In 1993, a new way to through the town of Klosters has finally been decided, is the most important structure in the channel length is Gotschna tunnel of 4.5 km, directly connected with the tunnel is the shengniboge bridge, the bridge and flowing in between Rand Kuat River Valley obstacle clearance height is about 50~60 m. Shengnibo Geqiao is the most notable building of the Davos channel, bridge conceptual design mainly depends on three conditions, namely, bridge structure shall be must meet high aesthetic requirements as well as integration of the scenery at the bridge site, caused by the adverse weather conditions are not normal maintenance high durability requirements, must attach great importance to the protection of natural environment factors during the construction of the bridge.

2. Integration Into the Landscape Design-led Concept Shengniboge bridge is located in the town of Klosters, is Switzerland Alps area one of the largest bridges. Taking into account the bridge-building capacity at that time, even though the bridge difficult topographic and geological conditions and is located on a curve segment, two hard questions, and build a bridge of this size will not be much difficulty. However, the bridge is in a highly visible, bridge integrates with the surrounding landscape is the biggest design challenge. In the valley in the open countryside, shengnibogeqiao was the only man-made structures. From a distance, this bridge is prominent, it is in Klosters resort around the landmark building. Although the height of the bridge with striking across the valley, but it was not overwhelming dominate the landscape of the valley. Taking into account the situation on the ground, the bridge must be designed with this rich rustic fusion in silence, maintaining beautiful bridge building

itself. Meanwhile, tourists arriving through the railway or highway, the bridge for their show should be bridge technology with unique architectural landscape. In view of the aesthetic design of the bridge was unusual, so select a cable-stayed bridge design (Fig. 4.70). The programmes that bridge has four towers, three-span larger main span and side spans of two smaller spans (Fig. 4.71). Considering this bridge is flat curved bridge, at both ends of the main beam not set abutment and main beam joints but overall continuous structure.

Fig. 4.70 Landscape design.

Fig. 4.71 Facade layout (size: mm) (a) Elevations; (b) Plans; (c) Cuts; (d) P2 Pier. Such structure allows the main beam in longitudinal and lateral movement of the piers is constrained, and by acting on the main beam in bridge piers load bending moment caused by decreased from pier to pier bottom line. Pier sizes reflect the variation of the bending moment in the pier. Taking into account the bending sections of bridge deck clearance requirements, bridge tower slightly outward tilt. Due to the continuous change of vehicles crossing a bridge on both sides of the landscape, the cable is vertical routing style choices as simple as possible harp arrangement. Deck consists of a panel, on both sides of the plate edges have a relatively long rigid components design schemes. Cost about 14% higher than traditional cantilevers programme costing at least. But considering the plan design enable this striking bridges located in the sensitive landscapes of unusual beauty, is well worth the additional investment was considered.

3. Technical Design Overview

(a) Pier Along the vertical piers of the bridge showed a parabolic cone, its width is also changed. The horizontal width of the pier the bottom 8.8 m to the main beam at the 13.4 m. Therefore a solid cup-shaped piers of the silhouette. Towers, were like partitions and high deck 15 m. Along the bridge longitudinal plate on the main girder of bridge tower from the local effect of vehicle load caused by the bending moment. Because the line is curved in the horizontal plane, on both sides of the cable forces of cable-stayed in different. Horizontally, the towers on both sides due to large transverse bending moment of tension arising from the different. Anchorage in built-in central pylon of cable-stayed steel plate. Bridge tower tighten to get main beam set a huge beam on the lower surface, passing on two great transverse bending moments in the tower, making the two pillars of the pier shaft different pillars bear some 60% on the inside of the curve, approximately the outer side of the pillars bear the 40%.

(b) Master Girder Width of main girder section contains 12.1 m plate and two side beams. Bridge transversal thickness 0.40~0.32 m. Lateral beam setting removable inclined cable anchorage points. For static reasons, thickness along a bridge longitudinally to the pier increased. Due to the method of construction, formed entirely of boundary beams using tensioned pre-stressed components. In the main beam part due to compensate because of the tension force of cable-stayed main welded connction axial force arising from falling, the department imposed vertical pre-stressing increases.

(c) The Cable Cables are wrapped with polyethylene, rigid sets of parallel wire strands form. Each cable consists of 125~160 diameter 7 mm structure of galvanized steel wire, wire rope use stress to meet the. σp,adm = 0.50 ftk. Because each of these is a separate anchorage of cablestayed, so it can be free to adjust cable-length. Cable anchorage has been specially designed so that it can be a great deal of variation of load.

(d) Process The bridge’s construction started in July 1996, to the end of October 1998. Nearly 2.5-year construction period need to fine planning of the construction process. Using the balanced cantilever construction method of bridge, the first phase of the No. 0 block, 13 m, after continuous construction of beam length is 6 m, use a pair of specially constructed traveler for main girder erection. At every stage of construction only current segmental beams of concrete and pouring of concrete on the veneer of a segment. Hanging basket prior to the move, cable-stayed cable-hanging cable and anchoring. Construction of four main towers on both sides of the suspension arms are made of 7~9.6 m length of main girder segment composition.

Fig. 4.72 Bridge photo. The bridge won the 2001, international bridge and structural engineering drive association outstanding structure award, first won the outstanding structure award the bridge project, and is considered to be “sensitive scenic areas a refined structure of the arts initiative”, the bridge is shown in Fig. 4.72 after the completion of the photo.

4.5.2 The Miho Museum Bridge 1. Special Conditions of Bridge Design Miho Museum in Japan state Midwest Shigaraki mountains in a remote, wooded valley. The wood has been used in the valley near NARA temple building. Now, the area has become a nature reserve, therefore, the construction very strict regulations in the area of control. Miho Museum entryway—Miho Museum bridge, is a need bridge of the harmonious combination of aesthetics and technology. Local beautiful mountain views of the bridge and transition between galleries, visitors will concrete will pass through a tunnel and across a canyon to get to the museum.

2. The Concept of Harmony between Aesthetics and Technology Leading Design Miho Museum bridge and other parts (a reception pavilion, gardens, two tunnels, and an Art Museum) together form a complex. Designers expected visitors to walk over the bridge to art galleries, but the bridge was still being asked designed to withstand the total wheel weight two-lane loading of 12 kN. The bridge even allow occasional higher rounds of heavy loads, such as dignitary guests use when visiting armed vehicles. Most visitors car park in the reception pavilion is located in the bottom of the steep slopes, the department also the bus get off point for tourists. Visitors before entering the tunnel need to be started by the walk along winding Canyon road, out of the tunnel once located on Miho Museum bridge, visitors at first glance at this time the entrance to the museum (Fig. 4.73).

Fig. 4.73 Arch and tunnel portal. Out of consideration for seriousness and spectacular, the appearance of the bridge and structure was carefully studied. The bridge spans the valley without using intermediate supports, makes ecological impacts to the minimum. The main steel truss girder height of 2 m, post tension cable in concrete tunnel to dangling roots. While the design and construction of the bridge forms the transition between architectural and structural design. Bridge. Structural engineer mainly responsible for bridge basic design tasks, and design consultants who are evaluating the bridge was raised by many of the lean fine views.

3. Technical Design Overview (a) Structure System Bridge design respectively in the post-tensioning pre-stressed bridges, cable-stayed bridge with cantilever bridges and other innovative design ideas in the system, so that the a visually beautiful and efficient structure of the bridge. Figs. 4.74 and 4.75 respectively in four main parts: tunnel exit, ring of steel truss girder, and post-tensioned cable-system. Because the bedrock is of better quality, so choose the tunnel as a cantilever span valley roots. The space at the bottom of the tunnel of axial pressure in truss rod and bolted to the top of the tunnel portal of post-tensioning cable the axial torque caused by bringing the main beam to the cantilever effect. Space truss with the bottom surface of the tunnel structure is continuous, cables interconnected with post-tensioning tendons in the tunnel wall. Therefore, gravity and lateral forces acting on the bridge together use the tunnels is mainly influenced by bending rather than pulling.

(b) Space Truss Because bridge restricted the traffic bridge on the aesthetic perception of conditions and light permeability is better than thick concrete structure, to select a steel. In may cases, studios and pre-fabricated tunnel within the range allowed by the steel members. Bridge 2 m only the height of the space of main girder steel truss. Most of steel pipe truss bar and cross-sectional triangle truss structure made in 7.5 m width of the driveway within the distribution of the three top chord, as well as a bottom rod (Fig. 4.76). Horizontal, vertical and inclined plane of truss consisting of diagonal supports the complete section. Best truss rod’s diameter is 267 mm. Rod direct size was selected to represent the poles distribution levels; rod diameter at specific levels remain unchanged, while the wall thickness of steel, with the load performance changes. Members generally use financial penetration welds

between tubes and tube connections. Bridge cover, flange bolting method suitable for site consolidation.

Fig. 4.74 Facade layout (size: m).

Fig. 4.75 Truss floor plan (size: m). The top chord of the bridge between the cable and screw anchor, the castings of the truss and screw set are interconnected. These castings to simplify connection detail of highly exposed and easily adapted to cable angle at each connection point. Museum-side 6 m at the bridgehead of high gravity type bridge pier. Restraint systems are installed at the bridge to live load resistance by cross-bridge girders ends upwards. The gravity type bridge pier of the restraint system is installed, constrains the beam under three piers direction of rotation, but allowed the main longitudinal elongation and shortening, while also allowing seismic beam under the action of lateral and torsional movement.

Fig. 4.76 The main beam section (size: m).

(c) The Cable One end of the cable and laid in the tunnel wall of post-tensioned pre-stressing steel cross anchor, through and at the mouth of the tunnel is a skew arch. The arch feature class similar to the vertical pier in the cable-stayed bridge. Cable by inclined arches was spread out to hanging truss girder per 2 m setting on a connection point has been to cross in the girder. Using these cables in post-tensioned beams to provide upward support force, in

order to balance live loads on the bridge. Post tension jacks when only in deck anchor homework and arch and the anchor end of the tunnel. Another set of cable systems and steel truss girder beam set attached to the pillars of the free ones (Fig. 4.76). These posttensioned cable-provided upward force and deflection control of both functions and arrangement of curved pre-stressed reinforcement in post-tensioned beams are alike. Beam setting you can adjust the screw fittings of the pillars in order to increase its length, vertical jacks mounted on pillars of cables can be done later. Backbone cables and two sets of cable-arch of the bridge-tunnel cable reduces the bending moment of steel beams together, making the bridge with the same compared to the non-prestressed bridge span, you can use smaller height of the girder and pipe diameters. Space of cable wound on the surface of galvanised spiral, diameter 22.4~60 mm a total of 6 different diameter steel wire rope structure composition. From arch-to-arch cable diameter, wire diameter also increased, resulting in a very high structural efficiency and beautiful style. In addition to these aesthetic considerations, wire diameter is not controlled by the structural strength, stiffness and more by can control.

(d) About Arch Arch tunnel side of the bridge can be significantly reduce the cable diameter, axial pressure of the main beam. In a horizontal direction began, arch between the plane and the tunnel portal of the deviation angle of 45°. Along the direction of the longitudinal axis of the bridge, by combination of steel box section arch shape consisting of a smooth parabola. Arch cross-section changes with the curve, this curve takes into account the structural and aesthetic requirements, high efficiency of arch ring structure, visual perception the United States. Skew and rotation is not constrained by spherical bearing pin. By post-tensioning cable stress caused by fixing the arch on the spherical bearing. Miho Museum bridge on both aesthetic and functional balance benefits to reflect grandeur and symbolism of the Museum. For several years, it design of novel structures and forward-looking as visitors to Miho Museum provides a sturdy and attractive entrance (Fig. 4.77). The bridge won the 2002, international bridge and structural engineering outstanding structure award, considered to be built lightweight transparent structure highlights build beautiful and artistic charm and perfect protection of the landscape under the bridge.

Fig. 4.77 Bridge photo.

4.5.3 United Kingdom Gateshead Millennium Bridge 1. Special Conditions of Bridge Design In the United Kingdom, Central District of Newcastle-upon-Tyne, Gateshead there six bridges have been built over the river, three of them with important history and drive meaning respectively, built-in 1849, by Robert Stephenson designed double-decker highway-railway dual-purpose bridge, completed in 1876, armstrong designed rotating bridge-bascule bridge opened in 1928, and designed by David Anderson looks like the Sydney Harbour Bridge two-hinged steel arch bridges, the three bridges represent the latest technological achievements and outstanding engineering innovations. In the mid1990s, gateshead City Hall puts on the redevelopment of the river and the nearby abandoned zones and with the Tyne Newcastle terminal connection plan, launched a collection spanning the Tyne bridge design contest, the contest attracted of the 47 teams from around the world to participate in, in which 6 teams passed the qualification examination and were invited to submit designs. Major design conditions of the bridge is to be a landmark structure in the city, and ensures 25 m high vertical clearance empty and terminal junctions around just a scant 4~5 m.

2. Open Innovation-led Concept Design In order to not only ensure navigation 25 m clearance and meet the requirements of terminals only high out of the water around 4~5 m, the only selection optional is the bascule bridge. From the bascule bridge has built, mainly by four forms, namely, vertical rotation, horizontal rotation, horizontal movement and vertical promotion, as shown in Fig. 4.78. After a full consideration of these traditional ways of opening, Gateshead Millennium Bridge was created to give a new open format, that is, in the direction perpendicular to the vertical plane—the so-called fifth-degree rotation space, rotation of the fifth dimension concept design is shown in Fig. 4.79. The bridge program is an innovative and adventurous design, it is a reversible form of bridge, consists of a pair of slalom composed of steel arch Hat elastic Fulcrum turns on. The opening of the bridge can be compared to a motorcycle helmet helmet goes up, or is man the eyelids open. Gross weight bridge 800t can rotate and open, making ships pass under the bridge, and in this regard it is the unique and convenient. Open systems is the use of hydraulic jacks pushing plate below the fulcrum, so as to achieve overall the purpose of rotating bridge. Pontic opened position, play a connecting role slings are horizontal, these slings will be tight this steel arch associated with key.

Fig. 4.78 Open schematic drawing (a) Vertical rotation; (b) Horizontal rotation; (c) Move horizontally; (d) The vertical Ascension; (e) Fifth-dimensional rotation.

3. Technical Design Overview (a) Arch Rib Parabolic steel arches by tapered in plan and elevation of kite-shape composition (Fig. 4.80), which is mainly composed of thick 35 mm plate assembly, and internal use of the longitudinal and transverse stiffening, anchor arch box toward cable-stayed plane. Outside of the arch, steel wire cable is used to connect the traditional opening of the fork-shaped tank, connections on a rib handle installed in the dome-shaped alcove with arch in the clapboard and stiffeners connected. 18 cable made up of galvanized steel wire, in junction with deck has an adjustable anchor, cable through an internal cylindrical cavity embedded anchor plate.

Fig. 4.79 Fifth-dimensional rotating concept design.

Fig. 4.80 Rib section.

(b) Deck Deck elevation for parabolic, plane is curved, it illustrates one of the most complex geometric shapes. Steel box junction frame is the main unit from the graphic point of view, from the quayside to the river center, steel box gradually narrowed. Box profile for anchorage of cable-stayed for space and anchor bolt from the bottom surface of the arch into the oval concave interior, steel box the size of the cable from its current location to restore the complex stress. Steel box on the surface to be coated non-slip epoxy coat. Horizontal steel beams suspended from a steel box about 3 m pitch and along a curve outward, which supports lightweight aluminum deck plate as bike lanes. Along the long bridge to the bike path constant width and 300 mm lower than the nearby sidewalk, which has different demands a high level of pedestrian fence and guardrail adjustment of a

uniform height on the same section (Fig. 4.81).

Fig. 4.81 The main beam section (size: m).

(c) Machinery The bridge needs a system that can be open the bridge, which could push pull, because in the process of opening the main center will be through fulcrum. Sufficient to operate the wind conditions, the process engine loads from 10000 kN thrust into 4500 kN pull of the bridge which set out clearly in the system fails to run or, conversely, under the condition of different emergency response procedures and requirements. River bank mechanical systems with synchronisation to ensure the structure is reversed reversing and control equipment to maintain distance between the two sites do not exceed 25 mm is extremely important.

(d) Decoration Aside from the strong visual impact of the bridge outside the general form, become bridges decorated with most direct contact part. Bike path is a series of connections of aluminium alloy section bars. Aluminum has excellent service diagram surface provides bike good grip, but it is also a light structure, which as the main cantilever part of its outermost is very important. With its lightness, a bridge deck also has a certain degree of transparency, when bridge tilt opening, soffit when fully opened, the bridge is particularly spectacular. Sidewalk bridge formed by the epoxy aggregate paving. At different heights one-by-one between sidewalks and bike paths and benches of metal barriers. Benches are available for people to stop down to rest and finish the bridge, enjoy the surrounding scenery than internally by the welding on the frame consisting of perforated stainless steel sheet fence in windy environments, can provide some degree of protection designer. Set up a series of doors on both ends of the bridge in order to ship crowd control when ship navigation. Two stretch into the river next to the bridge flow, concrete structure with a glass shell, one is charged room, and another prepared as favourites in the future exhibition purposes. The bridge won the 2005, international bridge and structural engineering drive association outstanding structure award, considered to be “a two arch ribs using a unique way connecting footbridge in a graceful curve and by rotating the opening to be able to satisfy the navigation requirements” (Fig. 4.82).

Fig. 4.82 Bridge photo.

4.5.4 France Darius Milhaud Bridge 1. Special Conditions of Bridge Design Darius Milhaud is a main bridge in Viaduct is on the A-75 motorway, connecting Northern Europe and Spain East. Milhaud city is located in the confluence of the Tarn and Dourbie rivers, two rivers in the ancient Massif central plateau is formed on two deep canyons. By the viaduct must be from the North Highlands across the broad valley of the 600 m 720 m of the Larzac plateau to the South, road route is not an easy task, not to mention but the Foundation due to instability caused by the clay in the soil. Follow the principles of bridge length choose bridge location, based on 601 m high in the North and South of 675 m even in a straight line, this line of about 2.5 km, straight line from bottom of the Tarn river, about 275 m (4.83), apparently high pier is a big challenge, the design of the bridge condition can be simply expressed as length of 2.46 km and high 275 m valley features a multi-span slim beautiful bridges, and adopt appropriate construction methods.

Fig. 4.83 The main beam section (size: m).

2. The Concept of Reasonable Hole Leading Design First of all takes more than 200 m across the Tarn river span larger pier height and span the lower adjacent bridge across the size and pier height is also quite closely, had little to do but others span and high pier of bridge. In the pursuit of architectural effect you should first think span bridges, and most traditional equal spans and high-pier continuous rigid frame bridge is generally continuous rigid-frame bridge spans 150~200 m, even the largest 342 m of long-span continuous rigid-frame also needs to set up 9 per cent of the high pier. In order to minimise the number of piers, bridges span must be increased, and will be span breakthrough 300 m must stay or suspension structures, this is in 1990, Michel Virlogeux first 7 Ta 8-span cable-stayed bridge scheme of basic ideas (Fig. 4.84).

Fig. 4.84 Bridge photo. And span bridge is established, must also take into account local conditions and construction methods. Traditional methods of construction of cable-stayed bridges are on cantilever construction method, which means about the bridge to proceed concurrently or successively in the 8 towers face 16 and 9 closure points of complex construction, so many separate construction sites, construction quality control. Adhering to the French romantic nature, stiffening of beam with a tower and part of the cable and the intermediate provisional pier reduce the span from both ends toward the middle of incremental launching construction method (Figs. 4.85 and 4.86), and creatively solve construction problems of adjusting measures to local conditions.

3. Technical Design Overview (a) Bridge Section Milhaud viaduct length of 2460 m long, formed by 6-span 342 m-stayed structure, two side spans of 204 m. Main beam orthotropic steel box girder section for concise line triangle (Fig. 4.87), the middle two webs is in incremental launching construction specifically set. Includes wind up deck full width is 32.05 m, located four lanes wide and two 3 m wide emergency parking strip. Emergency parking area outside on the wind up, specially designed to reduce lateral wind speed wind barriers in order to improve air traffic safety.

Fig. 4.85 Incremental launching construction from both ends.

Fig. 4.86 Pushing system.

Fig. 4.87 Bridge section (size: m).

Fig. 4.88 Pre-cast towers (unit: m).

(b) Pier Pier design must be take into account cross-asymmetric live loads caused by the longitudinal unbalanced forces and temperature at different heights on the box influence of cross section. In order to resist the bending moment due to extreme high, piers on the broad power of box-section, but on the most ends vertically into two forks in the 90 m

range (Fig. 4.89). Vertical pre-stressing of the deck using two pinned to the pier on fork bearings, then tack down the inverted v-shaped tower. Under extreme asymmetric live loads, each bearing can withstand 100 MN vertical loads. Two top high piers of 245 m and 223 m respectively, with tower cranes, you can reach 275 m heights. Because this is necessary for construction of tower cranes in every step, fixed to the piers. Each bridge pier foundation consists of four 4 in diameter consisting of open caisson of the deep ~5 m, 9~16 m.

(c) Pushing System Steel box girder deck push-starting from both ends, at the crossing of the Tarn river closure in the middle of the pier on both sides. In order to reduce the span, in addition to closure across the Tarn river in addition to temporary Pier in the middle of the set consists of a steel tube truss structure (Fig. 4.86). In order to control the largest cantilever length does not exceed 150 m, staging two piers spanning 12 m fulcrum. Push jobs each cycle is equivalent to 171 m, take 5d time under favourable weather conditions. When the weather forecast when wind speed is greater than 37 km/h, you must stop pushing homework.

(d) Bridge Tower On May 18, 2004 after the Tarn river span from factory pre-fabricated bridge components were transported to the tower each tower position (Fig. 4.89), fixed rear suspension installed and tensioned cables, the finished construction. The bridge won the outstanding structure award of 2006, International Association for bridge and structural engineering, and is considered to be “a fly in even the two deep beautiful slender bridge Canyon heights, creative technology of incremental launching construction of bridge construction has been driven into advance.”

Fig. 4.89 Typical pier (size: m).

REVIEW QUESTIONS 1. Taking into account the bridges you listed the main factors taken into consideration when planning, and one to two factors to explain illustrate? 2. Invite you to four selection scheme of Hong Kong Ting Kau Bridge and the final programme review them one by one. 3. Please you the five finalists in the first round of Stonecutters Bridge in Hong Kong voted for the one you think is the first name in the programme, and from bridges and the beautiful point of reason. 4. Amount of force structure, materials, construction methods and beautiful, what’s your view of box arch bridge and truss arch bridge. 5. Please talk about characteristics of bridge foundation construction conditions, these conditions are combine, bridge foundations designed should have philosophy.

REFERENCES [1] The sea-sails. Conceptual Design of Large-span Bridge Problems//proceedings of the 16th National Conference on Bridges. Beijing: China Communications Press, 2004. [2] Ocean Sail. Chinese and Foreign Comparison of Technological Innovation in the New Bridges//proceedings of the 17th National Conference on Bridges. Beijing: People China Communications Press, 2006. [3] Yan Guomin. The Modern Cable-stayed Bridge. Chengdu: Southwest Jiaotong University Press, 1996. [4] Lin Yuanpei. Cable-stayed Bridge. Beijing: People’s Communications Press, 2004. [5] Shao Changyu. Domestic and International Development Prospect of Composite Structure Bridges. The Bridge, 2009 (3). [6] Shao Changyu.—Hangzhou Jiubao Bridge Composite Bridge Concept, Technology and Innovation. The Bridge, 2009 (4). [7] Honshu-Shikoku Bridge Authority. The Akashi-Kaikyo bridge—Design and Construction of the World’s Longest Bridge. October,1998, Japan. [8] Man-Chung Tang,Dr. Record Spans. Civil Engineering, March 2010. [9] Aude Petel, Eng. ,etc. Design of an Innovative Road Bridge with Advanced Steel and Concrete. Structural Engineering International, 2010,20(2). [10] Jose M Simon-Talero,etc. Launching the Vicario Viaduct: Andalucia, Spain. Structural Engineering International,2009,19(4). [11] Yan Guomin. Bid on Design and Construction of the Oresund Bridge. Bridges Abroad, 1999 (3). [12] Yang Yidong, Hu Dingcheng. The Detailed Design of the Oresund Bridge. Bridges Abroad, 1999 (3). [13] Lin Yuanpei. Cable-stayed Bridge. Beijing: People’s Communications Press, 2002. [14] The Lei Junqing, Zheng Mingzhu, Xu Gongyi. Suspension Bridge Design. Beijing: People’s Communications Press, 2002. [15] Dr Lau Ching-kwong, et al. Hong Kong Bridge Design and Project Management. Beijing: Tsinghua University Press, 2008. [16] Wu Guoji, Huang Heng Zhi, Xu Zhihao, Huang Jianbo. Route Nineth Stonecutters Bridge Design Competition//14th National Bridge Beam Academic Conference Proceedings, 2000. [17] Wang Yingliang, Gao Zongyu. Bridge Design in Europe and America. Beijing: China Railway Publishing House, 2008. [18] Yin Delan. Deng, and bridge—China article. Beijing: Tsinghua University Press, 2006.

[19] The Yellow Melt.—Design and Construction of the Cross-Sea Bridge Donghai Bridge. Beijing: People’s Communications Press, 2009. [20] In highway planning and Design Institute, et al. Preliminary Design of Suzhou Nantong Yangtze River Bridge Project Across the River. 2002.11. [21] In Highway Planning and Design Institute, et al. Preliminary Design of SuzhouNantong Yangtze River Bridge Project Across the River. 2007-3).

DISASTER PREVENTION AND DURABILITY OF BRIDGE STRUCTURES

The design of concept is the early stage of project design, relying on the thorough study of the natural conditions of the bridge site, bridge function and the surrounding landscape and a series of basic data, concept creation and selection of work reflect the designer’s unique understanding of design objects, design tasks, the specific control and overall grasp of design goals. Meanwhile, conceptual design must be follow a few basic principles, such as early 3E principles abroad, namely, efficiency, economy and elegance, the early “utility, economy, where possible care for beauty” construction principles, China’s current “safe, suitable, economical, beautiful” principle, the 21st century international bridge “safe, suitable, economical, beautiful, durable and environmentally friendly” six principles. With the rapid economic development of society, the bridge built by ever-larger, systems become more complex with more and more functions, internationally known as “superstructure” (super infrastructure). Common characteristics of these projects are: huge investment, technologically complicated, severe environmental impacts, with increased probability of disaster (including heavy winds, earthquakes, tsunami, boat crash, terrorist attacks, etc.), and maintenance, repair and reinforcement are very difficult. Being confined to structural features, single level seeking structural safety, as used to be, is not enough, it must also be aimed at disaster prevention design of bridge structure and durability design set. From the 1970s, on the basis of lessons learned at home and abroad, in addition to continued emphasis on the structural design and construction safety durability, reliability, component interchangeability of different bridges structure and analysis of the disaster grade, level of risk, proposed the prevention design and durability design of new concepts. In real terms, disaster prevention design of structures and structural durability design to solve the problem is the economy, reasonable working life issues, namely, structural lifetime issue. Bridge structural durability and disaster prevention design in conceptual design has three main objectives: first, to learn about damages disasters may impose on the bridge, as well as the durability of bridge structures shown on the main issues so that at conceptual design stage fully estimate the severity of these disasters and problems; secondly, master the design of bridge structures to resist various disasters and durability basic principles of design, methods and effective means in conceptual design phase has prepared structural disaster prevention and durable plan and measures; third, to introduce the bridge structural durability design of prevention and advanced concepts, practices, and successful experience of pioneering economic, rational, comprehensive and innovative prevention and durability of design ideas. This chapter’s bridge structure disaster prevention focused mainly on wind-resistant, anti-ship collision with bridge and bridge aspect, coupled with resistance of bridges durability, and consists of four parts, focusing on bridge conceptual design stage of design concepts and methods in these four areas, in hope that bridge engineers can, from concept

design, fully and seriously deal with prevention and durability problems bridge structure design.

5.1 BRIDGE WIND RESISTANT DESIGN PHILOSOPHY For bridge structures, particularly large-span bridges, flexible structure, in addition to the necessary design and static analysis, you must also be carry out wind-resistant analysis and design. Design and analysis of wind-resistant behaviour of long span bridges include theory analysis and wind tunnel test and numerical simulation and field test, but in bridge conceptual design stage, generally technology, time and money do not allow refinement of the design and analysis of wind-resistant, so wind-resistant design of the bridge is especially important. In order to establish a wind-resistant design of bridges, first of all, one must master the mean and fluctuating wind characteristics and wind resistance bridges of the basic principles, which will be introduced in the first part of the wind resistance of bridge; secondly, you need to understand the concept of wind resistant design in reducing wind loads of bridge, part II, mainly from the point of view of bridge structure component —main girder and arch ribs, pylons and piers, main cables and so on—introduces briefly reducing wind load practices set forth, and one still needs to understand the concept of wind resistant design in reducing wind-induced vibration of bridges, the third part is about flutter from the main beam, and galloping, vortex-induced vibration of main beam and arch ribs, rain-wind induced vibration of stay cable, a brief introduction of engineering practice of reducing vibration hazard and experience and methods. Finally, one also needs to know when the wind-resistant properties of the bridge structure itself cannot meet wind resistance requirements, which can be used to control measures applied to improve wind resistance performance, part four introduces flutter control of main beam and main beam or arch ribs of vortex-induced vibration control of cables wind and rain vibration control of aerodynamic measures.

5.1.1 Wind and Bridge Wind-Resistance Wind is a natural phenomenon on the surface of the Earth, human society’s history of quantitative estimation of wind-induced effects began with “the first civil engineer “John Smeaton in 1759, who published the famous paper on mean wind load calculations; 120 years later, in 1879, when the world’s longest railway bridge—the 84-well United Kingdom Firth of Tay—were destroyed by strong winds the event advanced the wind load calculations to new era that fluctuating wind loads or wind loads must be considered; more than 60 years later, in the autumn of 1940, in the United States, Washington’s second large-span suspension bridge in the world—Tacoma bridge which was completed just over 4 months ago, under the action of force of winds underwent strong vibrations and collapsed completely. This event ended the era when human simple considering the static effect of wind load times. Modern wind engineering started from investigation of wind destroyed the Tacoma bridge accident, and has, over more than 60 years, especially in the past 30 years, made great progress, forming principles and norms of bridge and structural wind-resistant design.

1. The Wind Characteristics Human settlements are surrounded by a layer of the atmosphere as thick as 1000 km on Earth, the orbit around the Earth’s atmosphere from the top to the next can be divided into

hot layer, a middle layer, the stratosphere and the troposphere. Among them, the troposphere is about 10 km above Earth’s surface, within the atmosphere that human activities carried out mainly in the troposphere, such as airline flight in nearly 10,000 metres up in the sky, the Earth’s tallest mountain—the height of Mount Everest is 8848 m. Due to the uneven distribution of solar radiation at the Earth’s surface and the Earth inhomogeneity of the surface land and water distribution, the level of distribution as well as the rotation of the Earth result in the Sun’s uneven heating of the surface of the Earth, both temporal and spacial and the uniformity of tropospheric air temperature distribution in space and time, resulting in horizontal and vertical convection of air flow and thus the wind. Simply put, the wind is the movement of air relative to the Earth’s surface, mostly because of the spatio-temporal heterogeneity of heating of air by the Sun. When the air cools, its weight will be increase to sink when air gets hot its weight is reduced, it moves up. Hot air rises, cold air flows around to fill vacancies and thus forms wind. Air flow forms wind, due to the Earth’s surface topography and the impact of various obstacles, the flow of wind near the surface of the Earth (referred to as close to the wind) dislays disorders. From the anemometer records it has been found that wind velocity timehistory curve in the package contains two components: one is the period is greater than 10 min the long-period average wind components, general description in terms of random variables; the other is a period of only a few seconds or less short-period pulsating wind component, in accordance with the general stochastic processes to deal with them. The average size of the wind is usually divided into 0~12 or a total of 13 grades according to the English Beaufort grading, it is based on objects on land, sea and fishing boats and wind speed the height of 10 m above the sea level, wind detailed registration is seen in Table 5.1. Table 5.1 Beaufort scale of wind. At a considerable Land surface Sea and fishing Probably sea height from the features features wave height (m) Wind Name ground 10 m wind characteristic rating speed (m/s) English Range Median General Highest 0 Calm 0.0~0.2 0 Quiet, smoke Calm sea — — straight 1

Light air

0.3~1.5

1

Cigarette can show the wind direction, wind tale-tell does not turn

Mini-waves as scaly, no surf, on fishing ship on feels subtle movement, and can actually use the rudder

0.1

0.1

2

Light breeze

1.6~3.3

2

People feel there is wind, wind tale-tell

Wavelets, short wavelength, but shows clear

0.2

0.3

rotates

shape of wave; fishing boat can sail 1~2n mile with sails raised

3

Gentle breeze

3.4~5.4

4

Leaves and twigs are moved flags open up

Wavelets increases, crests begin to rupture; fishing boat can sail 3~4n mile with sails raised

0.6

1.0

4

Moderate breeze

5.5~7.9

7

Dust and paper on the ground are moved, tree branches shaken

Small waves, white waves appear; fishing boat can make the hull sideways with full sail raised

1.0

1.5

5

Fresh breeze

8.0~10.7

9

Small trees with leaves sway inland water shows small waves

Medium waves, with more significant wave shape; fishing vessels have to reef part of sail

2.0

2.5

6

Strong breeze

10.8~13.8

12

Big trees are moved, electric lines sound and difficult to hold umbrella

Mild waves begin to form; fishing boats reef most of the sail

3.0

4.0

7

Near Gale

13.9~17.1

16

Entire tree shakes, headwind prevents walking feel the inconvenience

Light waves, surf into foam strips along the wind direction; fishing is no longer out of port

4.0

5.5

8

Gale

17.2~20.7

18

Twigs snapped, one feels strong resistance facing the wind

Moderate big waves, longer wavelengths and all sea fishing boat stay in port

5.5

7.5

9

Strong gale

20.8~24.4

23

Buildings suffer small

Wild waves, along wind strips

7.0

10.0

damage, roof tiles being lifted, big branches broken

of foam is thick difficult to sail

10

Storm

24.5~28.4

26

Trees blow down, ordinary buildings destroyed

Wild waves, are long and rolled; motor boat sailing with Danger

9.0

12.5

11

Violent storm

28.5~32.6

31

Trees blown over, ordinary buildings seriously damaged

Abnormal waves; visibility affected motor junks in extreme danger

11.5

16.0

12

Hurricane

Hurricane rare on land, destruction power is tremendous

Slaughtering waves, the sea has turned completely white, visibility severely affected

14.0

—

>32.6

2. Wind Induced Disasters Storm is one of the most frequent and severe natural disasters, year after year, it has brought to our society great loss of life and property and caused a lot of structural damage and destruction, serious impact on our economic and social activities. Cyclone has characteristics of high frequency, secondary disasters (such as rain, waves, storm surges, floods, mudslides, etc.), duration, etc. In the second half of the 20th century statistical results showed that among the top ten worldwide natural disasters storms occurred most frequently, accounting for 51% of the total number of disasters; death toll caused by the storm, about 41%; economic loss caused by the storm, about 40%. Among 2005, World top ten natural disasters are two storms, of which the United States “Katrina” Hurricane caused damaged houses, collapsed bridges and inundated city, traffic disruption, leading to direct economic losses of about 2000 people were killed and economic loss upto more than $ 200 billions. China is one of the world’s handful countries worst affected by the cyclone. Our country is located in the West Coast of the Pacific North-west, the whole world. Most severe tropical cyclones typhoons are mostly generated in the Pacific North-west, and North-west or West along the path, had direct hit China’s Guangxi, Guangdong, Hainan, Taiwan, Fujian, Zhejiang, Shanghai, Jiangsu, Shandong, Tianjin, Liaoning, more than 10 coastal provinces, municipalities and autonomous regions, and that hurricane frequency high average annual Typhoon that landed in China’s coastal areas is 7, 6 Severe storm surge causing disasters. In 20054 of the top ten natural disasters in China are storms,

causing a direct economic loss of 55.1 billion Yuan, accounting for about ten two-thirds total losses from natural disasters. According to the World Meteorological Organization (WMO), the Typhoon Committee 1985~1997 annual report, China’s average economic loss caused by a hurricane is 7.3 times that of Japan, 10.2 times of Philippines, 12.3 times Korea, 22.3 times Viet Nam; the average total number of casualties and missing due to the Typhoon is 7.6 times that of the Philippines 19.3 times of Vietnam, 42 times of Japan. On 7 November, 1940, the United States main span of 853 m completed in just over 4 months, Washington (then the world’s second largest span) the Tacoma Narrow Bridge was vibrated in gale with wind speed less than 20 m/s wind-induced vibration, the bridge has experienced increasing amplitude 70 min of torsional vibration, and ultimately result in broken bridge structure fell into the Gorge frame as shown in Fig. 5.1. The terrible accident of winds destroying the bridge of Tacoma strongly shocked bridge engineering and air mechanical industry, and opened a comprehensive study on wind-induced vibration of long span bridge and Aero-elastic theoretical exercise. However, accident investigation gather historical information about bridge wind destroyed for reasons, people are surprised to find, from 1818 onwards, there have been at least 11 bridges destroyed by strong winds, and witnesses described scenes of wind damage can be clearly felt that much of the cause of the accident was caused by a wind strong vibration, although the mechanism of wind-induced vibration was unknown.

Fig. 5.1 Tacoma Narrow Bridge destroyed by strong winds (a) Wind induced torsion vibration; (b) Deck break fall.

3. Wind-resistance Principles When the wind encounters structures it converts some of its kinetic energy to external forces acting on the structures of power, this force is so-called wind loads. When the wind around generally non-streamlined (bluff) section of the bridge structure, generates vortices and flow separation, forming the complex of the air force. When the bridge span is small (200 m), when the stiffness, the structure is insured stationary, air acts as only the force of static, or static wind load, which includes average wind and pulsing wind load; and when the larger span of bridge structures (200 m), the less the stiffness makes it easier for structural vibration excited, this static characteristics of species not only has the effect of wind and dynamic characteristics, or dynamic wind loads. Wind dynamics inspires bridge vibration, the vibration of the bridge, in turn, affect the flow of air, change air force formation of wind-structure interaction mechanism. When the vibration caused by air force small, air force as a force, leading to finite amplitude forced

vibration of bridge structures, including vortex-induced vibration of bridge buffeting and bridge when air force under the influence of strong vibration, the air force subject to vibration feedback structure is characterised by a self-excited force, resulting in divergence of self-excited vibration of bridge structures, including flutter and vortex resonance. Effects of wind loads of bridge structure and its classification can be represented by Fig. 5.2. In addition, the cables of the cable-stayed bridge in the wind or rain occurs in different forms under the action of vibration, vortex-induced vibration of stay cable for example, parameters such as vibration, the vibration of wake galloping and rain.

Fig. 5.2 Effects of wind loads of bridge structure and its classification. According to the code for wind-resistant design of highway bridge (JTG/T D60012004), and wind-resistant design of bridge structure compliance with the following principles: may be appear in the bridge’s design life of maximum wind speed, structure should not ruin a divergent self-excited vibration in the most adverse design wind load combinations together with the other functions, should have the required strength and stiffness of structures and static instability should not occur; non-destructive wind-induced vibration of amplitude of the structure should meet safely, driving comfort and fatigue strength requirements of structural wind-resistance by aerodynamic measures, structural measures and measures to improve it. Wind-resistant design principles in order to carry out, in conceptual design of bridge structure while there is no need for a wind tunnel test method or simulation evaluation of wind-resistance performance test results and overall, but still can be arranged through the structure and components of fully embody the idea of wind-resistant design, chief among them included decrease static wind loads and wind-induced vibration and additional control measures.

5.1.2 Reduce the Static Wind Load Any object immersed in flow are affected by airflow, airflow to bypass the usually nonstreamlined or bluff-body section bridge structure, generates static wind load of the three components, as shown in Fig. 5.3, the FD or static wind load resistance components FH and the static wind load lift component FN or FL MT and static wind load lifting moment components, it can be expressed as follows:

In the formula: ρ = air mass density, 1.225 kg/m3; u = design wind speed (m/s) average wind load average wind speed, gust loads calculated using gusts; B, H = vertical and lateral projection width (m); CL, CD = lift and drag co-efficients in the axial direction; CN, CH = lift and drag co-efficients body in the axial direction; CM = lift moment co-efficient. Structure defined by the above three formulas three components of the static wind load, and design wind speed, cross-sections and dimensions of the three factors. Design basic wind speed, wind speed is determined by site conditions such as roughness and the height from the ground. In order to reduce the static wind load, bridge site should be an area with small base wind speed; under the same basic wind speed, the greater the surface roughness, smaller average wind speed, wind speed/gusts greater average wind speed increases with height above ground, but wind speed decrease with increasing height off the ground. Section types and dimensions of static wind loads according to the main beams and arches ribs, piers and towers, main cables and cables and other components were also be discussed.

Fig. 5.3 Wind and body axes coordinates under static wind load.

1. The Main Girder and Arch Ribs Section size and structure of main girder and arch ribs have large effects on static wind load . From a general point of view, section close to streamline smaller the static wind load and vice-versa section which is similar to a bluff body, greater the static wind load. Effect of static wind load set out the main structural dimensions are width and height of the main beam or arch rib section, the aspect ratio is greater, smaller the static wind load, on the contrary, width and height smaller than static wind load greater.

Fig. 5.4 Pouring of concrete box girder. Figure 5.4 shows the six commonly used concrete girder, in which, as in Fig. 5.4(a) minimum static wind load in the form, as shown in Fig. 5.4(f) Secondly, since the aspect ratio is a large, close to streamline; as in Fig. 5.4(b) maximum static wind load in the form, as shown in Fig. 5.4(c) second, because the small ratio of width to height, near bluff. Figure 5.5 shows the six solid web steel girder, among them, 5.5(a), (b), (c) and (e) forms of static wind load, as in the latter vertical webs close to the bluff body; 5.5(d), (f) form of static wind loads small, streamlined skew web better.

Fig. 5.5 Solid Web steel girder. Figure 5.6 shows four types of steel box girder, in which 5.6(b) form of static wind load minimum maximum height-width ratio. Figure 5.6(a), (c) forms of static wind load followed, both are similar, because the beam is large, but you have set the long wind up, which although not set the wind up, but small beam; 5.6(d) form of split-type steel box girder and static wind load is slightly greater than the above three forms, but wind-induced flutter stability of performance is especially.

Fig. 5.6 The main beam section (size: m). Arch typically have two or more than two tablets of arch rib, rib-section section compared with the width is much smaller. Role in each arch can be ignored as the static wind load on components of lift moment, leaving the drag and lift components depends primarily on the most lateral arch and its high profile, and each piece of the arch rib of the drag and lift forces is not the same. Reduce the static wind load is mainly increase lateral arch outline consisting of aspect ratio, or the use of arch rib section angle measure application of section to streamline.

2. The Piers and the Bridge Tower Piers and the bridge tower are usually vertical components: on the one hand, this kind of vertical component along the vertical section change of wind speed size is changed, so static wind load along the height variation is more complex on the other, this kind of vertical cross-section of the aspect ratio compared with the main beam is small, lift and the lift moment components can generally be ignored, so the static weight resistance to wind loads considering only a relatively simple as that. Piers and towers of static wind loads generally refers to a high component of wind resistance, simple geometric shape section of bridge pier and Tower of wind drag co-efficient can refer to Table 5.2. Table 5.2 Pier and Tower resistance co-efficient. Profile

t/b

Bridge pier or pylon of height-width ratio

1

2

4

6

10

20

40

*1/4

1.3

1.4

1.5

1.6

1.7

1.9

2.1

1

1.2

1.3

1.4

1.5

1.6

1.8

2.0

≥4

0.8

0.8

0.8

0.8

0.8

0.9

1.1

1.0

1.1

1.1

1.2

1.2

1.3

1. 4

0.7

0.8

0.9

0.9

1.0

1.1

1.3

0.5

0.5

0.5

0.5

0.5

0.6

0.6

When piers or height of the bridge towers static, wind load will be very large, sometimes you have to take into account the pier or pylon section of buildings-shape and static wind load. China’s largest suspension bridge spans—Shanxi Hou men bridge main span of 1650 m boat, bridge tower section once several rounds of selection of pneumatic, which on commonly used pair of rectangular cross-section in the first round, compared the three chamfer forms that is, outside the circle, concave circle and rectangle, as shown in Fig. 5.7. Four different forms of chamfers of tower column cross-section of transverse wind resistance co-efficient static wind resistance co-efficient Cy, Cx and obey directions as shown in Table 5.3, the maximum transverse direction to the outside wind resistance co-efficient cabochon heshun bridge angle less chamfer of about one-fourth; concave circular and concave rectangle two chamfers differ can also reduce some 30% of wind drag co-efficient. Therefore, on the premise of meeting the structural requirements, should be combined with building design, consider a rectangle chamfer cross-section as appropriate to reduce the static wind load.

Fig. 5.7 Four different forms of chamfers of Tower column cross-section (size: m). Table 5.3 Towers column section four different Chamfer wind drag co-efficient of static

forms. Coefficient Angle Simple rectangle Convex round Concave circular Concave (°) rectangular Anterior Posterior Anterior Posterior Anterior Posterior Anterior Posterior column column column column column column column column 0 1.45 1.88 0.37 0.34 1.06 0.49 1.03 0.50 Cross the 45 1.19 1.65 0.98 0.79 1.27 1.28 1.23 1.34 bridge 90 0.10 –0.11 –0.04 0.05 0.10 –0.15 0.10 –0.08 Along the bridge

0

0.01

0.01

0.01

–0.01

–0.10

0.00

0.00

0.03

45

1.49

1.71

1.21

0.95

1.49

1.36

1.58

1.41

90

1.95

1.91

0.54

0.54

1.40

1.38

1.36

1.37

The largest span in the world—1088 m Suzhou-Nantong Yangtze River Bridge main span cable-stayed bridges, bridge tower section has also be conducted the aerodynamic shape comparison, Fig. 5.8 shows the cross-section of the four forms. Table 5.4 shows the different sections of the static wind resistance co-efficient, cut surface form and section IV is wind resistance co-efficient 20% per cent difference in the transverse direction, along the bridge over 30% the difference, which is 300 m high bridge towers, the static wind load is considerable. Table 5.4 Four different forms of Chamfers of Tower column cross-section of transverse wind resistance co-efficient.

Section I Section II Section III Section IV

Transverse direction

1.449

1.491

1.511

1.789

Along direction

1.125

1.160

1.197

1.504

Fig. 5.8 Four types of tower column cross-section form (a) sections I and (b) section II (c) section III (d) section IV.

3. The Main Cable and Cable Of suspension bridge main cables and slings and cables in cable-stayed bridge, although generally possess a streamlined circular section, but they are still affected by static wind load effect, as with piers and towers, has only resistance component need to be considered. Modern parallel wire strands of long span suspension bridge main cables are generally made from steel wire, wire harness unit consisting of (strand), and consists of several beam unit into a main cable. With preformed parallel wire beam unit method (PPWS) beams tend to follow a regular hexagon line, common types of steel wire unit number 61, 91, 127, 169, composed of hexagons of shape stability. This arrangement can be facilitate beyond construction, you can also minimise the beam unit with the beam between the strands of the void, aim to reduce the cross-section diameter of the rope. Wind resistance co-efficient of main cables of suspension bridges in general constant, single main cable can take the value 0.7, so the outer diameter is smaller, static wind-resistance the smaller, proportional relation between them.

Fig. 5.9 The main types of cable-stayed bridge (a) steel cable; (b) parallel wire strands; (c) strand clue; (d) single strand. Is used in cable-stayed bridge cable general cables must be made with high strength reinforcing bars, steel wire or strand. Main cable type high-strength steel cables, parallel wire rope, PC strand thread, single strand, as shown in Fig. 5.9. At present, in large-span cable-stayed bridge parallel wire strands, and are most commonly used in steel strand leads two parallel wire strands of smaller voids, so the outer diameter of the same intensity less wind-resistance is relatively small; conversely, strand leads voids larger, so the large outer diameter, wind resistance is relatively large. Due to the influence of Reynolds number effect and cable than static wind-resistance co-efficient of main cables of suspension bridges, and general range of 0.8~1.0.

5.1.3 Reduce Wind-induced Vibration Bridge structure due to different bridge, span and materials, and produces various forms of wind-induced vibration of its main components, large-span girders of cable-stayed and suspension bridge would be flutter, galloping, buffeting, vortex-induced vibration and wind-induced vibrations, long-span arch bridge arch rib of a bluff body truncated vortexinduced vibration is raised, steel pylons for cable-supported bridges may be easily lead to galloping and vortex-induced vibration and long wind-induced vibration of cables of cable-stayed bridges and weather exciting possibilities, suspension bridges and wind vibration of arch bridge suspenders also has problems. Above wind-induced vibration and flutter, galloping is self-excited vibration of two divergent, according to wind-resistant design principles must be completely avoided, and vortex-induced vibration is a large amplitude vibrations, both a self-excited vibration and forced vibration characteristics of bridge wind-resistance design principle calls for stiffness requirements; rain-wind induced vibration of cables is a self-induced vibrations of large amplitude, it should meet certain strength and stiffness requirement; else buffeting and vibration is non-destructive forced vibration of finite amplitude, will not cause the bridge broken bad, as long as the traffic safety and driving comfort and fatigue strength. Bridge conceptual design stage, in order to improve wind-resistance performance implement the concept of reduction of wind-induced vibration, mostly on the main beam or beams flutter, galloping, vortex-induced vibration of arch ribs, cables, such as rain-wind induced vibration of divergent or self-excited vibrations of large amplitude, and other limited vibration non-destructive forced-vibration sites can be taken into account in the subsequent design stages.

1. Main Beams Flutter and Galloping Flutter is a destructive torsion or bending and torsional coupling divergent self-excited vibration when it reaches a critical wind velocity, vibration girders moving by air feedback continue to absorb energy to overcome structure damping results in increase of amplitude gradually until the structure destruction, flutter can occur in almost any form of girder, just flutter critical wind velocity of different sizes. Galloping is a destructive horizontal divergence of self-excited vibration of the bending in the wind, was mainly caused by the lift curve slope, galloping occur in non-circular side-length ratio is less than 4 blunt body similar to the rectangular components, seldom in the long-span bridges this height-width ratio of the main beam. Judge flutter instability of bridge, or the standard is whether bridge flutter testing wind speed is greater than the critical wind speed of flutter, which is design basis multiplied by the correction factor of wind speed wind speed and safety factor of a standard, the latter generally use segment models or full bridge model wind tunnel test and theoretical calculation method to determine flutter. Bridge conceptual design phase typically can be used code for design of highway bridge wind (JTG/T D60-01-2004), the estimation formula of critical wind speed of flutter of a preliminary the evaluation, which also contribute to the analysis of main factors affecting the critical wind speed of flutter.

In the formula: b = half-bridge width, b = B/2; ft = bridge torsional vibration frequency (Hz); m, Im = bridge of equivalent mass (kg/m) and the mass moment of inertia (kg · m2/m); ηs, ηα = section shape co-efficient, effect co-efficient and angle of attack, and can refer to the values in Table 5.5.

Table 5.5 Girder shape coefficient and angle of attack effect co-efficient. Section types

Shape co-efficientηs

Angle co-efficient ηa

Tablet

Damping ratio 0.005 0.01 0.02 1 1 1

—

Blunt-shaped

0.50

0.55

0.60

0.80

With cantilever

0.65

0.70

0.75

0.70

With cantilever

0.60

0.70

0.90

0.70

With wind mouth

0.70

0.70

0.80

0.80

0.80

0.80

0.80

0.80

0.35

0.40

0.50

0.85

With splitter plates Open panel beam

Estimation formula of critical wind speed of flutter (5-4) showed that flutter critical wind speed effect of section shape factors (including the damping ratio), angle of effect factor, main beam and mass moment of inertia and torsional frequency, and so on. Among them, the damping is relatively large, streamlined good section, has a higher flutter critical wind speed; –3° or +3° attack angle flutter critical wind speed of less than 0° angle of attack increases main beam equivalent mass or mass moment of inertia can be help improve flutter critical wind speed, but the effect is limited, just a relationship of onefourth power increase reversed the fundamental frequency of bridge, flutter critical wind speed can improve. Bridge conceptual design phase, in addition to judging by these four factors or improving flutter stability of bridges, you can also use bridge has been completed and the performance of dynamic characteristics and chatter, a simple comparison to design bridges

or contrast. Tables 5.6 and 5.7 respectively 10 has built structural properties of a typical cable-stayed and suspension bridge the natural frequency and vibration critical wind speed of flutter, concept design for long-span bridges. Table 5.6 Typical characteristics of cable-stayed bridge structure and fundamental frequency of vibration and flutter critical wind speed No.

Bridge name

1. Donghai Bridge stars Pearl Hill Bridge

Span Girder (m) material

Girder section

332 Composite II beam

Fundamental The critical frequency (Hz) wind speed (m/s) Vertical Reverse curve 0.3381 0.5287 95.0

2. Hainan century bridge 340 Concrete beams

II

0.2728

0.6248

138.0

3. Shanghai nanpu bridge

423 Concrete beams

II

0.3518

0.4498

66.4

4. Jingzhou Changjiang bridge

500 Concrete beams

II

0.1987

0.3983

101.0

5. Shanghai nanpu bridge

602 Composite II beam

0.2733

0.5093

81.0

6. Minjiang bridge in Fuzhou

605 Composite II beam

0.2075

0.5346

74.06

7. Nanjing Yangtze

628 Steel beam

Single girder

0.2426

0.7275

130.0

8. Nanjing Yangtze River third Bridge

648 Steel beam

Single girder

9. Shanghai Yangtze River Bridge

730 Steel beam

Single girder

0.2315

0.6175

> 100.0

10. Su Tong Changjiang bridge

1088 Steel beam

Single girder

0.1754

0.5321

88.4

Table 5.7 Typical characteristics of cable-stayed bridge structure and fundamental frequency of vibration and flutter critical wind speed. No.

Bridge name

1. Guangxi Red Bridge

Span Girder Girder (m) material section

380 Steel

Steel II

Fundamental The critical frequency (Hz) wind speed (m/s) Vertical Reverse curve 0.1915 0.3591 60.0

beam 2. Xiamen haicang bridge

690 Steel box Single girder girder

3. Humen bridge in Guangdong Province

888 Steel box Single girder of girder

4. Xiling Changjiang bridge

900 Steel box Single girder girder

5. Yichang in Hubei bridge

960 Steel box Single girder of girder

95.0 0.1117

0.4260

88. 0 >85.0

0.1050

0.4260

80.4

6. Wuhan yangluo bridge 1280 Steel box Single girders girder 7. Tsing Ma bridge in Hong Kong

1377 Steel truss Single girder girder

>95.0

8. Jiangyin Changjiang bridge

1385 Steel box Single girders girder

0.0890

0.2581

74.0

9. Runyang bridge

1490 Steel box Single girders girder

0.1245

0.2249

56.4

10. Zhoushan Xi Hou men 1650 Steel box- Single bridge in Shanxi beams girder

0.0999

0.2323

95.0

2. The Primary Beam or Arch Ribs of Vortex-induced Vibration Airflow typically blunt body when sections of bridge structural members, separation and re-attachment flow formation of vortex shedding occurs, resulting in alternating the vortex force, when the vortex shedding frequency is close to or equal to order natural frequencies of a structure, it will be bring out the structure of the vortex vibration, called vortexinduced vibration. Vortex-induced vibration will not cause the entire structure like a flutter, galloping on divergent vibration, resulting in dynamic power failure, but when the vortex-induced vibration frequency is close to the natural frequency, also appears larger amplitude, formation of vortex-excited resonance, this combination of characteristics of self-excited and forced vibration comfort and driving problems caused by light, severe cases may be cause deformation of the structure is too large, even strength. Vortex-induced vibration in lower wind speed range of limited amplitude. When wind speed is low, frequency of vortex-induced vibration less affected by vortex frequency and flow velocity has a simple linear relationship between as the wind speed increases, vortex frequencies and amplitudes step-by-step increases when the vortex frequency is close to the natural frequency, amplitude, reach the vortex-excited resonance states, at this moment, vibrational state, in turn, controls the frequency of vortex makes a range of wind speeds change cannot change the vortex frequency, which is characteristic of vortexinduced vibration the frequency of “locked”, the corresponding wind speed range, called vortex-induced vibration lock the wind speed.

Evaluation of vortex-excited resonance occurs there are three main indicators: first, the vortex-induced vibration lock the wind speed, the vortex-induced vibration velocity only if vortex-induced vibration lock the wind speed is less than the required design wind speed into account vortex-induced vibration problem for large-span cable-supported bridges, vortex-induced vibration locked wind speeds generally between 5~20 m/s; maximum amplitude of vortex vibration, which corresponds to a maximum amplitude of first order modal, highway wind-resistant design code of bridge (JTG/T D60-01-2004), vortexexcited resonance amplitude estimation formula is given, but it is recommended to segment model wind tunnel test as the standard, specification of vortex-excited resonance amplitudes are presented simultaneously allowed values, must-ensure that the maximum amplitude is less than the acceptable third, vortex-induced vibration frequency, which is associated with the economic indicators, theoretically speaking, if the vortex-induced vibration lock the wind speed less than design basic wind speed, and vortex-induced vibration of maximum amplitude is greater than the allowed value, it is necessary to consider the vortex-induced vibration control measures, but considering use of vortexinduced vibration control measures have to pay the economic price, recent advances show that can happen based on the vortex-induced vibration frequency analysis on bridge design reference period first vortex-induced vibration frequency and the cumulative time in vortex-induced vibration of two indicators to determine the need for vortex-induced vibration of control measures. According to the main girder of cable-supported bridges and latest progress of the study on vortex-induced vibration of long-span arch, based on theoretical analysis and model test and field measurements have been found to have varying degrees of vortexinduced vibration of famous bridges: Denmark Sea Bridge suspension bridge, Stonecutters Bridge in Hong Kong stayed Shanxi Hou bridge suspension bridge, boat, Shanghai Lupu arch bridge, and so on.

3. Cable Rain-wind-induced Vibration Long cables in cable-stayed bridges under wind and rain conditions vibration that occurs, called rain-wind induced vibration of stay cable, causing the vibration main cause is rain on the cable surface forming a line or the rain or rain up and down line. At present, the specification is still not on this type of vibration clear provisions on the issue. Cable section model wind tunnel test results show that the cables in the wind and rain conditions vibrations than the dry wind (no rain) under the condition of vibration is much more intense. According to the latest research advances, influence of rain-wind-induced vibration has three main factors: first, the cable orientation may generally be represented by inclination and declination, although in 25°~45° inclination and declination of amplitudes have some differences, but all have been, and this inclination and declination range cannot be avoided by the vast majority of cable-stayed bridges and, second, size of cable, which includes diameter and length, wind tunnel tests showed 80 mm diam, 200 m rain-wind induced vibration can occur above the length of the cable, the range of diameters and lengths are the vast majority of large-span cable-stayed bridges (400 m span) must be face the third, vibration of wind and rain conditions generally been represented by strong winds and rain, wind tunnel test results show that the wind speeds and rainfall intensity of 5~15

m/s and 5~60 mm/h caused by rain-wind induced vibration of cables, the wind speed and rainfall intensities are also often occur in the majority of rainfall. Therefore, large long rain-wind induced vibration of cables of long-span cable-stayed bridge’s problem is a common bridge designers have to face wind resistance performance problems conceptual design phase should be considered as early as possible counter measures.

5.1.4 Additional Control Measures According to the code for wind resistant design of highway bridge (JTG/T D60-01-2004), and wind-resistant design of bridge structure requirements of structural wind resistance by aerodynamic measures, structural measures and measures to improve it. Aerodynamic measures mentioned here mainly refers to change components of cross section shape or attach can alter air flow pattern around the appendages, such as stable plates, deflectors, skirt, wind nozzles, slots, because this method of structural change is small, lower economic costs, commonly known as the first choice for additional control measures; knot frame measures mainly refers to the increased rigidity of the structure or the quality and structure of external or internal constraints such as approach, which generally require pay a larger price, in conjunction with structural changes when considering the overall programme; mechanical measures refers to adding damping includes passive dampers and active damper and semi-active dampers, such as main beam of vortex-induced vibration and wind-induced vibration control of bridge tower passive dampers, lasuofeng TMD vibration control of semi-active damper, internal or external cable rain-wind-induced vibration control of magnetorheological fluid dynamic dampers. Will focus on the following main beam flutter control of main girder of aerodynamic measures, or arch ribs of aerodynamic measures and vortex-induced vibration control of cables vibration control of aerodynamic measures.

1. The Flutter Control of Main Girder of Aerodynamic Measures To illustrate the necessity of flutter control of main girder, presented in Table 5.8 currently has completed 10 of the world’s largest cross-suspension bridge, 5 of bridge flutter or a vortex-induced vibration problem has arisen. According to recent study on wind-resistance of long-span bridge and building established practice, irrespective of streamlined steel box girder is steel truss beam with good ventilation, the traditional ceiling flutter stability of long span suspension bridges about 1500 m, when even close to this limit is exceeded, designers must consider used flutter control measures improved aerodynamic stability; Flutter control of aerodynamic measures stiffening girder of suspension bridge main central stable boards, slotted or split box girder, stabilising plate and slotted combined, these measures can be guarantee suspension bridge main span of 5000 m flutter critical wind speed is high enough to meet the world wind in areas prone to wind-resistance requirements. Table 5.8 The top 10 largest span suspension bridge in the world. Order of span

Bridge name

Main Girder span forms

Windinduced

Control

Country Year built

(m) 1991

Truss

1

Japan’s Akashi Bridge

2

Shanxi Hou Gate Bridge

1650

3

Denmark Sea Bridge

4

vibration Chatter

Slotted/ stabilizer plate

Japan

1998

Girder Chatter

Slotted

China

2008

1624

Girder Vortex vibration

Spoiler

Denmark 1998

Runyang Yangtze River Bridge

1490

Girder Chatter

Stabilizer plate

China

5

The Humber bridge

1410

Girder No

No

United 1981 Kingdom

6

Jiangyin Changjiang bridge

1385

Girder No

No

China

1999

7

Hong Kong Tsing Ma Bridge

1377

Girder Chatter

Slotted

Hong Kong, China

1997

8

Weilunzuonuo bridge

1298

Truss

No

No

USA

1964

9

The Golden Gate Bridge

1280

Truss

No

No

USA

1937

10

Yangluo Yangtze River Bridge

1280

Girder No

No

China

2007

2005

Figure 5.10 depicts the central stabilising plate application in runyang Yangtze River Bridge, split in Shanxi Hou men bridge box-girder in a boat application, Italy Messina Strait Bridge to be used is split three-box girder scheme and 5000 m the stability of suspension bridges and open web portfolio.

Fig. 5.10 Flutter control of main girder efficient aerodynamic measures (size: m) (a) Stable Central Board application in runyang bridge; (b) Split in Shanxi Hou men bridge box-girder in a boat; (c) Three box girder bridge over the Strait of Messina split plan; (d) 5000 m stability of the suspension plate and slot combinations.

2. The Flutter Control of Main Girder of Aerodynamic Measures With the increase in recent years of large-span bridge span, in addition to the main beams flutter problems, main beam or arch of vortex-induced vibration problem more and more, previously mentioned in the vortex-induced vibration problem of several famous bridges in the world. In fact, the typical bridge vortex-induced vibration reasonable solutions to their problems, and eventually settled on pneumatic control measures in the future has a good model of vortex-induced vibration control of long-span bridges used. For this reason, Fig. 5.11 depicts several bridges the vortex-induced vibration of pneumatic control measures, for example, Denmark Sea Bridge and Hong Kong stonecutters Bridge is using principles similar to the spoiler, Zhou Hou men bridge deck wind barrier measures have been adopted in Shanxi, Shanghai Lupu bridge baffle wall plate is used.

Fig. 5.11 Flutter control of main girder efficient aerodynamic measures (size: m) (a) Denmark sea bridge plate; (b) of Stonecutters Bridge in Hong Kong guide plate (c) Shanxi Hou men bridge deck boat windbreaks; d) isolation of Shanghai Lupu bridge plate.

3. Vibration Control of Aerodynamic Measures As the main cause of rain-wind-induced vibration of stay cable is cable surface form the rain line, thus changing the cables was originally non-streamlined circular section, so rainwind induced vibration of cables of the most effective methods of control should be the formation of rain can damage the surface line measures. After a great deal of wind tunnel test and field test, mainly through pneumatic controls there are two, that is wrapped on the cable surface around the Helix (5.12A) or engraving irregular pits (5.12B), these two methods can effectively reduces the amplitude to allowed values (L/1700) range.

Fig. 5.12 Vibration control of aerodynamic measures. (a) Winding spiral; (b) Engraving irregular pits. In addition to rain-wind induced vibration of cables using aerodynamic measures of control, auxiliary cable for cable measures can effectively reduce rain-induced vibration and other vibrations, such as the Normandy bridge, but the measures are rarely used, mainly because the secondary cables and cable connections difficulties. In addition, if you can improve the cable damping can achieve the purpose of vibration control, increase the lasuozu can be used based on different mechanisms for damper, oil damper and viscous

shear damper and friction damper, high damping rubber damper and electricity, magnetic dampers.

5.2 BRIDGE WIND RESISTANT DESIGN PHILOSOPHY As with wind-resistant design of bridges, bridges including theoretical analysis, seismic design and analysis and shaking table test and numerical simulation of earthquake damage investigation, but at the concept design stage, generally does not allow for refinement of the seismic design and analysis, so build bridges located meter idea is particularly important. In order to implement the concept of seismic design of bridges, first, I had to learn the basic characteristics of earthquake ground motions—Magnitude and intensity, Bridge Seismic damage and aseismic design method, which will be introduced in the first part of the earthquake and seismic; Secondly, the need to be familiar with a variety of bridge seismic design principles, part II briefly introduces four beam bridges, arch bridges, cable-stayed bridge, a suspension bridge kind type of structure dynamic characteristic and seismic response characteristic and aseismic design principle, and requires an understanding of domestic and international bridges case studies in order to draw them in the conceptual design, and application and development of, and the third part focuses on the structure, load-bearing structures and foundation case; and, finally, two vibration reduction measures to understand the common—dampers and bearings, part IV including damper and vibration reduction, locking device and buffer supports.

5.2.1 Earthquake and Anti-seismic Earthquakes are the results of crustal rocks sudden rupture due to tectonic stress concentration accumulated in the Earth’s crust, earthquakes can be graded with magnitude of intensity and size. Earthquake particularly strong results for bridge damage is enormous, which generally included on earthquake damage to structures, support and ancillary facilities such as earthquake damage and earthquake damage to structures in the lower part. Learn bridge seismic design code for various types of bridge seismic design principles, mastering various types of bridge seismic analysis results and on the basis of experience, can help us in read design, clear requirements for fortification, on consideration of seismic performance of more focused conceptual design.

1. Earthquake Earthquakes are a natural phenomenon caused by the Earth’s internal structure movement. In strata movement, more dramatic break bad sport, can cause tremors, on above-ground or underground buildings in different levels of earthquake damage, and led to loss of life and damage to property. Size of seismic vibration can be described by two indicators, namely, their magnitude and intensity. The former is a measure of earthquake size indicators, usually with the maximum amplitude (Table 5.9) or source release of strain energy (Table 5.10) to represent, whereas the latter is used to indicate seismic degree of impact on surface and building, it not only with the release of seismic energy, depth and distance from the epicentre, and engineering geological condition and seismic wave propagation characteristics of a building and so on, the rules of the seismic design of highway bridges (JTG/TB02-01-2008) provides seismic fortification intensity of relations and horizontal design Basic acceleration of ground motion as shown in Table 5.11.

Table 5.9 Earthquake magnitude according to the defined maximum amplitude (m = 1gA). Category Large earthquakes

Shock level M Category M ≥ 7 Tiny earthquakes

Shock Level M 3 > M ≥ 1

Medium Earthquakes

7 > M ≥ 5

1 > M

Small earthquakes

5 > M ≥ 3

Ultra-tiny earthquakes

Note: A indicates the maximum amplitude. Table 5.10 The earthquake magnitude and strain energy released. Magnitude

Energy (erg)

Magnitude

Energy (erg)

1

2.00 × 1013

6

6.31 × 1020

2

6.31 × 1014

7

2.00 × 1022

3

2.00 × 1016

8

6.31 × 1023

4

6.31 × 1017

9

3.55 × 1024

5

2.00 × 1019

10

1.41 × 1025

Note: 1 erg = 10–7 J. Table 5.11 Seismic fortification intensity and horizontal design Basic acceleration of ground motion. Seismic intensity

6

7

8

9

Acceleration peak

0.05 g

0.10 (0.15)g

0.20 (0.30)g

0.40g

2. Earthquake Disasters Earthquake disasters have been recorded in history as early as there is a record of strong earthquakes often cause surface changes, such as topography, and landslides and liquefaction facility damage and fires, floods, pollution, disease and other secondary disasters caused by human or animal casualties and socio-economic loss. Bridges without the reasonable seismic design will be lead to serious damage in the quake. Turns out, both at home and abroad because of the number of bridge structural damage caused by the earthquake, far more than by storms, ship collision damage caused by other reasons such as. For example, in China in the 1975, haicheng earthquake in China, 618 bridges in earthquake regions in the 193-seat suffered varying degrees of damage, accounting for about 31% in the 1976 Tangshan earthquake, suffered earthquake

damage of railway bridges accounted for 39%, Tangshan earthquake disaster of highway bridge 62%, earthquake damage to highway bridge in Tianjin 21%; in the 2008 Wenchuan earthquake, there are 6 different types of bridge-more than 6000 square beam structure subjected to earthquake disaster, about 10% of them were badly damaged or collapsed, needs to rebuild after demolition. According to bridges disaster investigation, seismic damage of main bridge structure is reflected in various parts of the structure, and can follow the structure from top to bottom is divided into earthquake damage to structures, support and ancillary facilities such as earthquake damage and earthquake damage to structures in the lower part. Earthquake damage to superstructure, bridge or arch bridge upper structure subjected to earthquake damage and destroyed rare, often by other parts of the bridge structure damage caused by breakage of the girder and arch, such as caused by adjacent girders colliding beam end and deck structural damage in the vicinity of the department, and so on. When sliding displacement of earthquake damage beyond the pier when the bearing surface, it would have been serious the falling beams (Fig. 5.13). The earthquake, bearing of Bridge Seismic damage is extremely popular and has long been considered a weakness on the seismic performance of bridge. Damage was mainly for pot bearing anchoring bolts were pulled out, cut or shear failure of the bearing itself, plate bearing is pushed out, cut or cut-out damage (Fig. 5.14). In addition, bridge ancillary facilities block masonry shear or cut-tension-bending damage joints horizontal shear failure occurs, vertical or horizontal tension and compression shear failure damaged railings can also occur lateral deformation, deformation and failure of the vertical or horizontal tensile failure, and so on. Substructure or the serious damage of bridge pier and abutment is mainly due to soil liquefaction, ground subsidence and slope slip or break causing, the main earthquake damage included bridge abutment pier cracks, cracks, joints cracked, serious results in pier collapse (Fig. 5.15).

Fig. 5.13 Miao Zi ping whole spans of minjiang River Bridge in Wenchuan earthquake in Wenchuan earthquake, Luo Liang Tu.

Fig. 5.14 Rubber cut-out damage.

Fig. 5.15 Bridge in Wenchuan earthquake cracked and collapsed.

3. Bridge Aseismatic Design Method The seismic design of highway bridges regulations (JTG/T B02-01-2008) earthquake provisions according to the various types of bridges categories and their corresponding target for fortification, as shown in Table 5.12. The bridge seismic design category in the table are as follows: type a, 150 m extra large bridge with single span; Class b is a singlespan span no more than 150 m on the highway, highway bridges span no more than 150 m of single span bridge on secondary roads, bridges; Class c is a secondary Highway in the bridge, bridge, single span diameter not exceeding 150 m of category IV road, bridge, bridge; d Category is the category IV Bridge, the bridge on the highway. Table 5.12 Various types of Bridge anti-seismic fortification goal . Bridge Fortification goal antiE1 earthquake effect E2 earthquake effect seismic class Class A Generally can continue Local minor damage may occur, do not need to fix or using without damage simple fix may continue to use or repair, Class B

Is not damaged or does Assurances of no collapse or serious structural not need repair can damage, after temporary reinforcement may be usedcontinue using emergency communications

Class C

Without damage or repair, can continue to use

Assurance against collapse or serious structural damage, after temporary reinforcement may be used emergency communications

Class D

Without damage or repair may continue to use

Set forth in the rules for the seismic design of highway bridges using the principle of two levels of fortification, two-stage design. The first phase anti-seismic designs, the elastic seismic design; the second phase of the seismic design ductility seismic design methods, and capable of protecting designs principle. Through the first phase of the seismic design, which correspond to E1 earthquake seismic design can achieve similar levels and original specifications earthquake fortification level. Through the second phase of the earthquake-resistant design of the corresponding E2 earthquake seismic design to ensure the structure adequate ductility capacity, by checking to ensure structural ductility capacity is greater than the ductility demand. Design by introducing the ability to protect the original then, ensure that the plastic hinge in the selected location appear, and there is no shear damage failure modes. By aseismic measures set meter, ensure that the displacement of the structure with sufficient capacity. The seismic design of highway bridges rules according to the complexity of dynamic response under earthquake excitation, bridge structural dynamic response calculation of bridge structures subjected to earthquake-resistant design and verification will be divided into two broad categories, namely, rules bridge rules and non-bridge. Among them, the rules of bridge beam is the largest single span is less than or equal to 90 m, and Pier height is less than or equal to 30 m bridge, bridge seismic rules must in strict accordance with the rules in addition to all the other bridges, including do not satisfy the conditions of beam bridges, arch bridges, cable-stayed bridges, hanging bridges and other bridges are nonrules, rules only irregular bridge seismic design principles are given, including seismic concept design provisions.

5.2.2 Bridge Anti-Seismic Principles While bridge because of its span, scantlings and based in a different form, exhibit different seismic response, however, the same type of bridge exist in dynamic characteristics and seismic response of some rules to understand these rules and characteristics, it helps in conceptual design by doing some basic judgement. In addition, knowledge of bridge seismic design principle, during the conceptual design phase is also very important.

1. The Beam Bridge Bridges can be divided into irregular bridges and bridge rules, but no matter what kind of dynamic characteristics and seismic response of bridges are familiar with the. Seismic design concerned may be refer to the rules for the seismic design of highway bridges, among them, the most important thing is should try to use a symmetrical structure, connections between superstructure and substructure construction be as symmetrical as possible.

2. Arch Bridge Arch bridge is a compression arch rib of component—as a major component of the bridge, and so determine the span cannot be very large, structure stiffness is very small. Structure dynamic characteristics and seismic responses in the light of the rules for the seismic design of highway bridges are analysed. The most important anti-seismic design principles are important: built in areas of seismic fortification intensity 8 or 9 degrees of long-span arch bridge, the torsional strength of main arch ring should be used good stiffness, the overall cross-section; when using reinforced concrete arch, and must strengthen horizontal links in the lower deck and arch wind support should be set, and the beam rigidity should be strengthened.

3. Cable-stayed Bridge Frequency and vibration mode characteristics of cable-stayed bridge and its rigidity and quality-related, such as closed-box girder with vertical deflection frequency of open crosssection height. The others under the same conditions, of harp-type cable arrangement of vertical deflection frequency will be lower for radial arrangement. Large span cable-stayed bridge is a long-period structure, its first mode—floating vertical vibration on seismic response of main tower along the bridge to the tribute offering an absolute advantage. Floating structural system of cable-stayed bridge in the largest contribution to the transverse seismic response of the tower is the main tower vibration modes (transverse vibrations of transverse vibration of symmetric and anti-symmetric). From the seismic requirements, wish to structure flexible. Vibration of flexible structures because long seismic response of a smaller, but the displacement reactions great and should be attract attention. Built on the seismic fortification intensity 8 or 9 degrees of cable-stayed bridge should be a priority in the area of floating system; floating system resulted in large beam the nodal displacements, we should use the tower, elastic or damping constraint system.

4. Suspension Bridge Due to the suspension, bridge is a flexible structure, with floating structural system of cable-stayed bridge as the basic cycle is very long and is thus subject to earthquake load control can be small. However, the vertical earthquake component on stiffening girder, effects of bending moment of beam main tower, tower, the effects of axial force of piles shall be pay attention to. Relative displacements between the girders and beams is another characteristic of flexible structures. Ensure the role of expansion joints, located reset the block, damping bearing, are better measures for reducing relative displacement, to prevent falling beams. Main load-bearing structure, the towers should be choices helps to improve the structure and volume of ductile deformation capacity and avoid the occurrence of brittle failure.

5.2.3 Anti-seismic Design Success Stories In areas of high seismic intensity and seismic response factors that tend to control the

design of the structure, so, in concept design, the overall vision of the structure, structural system, forms the basis of planning must take into account its seismic behaviour and seismic system, easy access to good structural performance; on the contrary, is not conducive to seismic system, in order to meet the seismic loading carrying capacity, sometimes takes a huge price. Therefore, the conceptual design is of course due to the earthquake on seismic performance of structures needed innovation plays an important role in the concept.

1. Select the Seismic Favourable Structural System Most of the mass is concentrated in the upper part of the structure of the bridge, and seismic inertial forces are also concentrated in the upper structure. The upper structure of seismic inertial force through connections between superstructure and substructure construction (support) to the pier, and then passed by the pier to the base foundation. For example, three-span continuous girder bridge with large span, under normal circumstances, a pier supporting system, able to cope with temperature degree, required for normal use such as vehicle loading and deformation, however, seismic response, massive beams of the seismic data stress transfer to the pier and foundation of a pier appears unreasonable and uneconomical in bear, from conceptual design ideas would like to have such a system: normal use is a pier supporting system for when the earthquake struck, four piers shared beams seismic reaction forces. This similar concept of problems will require design-time to think and find a solution. Example 5.1 Greece Rion-Antirion Bridge: “reinforced earth base isolation.” Design: vertical and transverse floating cable-stayed bridge system. The bridge (Fig. 5.16) connecting Greece Mainland and Peloponnese peninsula, between the Gulf of Corinth. Bridge is located in bedrock depth ultra 500 m, 2000 year return period earthquake with maximum peak acceleration of 1. 2 g, and the peninsula of 8~11 mm, the rate float away land and seismic safety is the most important controlling factors.

Fig. 5.16 Rion-antirion Bridge (size: m). In order to avoid displacement of great earthquakes and Taki, selects five of the bridge span continuous floating structural system of cable-stayed bridges, superstructures for girder bridge, between the pier and beam transverse directions how to connect? If you like float system cable-stayed bridge, between the transverse taliang replaced by wind-resistant connection, Tower’s Foundation during the earthquake forced to fail. If this connection is released, main beams and the top horizontal displacement, cable tower base forces were too large. Finally, the taliang transverse direction is set between five additional mechanical device when an earthquake occurs allowing the middle insurance limit device in a certain damage under earthquake loads, and the remaining four dampers will be play the role of damping to protect the bridge tower security and main beam lateral seismic displacement

constraint. Usually, side-wind effects, insurance limit device to ensure that horizontal and pylon of the bridge-solid will be connected together (similar to the wind resistant bearings), guarantee that no master Liang Hengqiao rock. Beam installed adaptive main beam vertical limit of displacement, lateral damping devices installation schematic in Fig. 5.17. Example 5.2 Main channel bridge of Su Tong bridge. Design: integrated static, wind and seismic analysis results, eventually adopted dampers (wind time) connection. Su Tong bridge on the damping limit restriction system, a hydraulic buffer (power locked) limiting constraint system and the elastic system static and seismic response analysis of results, and compare responses of floating system, as shown in Table 5.13 below. Table of seismic response of two number values are: North beam (Tower)/ Liang Dynasty (Tower). Can be obtained from Table 5.13 to the following conclusions: longitudinal seismic damping constrained systems reaction is slightly larger than the lock binding system, much less than the float system, floating system of 40%; in the system of four structural damping constraint system of longitudinal shear force and bending moment at the end of minimum locking restraint system the largest damping constrained system of vertical bottom shear is a floating system of 86%, locking constraint 68%; damping constrained system of longitudinal tadi moments is a floating system of 76%, lock 66% restraint system (average of the North and South towers).

Fig. 5.17 Tower-beam cross-linked and attach the beam layout. Table 5.13 Comprehensive comparison of three kind of restraint system and float system. Constraint name

Damp limit constraints

A tower connection restraint C =15 000 =0. system parameters 4 ±750 mm limited

Lock limiting constraint

Flexible constraint

Dynamic locking 750 mm limited

Elastic stiffness 50 MN/m

Floating structural system —

Horizontal 0.285/0.272 displacement of beam (m)

0.190/0.170

0.483/0.470 0.690/0.673

The top horizontal

0.237/0.227

0.637/0.625 0.820/0.818

0.371/0.368

displacement (m) Earthquake Tugend shear reaction (MN)

31.7/34.3

46.9/50.4

35.6/39.6

36.8/39.6

Tugend bending 2280/1.740 moment (MN·m)

3160/2950

2740/2500 2790/2490

Device trip (m)

0.293/0.271

0

0.421/0.439 0.683/0.673

Device binding (MN)

12.1/11.6

64.2/76.2

21.0/22.0

—

Note: C is the damping co-efficient, measured in kN/(m/s)0.4, α index for speed. Synthesis comparison of seismic response analysis results mentioned above, longitudinal talianglian with rigid limiters with rated travel and power device for damping composite systems.

2. Improving the Load-bearing Structure Seismic Performance As the main load-bearing structure of the tower, piers and arches can be designed with ductile deformation capacity of structures, resulting in earthquake energy dissipation through component under, such as sacrifice part of its detailed structure, achieve the goal of avoiding brittle failure. Example 5.3. United States San Francisco new Bay Bridge. Design idea: The seismic ductility design of Tower column. San Francisco Bay Bridge East of the original bridge damaged in the 1989, earthquake in Montenegro, the Municipal Government decided to build a tower to meet seismic requirements of the new bridge. “Self-anchored suspension bridge” system with a main span of 385 m, tower height 180 m. Current concepts general prevailing notion that, at such a high intensity earthquake area, bridge-tower should be. In this way, the beams of the tower under earthquake to earthquake energy consumed can form a plastic hinge, making vertical pylon remains elastic. During the preliminary design, the gantry tower and a single tower with different types of studies were carried out (Fig. 4.24). According to the calculation a single tower can meet current seismic design requirements, but the towers is not a statically indeterminate structure, once the plastic deformation will be lead to destruction, so that this type is not appropriate. However, despite these concerns, still the appearance of single tower therefore, studying how gantry tower looks more like a single tower. Move closer to the two towers, beam will be cut short, beam cut short, it not in bending yield but caved in under the cut. We asked ourselves, why not make it just under the shear yield? Such as make it just under the shear yield? If it doesn’t look like the usual tower bends bend, but the shear yield the tower look like a single tower structure

Fig. 5.18 Tower anti-seismic conceptual. Thus, an innovative single-tower scheme surfaced, as shown in Fig. 5.19. Results indicate that this structure under earthquake action loaded with good performance, as shown in Fig. 4.26. In fact it is more excellent than conventional gantry tower, because now we can as needed in the two tower set between different positions more shear, thereby significantly increasing the frequency of bridge tower of statically indeterminate.

Fig. 5.19 Towers-shear keys.

3. The Design Earthquake Benefit of Bridge Foundation First is passed from the base to the entire structure of the earthquake, so, for high intensity area, designed in line with geological conditions meets the water conditions, in line with the upper structure needs, in line with the basis for the construction equipment is not enough, it must also be based isolation capacity, keep a good shock, shock absorbing the first hurdle. Different forms, exhibit different reactions, how to enable the foundation to seismic responses of weakened or separated, sometimes addressing earthquake issues would be more effective in the superstructure, economy is more obvious. Example 5.4 Greece Rion-Antirion Bridge: “reinforced earth base isolation”. Design: Reinforced earth, base isolation. In order to avoid strong earthquake forces, Greece Rion-Antirion selection five-span

continuous bridge full of floating structural system of cable-stayed bridge and high 65 m, Pier and base diameter upto 90 m at the end of circular bridge piers in f 2 m diameter, depth 25~30 m steel pipe piles with solid and topped with 3 m thick mat composed of sand, gravel and crushed stone layer, formed relative sliding of “reinforced earth base isolation” (reinforced soil Foundation), which is the Foundation of an innovative form, which is based on isolation as shown in Fig. 5.20.

Fig. 5.20 Greece Rion-Antirion Bridge: “reinforced earth base isolation”.

5.2.4 Common Seismic Mitigation and Isolation Measures On the whole, considering the conceptual design of seismic resistance requirements and performance, in relation to meet seismic requirements must be have better performance, but, in many cases, the security situation and structural characteristics of, you also need to consider some of the needle anti-seismic measures relating to seismic response to some general or localised weaknesses, improve the conceptual design. Should be presented in conceptual design targeted measures and programmes.

1. Dampers, Locking Device and Buffer Structure or additional damping ductility of earthquake energy consumed, in order to reduce the loss of the main structure of the bridge. This form of shock-absorbing technology ever used in Su-Tong Yangtze River Bridge, in Greece the Rion-Antirion bridge has a similar device. Damping device of many types, from the relation of the output damping force and displacement curves are generally divided into viscous damping, friction resistance nepal, elasto-plastic damper and visco-elastic damping four, here’s more application of viscous damping devices in recent years. Figure 5.21 shows the United States Taylor produced the viscous damping device schematic.

Fig. 5.21 Viscous damping devices.

1—piston rod; 2—cylinder; 3 and 4—compressible silicone oil; 5—accumulator tank; 6— seal rings; 7—polyvinyl resins; 8—room A; 9—damping hole live plugs and 10—room B; 11—control valve. The output equation for viscous damping devices: In the formula: F = damping force; C = damping coefficient; α = speed index: for the bridge project, α 0.4~0.5 for low intensity earthquake area, α-2; to resist the wind-induced vibration of bridges, α 0.5~1. Ideally this damping devices damping ratios range from 10% ~45%, damp from the 0.5~80 MN, the journey from 25~1500 mm. Locking device is a special damping devices, its locking force and velocity equations with damping devices similar to the device lock rated locking force is defined as the output of the transmission speed, and its value is less than the structure due to earthquakes, caused by wind-induced vibration velocity, speed is greater than the thermal displacement induced by locking speed mm/sec magnitude. To lock the device in Fig. 5.22 comparison of damping and damping device output force-response curve, abscissa speed (in/s), ordinate for the output damping force (×103lb) and locking device locks the output equation: F = 40 × 106v, when v = 0.005 in/s, rated locking force, damping force equation is: F = 45730 × v0.4, v = 40 in/s, rated damping force as can be seen in the similarities between. (Note: 1 in = 25.4 mm,1 lb = 4.448 2 N). Here when the two constraints of the single particle vibration displacement curve description locking devices from conceptual difference and damper, Fig. 5.23 for the damping ratio is 32.6% single particle vibration displacement time history curve, Fig. 5.24 for the single particle under the effect of damping, lock set the pace for 30 mm/s of displacement time history curve. It can be seen that locking device for structure acts as a quick stop role of dampers for structural movements play a role in energy consumption and vibration attenuation.

Fig. 5.22 Dampers and locking device output response curves in.

Fig. 5.23 Single mass-damping vibration displacement time history curve.

2. A Variety of Seismic Isolation Bearings (a) Laminated Rubber Bearing Laminated rubber bearing by alternating with thin steel plate and sheet rubber, and binding steel plate on lateral deformation of the rubber sheet, increased vertical stiffness of rubber, because of a hierarchical set of reasons, deformation of laminated rubber bearing level can greatly increase added system flexibility, improve cycle, but its rubber materials for special preparation, increase material viscosity, which absorbed energy and achieve the aim of cushioning. In the 1980s~90s, in the construction of small-span continuous beam bridge, laminated rubber bearings were widely used commonly, but with the increase of age, aging of the rubber bearings in the natural environment of restriction of its bridge applications.

(b) Lead Rubber Bearing Around the middle or center of rubber bearings vertically into the purity of 99.9% lead-on the formation of lead rubber bearing (Fig. 5.25). Support poured into the lead rods can be improve the bearing at the center of the early stiffness, to control the wind and against the foundation’s micro-vibrations favour. The other hand, due to the lower yield strength of lead rods and elastic-plastic deformation conditions with good fatigue resistance the performance, which has a strong energy dissipation capacity. Although lead-bearing combines the characteristics of laminated rubber bearing with lead damper, seismic excitation has a lower level of stiffness and damping characteristics of the larger, but quite a number of applications showed that low frequency characteristics small amplitude excitation may be cause the amplification of the seismic response of lead-bearing system. Bridges with more flexible piers, its isolation effect is not very good.

Fig. 5.24 Single-particle damping lock displacement time graph.

Fig. 5.25 Lead-rubber bearing. In China there are already using lead rubber bearing isolation buildings and bridges. But in the LRB’s works application, the current design of indicators and parameters are reference architecture specification, while the actual application of bridge engineering environment structural harsh lead rubber bearing in bridge structure are often in a very hostile environment, such as high temperature, low temperature, large temperature changes, poor atmospheric corrosion, erosion and the long-term repeated creep deformation, shock and vibration, and so on. Because of this, their poor fatigue and limited carrying capacity, durability is insufficient to meet today’s bridge of long-span and heavy loads and long life requirement.

(c) Steel Energy Dissipation System Steel consuming bearing consists of a series of circular arrangement of the C-shaped (or E-shaped) steel units of energy (Fig. 5.26). Transverse force under the action, through C(or-E) deflection of steel itself to provide movement and damping. Its design should be pay attention to all section face in the same direction of movement stress, was able to achieve a good effect energy consumption, design and processing is very difficult. Also, this class bearing belongs to the material energy system, it shall ensure that energyconsuming materials in elastic and plastic deformation zone has a good set of fatigue, which has high elongation and low hardenability and that is connected with the energy unit, and supports key components (such as PIN) is better with higher strength and fatigue resistance.

Fig. 5.26 Energy of C-shaped steel supports connection (size unit: mm).

(d) Black Elastic Sliding Bearing Elastic sliding bearings consist of a group of overlapping and slide against each other by placing perforated PTFE sheet rubber, and a Supporting Articulated material central core, a number of satellite rubber core. This friction slider isolator is a rubber core provides a

link to the equilibrium position of the restoring force, while controlling oversized on the displacement and friction between layers of rubber and PTFE sheet Chrome plated steel spherical to burn off energy. Adjustment between PTFE the co-efficient of friction the diameter of the central rubber nucleus can be achieve good isolation properties. But this isolation bearing structure is more complex, because of its reasons for using rubber, there are aging, poor durability.

Fig. 5.27 Friction pendulum bearings.

(e) Friction Pendulum Bearings Friction pendulum bearing (Fig. 5.27) works like a pendulum: middle-tier sliding block formed by pressure resistance of high-strength materials, the sliding surface of the slider below when seismic displacement structure, due to the gravity of the superstructure and circular-arc the bottom sliding surface design, can be always point to the equilibrium position of the reply force, but throughout the course of the earthquake by friction between the slider and sliding surfaces dissipation of energy. On the other hand, due to the rotation of the slider on the surface and cover closed contact upper structure always remains horizontal. This support meaning is clear and concise design, simplicity, durability and with self-recovery capability, in the United States, and Canada and other countries of the bridges and isolation to the epicenter has been widely applied and achieved good economic efficiency lean and very good damping effect.

(f) Structure and Work Principle of Double Spherical Aseismic Bearing Mainly consists of double spherical aseismic bearing seat plate, plate, bottom plate, spherical stainless steel spherical under skateboarding, stainless steel PTFE under PTFE on skateboards, skateboarding, skateboards, shear pins, secure the screws and sealing device consists of several parts, of which four fluorine PTFE under skateboards and skateboards using fragmented mosaic of filled PTFE composite laminated skateboards. Bearing structure as shown in Fig. 5.28.

Fig. 5.28 Sketch of structure of double spherical aseismic bearing under 1—seat board; 2 —guide plate; 3—shear pin 4—security screw; 5—seat plate; 6—dust seal unit 7—sphere stainless steel skate board; 8—PTFE skateboards; 9—seat board.

Double spherical aseismic bearing is based on general ball-bearings developed, through the use of large-diameter spherical friction takes a common ball-type bearing flat friction pair, and limit restraints designed F (x) (Shear) a new bearing. The bearing using a pendulum KP mechanism to extend the natural vibration period of bridge can be provided through the deck weight reset capabilities needed to help x (Relative displacement) bridge superstructure to its original position. Of double spherical aseismic bearing isolation works: when an earthquake occurs and horizontal lateral force exceeds a predetermined value, limited the shear pins and safety device cutting off screws, bearing the transverse limit restriction was lifted, large-diameter spherical transverse of friction slide freely through friction gradually consumes energy. Thus, prolong the earthquake cycle, achieve the effect of damping and earthquake; after the earthquake, structural weight and re-silience can be formed so that bearing reset. Bearings hysteresis curve is shown in Fig. 5.29.

Fig. 5.29 Sketch of structure of double spherical aseismic bearing.

5.3 BRIDGE WIND-RESISTANT DESIGN PHILOSOPHY Due to cruise ship-bridge collision accidents often occur of bridges and caused great damage to life and property and, therefore, from the bridge beam concept design phase begins to take control of ship collision design has gradually developed a consensus among members, and engineers in the span of the bridge layout stage of economic comparison of navigation requirements and span selection problem in a new light. In order to carry out the protection of ship collision design idea, the first, you must have fortification standard and design principles of the protection of ship collision, it will be told in the first part of the fortification level and design principles. Conceptual design on the ship collision-resistant function of structures considering the ship collision prevention concept and the fortification level, bridge and bridge axis selection examination considering the factors of ship collision, conceptual design to structural considerations, conceptual design of ship collision-resistant function of ship collision-proof measures of four bars contents. Conceptual design for structure of ship collision prevention performance considerations, conceptual design work is an important group in multiple areas of expertise assembly.

5.3.1 Fortification Standard and Design Principles Ship or Driftwood collided with the bridge structure is very complicated, when environmental factors (waves, climate, waters and so on), ships characteristics (type of ship, vessel size, speed, loading, and the bow, the strength of the hull and deck and the newly and so on), bridges (bridge component sizes, shapes, materials, quality and resistance characteristics) and the driver’s reaction time factors is very big, therefore, accurate determination of ship or Driftwood-bridge interaction is very difficult. According to the characteristics of the navigable waterway and traffic characteristics of a ship, that need to be taken into account of ship-bridge interaction inland waterway and prevailing sea river divided into two broad categories. On behalf of the former mainly for river cargo barges, one to seven levels inland waterway tonnage, respectively, corresponding to the 3000t, 2000t, 1000t and 500t and 300t, 100t, 50t. Prevailing sea channel with seagoing vessels as representing ones. Collision with the bridge structure of the two mechanisms differ results are also quite different.

1. Ship-colliding Fortification Level Bridges should be used according to their function is divided into A, B, C three ship class. Among them, the class a refers to the Bay, Grade on the approaches to the bridge; Category B refers to the II~IV on the approaches to the bridge; Category C refers to the V on the approaches to the bridge. General Bridges shall be determined according to Table 5.14 ship security performance objectives. Table 5-14 Bridge vessle bumping performance requirements.

Fortification Fortification Performance class level objectives

Bridge state

Consequence of failure

L1

I

Bridge can produce mechanical Slight properties do not affect the structural integrity of local damage, normal traffic will not be affected the whole structure in the elastic state minor

L2

II

Can be easily repaired injury medium

L1

I

Bridge can produce mechanical Slight properties do not affect the structural integrity of local damage, normal traffic will not be affected the whole structure in the elastic state minor

L2

II

May have a more serious injury, Serious but not serious collapse

L1

I

Injury medium may occur but can be easily repaired

L2

II

May have a more serious injury, Serious but not serious collapse

A

B

C

Moderate

Moderate

Note: The ship hits the fortification level L1 is a 100-year return period, L2 1000 return periods.

2. Prevention of Ship Collision Design Principles Combining bridge vessle bumping fortification level and performance goals, according to the navigable levels and tons of ships, must be adhere to the following three control ship collision design principles. First is avoidance or isolated concept, bridge or conditional increase of particular importance for long-span bridge (added span economy were better than the increased span and setting the anti-collision facilities), or ship’s tonnage is greater than 50000 DWT fairways, avoiding or isolation of the pier and the ship concept; the second is the collision idea, not increased-span bridges (increasing the span of economic deterioration in does not increase the span setting the anti-collision facilities), or tonnage of the vessel is greater than 3000 DWT, less than 50000 DWT fairway collision energy dissipation measures and pier-resistant combination of ideas; the third is: resistant concept, for long-span bridge, or tonnage of the vessel is less than 3000 DWT waterway, crashworthiness and anti-collision measures as a supplement to Pier’s philosophy. Figure 5.30 is analysis on anti-collision concept conceptual design schematic diagram, x-axis is abscissa navigable spans of the bridge, y-axis is investment tendered for the bridge construction, curve j bridges (excluding requirements of ship collision prevention

facilities and substructure of ship collision force) construction investment and long-span relation, curve i is included in ship collision proof requirements for facilities and infrastructure effect of ship collision with bridge investment. It can be seen that for most of the big long-span bridges, AB intervals span substructure design included influence of ship collision force and rarely hardly increased lower investments, also may be subject to large ships impact the pier, according to pier’s own ability to withstand impact, the location and appearance of the pier, flow rate, water level and speed of navigation collision of ship types, and factors for bridge crash (energy) infrastructure design. Therefore, the collision idea, its structural safety, crash risk and Economics is acceptable

Fig. 5.30 Analysis on anti-collision concept conceptual design schematic. For large-span bridge, interval greater than b in the figure, due to the high class of waterway, ship impact force and design of bridge substructure ship collision force controlled ship combination may be much greater than other load combinations, and will be lead to the bridge construction investment has increased substantially. This needs to count collision effects in a relatively small span with increased span, avoid collision or substantially reduce the risk of collision scenarios economic comparison chart, invest the same points C and D, but the span increased a lot. Same points C and E span, by taking into ship collision force and facilities against dash, investments increased significantly. In the context of DE, we can access increase the span of avoiding ship collision or drop optimal scheme of low ship collision risk. Due to bridge technical restrictions (limitation span of cable-stayed and suspension bridge, deep foundations, etc.), cannot be obtained by increasing the span economy better programmes, only a substantial increase in collision avoidance measures (such as independent impact structure separate from the bridge collision hit protective structures, Pier regardless of ship impact force), or piers considering the huge ship change the force of the impact Foundation, increased base quantities, then in case of ship collision with energy dissipation devices and other measures. These two programmes will be eventually lead to a substantial increase in total investments. For the average span bridges when the span is smaller (less than 100 m), horizontal impact force resistance of the structure itself is bad, need to increase the amount of bottom structure and foundation engineering to satisfy the anti-ship force requirements, which will be lead to increasing bridge investment, as shown in Fig. F point and the G spot, the same span structures considering greater investment in shipping after the force of the

impact. Therefore, increasing general bridges (such as non-navigable spans of the bridge beam) span, increasing the impact resistance of the structure itself, can achieve good economic efficiency, and reduce the risk of ship collision accidents.

5.3.2 Rational Selection of Bridge Site and Bridge Axis Axis of the bridge and the bridge site should be selected taking into account navigational safety, and meet the following requirements: 1. Bridge upstream and downstream waterways and ports development and planning, as well as utilisation of the shoreline. 2. The bridge should be selected in channel straight River, deep grooves and the riverbed or seabed stability, water depth and flow condition on the good leg, bridge water bed (seabed) scour and modest. 3. Bridge should avoid the bends, branch road, Rapids, segregation and concentration port anchorage, port operation area, such as, the distance should be able to guarantee safe navigation of ships. 4. The bridge axis should be perpendicular to the current trend and orthogonal design routes if possible, water flow and bridge axis normal angle should not exceed 5°. In fact, route straight bridge is the case, or drifters crashing head-on with the bridge of the ship will be very small, more oblique collision of bridge piers and abutments. Oblique impact angle of less than 45°. When the skew bridge and waterway, the regular to oblique impact of piers and abutments are possible. Moreover, when the axis of the bridge have a greater angle between the normal and mainstream, will produce to impede the safety of navigation of bad water. As the flow angle and bridge axis normal to not meet the requirements, you should consider increasing across the span of the bridge to ensure the safe navigation of the ship.

5.3.3 Anti-ship Collision Design Success Stories Bridge conceptual design of ship collision-resistant function of bridge structure considering, in structure, consider the ship collision and economic basis on this, the type of the macro issues such as piers, span arrangement, the water research, conceptual design ideas, to ensure the knot construction safety, marine safety, and economic goals. To this end, the following gives some anti-ship collision design success at home and abroad cases, including fully meet the requirements for navigation, select the appropriate type of bridge piers and span arrangement, set up in the water sample, for reference.

1. Fully Satisfy the Navigation Requirements From maritime safety and ship protection impact perspective, bigger the better bridge span, bridge away from the ship, but here it may be to increase long-span bridge and waterway isolation and meet the channel setting collision under the conditions of facilities both economic analysis and comparison.

In general, appropriate to increase the span to make the piers on shore or away from the Sham Shui Po District are a more economical option, which is the concept of avoidance. In contrast, to make the piers out of the water and multiplied spans is not desirable. When there are no conditions across the river, for high level route, ship impact force is huge, bridge structures and separation of ship method is also commonly used and available, which is the concept of isolation. Isolation concept common measures through the artificial islands and independent impact structure to stop the ship from the force of the impact to the bridge structure. Example 5.5 Denmark Sea Bridge. Design: Select the bridge span by shipping studies, on the channel axis alignment adjustment, the structure of the selected ship can withstand impact anchorages and piers used artificial islands protected, establishing vessel traffic management system. The bridge a total length of 6.8 km, across the sea strait between Zealand and sibolaogendao to the East. During the initial design phase, had considered the channel span down to 780 m, which according to the results of study of ship collision, and the bridge program and comprehensive study on span, coupled with adjustments to channel axis alignment finally chosen as the main span 1624 m. This alignment adjustment the sailing angle relative to the axis of the bridge changed from 68° to 78°, so that the axis of the bridge on both sides of the fairway bending distance of 2300 m. Fairway center line vertical clearance of 65 m width of the channel is 750 m, all structures that are struck by ships in accordance with established collision avoidance model designed to withstand the impact of the selected ship, ship chosen by 2000 DWT 250000 DWT, which collided with a pier of the maximum impact force of 673 MN. Anchorage and some foundations are made of artificial islands protection, and establishing vessel traffic management system. Example 5.6. France Normandy bridge. Design idea: The South Tower Pier was built on the land and, after pier at about 25 m, the north side of the pier was built in the North of the low embankment outside set and bull island. Normandy bridge is used to create a world record of 856 m long-span cable-stayed bridge, in 1995, opened to traffic, the bridge with four lane, across the river Seine in the Bay area, the navigation clearance of 50 m, the original design of the bridge span as a 510 m, the north side of the pier close to the fairway, and there are four piers in the river. In the early 1980, reports about ship collisions and related damage of many bridges, Influenced the decision of adopting from the left bank of the river to the end of the North breakwater of the pier are not required in programmes across the Nar, R., thus separating the north side of the river and the marshes, on the South Tower Pier was built-in the land, at the dock behind 25 m office, which would not have been in actual navigable ship collision, the north side of the pier was built-in the North of the low embankment outside nearby, this keeps the span without adding too much. However, the pier was built at this location will be the basis of deadweight tonnage upto 130000 DWT ship slammed, so they decided on this basis built around a special type of protection structure. The bridge’s main span spans end up 856 m than in the design of cable-stayed bridge, whether it’s design or span

is a great leap forward (Fig. 5.31). Example 5.7. United States Houston ship channel bridge. Fulaiteha took off across the Houston ship channel Pullman (Fred Hartman) cablestayed bridge is a pair of steel-concrete composite deck, frame as shown in Fig. 384.6 m, 5.32. Navigation vessels can be upto 228 m (according to the statistics made by general cargo ship, over 65,000 DWT). Double diamond side pylon arrangement on a man-made island in the middle, to prevent the collision of ships on the other tower Pier Set on the East Coast.

Fig. 5.31 France Normandy bridge.

Fig. 5.32 United States Houston ship channel bridge.

2. Select the Appropriate Type of Bridge and Span Arrangement Bridge type selection, according to water depth and predictable water level change, fully meet the channel width and headroom requirements avoid embezzlement waterway, especially when selecting a deck and deck-type arch bridge, should pay special attention to the ring of ship impact risk. If needed, may be appropriate to enlarge span, near the arch ring of arch away from the waterway clearance. Example 5.8. Sweden old Tjörn Bridge. Sweden old Tjörn Bridge (Rong Qiao) across 278 m filled steel tubular rib arch bridge,

in January 1981, the thousands of tons of the Netherlands Freighter collision steel pipe Arch of bridge base, resulting in steel tubular arch collapsed, collapse of the superstructure in the sunken ship, killing more than 10 people, Fig. 5.33 new bridge design drawings, Fig. 5.34 for ship collision accident photos, Fig. 5.35 for the new cable-stayed bridge.

Fig. 5.33 Sweden new Tjӧrn Bridge design drawings (size: m).

Fig. 5.34 Ship collision accident.

Fig. 5.35 A new cable-stayed bridge. In most cases, due to the width of the water causes (such as Suzhou-Nantong Yangtze river bridge the river width upto 8 km), the bridge cannot be implement a design of crossing the river, and hydrology of river conditions, such as water depth, scour, elusive

DUN ship quarantined (artificial island or independent impact structure) programme, pier must be able to resist the ship collision with power, and the use of ship collision with energy dissipation devices, to protect bridges and ships, reducing the role of ship impact force. Due to the bridge span and resistance to impact, waterways and ships there is some inherent relationship between impact force and channel high level of ship impact force and large-span bridges, pier and tower structure, and strong horizontal impact performance, and vice-versa. This collision idea has economic rationality. Of course, it should be removed from the two special cases: one is the huge ship, bridges difficult or costly to bear; the other is due to various reasons the owner cannot accept any ship collision risk, to be adopted take DUN ship quarantined. Example 5.9. Ship collision prevention design of Su Tong bridge. Su Tong bridge design-time consideration of ship impact force as shown in Table 5.15, and energy dissipation were specially designed protective devices. Table 5.15 The ship collision design with bridge piers foundation Bridge pier

Direction

Transverse Main bridge main pylon pier

DesignTypical collision condition resistant force (MN) 130 50,000 ton 4m/s being hit, 2m/s side crash

Along the bridge to

65

Transverse

40.6

5,000 ton 3.5m/s is hit, a 10,000 ton 2.5m/s head on crash

Along the bridge to

20.3

5,000 ton 2 m/s front hit

Transverse direction

14.5

5,000 ton 1.5 m/s front hit

Transverse direction

14.8

5,000 ton 1.5 m/s front hit

Transverse direction

14.5

5,000 ton 1.5 m/s front hit

Transverse direction

14.8

5,000 ton 1.5 m/s front hit

Transverse

60

50,000 ton 4 m/s front hit, 1 m/s side crash

55

50,000 ton 4.1 m/s front hit, 5 m/s side crash

Near of main auxiliary piers

Near of main auxiliary piers

The main bridge abutment

Main piers of auxiliary bridge of continuous rigid-frame Along the bridge bridge to

50,000 ton 1.5m/s is hit, 1m/s side crash

navigation Crashworthy Structure Features: 1. The anti-collision facilities main function is, when designing a ship collision, to facilities damage amount of dissipation; avoid ship protrusive parts direct impact drilling pile and pier, tower structures reduce the damage length. 2. When serious collision occur, the anti-collision facilities through its own kinetic energy of deformation and failure to fully absorb the shipping to reduce pier the force of the collision, when relatively minor collision, the anti-collision facilities of sufficient strength and resistance to deformation, use of facilities around the baffle box energy absorber to protect the overall integrity of the structure of facilities subject, while reducing the impact the ship’s damage. 3. Under normal conditions, the anti-collision facilities with full-floating ability, flexible, easy to use water ballast makes the anti-collision facilities keep good floatation; after being damaged due to collision, and can limit the extent of damage to certain areas within the buoyancy of the anticollision facilities remains must be and the necessary buoyancy without sinking, easy fix. The anti-collision facilities primarily: facilities dimension is based on the actual possibility of impact conditions, calculate the length of the damaged facilities, determine the facility should have a width. Vulnerable to collisions between facilities on the side width: 12 m, determined by the 50,000t 4 m/s was hit. Facilities side and rear width: 6 m, determined by the 50,000t 3 m/s was hit. 50,000t ship’s draught depth 12.5 m, the first vertex distance balls contains watermark, 7 m, in order to avoid the anti-collision facilities was lifted by ball, facility draft is 8.2 m. Freeboard is 4.3 m making facilities have plenty of buoyancy reserve, the anti-collision facilities were first ships pressed into the surface of the ball, while facilities damaged cases have a reserve of buoyancy.

3. Reasonable in Setting Water Pier Both navigable and non-navigable water pier, it is necessary from the point of structure to increase impact resisting ability of piers and reduce ship collision risk. Especially the nonnavigable spans of the bridge pier, generally not considered or taken into account in the design of a small ship in the event of ship collision accidents, often a severe loss of life and property.

(a) To Minimise in-water Pier Number In-water pier in particular DUN usually spans a smaller non-navigable waters, Pier’s performance against horizontal force is low, it is sometimes necessary to and increase the number of piles and cross connect two pieces of bridge sub-structure as a whole, against ship collision, and this design in addition to ship against the wind insurance, a structural design itself was also uneconomical. Therefore, appropriate more navigable and nonnavigable spans of the bridge span and river hong, navigation, road safety, but also increase the crashworthiness of the pier.

(b) Under-water Pier Should be Placed in the Shallow Water as Permitted According to the marine casualty investigation and analysis, impact the number of incidents of non-navigable spans of about of main navigation span for impact twice as long. Therefore, should be come via navigable bridge reasonable cross, to set the nonnavigable spans of the bridge piers in the water as much as possible in the shallow water, but to avoid a large number of the anti-collision facilities of non-navigable spans of the bridge. If the depth of non-navigable spans of bridges still can meet the general small cargo ships sailing, its role in pier design must be taken into account when the ship crashed into. When necessary, to take ship collision prevention measures such as the floating block units.

(c) Piers Constructed in the Water should have a Certain Degree of Redundancy In water pier constructed forms have a certain degree of redundancy, avoid rapidly collapses on impact. As a tri-pillar box after the pier a pier was hit, the remaining two piers still constitute a vertical load-bearing system, avoiding the full-bridge collapse. When you must be in single-column bridge piers, should properly enlarge pier crosssection dimension and strengthen its impact resistance.

(d) In-water Pier can Withstand Ship Impact Force If the piers in waters without independent facilities against dash, ship collision load must be considered in the design of piers, ship collision specification or identified through the case studies. Even taking into account a certain amount of protective measures, such as adhesion-type energy dissipator, box device which, although these facilities can be part of the energy consumed, but also residual impact energy is absorbed by the pier and foundation, and the facilities to carry energy of varying ability and generally not high, so the pier and foundation must be considered in the design of ship impact force. Example 5.10. Completion of Canada Federal bridge across the Northumberland Strait. Design: Pier can afford to ship impact force, compulsory pilotage. Confederation Bridge, 13 km, lies between Prince Edward Island and xinbulusiweike, was opened in 1997. The bridge is double lane road bridge, the main bridge by 43 spans, each 250 m, piers for pre-cast concrete pier, central part of the main bridge with a through navigation, clear width of not less than 200 m, the clear height of not less than 49 m. Specified in the initial performance requirements for engineering: both sides of the channel close to the main pier and the pier artificial island facilities against dash should be used to protect other neutral line on each side of the 500 m range piers island or piling the anti-collision facilities should be used to protect it. The final design of the bridge did not use artificial islands, or pile in your anti-virus facilities, but the design show: channel side of the bridge must be able to withstand 37000 DWT ship within 4.2 m/s speed bump strike force (37000 DWT ship impact force by United States Code, equivalent to 100 MN); two adjacent piers with must be able to withstand a mean high 50 MN shock; all other piers can withstand 8 MN shock.

5.3.4 A Variety of Ship Collision Prevention Measures Bridge design engineer in addition to the bridge structure is designed to have a certain amount of resistance to shock loading of ships outside, you should also consider the buffer device and protection system, change the direction of ship impact load or reduce shock loading of the pier, its destruction to minimise the extent and also reduce the loss of ships and the destruction of the anti-collision facilities, namely, anti-collision design referred to in the “three is not bad” principles. In accordance with the anti-collision facilities and bridge relationships, passive collision avoidance system is divided into independent collision avoidance systems, integrated impact cafe attached collision avoidance systems in three categories. In addition, in accordance with the anti-collision facilities structure can be divided into floating protective systems, gravity system, posts protection system, shield protection system.

1. The Floating Protective System Arrays, used to anchor the rope floating buoys and anchored to the fence and other protection systems, drifting the prow of the vessel embedded cable NET or anchor buoys suspended due to gravity anchor end of coastal towing. Floating protective system for the protection of deep water bridge piers is a viable option (Fig. 5.36). The main advantage of this protection method is: (a) can absorb a great deal of momentum; (b) ship injuries limited; (c) the system can be installed in deep water and work. Main disadvantages are: (a) it around Bridge take considerable space; (b) it withstand storms and ice floes in waters which made durability a question; (c) major collision repair cost higher (d) long-term maintenance cost obviously depends on the scope of anti-corrosion measures and results.

Fig. 5.36 The floating protective system (a) The bulbous bow cross brake system (b) The bulbous bow may not cross brake system; (c) Tilt the bow may over braking system; (d) Flat end of the bow may become more brake systems (e) Floating protective system photos. Another floating energy dissipating the anti-collision facilities by installed around the main pier cofferdam or pontoon, using materials such as steel and rubber to achieve the goal of energy dissipation. Energy dissipation steel structure main body of the anticollision facilities of floating deck structure, platform, structure, floor structure, vertical and horizontal bulkheads, inner walls, perimeter wall, horizontal truss elements, such as, at the same time external wall form multiple watertight compartments and ballast tanks, on the inner wall set the rubber parts of the anti-collision facilities can be improved contact with the pier bearing platform can. Floating the anti-collision facilities under the

advantages of buoyancy along the pier move up and down so that it can adapt to the change of water level, range of the protection pier; disadvantage is that complex, Pier and pile cap shape required. Yellowstone bridge of floating the anti-collision facilities as shown in Fig. 5.37.

Fig. 5.37 Floating energy dissipating the anticollision facilities in Huangshi Yangtze River Bridge main piers.

2. The Floating Protective System Piers in the water or gravity bridge protection pier protection. Protection pier by the lattice into the steel sheet pile structure, fill in boxes with stone and concrete cover, protective pier and recoverable using pre-cast concrete piles, protection pier by net quality low energy barge towing collision resistance, but when high energy collisions, tends to the rotation, deformation, thereby tends to impact damage. This method is suitable for low and medium energy used in the ship collision incident, is more economical effective. The main advantages of this system are: (a) it is an independent system, before the ship reached Pier deflected or absorbed collisions energy it can be reasonable, cost effective installation in medium-depth water; (b) aim at long-term maintenance costs are relatively low. Main disadvantages are: (a) can absorb kinetic energy is limited to middle level; (b) ships had significant injuries; (c) the high cost of repair after a major collision. United States Sunshine Skyway Bridge main Pier and island protection, as shown in Fig. 5.38. Main piers on each side of 5 pier-production build sand cofferdam with thin shell protection, these side pier is after a risk analysis concluded that piers of most vulnerable to ship collisions. Diameter size is 60 ft (1 ft = 0.3048 m) seal can withstand loaded freighter or 8763000 DWT empty loading wheel 300 DWT. Impact 54 ft diameter seal able to withstand 65000 DWT loaded barge or 70000 DWT unloaded ships collision diameter impact 54 ft diameter seal able to withstand 65000 DWT loaded barge or 70000 DWT unloaded ships collision diameter Ship speed 10 kn (1 kn = 1.852 km/ h).

Fig. 5.38 United States gravity Sunshine Skyway Bridge protection system.

3. The Floating Protective System Supporting pile protection systems including common primary stake some intricate movements connected by rigid cap of pile with large diameter, the department EC can make the boat collision force is completely separated from the pier, can also be supported on piers. The main advantages of this system are: If you choose the right shield shapes can make bias or floating vessel steering, only pier with moderate damage. Main disadvantages are: (a) is not valid for high energy collisions; (b) building costs relatively expensive; (c) valid only in medium-depth; (d) after a major collision repair costs are relatively high. Argentina Rosario Victoria 350 m main span of the bridge, using flexible anticollision pier of the bridge protection form for pylon pier two and seven-side pier protection, as shown in Fig. 5.39. By design, the anti-collision facilities of main piers can resist 100000 DWT ships in 4.64 m/s speed for impact.

4. The Shield Protection System This system has been applied in a variety of forms in United States and Germany on inland waterways Harbour estuary, most of the bridges and many marine knots on the frame, they are a common form-oriented shield is to guide ships through the narrow little plays an important role in this oriented or protective plate can only have a protective effect on low-energy collisions, exert protective effects on high energy collisions, it is usually the original based on the outside ends of sheet-pile-supported by bollards (Figs. 5.40 &

5.41). The main advantages of this system are: (a) shield configuration or to help navigation of ships through the narrow route, thus helping to avoid collisions; (b) in the construction of bridges, this system takes the proportioned cost; (c) piers supporting grid configurations, it can float the boats go stray; (d) fire proof take friction surface. The main disadvantage of this system are: (a) is not valid for medium or high energy collisions; (b) after major crash repair costs are quite high; (c) aim at long-term maintenance costs, and even very small ships bump after its logs should also be replaced.

Fig. 5.39 Argentina Rosario-Victoria-pile protection system.

Fig. 5.40 Germany Neckar River Bridge fender system.

Fig. 5.41 Germany shield Crown Prince Arch Bridge system.

5.4 BRIDGE WIND-RESISTANT DESIGN PHILOSOPHY From the 80’s of the 20th century, Europe and the United States found that corrosion of pre-stressed cables in cement pipes pulp of severe corrosion in the pipe, causing the international bridge community’s attention, and raised the issue of durability. In 1989, the international qiaoxie conference on the Lisbon “structure durability” as its theme, was devoted to how attached to the structure’s durability during the design phase, so as to avoid early deterioration due to pay high costs of maintenance and strengthening. In order to implement the concept of durability design of bridges, first, we must clarify what is the durability of bridges to ask questions, durability of concrete bridges and steel bridge’s main problem is, this will be the first part of the structure durability of agency shaoxing; second, you need to be familiar with existing principles of bridge durability design, part II briefly involved in structural durability design detectable resistance, repairable and replaceable nature, health, controllability and sustainability; then, you need to understand durability analysis case studies in order to draw them in the conceptual design, and application and development of, and the third part focuses on the structure, load-bearing structures and durability, choose durable materials and durability design of main girder of cases; and, finally, to understand the common structure durability assurance measures part four introduces the sacrificial protection, detail design, interchangeable, easy maintenance measures, inspection and conservation facilities.

5.4.1 Structural Durability Refers to the bridge to resist natural weathering durability of bridge structures, chemical, mechanical abrasion and other degradation processes of invasion capacity. A good steel or concrete structure durability when exposed to normal conditions will be remain outside of its original components quality and service features of form and structure. Our current specifications, the bridge structure durability or life span of 100 years, but load bearing actually there are often certain flaws, resulting in bridge structures within the prescribed period had to be re-built, some bridges to demolition and reconstruction is required in the expected half life. But the lack of durability of bridges, often in use during the first table showed durability problems such as cracking, deformation, deflection, which, the cracking of the concrete cable-stayed bridges, concrete girder bridges under torsion and orthogonal different study on fatigue crack of steel bridge deck durability is the most common and most issues need to be addressed.

1. Concrete Cable-stayed Bridge Cracks Since 1975, construction of cable-stayed bridge in China, and to date has been built over more than 200 cable-stayed bridge, over 80% production using pre-stressed or reinforced concrete girders, concrete cable-stayed bridge. In all large-span concrete cable-stayed bridge, about 20% of concrete beam crack appeared, and crack like, it’s concrete cable-stayed bridge to encounter the most serious durability problems. Numerous studies show that cracked concrete cable-stayed bridge there are four typical forms, namely, roof cracks, cracks in floor, cracks and partition of the Web. Table 5.16 lists 8 typical cracking concrete cable-stayed bridge, where the girder

webs and there has been a lot of cracks, the useful life of these bridges from 11 to 27 years, the average life span of 19 years, far less than the life expectancy of 100 years of bridge structures. Durability of concrete cable-stayed bridge cracking causes of problem generally boils down to two major reasons: including design, construction, materials and subjective error factors of cracks caused by construction and by including overload, temperature load, shrinkage and creep of concrete and objective contact factors causing cracks. Although a large number of field surveys and case studies, also used to explain the individual bridge crack specific reasons, but still it is difficult to draw general conclusions of the crack of concrete cable-stayed bridge. In the Jinan Yellow River Bridge cracks motor as an example, longitudinal cracks in roof and partition of vertical cracks due to the absence of transverse pre-stressing force and thermal stresses in roof and floor plate distribution caused by cracks in a plate and webs due largely to frequent overloads and shrinkage and creep of concrete. Table 5.16 Part of cracking concrete cable-stayed bridge S.No.

Name of bridge

Location

1.

Jinan Yellow River Bridge

Shandong

2.

Shanghai Maogang Bridge

Shanghai

3.

Tianjin Tianjin Yonghe Bridge

Layout the Built Number of cracks span (m) time (in Roof Floor Plate Separators years) 40 + 94 + 1982 1386 11 52 1794 220 + 94 + 40 85 + 200 + 85

1982

Many

120 + 260 + 120

1987

2

4.

Shimen Chongqing 200 + 230 Yangtze River Bridge

1988

33

5.

Ningbo Yongjiang Bridge

Zhejiang

105 + 97

1992

147

6.

Qiantang River Bridge

Zhejiang

72 + 80 + 168 × 2 + 80 + 72

1996

7.

Lijiatuo Bridge

Chongqing 169 + 444 + 169

1997

Many Many Many

8.

Guangdong Panyu Bridge

Guangdong 70 + 91 + 380 + 91 + 70

1998

Many

2 84

78

164

Many 148

Many

2. Concrete Girder Bridge Deflection Concrete girder bridge in China is widely used in medium-or large-span bridges, mainly in pre-stressed concrete continuous girder bridge and pre-stressed concrete continuous rigidframe bridge with two forms, both bridge types suitable for 100~300 m long-span bridges, the latter being more bigger than the span of the former. China has nearly 60 long-span pre-stressed concrete beam bridge of 200 m in span, although the Wuhan Yangtze River Bridge main span of double-line bridge of up to 330 m, but it has a steel beam, which belongs to the steel-concrete composite beam, maximum span concrete beam bridge should be completed in 1997, Deputy channel bridge of Humen large bridge main span of 270 m. For large-span pre-stressed concrete girder bridge, maximum durability problems is excessive deflection of the main span, and this deformation causes of concrete beam crack-related. Structure deflection will be cause cracking of box girder with floor more, thereby lowering knot frame stiffness and eventually have greater deflection, creating a vicious cycle. Table 5.17 shows 9 domestic and foreign large-span pre-stressed concrete bridges, there are 3 of them and 6 abroad are produced across the deflection of phenomenon. Under torsion, lasting from 3 to 28 years ranging from 11 years on average, far less than the bridge’s design life of 100 years. Research results show that concrete continuous beam bridge main spans and concrete continuous rigid frame bridge under torsion is not China-specific issues, but the problem of universal from the structure design, construction and maintenance point of view it is difficult to avoid the occurrence of deflection, mainly to control the mode by setting the camber, for example, Norway according to the span of 0.5% is the deflection; once scratched after is hard to take steps to restore, for example, the United States had deflection occurs after the restoration of strengthening construction of cause of the bridge collapse accident. Table 5.17 Some deflection of pre-stressed concrete beam bridge S. No.

Bridge

Country

s = span (m)

1. Stolma

Norway

301

1998

92

2001

3

2. Humen

Bridge

270

1997

223

2004

7

3. Yellowstone Bridge

245

1995

305

2002

7

4. KororBabeldaob

United States

241

1978

1200

1990

12

5. Stolma

Norway

220

1993

200

2001

8

6. Parrotts

United States

195

1978

635

1990

12

7. Grand-Mere Canada

181

1977

300

1986

9

8. Kingston

143

1970

300

1998

28

United Kingdom

Construction Deflection Time of Duration time (years) (mm) measurement (years) (years)

9. Sanmenxia River

Bridge

140

1992

220

2002

10

3. The Fatigue Crack of Orthotropic Steel Deck As compared with the heavy concrete beam bridge panel or orthotropic steel deck plate is a lightweight construction system, so large-span suspension bridge and cable-stayed bridge in China, orthotropic steel bridge deck pavement using more common, there have been some fatigue cracks. Completed in 1997, the Humen bridge, the orthotropic steel bridge deck asphalt pavement was found shortly after the opening question, by 2007, is exposing stepped in at the plate and welded longitudinal ribs crack problem, seriously affected the normal passage bridge, also in the Chinese bridge beam sector attracted great attention. The bridge deck is an example of an orthotropic steel deck, steel box girders of the total width is 35.6 m, beam depth is 3.0 m. As an orthotropic steel box girder roof panel thickness of 12 mm, and the spacing is 620 mm, thickness 8 mm U-shaped rib for stiffening. Currently found in the orthotropic steel bridge deck a lot of fatigue cracks, the crack sewing can be divided from A to E, 5 types as shown in Fig. 5.42. Among them, A crack appears on the roof, roof and weld of vertical U-shaped ribs; Type B cracks on webs in the U-shaped ribs along the roof and vertical U-shaped rib connector, and much of that in the U-shaped rib bending; Type C U-shaped ribs crack appeared in the seams between segments; Type D cracks in U-shaped rib of webs, located in the welding at the foot of the cross connection; E-type A cracks on the diaphragm, in the D U-shaped ribs connected to welding B E at the foot of this cracks along the C diaphragm from the U-shaped box hole water spread flat or inclined, or along a seam spreads.

Fig. 5.42 Observation of fatigue crack types. Preliminary analysis shows that cracks in fatigue of orthotropic steel bridge decks frequent overloading was the main reason, including vehicle density and axles two aspects of weight. To this end, the first traffic statistics analysis of daily traffic increasing from 14928 vehicles in 1997 to 2008, 62439 vehicles, increased by growth factor of 4.2, which in the past 11 years, the six-lane bridge has withstood the role of 1.55 billion unregistered trips, the average per lane bear 2.58 million vehicles, far more than the fatigue strength. Then the axle statistical analysis of the heavy, showing three axle load peaks, 50 kN, 150 kN and 400 kN, respectively, and bridge design is 200 kN, almost half of the axle load exceeds design axle load. Final field surveys and experimental studies have found that these cracks occur mainly in heavy trucks driving on both sides of the driveway, because

the trucks are overloaded and traffic density is high, steel deck plate with thin, after the destruction caused by pavement roughness of asphalt paving, increasing impact, precisely because of these combined factors led to the opening of the orthotropic steel bridge deck in less than 12 hours because of repeated overload and produce severe fatigue cracks.

5.4.2 Durability Design Principles Since the 1970s, on the basis of lessons learned at home and abroad, in addition to continued emphasis on the structural design and construction safety, durability, reliability, component interchangeability have been considered, and based on different bridges structure analysis of the disaster grade and level of risk, prevention design and durability design were proposed as new concepts. In essence, structural durability design to solve the problem which is economical and reasonable service life problems, namely, structural problem in life-cycle. A large bridge to serve 100 years or even longer, for investing huge super long span bridge or sea-crossing bridge, life period should be taken into account to 150~200 years, taking into account the rapid development of modern science, the economy, and during the life of the structure, in addition to knot outside the frame itself, the aging and decay of internal, external factors change is big. For example, the usage requirements of the bridge structure to be predicted years, developed various standards of design is hard to achieve. However, the engineer should be able to make structures adapt to change, adopt with various measures for the structure to provide additional “stamina” opportunities. In order to achieve this goal, in design-time architecture must have six characteristics of checking resistance, repairable and replaceable controllability nature, health, and sustainability. Engineers must recognise that the overall structure of the lives and the various components is not exactly the same, such as service life of rubber bearings for more than 20 years, cable sheathing tho life for 10~20 year life of up to 40 years, cable wires, steel structure paint’s maximum life-span is 20 years, and so on. These parts whose life span is below the design life of the structure components must be able to be tracked, repaired, replaces, and can be strengthened. In external changes cases, the structural deformation in structure of “manageable”, that during the operational phase for bridge maintenance and reinforcement work, so as to ensure the durability of the structure. In order to ensure the safety and durability of bridge engineering implementation of the design concept, the first job was to develop the design, construction and maintenance specifications, procedures, standards and guidelines. In fact, normative and standardsetting also reflects a country’s construction level. During the 1923-1963, year the allowable stress method, and after 1963 to 2003, year of limit State method from 2003 since developed countries have committed to performance-based design specifications (performance-based design code) designed to improve infrastructure especially major infrastructure design and construction standards. Developed and compiled based on durability requirements, whole life insurance design and sustainability of performancebased bridge engineering design codes and standards should become a 21st century bridge engineering one of the most important tasks.

5.4.3 Structural Durability How to bridge design began to study bridge, general layout, it introduces the idea of durability, take fully into account the special the environmental conditions and other factors, such as what kind of main girder form durability to meet specific environmental, what kind of main girder form help maintenance, what kind of cable tower model need to use steel, what kind of cable tower model available and high performance concrete and component layout consider the need to not need to be replaced, can change, for example, replacement must be set aside for replacing the space, these are bridges to ensure durability initiatives, are major factors for durability, compared with other external measures, they are more important for bridge life-cycle maintenance costs and durability and play a decisive role.

1. Structural Redundancy Design Structure using a redundant design helps us to better face the problems that might arise, and that the increased costs of tend to be very small or even zero. For example, since the Portsmouth Bridge designed in the early 1980, of the 20th century, it always has to take into account in the design of cable-stayed bridge cable the possible broken truck collision. Carefully designed cable configuration such accidents can be the bridge to withstand shocks without interruption caused by traffic on the bridge. Opposite example is the early tied arch bridge in China, and used boom suspension crossmember, installed on the beam longitudinal decking suspended deck system design, this kind of system, such as hangers by accident, fracture, will cause the beams and decking to collapse significant fall occurred. 2001 Yibin in Sichuan province Xiao Nan men bridge collapse was due to the boom of durability issues caused by suspended deck system design make deck non-redundant design, boom broken, the bridge collapsed. This system also needed to replace suspenders it is difficult to replace.

2. Construction and Durability In many cases, construction method and arrangement of bridge-type are inextricably linked. Therefore, concept design, according to environmental conditions, research of bridge layout and materials durability requirements, and appropriate construction methods.

(a) Construction Determines the type of Bridge Study on structure of main bridge of Suzhou-Nantong Yangtze River Bridge the early research 110 m + 300 m + 1088 m + 300 m + 110 m five-span programmes, side 120 m length of main beam using pre-stressed concrete box girder structure. Such an arrangement, side effect, cable stiffness, helps to improve the main span rigidity. However, the resulting problems must be taken into account, that is, concrete beam segment of Jiang Shi work methods: pre-cast erection due to lifting weights is difficult to achieve, stent placement, supports in the river in flood season and the usual anti-collision problem resolved, more important is that supports in-situ concrete quality control in the river, weighed, design group believes that the main structure of a durable must ensure, under control. So, finally gave up, hybrid cable-stayed bridge scheme.

(b) Full Cross-section Integral Construction Can cause severe corrosion of the environment of the region, such as bridge or cross-Sea Bridge in coastal areas, such as, at the design stage, avoid violence show large type steel structure of component surface area requires special maintenance structure, such as an open-beam or steel tower; eliminates choice requires a lot in field (coastal or maritime), pour concrete, making it difficult for concrete quality control and eventually structural durability, such as on-site pouring piles and pre-stressed concrete box girders, etc., avoid using partially prestressed b parts and component with cracks, affecting its durability, such as continuous pre-stressed concrete beams and pre-stressed concrete bent cap; avoid using a surname sewing and assembling, durability of the gel influences the durability of the seams. Composite beam section forms a lot, generally speaking, although the steel I-beams with section advantages of simplicity, ease of construction, but box-shaped composite beams is a combination I-Liang bi exposed steel surfaces, paint maintenance workload is relatively large, box-shaped composite beams the outer surface is easy to maintain, facilitate the use of dehumidification system inside the box, box at the durability of the coating is guaranteed. Of steel and concrete composite technology, pre-cast concrete panels, installation, wet joint pouring after’s approach stresses of steel and concrete can be full, however, used bridge deck durability of lap it is easy to become weak links, and first concrete bridge deck on the steel girder segment, and then overall segment installation of steel and concrete composite technology solves durability problem of steel-concrete combined surface and, of course, the lack of technology affect the steel and concrete of the two materials can give full play to their dominant performance, therefore, required under the environment category and grade, choosing the right combined process. Figs. 5.43 and 5.44 are two kinds of process engineering.

(c) Pre-fabrication and Pre-casting of Segments If water conditions permits, large crane to hoist girder is the excellent solution to beam quality and installation, also is a preferred solution, however, when circumstances in depth does not permit, such as beaches, only the use of movable frames, segmental processes of segmental seams for durability issues need to be addressed. Pile caps piers and pre-cast problems for a growing cross-Sea Bridge, Pier poured in place concrete pile caps and Pier shafts will shadow casting quality and duration, pre-cast method is a common method of choice, but how to avoid assembly joint impact durability and problems, in addition to the adopting some good performance sealed materials, must ensure the durability of these joints on the design details, such as the joints of pile caps and pier concrete, pier over seams in the splash zone, and in a state of compression and so on.

Fig. 5.43 Composite beam segment technique of casting concrete (a) steel box beams of Donghai bridge; (b) Greece combination girder of Rion-Antirion bridge.

Fig. 5.44 Pre-cast concrete combination girder construction. Using rectangular hollow section of Donghai bridge, vertical prestressed with high strength reinforcing rebar, concrete cross-section under design load does not arise under tensile stress. Pre-cast the pier shaft the whole section. Seams of high pier located in the splash zone or above, outside seal the deal on the inside cast in place concrete reinforcing and improving structure durability. By closely matching method of pre-cast pier. Set new concrete pier, to avoid assembled rubber joints, make sure that the connection parts durability requirements. Pre-fabricated site arrangement in Shen Jia Wan, island of 300,000 m2 prefabricated field, which two pieces of pier precasting yard, a venue precast pier of the 60 m span from “venture” floating crane for lifting installations. Another piece of venue precast pier of the 70 m span, make them ourselves, “erecting one barge” lift installation, as shown in Fig. 5.45.

Fig. 5.45 Donghai bridge installation of prefabricated bridge pier (a) “venture” floating crane; (b) “erecting one barge” Pier installation vessels.

3. Preference for Durable Materials

According to environmental conditions, conceptual design to structural material properties used by targeted requirements, and discusses their use of reason, material technical characteristics and application purposes, as well as from the total life-cycle cost analysis shows that the use of durable materials economy. Selection of durable materials are conceptual design for structure durability of concrete is considered one of the most important aspects. Stonecutters Bridge design comes from the concept of a bridge design competition winner works, its appearance is very beautiful, how can design features to be durable without the need to take a very expensive maintenance costs is an important design consideration. In Hong Kong, the bridge is designed to generally live for 120 years. Environment for those who are taking a toll bridges, formulate a scientific, rational and economic durability the case is definitely a major challenge. The Stonecutters Bridge design competition award-winning design of the upper part of the tower is a round steel, is of a design feature. The design add a modern element to this bridge built-in 21st century. On optimisation of design process, in order to improve the bridge aerodynamic performance and maintain the appearance of the bridge towers, the upper half of the tower to a steel shell and inner wall of concrete composite structure. In the concrete construction of the tower is not using the common method of pumping to avoid early-age shrinkage cracking. And mixed with Silica fume (Micro-silica) as well as the outermost layer of stainless steel reinforcement, reduced to chloride ion penetration, increased corrosion of reinforcement, can be said that the maintenance of durability of concrete towers and pay greater attention to service life of 120 years. Shell is not stainless steel shell instead of ordinary carbon steel, to further improve the bridge tower design and enhance the durability of metal finishes, without new surface coating for steel structure on a regular basis. Extending bridge main span and side spans of 49.75 m long section of steel box beam structure, two girder beams together, in the main cross-section spacing is 18 m, and the side spans part of the pitch was 15 m. Air humidity are controlled within the deck box, provides relative humidity lower than 60% environment. This will-effectively prevent inner corrosion in the steel box, thereby reducing the outer layer with precision anticorrosion measures needed. Dehumidification system operating in the deck are expected to cost less than a new paint layer of costs.

4. The Durability Design of Main Girder Our bridge engineering is increasingly concerned about the structure durability of concrete cable-stayed bridge. Taking the Ningbo Yongjiang bridge as an example, the original design of the bridge is a long-span concrete cable-stayed bridge of 468 m, [Fig. 5.46 (a)] as shown in the tendons concrete bilateral main ribs. In the preliminary design review, expert review committee does not support the bilateral section of the main rib bridge programme, is a major reason why it existed had durability problems found. According to experts recommendations of the CRIC, the design from the original concrete combination deck to deck, that is, two steel box girder with prestressed concrete slab, as shown in Fig. 5.46(b) shown below. Obviously, mixed beams of concrete-filled steel box girder to completely avoid cracks in the breast, abdomen and diaphragm, and prestressed concrete

bridge deck slabs for the roof though may crack, but it can be replaced in the future, this greatly improves the durability of the structure.

5.4.4 Structural Durability Measures Concept design should consider structural durability measures and the maintenance care after bridge completion, take necessary steps against key parts of structures, and form the basic ideas of the conservation scheme.

Fig. 5.46 Ningbo Yongjiang Main beam cross-section (size: m) (a) originally concrete bilateral main rib section; (b) eventually steel box girder and concrete composite beams.

1. The Sacrificial Protection For structural components (such as pile and foundation) in a periodic inspection and maintenance inaccessible concerned, they add a layer to the sacrificial protection is a good idea under certain circumstances, at the expense of the protective layer will persist a certain time so that before the protective layer structure members do wear from external erosion. Piles are a classic example. Most of the pile can’t close inspection after the construction is completed. We have concrete, the outer bread with a layer of expense of the steel shell, Acosta Bridge, Florida (Acosta Bridge) is one such example. Similarly we can also be coated with a layer of steel pile under environmental erosion protection layer to withstand a certain period. In San Francisco, Oakland Bay Bridge eastern section , this kind of sacrificial protection was used on the surface of steel pipe piles. Currently steel pipe wall thickness epoxy powder coating is mostly used as anticorrosion measure to guarantee service life.

2. Design Details Design details include: 1. high durability concrete, reinforced concrete compaction, increase their ability to resist breakage; 2. strengthen the bridge surface drainage and waterproofing layer design, improving the environmental condition of the bridge; 3. improvement design of bridge structures, including increasing the thickness of concrete cover; strengthened structural reinforcement to prevent cracks; 4. corrosion protection of steel; black surface coating for steel structures have to be reasonable, combining bridge environment suitable corrosion protection methods; 5.

for important structures with multi anti-corrosion measures and check them regularly, as well as corrosion protection measures be adopted, surface anti-corrosion coating of epoxy-coated reinforcing steel, concrete, corrosion-inhibiting admixtures, infiltration of surface layer template, cathodic protection (corrosion protection of steel pipe piles corrosion protection), etc.; 5. strictly for design and control of stress, cracks and other details.

3. Replacement Measures Not every bridge structural unit of life and as long as the bridge’s design life. If we gave every structural unit life expectancy and the bridge’s design life of the same, costs may be very high. Design in general, as a matter of routine, in certain structural elements can be replaced after a certain time. Supports, expansion joints and wearing course fall into this category structure. It can be seen that structural unit of easy substitution becomes very important. Any traffic would increase maintenance costs, although the costs and life-cycle costs are not an order of magnitude. One takes far too long to maintain nearby commercial projects often troubled by serious damage.

4. Ease of Maintenance Measures Ease of maintenance is extremely important and accessible is the first step toward maintainability. Caused by human behaviour, and hard to reach compare with invisible part, accessible and visible parts can often be checked more frequently and more thoroughly. Due to the need of maintenance surface is limited, small box girder beam or truss is preferable. Box girder can be formed inside a closed space through machinery and equipment to provide ventilation, controlled humidity and temperature. Another way to help achieve the maintainability issues is to display a warning sign before a problem actually occurs. For example, there are two types of cable-stayed bridge cable methods of changing colour, either use a coloured thin layer over a black base layer of double-layer PE pipe, or wrap on top of a black tube with a layer of colored PVF, in many cases, the latter is better because wrapped taping for PE tube provides a layer of coat, if there is damage, coats get stripped, attracting attention for maintenance and repair.

5. Inspection and Maintenance Facility Tower conservation and repair lifts, ladders and simple platform setting, should be available in cable tower, and equipped with lighting and fire setting device, towers should be reserved for laying cables on embedded parts for repair, replace the corresponding facilities, as necessary to reach the site and channel should be set ladder and guardrail repair. Closed flat streamlined steel box beam structure, stiffened a lot inside the box, if the paint anti-corrosion, maintenance painting work and because of the steel box beam inside a closed environment, difficult volatile solvents for paints and construction and maintenance personnel’s working environment is very inferior. Corrosion of the steel box girder internal layout dehumidifier light are commonly used as antiseptic and protection system, internal requires steel box girder the humidity is less than 50%.

In order to facilitate the operational phase of the bridge maintenance and construction of steel box girder of steel box girder of circular seam welding, large steel box girder bridge beams are required to set the maintenance vehicle. Maintenance vehicle based on the main girder structure, are commonly used as cantilever-mounted crane programme, namely, driving through steel wheel poured into I-steel track, trusses are connected by a door frame and drive mechanisms. Driving mechanism of general electric and manual. Electric one requires sliding transmission line , its price is higher than a manual one.

REVIEW QUESTIONS 1. Cross-channel titled construction of super long span cable-stayed bridge, suspension bridge, proposed to deal with technologies such as wind, seismic and anti-ship collision-resistant collar concept of the design field, through investigation both at home and abroad have put forward new ideas, in relation to a concept of a field of one’s own design. 2. Aiming at the vessel bump bridge accident, from analysis of bridge engineering and marine technology, how to prevent this type of accident and reduce the losses caused by the accident. 3. Examples of bridge engineering in disaster prevention and new concepts in durability, wind and earthquake-resistant, anti-ship separately and durability cited an example in the field of technology. 4. Please give examples at present, China has built bridges in the durability inadequacies, and problem-solving approaches.

REFERENCES [1] Xiang Haifan. Chinese and Foreign Comparison of Technological Innovation in the New Bridges//proceedings of the 17th National Conference on Bridges. Beijing: People China Communications Press, 2006. [2] Xiang Haifan. The Durability of Bridges in China. The Bridge, 2009 (4). [3] Deng Wenzhong. Observation of Bridge Durability. The Bridge, 2009 (4). [4] Xiang Haifan, et al. Modern Bridge Theory and Practice of Wind Resistance. Beijing: People’s Communications Press, 2005. [5] Fan Lichu, et al. Seismic Design of Long-span Bridges. Beijing: People’s Communications Press, 2001. [6] Fan Lichu. Safety and Durability of Bridge Engineering—Looking into the Progress of Design Concept. Shanghai Road, 2004 (1). [7] Xu Zhihao, Huang Jianbo. Stonecutters Bridge, Durability, Maintenance, and Safety//17th National Bridge Conference Papers, China Communications Press, 2006. [8] Hu Renli. Seismic Design of Bridges. Beijing: China Railway Publishing House, 1984. [9] Wang Junjie and Geng Bo. Bridge—Vessle Bumping Risk Assessment and Measures. Beijing: People’s Communications Press, 2010. [10] Institute for Marine Steel Structure in Shanghai. Ship Collision with Bridge Selected Papers. China Shipbuilding, 2000. 5. [11] Chen Zhengqing. Bridge Wind Engineering. Beijing: People’s Communications Press, 2005. [12] Ye Wenya, Li Guoping, Fan Lichu. Preliminary Analysis of Bridge Whole Life Costs. Highway, 2006 (6). [13] Xu Guoping, Liu Minghu, Geng Shuang. Method of Bridge Whole Life Design. Highways, 2007 (10). [14] Wang Rengui. Hangzhou Bay Cross-sea Bridge Structure Durability//proceedings of the 2004 National Conference on Bridges. Beijing: People China Communications Press, 2004. [15] Zhang Jinping. Denmark Bridge Maintenance Philosophy. Bridges, 2008 (3). [16] Huang Qiao. Study on Durability of Bridge Structures and Life-cycle Design. Bridges, 2008 (3). [17] The People’s Republic of China Industry Standards. JTG/T B07-01-2006 Road Engineering Technical Code for Anti-corrosion of Concrete Structures. China Communications Press, 2006. [18] The People’s Republic of China Industry Standards. JTG D60-2004 General Specification for Design of Highway Bridges and Culverts. Beijing: People’s

Traffic Press, 2004. [19] The People’s Republic of China Industry Standards. JTG D62-2004 of Reinforced Concrete and Pre-stressed Concrete Bridge Design Regulations. China Communications Press, 2004. [20] People’s Republic of China Industry Standards. JTG D60-01 General Specification for Design of Highway Bridges and Culverts. Beijing: People’s Traffic Press, 2004. [21] The People’s Republic of China Industry Standards. JTG D02-01 General Specification for Design of Highway Bridges and Culverts. Beijing: People’s Traffic Press, 2008. [22] Liu Ziming, et al. and bridge maintenance and repair manuals. Beijing: People’s Communications Press, 2004.

BRIDGE STRUCTURE SYSTEM AND KEY MECHANICS QUESTIONS

6.1 BRIDGE STRUCTURAL SYSTEM 6.1.1 Bridge Structure System and its Classification Architecture is a structural unity of function, shape and stress pattern. Structure and function of architecture is the first hierarchy, such as function of the building structure is for the living space of the form must be primarily surrounding structure; bridges function is for people to cross the obstacles and objects (rivers, valleys, etc.), main span structure. The second structure is a hierarchy system, according to the structure, the bridge structure can be divided into four basic system: beam, arch-suspension bridges, cablestayed bridge system. Forms can also be further sub-divided under the same bridge, such as the tower’s few cable-stayed bridges can be divided into single-tower cable-stayed bridge, twin and multi-tower cable-stayed bridge with cable-stayed bridges and so on. When among the various systems in combination with each other, but also derived the cable-stayed suspension system, cable-stayed continuous rigid frame-continuous beam or collaboration system. Loading form is the third level of the structure system, stress patterns include delivery of loads within the structure and its internal forces status on balance, it is the kernel of structure. Even within the same form of bridge system structure loading remains very diverse, its most influencing factors can be categorised into three areas: external constraints on the structure, such as the structure is statically determinated the temperature, support sink on the effects of structural systems; connections between main load bearing structures (transfer) forms, such as the tower of cable-stayed bridges, connection of beam, pier will be affect the structure transmission of loads; stress distribution between the main components, such as the arch flexible beams, arches, rigid beam and flexible arches divided into rigid beams. From the above three levels to define the structure and system of bridges and other structures can be distinguished, and systems to bridge the outline and basic mechanical properties, but also lays the groundwork for systematic study of bridge structure system. According to the above definition and hierarchical relationships, bridge structure system of classification can be simply shown as shown in Table 6.1. Table 6.1 Structure classification summary. First level

Second level

Third level

Bridge

Beam Bridge

• A threespan continuous beam • A multiplespan continuous beam

• External constraints: The simple supported beam, Continuous beam, Fixed end beam, Cantilever beams. • Internal connection: Continuous beams, t-shape rigid frame, Rigid frame. • Stiffness distribution: Beams with even crosssections, Beams with variable cross-sections

Arch Bridge

• Deck bearing • Middle bearing • Bottom bearing • Single loadbearing surface • Leaning arch • Continuous arch

• External constraints: Hingeless arch, Three-hinged arch, Single span arch, Continuous arch. • Internal connections: Double-hinged arch, Threehinged arches; Arch with fixed connection, Hinged arches, Free arches. • Stiffness distribution: Rigid arch flexible beam, Rigid arch rigid beam, Arch with even cross sections, Arch with variable cross-section.

• External constraints:Auto-anchored cable-stayed bridge, Ground-anchored cable-stayed bridge, Partly ground-anchored cable-stayed bridge. • Internal connection: Full-floating structural system, Semi-float (supporting)) system, Tower-beam-Pier consolidation system, Tower-beam conjugation, Tower pier hinged system. • Stiffness distribution: General cable-stayed bridge, Low pylon cable-stayed bridge.

Stayed Bridge

• Cablestayed bridge • Singletower cablestayed bridge • Dual-tower cable-stayed bridge • Multi-tower cable-stayed bridge • Single-pole cable-stayed bridge • Twin-pole cable-stayed bridge • Three-pole cable-stayed bridge • Single tower suspension bridge

• External constraints: The self-anchored suspension bridge, Ground-anchored suspension bridge. • Internal connection: Two-span simple support suspension bridge, Double-span continuous

• Twin tower suspension bridge • Multitower Suspension suspension Bridge bridge • Single pole suspension bridge • Twin pole suspension bridge • Three- pole suspension bridge • Continuous rigid frame bridge • Girder and arch Combined combination system • Cablestayed suspension • Collaboration system

suspension bridge, Three-span simple support suspension bridge, Three-span continuous suspension bridge. • Stiffness distribution: Rigid Tower suspension bridge, Flexible-tower suspension bridge.

……

Study of bridge structure system is to find out its mechanical properties in order to carry out system of bridge structure and apply to practical engineering according to local conditions.

6.1.2 Evaluation Standards for Bridge System Quality A certain bridge structural system corresponds to its unique mechanical properties. But the same structure used in different occasions may be good, or it may be bad. Therefore, clear criteria for judging quality of bridge structural system is particularly important. First the reasonable structure span. Each bridge has its range of reasonable span, simply-supported beam cannot exceed 100 meters, otherwise it is uneconomical or impossible; vice-versa, unless for special requirements such as landscape, it’s hard to imagine long-span suspension bridge system is used in bridge with a span of only dozens of meters. Any approaches or exceeds the span record in the system will be require careful assessment, a system beyond the record in general is more expensive and difficult to

implement in the short term. Secondly, the system must adapt to the geological and hydrological conditions at the location of the bridge. Force structure the first aspects to which it corresponds the outside world structure system constraints. Such as: soft ground area should not be resist horizontal force, hence the thrust arch is generally not reasonable options, foundation bearing capacity under the condition of high in the mountains, have thrust arch tend to also be the best programme. Furthermore, the system internals transfer effectiveness is also important, it corresponds to the force structure forms the second aspect of internal connection forms between the components. For example, the large-span cable-stayed bridge in the form of talianglian, hope floats under temperature effect to release the temperature stress, while in vertical static wind load consolidation system wants to reduce tower loading, system selection selection should be based on the situation at the bridge, and find out the principal contradiction, can overcome the principal contradiction of the system, and for a variety of spears shields are more prominent, main beam limiting device is used in the project, in the context of a given can be freely modified, to displacement limits to become consolidation system, a reasonable solution under a variety of loading force demand contradiction. Also, the collocation rationality of rigidity of the system may reflect their strengths and weaknesses. This corresponds to force form the third structures: stress distribution between the components. In a good architecture system, not only all the structural components share optimal stiffness distribution but also bear mechanical load in a balanced manner, although it is impossible to reach the ideal state of equal strength, but at least it should guarantee the mechanical safety components differ. To sum up, no absolute standard for evaluation of bridge system. Determining bridge system must be combine the requirements of integrated considered, and finally make the best choice. Following Tianjin guotai bridge design in the system of selecting, for example, illustrate the applicability of bridge evaluation criteria mentioned above. Guotai bridge, a bridge across the Haihe river in Tianjin, 4 internationally renowned design firms compete, truss arch bridges (Fig. 6.1) standard, successful units with arch system (Fig. 6.2), the study shows that key has the following problems: 1. For soft soil ground in Tianjin, and arch not only horizontal force on the basis of the system, there is a large bending moment, seismic and long-term load effects were negative, and this is the principal contradiction in the system and condition of building the bridge; 2. In order to reduce the annual effect of temperature on the structure and need to set a Corbel arch-beam, horizontal thrust long level pull cable under deck setting you want multi-channel expansion joint, makes the structure of complex, and driving comfort; 3. The bridgehead buildings you pass arch winding tension, under complicated stress and poor seismic performance of the system.

Fig. 6.1 Tianjin Guotai bridge.

Fig. 6.2 Fixed end arch architecture diagram (unit: mm). Analysis and research on the basis of the programme, the principal contradiction is grasped, determine the structure of the new system: the middle three-span thrust free archbeam composite system (Fig. 6.3). Fully preserves the original scheme of the system’s function and landscape modelling, by changing the connection mode of outside constraints and internal components of the system, improve the behaviour of structure:

Fig. 6.3 Sketch of girder and arch combination structure system with three-span non thrust design (unit: mm). 1. modification became hinged arch at the foot of solid, release the horizontal constraint, based only on vertical and horizontal girders bear; 2. structures freely in the horizontal direction, so annual range of temperature has less influence, arch-beam used in consolidation, deck without increasing expansion joints; 3. the bridgehead building separate from the main structure, landscape and ballast only, system performance is much improved. Two structure such as shown in Table 6.2, after optimisation, mechanical performance will be significantly improved not only the structure and make the whole engineering cost reduced. Table 6.2 Structure system comparison. Comparison project

Solid duangong system

No thrust beam arch

Supporting constraint Arch fixed thrust

combination system Hinged arch, no thrust

Force base

Vertical force + horizontal force + moment

Nearly vertical force

Rib

Force transmission path is not smooth

Smooth power transmission path clear

Horizontal thrust balanced approach

Basic level of cable and tie beam in Tie beam itself bear set

Deck system

The main impact of bridge expansion joints driving comfort

No main bridge expansion joints

Bridge construction

Large projects shall be provided with vertical pre-stressing

Engineering, without setting vertical prestressing

Technical difficulty

Great

Small

Security

There are security risks

Okay

Seismic performance Poor

Better

6.1.3 Mechanical Properties of Various Systems As mentioned earlier, bridges are classified as beam bridges, arch bridges, cable-stayed bridge, a suspension bridge with four basic system, each system has its special some mechanical characteristics. Warping (Fig. 6.4) is a vertical structure of anhydrous rehabilitated under the action of load, because the force is exerted and axis of the structure nearly perpendicular, so compared with other structures of the same span, bridge bending moment within the maximum usually takes tensile properties of materials used to build it.

Fig. 6.4 Beam bridge. Arch bridge (Fig. 6.5) the main load-bearing structure is arch or arch. Traditional arch bridge under the action of vertical loads, piers and bridges the horizontal thrust and piers provide arch with a pair of horizontal force, the basic offset within the arch is composed of horizontal force load moment, so arch is the main structure of stress. Compared with equal-span beams, bending moment, shear force and deformation of arch a much smaller, can take full advantage of good tensile properties and compressive properties of masonry materials (stone, concrete, etc.). In addition, beam bridge differences before closing lower because of failure to maintain balance and thus must rely on the support, in the construction of arch bridge cable-stayed cable of auxiliary support measures. Thrust arch built-in the ground conditions are not appropriate for cases, or you can build the horizontal thrust of the horizontal bar withstand thrust free arch bridge [Fig. 6.5(d), (e)]. Cable-stayed bridges (Fig. 6.6) consists of the foundation, the main tower, girder and cable composition. Main beam of inclined cable tension to provide more flexible support, and passing girders bear the load to the main tower, and then spread to the base of the tower. Tower is basically dominated by compression. Large master girder works like a multi-point continuous beams with elastic supports. Because of the horizontal force of cable-stayed, girder foundation the force character is eccentric, Yu Liang-type bridge, girder size greatly reduced structural weight significantly reduced, greatly improves the diagonal laqiao’s crossing ability. In addition, towers, cables and main beams form a stable triangle, greater structural rigidity of cable-stayed bridge.

Fig. 6.5 Arch bridge.

Fig. 6.6 Cable-stayed bridge. Suspension bridge (Fig. 6.7) is a powerful main cables suspended between the towers on either side as the main load-bearing structure. Vertical load on the bridge by Suspender cables under a lot of tension, in anchorage in suspension bridge main cable at both ends. In order to withstand the huge main cable pull anchorage structure is normally required to do very big (gravity anchorage), or rely on the natural integrity of rock to withstand the horizontal force (tunnel anchorage). Relative to the former system, suspension stiffness is a flexible structure. Under external loads, the suspension bridge by larger variants in order to achieve the balance of forces. For a variety of system, its mechanical feature naturally inherited the basic mechanics characteristics of systems. For example, cable-suspended collaboration systems in different parts of the structure mechanics characteristics of cable-stayed and suspension bridge, respectively. Combination systems are concentrating on is how to implement a different system of “seamless connectivity”, that is, at the junction of different systems, great properties for its change shall be monographic study and adopt structural measures to solve related problems. For example, cable-stayed-suspension system side sling struggles labour has attracted the attention of scholars, arch girder and arch combination

system of complex stress states shall take special countermeasures in the design.

Fig. 6.7 Suspension bridge.

6.1.4 System Innovation Bridge structural system of innovation is fundamental to meet the specific conditions of building the bridge structural system change, group, or its innovative work on change of force patterns. Because of system innovation, there is a bridge between today’s rich and varied structure. Structural changes can radically change the structure of the system of mechanical properties, so as to break through the bottleneck of the structure itself. Because of its traditional arch bridge arch at the foot of horizontal force, it can hardly be applied in soft soil foundation greatly hampered its development. In order to avoid the influence of arch the thrust on the basis, developed part of thrust and thrust free arch bridge (Fig. 6.8). Selections below are to introduce several of bridge engineering system innovation success stories. Example 6.1. Beam bridge system double-line bridge of shibanpo Changjiang River Bridge Chongqing. Chongqing Shibanpo Yangtze River Bridge (Fig. 6.9), built-in 1981, with a hanging beam of pre-stressed concrete T-shaped rigid frame bridge long combined span of 86.5 m + 4 × 138 m + 156 m + 174 m + 104.5 m. To meet the traffic demand in existing old bridge build a new continuous rigid frame bridge of double-line bridge of Shibanpo Changjiang River Bridge. By channel experts argues that the main span of the new bridge will be 292 m waterway must clear width. Taking into account the new bridge and old bridge pier locations corresponding to requirements, only the 156 m and get rid of 174 m between the two main span piers, so the main span of the new bridge span to 330 m, breaking the steel girder bridge span in the world record—300 m, box-girder roof and floor will be become thicker, creating difficult and economically reasonable; the new bridge span also break concrete girder bridges span the world record 301 m, light weight concrete must be used, but the aggregate imports economically unreasonable, domestic conduct their own testing is expensive and time consuming. Therefore, changing the material composition of the main beam, main span uses steel girders replacing the lightweight concrete plan would eventually be adopted. By

calculation, 330 m adopt steel box girder for main span of one-third makes the top of pile under negative bending moment decrease about one-third, which is about the domestic implemented 270 m pier of long span concrete beam bridge bending moment, so at the current level is suitable under some conditions for this scenario.

Fig. 6.8 Bridge diagrams (a) thrust system; (b) part of the thrust system; (c), three-span continuous lift system; (d) simple support without thrust system.

Fig. 6.9 Double-line bridge of Shibanpo Changjiang River Bridge. But this does not mean that the steel beams in the middle period of the longer the better. In terms of cost, steel box girders is more expensive, their length, greater the

difference larger in terms of construction, hoping to integral lifting of steel box beam segment, both in weight and has some limitations. After overall consideration, determine cross-beams in a length of 103 m, plus the ends of the steel-concrete combined sections, the whole cross-beams length is 108 m, weighs 1400t. In addition, double-line bridge of Shibanpo Changjiang River Bridge a total length of 1103.5 m, as shown in Fig. 6.10. With Master Liang Gu knots side Pier will be bear too much horizontal force for this system as middle using a combination of rigid frame, side pier of continuous girder system.

Fig. 6.10 Double-line bridge of Shibanpo Changjiang River Bridge in general layout (size: m). Double-line bridge of Shibanpo Changjiang River Bridge in the main span without use of lightweight concrete, but breaking with steel beams instead a concrete beam, through material changes in the composition of main girders, to vary the winner Liang Heng load distribution, thus opening up the steel-pre-stressed concrete continuous rigid-frame bridge this bridge, on economy, safety, durability and so on to meet the premise, solution summary of continuous rigid frame bridge of long-span 300 m problems. Example 6.2. Arch bridge system of Chongqing Caiyuanba Yangtze River Bridge. Chongqing Caiyuanba Yangtze River Bridge is the first orbital dual-use of King Road, city of steel and concrete composite rigid frame structure and tied-arch bridge (Figs. 6.11 & 6.12 ).

Fig. 6.11 Chongqing Caiyuanba bridge.

Fig. 6.12 Overall layout of Chongqing Caiyuanba bridge (size: m). Because it is public rail-cum-road bridge, decide to beam must reach 11 m, rigid beam, Liang Rou arch system is used. Before This, almost all of deck tied arch bridge in side

span all columns to support the weight of the beam [Fig. 6.13(b)]). But in the vegetable garden dam bridge, rigidity and side spans only 102 m, so the primary beam can span the entire side without column support, side span became very open, light weight of the bridge presents its elegance.

Fig. 6.13 Comparison of supporting tied side arch span with or without pole sets (a) Caiyuanba bridge across no pole; (b) common bridges across any vertical poles. After removing the post, side spans of arch ribs no longer subjected to vertical loads, and can be made into a straight bar, arch bridge structure can be used at the lower portion of the Y-shaped the concrete structure, under the continual fluctuations in water level do not require special conservation as well as steel. Three pole pieces large y-shaped structure seems solid, steady, and increase impact resistance capacity. In this way, in terms of structure, caiyuanba bridge consists of three elements: a Yshaped pre-stressed concrete rigid frame on each side and the steel box tied arch bridge in the middle (Fig. 6.14), the calculation so as to allow the centre of bowstring arch span is reduced from 420 m to 320 m and improves overall efficiency while reducing a key substructure design more difficult.

Fig. 6.14 Y-shaped rigid-frame structure and tied-arch load path diagram. Compatible with the three independent units, this bridge has also been used in the design of vertical isolation system tie rod, vertical tie bar divided into cross-tie bar and side span bow string, and anchor its independence. On this basis, and additional vertical tie bar at side pier. Three sets of independent tie rod systems are available in the implementation process of the main body of the bridge (rigid frames and the main arch) force and the adjustment of the linear space control: under constant load by adjusting the frame on each side of the tie rod and the tail end of the vertical cable, rigid rod bending torque to reduce and regulate the bowstring cable force of arch in the middle, perfectly balanced horizontal thrust, only vertical forces on both sides of the Y-shaped rigid structure. At constant load under three separate, and consider this to achieve an optimal stress. Since then, under the live load action, tied with other the longitudinal member

according to the level of stiffness distribution of force. But due to live load accounts for only a fraction of the total load, there would be no essential impact on the system as a whole. In short, Caiyuanba bridge through structural innovation in the system, separate tie rod using active control technology enhanced material efficiency rate, saving a lot of permanent structural steel. Example 6.3. Cable-stayed bridge system—Greece Rion-Antirion Bridge. Rion-Antirion Bridge (Fig. 6.15) across Greece Corinth isthmus, composite girder cable-stayed bridge of main bridge for more tower bridge continuous, using floating fivespan structure, span consists of 286 m + 3 × 560 m + 286 m (Fig. 6.16).

Fig. 6.15 Rion-Antirion Bridge.

Fig. 6.16 Overall layout of Rion-Antirion Bridge (size: m). The bridge construction is very complex, requiring bridge can handle upto 2000 years of seismic, the maximum peak ground acceleration 1.2 g the bridge can withstand maximum 2 m of vertical and horizontal fault displacement, as well as 180,000 DWT tankers to 8.2 m/s velocity of impact force and strong winds. Apparently, the site conditions suitable for the construction of a suspension bridge, but the geographic conditions eliminated the suspension bridge scheme in the conceptual design phase. In order to make the bridge is feasible, and the overall cost can be received, select bridge beam and gaps must limit the number of piers in the middle. Finally chose to have 3 across all of 560 m, 2 side spans of 286 m cable-stayed bridge as designed. Found great difficulty in the design of cable-stayed bridge pier foundation. Foundations at depths greater than 60 m, while resisting a huge the seismic forces, where bad scope 20 m deep sea bed soil mechanical properties, so you must take special bridge pier foundation structure. Main bridge tower foundations ultimate structure is shown in Fig. 6.17, using 90 m in diameter of circular reinforced concrete raft foundation. To improve the performance of

soil, took 25~30 m, diameter 2 m steel pipe based on 7~8 m spacing, soil reinforcement, each under a pier, there are about 250 steel piles. To allow sliding between the foundation and the foundation laying on the pole 50 cm with filter sand, laying on the thick and 2 m in diameter for 10~80 cm pebble layer, the top lay thick gravel layer 50 cm. In this way, bridge foundations are put gravel on the total thickness of 3 m above, connections between the foundation and the gravel is weak, may be produced when the earthquake up left and right to move (But in the operational phase and small earthquakes without sliding), plays the role of isolation, which formed the basis of an innovative for the sliding of the “reinforced earth base isolation” (reinforced soil foundation).

Fig. 6.17 Rion-antirion isolation base diagram.

Fig. 6.18 Pier damping system layout diagram. Due to seismic requirements, the bridge incorporates a five span continuous structure of floating. Because the cable is not the main beam to provide effective lateral support, so the floating system must exert some lateral restraint and reduced live load and lateral displacement due to temperature. Final installation of an intermediate connector (fuse restrainer) at each pylon to allow force 10 MN, can be adapted to the vertical displacement of the bridge 1.6 m in transverse direction is almost not moving, so when the lateral load does not exceed the design when the ability to hold the main beam and the lower structure

rigidly connected in transverse. Additional 4 sets of viscous damper, each allowing for 3,500 kN adaptable beam tower 1.3 m addendum modification. When the intermediate connection piece under the action of earthquakes or storms after the failure, the main beam in viscous resistance free swing under control, as shown in Fig. 6.18. Rion-Antirion Bridge features a “reinforced earth base isolation” and transverse dampers, couplings, has created for cable-stayed bridge a new system. Example 6.4. Suspension bridges system—United States New San Francisco Oakland Bay Bridge). San Francisco Oakland Bay Bridge is located in the United States in San Francisco, East of main bridge for steel cantilever truss bridge in 1989, San Francisco decided to rebuild after the earthquake. San Francisco Bay areas, poor geological conditions in the Bay area, the ground surface with a soft, sticky thick layer of soil covering layer, the seismic stability of bridge when you become the controlling factor of bridge design. Under the current common sense, in the earthquake zone construction of suspension bridge tower gantry structure should be. When the earthquake came, at Tower cross can form a plastic hinge at the beam to change lateral stiffness of the structure, reducing the seismic responses. But over the Oakland Bay Bridge project discussions, bay area residents do not want to build another bridge, the gate tower, and fond of single-column pylon of the programme. Meanwhile, the owners also demand that the bridge could resume traffic immediately after an earthquake, requiring bridge due quake damage at repair can go without disrupting traffic. In the form of the then existing structure, this basic is unlikely to meet requirements. Engineers are under study, breaking the existing concepts, the concept of developing a shear key. In fact, this idea is a variant of gantry tower. The principle was to have the tower columns of two in a gate-tower closely placed together (Fig. 6.19). On the tower beam is very short, became—under the shear yield shear keys, instead of the usual tower beams in bending yield. And because the two tower is placed within only a short distance, shear key and doesn’t have a problem with a few more, increase the redundancy of the Tower, strengthening the security of bridges, and instead added more beauty.

Fig. 6.19 Changes of bridge tower form.

Fig. 6.20 Main tower section. Meanwhile, further improvements, the tower is divided into four legs, and connected them with shear key (Fig. 6.20), outside the tower appears to be single column tower (Fig. 6.21), but also have excellent seismic performance and design requirements. In fact, this design’s mechanical characteristics are superior to the gantry tower. San Francisco New Oakland Bay Bridge Towers by changing the connections within the form, with shear key structural measures effectively resolved seismic problems of the single tower, its design is very innovative. Example 6.5. System of partial cable-stayed bridge without backstays—Kunshan summer driving River Bridge. Summer driving bridge (Fig. 6.22) is located in Kunshan development zone, planned recreational area at the location of the bridge, so the bridge landscape demand is higher.

Fig. 6.21 New San Francisco Oakland Bay Bridge.

Fig. 6.22 Kunshan summer driving River Bridge. This bridge spans over the river of with the width of about 50 m, there is a certain navigation requirements, and therefore determines the span of the bridge in 60 m. Bridge types to choose from including girder and tied arch bridge, and so on. Main span simply supported beam of 60 m goes beyond reasonable span; mains even across 60 m continued beam to match the side spans of length 35 m, uneconomic; there is already more than a dozen tied arch, landscape, and people are not welcome. Therefore cable-stayed bridge without backstays could be considered. The world’s first cable-stayed bridge without backstays are designed Alamillo bridge by Santiago Calavtrava, (See Fig. 6.23). Only single tower cable-stayed bridge without backstays lateral funiculus, if mechanical analysis of bridge tower were taken separately, its mechanical performance of cable force for cable and of a cantilever beam under the action of gravity, relying on body weight the overturning moment of torque balance cable. Consolidation with tower, girder, piers, main beams hinged at the other end, full-bridge for a statically indeterminate system. Cable-stayed bridges without backstays overall balance as shown in the schematic is shown in Fig. 6.24. Wt is the weight of main tower, lt the distance between tower gravity

center and tower-solid beam end , Wd weight of main girder of, ld the distance between gravity and the end of tower-solid beam.

Fig. 6.23 Spain Alamillo bridge.

Fig. 6.24 Sketch of overall balance of cable-stayed bridge without backstays. Cable main beam on the overturning moment of Ta Liang Gu node Md = Wd ld, Tower weight resistance torque Mt = Wt lt, tugend under dead load, bending moment M = Mt – Md = Wt lt – Wd ld, to ensure the pylon roots dead load in axial compression state, Wt lt = Wd ld. In this case, only the main tower structure under live loads and load moments. It is clear that conventional cable-stayed bridge without backstays often towers selfweight and stiffness are large. Weight is generally used for main girder light beam in order to reduce the tower’s weight, but makes the whole bridge cost increases, is rarely used in actual projects. Summer sail a River Bridge with pre-stressed concrete girders, and by changing the structure of the internal components of the force, without back-stays partial cable-stayed bridge system, namely the main girder pre-stressing endured after the load is divided into two parts: Wd = Wd1 + Wd2, Wd1 tower weight balance by stayed cable transmission to the leaning tower; Wd2 borne by the main beam (Fig. 6.25). And greatly reduces the weight requirements, tower light weight, ease of construction, and take full advantage of the main beam of material, reducing the cost.

Fig. 6.25 Conventional cable-stayed bridge without backstays and sketch of loading at

non-backstay section. Driving medium within the span of the bridge through the river in summer to adjust the component of force distribution within the structure, using the pre-mix concrete girders, with a leaning tower of auxiliary forces, while ensuring economic performance good aesthetic effect is obtained. Example 6.6. System of the new structure of super long span cable-supported bridges. Traditional super long span cable-supported bridges—a cable-stayed bridge [Fig. 6.26(a)] and suspension bridge [Fig. 6.26(b)] two systems have emerged in recent years cable-stayed-suspension system [Fig. 6.26(c)] and partly anchored cable-stayed bridge [Fig. 6.26(d)]. By studying the above systems, one may conceive partly anchored cablestayed suspension system [Fig. 6.26(e)]. It is not difficult to imagine, the system will both parts of main girder of cable-stayed bridge with reduced axial force and anchored cablestayed-suspension advantages of cooperative system spanning large and become a more long-span van restricted bridge could be considered.

Fig. 6.26 Idea of cable-supported bridges system —Tower system (a) cable-stayed bridge; (b) suspension bridges; (c) cable-stayed-suspension system; (d) partially anchored cablestayed bridges; (e) partially anchored cable-stayed-suspension system. Separately, there is already a multi-tower cable-stayed bridge [Fig. 6.27(a)] and multiple-tower suspension bridge [Fig. 6.27(b)], can be conceived multi-tower cablestayed-suspension system [Fig. 6.27 (c)] based on total anchored suspension bridge [Fig. 6.28(a)] idea, conceived two series of common anchor system, one for “combo” system, as shown in Fig. 6.28(b)and (d) shown in second for “mutual combination” system, as shown in Fig. 6.29(a) and (c) as shown, and continues to expand. This structure for super long span cable-supported bridge offers a variety of options and new ideas.

Fig. 6.27 Idea of cable-supported bridges system —Multi-tower system (a) cable-stayed bridge; (b) suspension bridges; (c) cable-stayed-suspension system.

Fig. 6.28 Of cable-supported bridges system ideas–a anchorage-sharing system (a) winanchored suspension bridge; (b) a total of anchored cable-stayed bridge anchor in part; (c) a total of anchored cable-stayed-suspension system; (d) total bolt partially anchored cablestayed-suspension system.

Fig. 6.29 Cable Supported Bridges mutual combination system conceived—Total anchor system (a) Total anchored suspension bridge—partly anchored cable-stayed bridge; b) Total anchored suspension bridge—stayed—suspension; (c) Co-anchored suspension bridge—partly anchored cable—stayed suspension system. Through the above described can be seen: clear structures and contents, and lay the foundations for bridge structural system; analysis of bridge structural system of force, force transmission route, can be provide clear direction for rational selection of bridge structure system, may also be looking for method of bridge structural system innovation; system for optimising the force structure, reduction of construction investment,

construction convenient, reduced maintenance costs, and meet the needs of engineering, extending the applicable conditions is very important meaning for the construction of the bridge. And bridge system space is vast, systems change can bring new life into this ancient engineering of the bridge.

6.2 IMPORTANT DESIGN PARAMETER OPTIMISATION AND ADJUSTMENT 6.2.1 Classification of Design Parameters of Bridge Structures Design parameters of bridge structure can be divided into general layout parameters and system parameters. General layout parameters primarily deal with structures description, the main span and side spans of cable-stayed bridges, high towers and the cross-ratio, beam and cross-ratio and wide-span ratio is in the design of cable-stayed bridge indexes. System parameters refer to the same type of bridge with different loading systems, such as external constraints, internal connections, etc. Different bridge structures differ greatly in structural design parameters. Bridge design parameters not only reflects the structure of the bridge structure system external form, but also reflects the bridge structure under load forces and their stress response. Table 6.3 shows the four basic types of the main structure of the bridge design parameters. Various parameters of bridge structures (General layout of system parameters and parameters) interact with each other. Structure parameters determine the shape of the structure, load, resistance and stress patterns. Meanwhile, adjust and optimise the structural parameters, can be changed. Variable structure properties, the mechanical properties of structural and economic performance status. Table 6.3 Bridge structural parameters. Bridge type The overall layout parameters

System parameters

Beam bridge

Arch bridge

Cable-stayed bridge • Cross-over the • Span ratio • Cross-over the edge • Arch axis edge • Compared with coefficient • Tower height the midspan • Rib (circle) and mid-span girder high span ratio ratio • Pier high and • Rib (circle) • Compared with mid-span ratio wide span ratio the mid-span • Continuous • Boom or girder rigid frame column spacing • Lasso dip bridge • Component • Wide span ratio • Component form • Cable distance form • Component form

Suspension bridge

• Boundary constraints • Beams, pier connection form

• Main cable anchorage • Tower, beams, piers connection

• Boundary constraints • Arch their connection

• Boundary constraints • Tower, beams, piers connection

• Main cable span ratio • Cross-over the edge • Tower height and mid-span ratio • Compared with the mid-span girder • Beam width and the cross- ratio • Hanger spacing Component form

• Beams, pier stiffness ratio

conditions • Arch , connecting beams form • Arch , beam stiffness distribution

form • Tower beam stiffness distribution

form • Pylons stiffness

6.2.2 Effects of Design Parameters on Structure Loading 1. General Layout Parameters Affect the Structure of Parameter change form has different structural shapes, and affects the structure of the force. Such as tower cable-stayed bridge to span ratio changes that will be affect the force of cable-stayed bridges. Example 6.7. A cable-stayed bridge with a main span of 1400 m programme, the towers span ratio, respectively taken as 0.21 and 0.16, compared with its mechanical properties. General layout as shown in Fig. 6.30. Fig. 6.31 shows results of analysis of the main beam constant load axial force. Main beam buckling under various load safety factors are shown in Table 6.4. Tower height and span of the bridge (Tower) by 0. 21 to 0.16, the reasonable finished dead state of cable has increased 26%, the bridge towers mounted on the main beam axis increased by 34% (Fig. 6.31); live load tower under the action of horizontal displacement 21% and a main span of vertical displacement 22%, column, beam, cable’s internal force increases in about 40%; tower height reduced, stability of pylons is clearly improved, but the stability of main beam was significantly reduced (Table 6.4). Cross-ratio decreases and cable angle decreases and cables on the main beam with elastic supports weakened, resulting in the aforementioned force sensitivity reactions.

Fig. 6.30 General layout scheme of cable stayed bridge with a main span of 1400 m (size: m).

Fig. 6.31 Comparison of main beam constant axial force. Table 6.4 Effect of column-span ratio on overall structural elastic and stability. Load condition

Constant load

Constant load + live load

Dead load + live load + lateral still wind

Elastic buckling simulation Bridge tower vertical buckling

Tower span ratio = 0.21 4.509

Tower span ratio = 0.16 5.948

Main beam outsidesurface buckling

4.474

2.694

Main beam insidesurface buckling

4.714

3.456

Bridge tower vertical buckling

4.168

5.353

Main beam outsidesurface buckling

4.117

2.416

Main beam insidesurface buckling

4.26

3.098

Bridge tower vertical buckling

4.143

5.313

Main beam outsidesurface buckling

4.094

2.397

Main beam insidesurface buckling

4.229

3.074

This shows that the towers and the cross-ratio is one of the most important parameters of cable-stayed bridge in cable-stayed bridge design should take a reasonable height ratio.

2. Effects of General Layout Parameters on Structure Loading Similarly shaped structure by changing system parameters, will be produce different patterns of force, from external constraints, internal company joint stiffness distribution of

these three aspects of the mechanical effect of system parameters on the structure.

(a) External Constraints External constraints implemented through structural supports, different support forms of influence on the behaviours of structures are different. [11] three supported forms of main bridge of Chongqing chaotianmen Yangtze river provided a detailed comparative analysis of results as shown in Table 6.5. Table 6.5 Analysis and comparison of different support systems. Scheme form

Main technical issues (Advantages and disadvantages)

Technical difficulty and countermeasures

Conclusion

1. Clear bearing pattern in upper and lower structural system; 2. Does not form force on the foundation thrust; 3. The temperature had little effect on the structure; One side of 4. Even tie rod force; main span 5. During the arch is a construction structures fixed hinge may be subject to bearing, the displacement adjustment other side without affecting the flexible force structure; hinge 6. The lower road surface bearing landscape effect is good; 7. The need to set up heavy support base

1. Large support has been used at home and abroad and existing technological ability is sufficient; 2. The relevant authorities of the mainland has heavy support research, design ability and technical assurance; 3. Capacity of domestically designed heavyload jack has reached 4,000t, providing a bearing replacement technical assurance.

Clear System load, structure loading reasonable, mounting rack technology is relatively mature and during the construction loading has no effect on structure force bearing, easy to maintain bridge shape and the stress state. Integrated technology indicator is better.

1. Clear bearing pattern in upper and lower structural system; 2. The structural stiffness is better; 3. During the

1. Large support has been used at home and abroad and existing technological ability is

Has a Clear effect on System load, installation technology is relatively mature. The construction requirement is High, construction affects the bridge line, horizontal

Both sides of main span arch uses fixed hinge bearing

construction structures may be subject to displacement adjustment does not affect the force, but was unable to make structural displacement adjustment, effects of construction error and temperature on closure are great; 4. Effects of temperature stress on bearing substructure are big; 5. Does not form force on the foundation thrust; 6. Maximum main truss rod force is stronger; 7. The need to set up heavy support base.

1. The structural stiffness is a little better; 2. During the construction it is unable to make displacement adjustment to structures and angle adjustments, required full Cable construction line, effects Both sides of construction internal forces on structure force of main span arch bearing force are big; 3. Effects of temperature use fixed main pier stress on bearing substructure are big; and the main beam 4. The pivot rod end conjugation bending moment of consolidation is Large

sufficient; cables have high tonnage and 2. The lower large number, anchor structure and placement difficulties. Foundation design requires considerations of live Load and temperatureinduced force; 3. Constant load thrust requires the use of largetonnage level cable for balancing, anchor placement difficulties; 4. The structural closure is very difficult, the need reaming and hole drilling of components for closure, bridging shape is affected by construction, the precision of the closure. 1. The lower structure and foundation design requires considerations of live load and temperatureinduced force; 2. Constant load thrust requires the use of largetonnage level cable for balancing, anchor placement difficulties; 3. Construction process full of

The construction requirement high implementation difficult cables have high tonnage and large number, anchor placement difficulties.

(52000 kN.m); 5. No need to set up heavy support base.

cable bridge shall ensure linear, control is difficult; 4. The structural closure is very difficult, the need reaming and hole drilling forced closure.

Can be found through analysis, changes of external constraints on the behaviour of structure affects the chaotianmen Yangtze River Bridge end used across the arch of the foot side of the fixed hinge, hinge side activity programmes.

2. The Components Connection Internal connection of components is an important system parameters, it changes the same mechanical form of bridge structure can be changed. Large span taliang cable-stayed bridge currently exists between the following five connection types (Fig. 6.32).

Fig. 6.32 Large-span cable-stayed bridge with different forms of connection diagram. The Su Tong Bridge main span of 1088 m, in the design process, the first four talianglian forms are compared. and their stress response. Results are shown in Table 6.6. Table 6.6 Results comparison between different structures under static conditions. Calculation condition

Structure response

Full Vertical Tower beam Horizontal floating support consolidation elastic restraint Cable Towermain beam 5.5E4/ 1.6E4/ 7 800/ – 5.4E4/ –

Live loads

bending moment (kN.m)

– 4.1E4 –7.6E4 1.1E5

4.3E4

Bottom bending moments (kN.m)

1.0E6/ 1.0E6/ 7.9E5/ – –2.8E5 –2.8E5 3.2E5

1.0E6/ – 2.9E5

Main span deflection (mm)

–2190 /145

–2190/ 145 –139/168

The top horizontal displacement (m)

–75/508

– – –66/502 188/603 188/602

Bottom bending moments (kN·m)

Automobile braking force

3772

3.89E5

3.82E5 3.82E5 4.93E6

6805

4.89E5

Horizontal displacement –365 of beam end (m)

–366

–249

–363

The top horizontal displacement (m)

–203

–147

–202

980

–1.69E3

–3 991

–203

Cable Tower main beam 844.1 bending moment (kN.m) Vertical wind turbulance

–2170 /135

Horizontal displacement – – –9/46 of beam end (m) 366/395 367/394

Cable Tower main beam 755.4 bending moment (kN.m) The overall temperature difference 30°

–2190 /146

Bottom bending moments (kN.m)

– – –4.61E5 8.62E5 8.62E5

– 6.28E5

Horizontal displacement –268 of beam end (mm)

–268

–9.5

–116

The top horizontal displacement (mm)

–296

–296

–29

–139

Cable Tower main beam 1 378 bending moment (kN.m)

1 499

–875E4

–3963

Bottom bending moments (kN.m)

– – –1.16E5 5.58E5 5.58E5

–2.99E5

Horizontal displacement –287 of beam end (mm)

–287

–2.1

–120

The top horizontal displacement (mm)

–298

–3.0

–124

–298

Comparison results can be seen from the Table 6.6: compared with float system, Ta

Liang Gu pairing in the primary beam vertical stiffness effect is large, but significantly increased the longitudinal stiffness of the structure. Floating system frees up horizontal forces caused by temperature, but longitudinal wind and steam tower of the vehicle braking force bending moment at the end is 1.9 times and 4.8 times larger than the consolidation system. Set a certain bridge tower vertical elastic constraints with certain rigidity, on the one hand by live loads can be reduced, and vertical wind turbine and tower of automobile braking force taliang and bending moment at the end of the horizontal displacement. The other hand, compared with the consolidation system, released system significantly effect of temperature stress on bottom bending moment. Some of the more typical engineering tower cable-stayed bridge, the beam pattern is shown in Table 6.7. Arch system, connections within the structure of influence of loading form is very obvious. Fig. 6.33 shows the same arch of reamless arch and single arch, two-hinged arch, three-hinged arch under the same load bearing forms.

Fig. 6.33 Envelope diagrams of Arch structure bending moment: (a) hingeless arch; (b) single hinged arched; (c) of two-hinged arch; (d) three-hinged arch.

3. The Stiffness Distribution Component stiffness type also have an impact on the structure patterns of force. Through simple support girder and arch combination system, for example, analysis showed that uniform load acting on the flyover, vault, beam, Derrick’s stiffness on structural mechanical behavior effects are as follows: Table 6.7 The typical structure of large span cable-stayed bridge. Bridge name Country Time Main Main Structure system and main beam (years) span girder restraint (m) Stonecutters China 2007 1018 Hybrid Sarasota office is located hydraulic bridge girder cushioning restraint devices Luo bridge

Japan

1998

890

Hybrid Sarasota office is located rubber bearing girder (vertical support, longitudinal elastic restraint)

Normandy bridge

France

1998

856

Hybrid Tower pier beam consolidation girder

The second bridge

Nanjing 2000 China

628

Steel beam

Qingzhou minjiang bridge

China

2001

605

Hybrid Sarasota office is located rubber bearings, girder unilateral pylon cable set level constraints

Yangpu bridge

China

1993

602

Hybrid Sarasota office is located 0 Faso, full girder floating

Meiko in bridge

Japan

1996

590

Steel beam

Sarasota office is located longitudinally strand restraint devices

Tsurumi channel bridge

Japan

1995

510

Steel beam

Sarasota office is located stand, horizontal cable restraint and propeller damper.

Sarasota office is located steel bearing (vertical support, vertical sliding)

1. Alongwith increase in bending stiffness of arch rib, increased uniformity of suspender force and suspenders to one-fourth across the nearby boom pulling force reduction, small suspender force increased bending rigidity increase of arch ribs, arch spans the central axis decreases, moment magnification, bending moment decrease when Earch Iarch/(Earch Iarch) changing between 1~10 and structure changed a little, but when Earch Iarch/(Earch Iarch) >10, arch rib axial forces significantly decreased, in cross-bending moment increases sharply. 2. With the increase in bending stiffness, arch passes the load decreases, tie beams transfer loads increased beam span moment magnification, and arch rib in the axial force and bending moment decrease; when Earch Iarch/(Earch Iarch) at 0.1 to 10 when the structure changes small, but when Earch Iarch/(Earch Iarch) >10. Trans-axial forces significantly decreased, beams in bending moment increases sharply. 3. Boom axial stiffness on structural properties of available hanging suspenders hanging stiffness parameter

to reflect beams, suspended when

in 1~1 000 changes, Derrick obviously rigidity, stiffness of the system increase. Tie beams uniformly distributed load, trans-axial force increases, and arch ribs and bending moment decrease when

after Derrick stiffness

decreases, can basically be ignored. When hanging EAhang → ∞, and trans-axial force at max, arch and bending moments to a minimum. Local increases the side hangers axial stiffness, can significantly improve the inhomogeneity of suspender force. Therefore, a reasonable percentage change major component stiffness of structural system and structural performance can be optimised.

6.2.3 Design Parameter Optimization and Adjustment During the conceptual design phase, how to determine if bridge’s main structure parameters and component size, or in determining the structure detected after an item index not upto design requirements (including do not meet the requirements), how to adjust parameters to improve indicators of concern are two very important questions. Relationship between structural parameters of bridge and structural response is complex and difficult to describe a specific function. Beginning of bridge design, designers always seek to meet the conditions of the structure parameters and structure parameters of a reasonable solution, but the not a direct, intuitive, but repeated, complex. Is the search for reasonable design parameters of design parameters optimisation and adjustment. Primary goal is to make the design of design parameter adjustments meet the requirements of the code, namely, strength, stiffness, fatigue and durability, economics of demand, while meeting various external constraints. Design parameter’s ultimate goal is to seek to meet design of optimal parameters of structure parameter optimisation. Under a pedestrian bridge to illustrate methods of optimisation of design parameters. Example 6.8. A hingeless arch footbridge spans the 70 m rise 8 m rise span ratio 1/8.75, design effect is shown in Fig. 6.34. The arch bridge design of concrete filled steel tubular structures, pipe 20 mm outer diameter, 800 mm wall thickness, padding C40 concrete, as shown in Fig. 6.35. By the analysis of the following issues: (a) on the bridge was constructed in soft earth foundation under horizontal force great; (b) using concrete-filled steel tube arch rib structure increases the weight, but also increases the horizontal thrust of arch; (c) bridge selfvibration frequency rate is small, cannot meet the pedestrian bridge design specifications. Optimization of design parameters of the bridge.

Fig. 6.34 Pedestrian arch bridge design renderings.

Fig. 6.35 Design cross-sections (unit: cm). While maintaining the original bridge design based on mechanics characteristics of reamless arch bridge, reducing weight is to reduce the horizontal thrust efficient way, but also improve the frequency key. Optimisation scheme using an empty pipe section of the bridge, and dimensions of the pipe cross-section the most optimal solution. Following typical mathematical model is constructed as follows:

In the formula: X = variables; gi(X) = constraints; f(X) = the objective function. Main arch ring of outer tube wall thickness and diameter Ds Ts as a design variable structure self-vibration frequency and maximum stress as mainly around bundle conditions with total weight of steel as the objective function. Results for the diameter of 1.2 m, 18 mm steel wall thickness as the final solution, optimised bridge structures safe and suitable for general premise, steel consumption at least, integrated its cost optimised solution is superior economy. In design, as the parameters of the diversity and complexity of the objective function, you seldom work directly with structural parameter optimization method to determine design parameters, more of a design method of adjusting parameters. Parameter adjustments can be summarised in three ways: the experience method, analytical method, the parameter analysis method.

1. Experience Method Experience is established on the basis of experience in the design, use sum engineering statistics, identify design parameters of a reasonable range of values to guide the design of the new bridge. This method of bridge structures with regular system is the most convenient way.

Fig. 6.36 Uniform radial load of uniform cross-section circular arch.

For example, we design high beam, girder how big is it? Experience has shown that its height-span ratio in the range 1/15~1/30 are feasible, but often controlled within 1/18~1/20 to the design, which is proven by the reasonable, economic height-span ratio. In Article 6.4.2, the reasonable scale of conventional bridges described is the value of experience in conceptual design of the structure parameters. Because this approach is based on completed projects, and new complex structures and bridges are not necessarily effective.

2. Analytical Method Analytical method is through theoretical mechanics obtain design parameters and mechanical values of relationships, a methods used to make adjustments to the design parameters. This method requires designers have good mechanical skills and deep understanding of the structural system. For example, we want to improve radial load lower sectional arch (Fig. 6.36) of the inplane buckling factor analytical method can be used to export its critical load Expression:

, where K and rise span ratio

and arch hinge related to the

number, as shown in Table 6.8. Table 6.8 Critical load of arched co-efficient. ξ

Hingeless arch K1

Double hinged arched K2

Three-hinged arch K3

0.1

58.9

28.4

22.2

0.2

90.4

39.3

33.5

0.3

93.4

40.9

34.9

0.4

86.7

32.8

30.2

0.5

64.0

24.0

24.0

Table 6.8 data indicated that decreased with increased number of hinge the stability of arch; various arches of critical loads in ξ is 0.3, maximum, this is because the ξ-hour arc length is short but high pressure, pressure at large ξ is small but the arc length is longer. Therefore, the formula derived by analytical method, methods of improving qcr increasing EIx, strengthen internal and border around harness changing the ratio of height to span. What specific measures can be determined according to the actual situation.

3. The Parameter Analysis Method For more complex power relationships, parameters and structural response, analytic expression is very difficult, you can use numerical analysis to complete parameter adjustment. Parameters analysis is conducted through the bridge design parameters of quantitative

parameters, and each parameter and structure the numerical relations of the response, which can curve a graphical representation or expression values. Example 6.9. In designing some of the anchored cable-stayed bridge with a main span of 1400 m (Fig. 6.37) the time required to find the ground anchor main beam length range. To main beam length of anchoring segment for parameters, analysing the impact of changes to the force structure. The length at 0~1400 m changes between (0, 200 m, 400 m, 600 m, 800 m, 1 100 m, 1400 m), end span also makes a corresponding adjustment. To main beam length of anchoring segment for different computational models can carry out a detailed analysis of live load effects, results are shown in Fig. 6.38.

Fig. 6.37 General layout scheme of cable stayed bridge with a main span of 1400 m (size: m). Results showed that anchor main beam length is increased, the principal bending moment decrease, main beam length of anchoring segment for more than 400 m changes flattens; main beam stress in axial force decreases tension increases; bending moment decrease main tower, main beam length of anchoring segment for more than 600 m changes flattens; main column axial force changes little; main pylon of main beam displacement and displacement, main beam length of anchoring segment for more than 600 m changes slowly. Therefore, a main span of 1400 m partially anchored cable-stayed bridge anchor section main beam length in the 400~600 m is reasonable. If you want to further optimise the mechanical indices, you can refer to the trends of the curve obtained, the main beam length of anchoring segment for minor adjustment.

Fig. 6.38 Comparison of live load effects (a) bending moment extreme value; (b) main beam axis force; (c) beam displacement extremum; (d), main tower of moment extreme value; (e) main column axial force; (f) extreme value of main tower of displacement.

6.3 CONSTRUCTION METHOD SELECTION AND SAFETY IDENTIFICATION 6.3.1 The Construction Method of Bridge Structures Design and construction of bridge structures are inextricably linked, and in order to do a design, designers must have conventional construction methods and new construction technology. Common construction methods are: overall construction method of cast in situ and pre-cast-install method by span construction method of cantilever construction method, turn construction method of jacking construction method, shifting method, lifting construction method. Each method has its advantages and disadvantages and scope of application, as shown in Tables 6.9 and 6.10. Table 6.9 Method comparison. Construction Processes method Integral in- In bridge place poring erection method bracket, bracket poured on bridge concrete, concrete Redundant template design strength, BRACKET

Strengths

Weaknesses

No pre-fabricated site, no largescale lifting and transportation transportation equipment, a bridge structure integrity

Long duration, quality of construction is not easy to control, frame, template usage is large, high construction costs; big impact on flood relief, navigation, construction period may be threatened by flood and floating subjects

Pre-casting and installation application method

Use mounting methods beam installation, connection, complete the construction of bridge structures

High component quality and On construction lifting dimensional accuracy; short equipment has a higher construction, reducing concrete request shrinkage and creep deformation effect on navigation capability under the bridge depending on the set up.

Hole-byhole construction method

Using a device from a bridgeend-by-span construction until the other side

Without ground support, without affecting the navigation and bridge transportation construction of safe and reliable construction environmental conscience well, guaranteed quality, mold flow frequency, it can be prefabricated field

Investment in equipment and construction preparation and complicated operation

production; degree of mechanisation and automation high, labour-saving, reduce labour intensity Cantilever From piers to construction span method continuous extending beam components (including assembling and in situ casting)

Simple construction, structural Requires high integrity, and construction speed construction precision fast, mounts using a little, does not affect navigation or under bridges pass, save on construction costs, reduce project cost

Poring method

According to local conditions, strong adaptability; during construction period does not affect the traffic under the bridge, construction tools minimal, simple, easy to make and control; easy construction, fast with little operation in the air

Convert supports upon construction completion

Equipment is simple, low cost of construction, smooth no noise, wide application range; strong continuity of operations, construction management, avoid Spider-man operation; good construction integrity

Stress changes, designed to satisfy both the construction and operation needs high steel consumption; does not apply to variable slope, variable height of multi-span continuous girder bridges and bridge with plane curve or a longer vertical curves

The bridge component precasted at bridge site (or roadsides or appropriate location), when the concrete reaches design strength the components are spun back in place

Jacking Pre-cast girder construction is pushed by method incremental launching device towards the designated position

Traverse Next to the fold Do not change the structure of construction structure of the the bridge system method position the structure and lateral moves to gauge fixed position

Lateral movement during the temporary supports required to supporting the construction of the structure weight, support requirements

Traverse Placement of Increase tonnage construction structures in the future premethod fabricated structure on the ground and lift in place.

Requires suitable land or water surface set preparation of high lifting capacity requirement; promoted knot frame should be balanced

Table 6.10 Major construction methods of various types of bridge. Construction Applicable Girder bridge Just Arch bridge method span (m) Simply Cantilever Continuous shelf Arch Masonry Combined supported beams bridge bridge arch arch beam Standard system Construction 20~60 method for integral brackets cast, laying Large precast construction method for installing

20~50

Span-byspan construction method

20~60

Cantilever construction method for

50~320

Poring method

20~140

Incremental launching construction of

20~70

Traverse construction method

30~100

Lifting

10~80

construction method

6.3.2 Relations between Construction Method and Structure Bearing Constant load stress of bridge structures and construction methods are closely related. Construction methods, dead load stress is different. Below is a case study of continuous girder bridge and illustrate the use of dead load stress in different construction methods (Figs. 6.39 and 6.45). Framing in situ method is used during the construction phase I dead load and dead load effect in terms of once full continuous bridge structure on the building, main girder structure at this time is the ultimate system, superimposing these two will get the final construction phase of the internal forces of constant load use simply supported. Continuous construction method, a dead load on the system of simply supported, two dead loads acting on the continuum, each segment without stress superposition with the construction phase, will be eventually constant load; when using span-by-span construction method, a period of constant load distribution in framing between casting method and the method of simply supported-continuous, internal forces of each construction stage stack getting a constant load, phase II constant load the same way as simple supported-continuous; when using incremental launching construction, changing structures in the process of thrusting, so girder has been changed, a period of constant load is pushing the structure in place of the internal forces, two dead loads acting on the final row on the system using balanced cantilever construction method, internal forces of cantilever construction produced by the constant load distribution close to the force on the cantilever bridge state, cantilever bending moment of beam span the negative moment of the transfer as a fulcrum, greatly improving the bridge span.

Fig. 6.39 Full scaffold construction of continuous Liang Heng contains internal force diagram.

Fig. 6.40 Simple supported-continuous constant load internal forces diagram.

Fig. 6.41 Pan-by-span construction internal forces diagram.

Fig. 6.42 Cantilever construction of continuous beam constant load internal forces

diagram.

Fig. 6.43 Incremental launching construction continuous beam ridge pivot bending moment diagram. Creep effects after the bridge, re-distribution associated with construction methods and duration, and live load stress condition and construction of structures has nothing to do. The construction and design of bridge structure has a very close relationship, on the different structures used in construction of bridge structures methods can be different, the same structural form may use different construction methods. During the conceptual design phase, must take full account of construction methods, through proper construction techniques ensure that the design is achieved. Meanwhile, development of construction technology of the bridge, in order to achieve bridge design, offers a flexible and powerful tool, as well as increased span, improved structure and the use of new materials, provided the necessary conditions. Therefore, the design and construction are complementary, mutually binding.

Fig. 6.44 Cantilever construction of continuous beam constant load internal forces diagram.

Fig. 6.45 Incremental launching construction continuous beam ridge pivot bending moment diagram. Bridge system is complex, and often fail to press the picture and complete the construction, and need to go through a number of structural system of transfer change. Therefore, when considering design, taking into account the possibility of construction, economics and rationality. With vertical pre-stressed reinforcement of continuous beam configuration below to

illustrate the relationship between design and construction methods. Layout of vertical pre-stressed reinforcement of continuous beam under different construction methods are: sub-paragraph continuous reinforcement, reinforcement, and so on.

1. Continuously Reinforcement Construction of cast in situ continuous beam, longitudinal pre stressing tendons in accordance with distribution in all parts of the force requirements of the bridge beams. Usually quantity in the line up of the parabolic trajectory. As Fig. 6.46(a), as l1 l2 l3 l4 shown in the side across and are made up (a) of multi-section parabola, and anti-between inflection points of the curve. Reinforced concrete according to figure 6 layout can be considered as in Fig. 6.46(b)) shows, which close to the fulcrum by negative bending moment area turned to positive bending moment areas, while the bending point of view slightly (b) weakened, but near the fulcrum cross-section shear resistance is greatly improved.

Fig. 6.46 Continuously reinforced rib layout.

2. Fragmented Reinforcement Piecewise is cantilevered construction of reinforcement and construction of simply supported-continuous continuous most commonly used reinforced concrete beams. Cantilever construction of continuous girder bridge, is starting from the pier to the symmetrical cantilever construction, in order to support girders and construction of selfweight load set out in cantilever construction of pre-stressing requirements. System when tensioning forces reinforced and complemented other positive moment required to use phase quantity, this quantity is also called secondary tensioning bars or late bar. Fig. 6.47 shows the cantilever construction continuous beam bridge reinforcement general construction, where solid gluten is tensioned reinforced during the construction process, dashed line is reinforced later in the system conversion stretching tendons.

Fig. 6.47 Sketch of sectional reinforcement of cantilever construction continuous beam. Installation consists of simply supported-continuous construction of continuous girder bridge, which is adopting the sectional reinforcement of prestressed tendons Fig. 6.48. Pre fabrication pre-fabricated components based on force and consider lifting must be secured with tensioning, simple installation levels, this secondary tension reinforcement of pier site layout, then the secondary tensioning.

Fig. 6.48 Sketch of sectional reinforcement of cantilever construction continuous beam. To sum up, portrait of pre-stressed concrete continuous beam bridge stress reinforcement layout are many and varied, which is used by builders and has a close relationship. Different methods require different kinds of pre-stressed reinforcement layout, while the number of prestressed reinforcement depends not only on the force structure in using also depends on the structure during the construction phase of the force.

6.3.3 Selection of Construction Method Due to construction methods and stress are inextricably linked, in the conceptual design phase to select the construction method. Construction method selection principle should be practical, safe and effective. First according to the type of structure, the span of the bridge, piers low height, base depth, and overall size, it puts forward some feasible methods of construction, and then fully into account location natural environment, topography, geography, geological and hydrological conditions and transportation conditions, weigh the various construction methods applicability of filter. For example, to complete the construction of a deep foundation, and the construction method can be guarantee before the floods came out of design flood water levels, even taking into account if the flood comes ahead, with or without remedial construction method can guarantee the safety of du Hong. If you are not guaranteed, you want to consider other options. Advanced construction methods generally have good benefits, for speeding up construction progress, reduce material consumption and improving project quality volume is an important way. In order to determine the inclusion or exclusion, and also lack of experience should give full consideration to adoption of new technologies can bring a certain amount of risk.

Bridge construction period requirements, sometimes will have a larger selection of construction method, to determine impact. Such as pre-constructed segment of construction speed is much faster than the cast assembled, and beam quality is assured, and repeat for the construction of the overhead bridge more economy. Social and environmental impacts are also factors that must be taken into account in the choice of construction methods. Should be given to the construction on the environment pollution, destruction of the landscape, the interference of traffic, as well as the impact on the surrounding ecosystem. In the choice of construction methods, influence of various factors must be taken into account, through the comparison and determine the best builders in order to save investment, shorten, improve construction safety, advanced construction techniques could be appropriate, on the reduction of low construction costs, ensuring the quality, accelerate the construction schedule and safety are very important. Example 6.10. France Millau bridge. In France across the Tarn Gorge in southern Millau bridge (Fig. 6.49) is a consecutive seven-tower cable-stayed bridge span into 204 m + 6 × 342 m + 204 m. Their deck to the highest point is 270 m, the equivalent of 90 stories high, pier 2nd cable highs reach the height from the ground 343 m. In such conditions, conventional framing, sized cantilever or assembling difficulty completing tasks. In order to ensure the smooth construction of the bridge, research a set of suitable cable-stayed bridge incremental launching construction method: select P2~P3 as closure, the steel box-beam push from both sides to closure. In order to push closer to 150 m, the middle span erecting a set fitted with tow equipment of steel-tube truss of Falsework (Fig. 6.50). In the process of pushing for reduced cantilever base bending, thrusting structure on both sides of the front beam guiding beams are installed, install a bridge tower closest to the end and 6 on cable, and push the process of adjust tension by adjusting the internal force of girder (Fig. 6.51). After the closure of the bridge, trailer to transport other pylons to the corresponding position and rotation in place (Fig. 6.52). Thanks to these advanced construction techniques, makes this a special bridge (Fig. 6.53) possible, but also saves construction costs.

Fig. 6.49 Facade layout (size: m).

Fig. 6.50 Temporary support Pier used in the pushing process.

Fig. 6.51 In the process of pushing the front beam installed pylons and cables.

Fig. 6.52 The rest of main tower installation drawing.

Fig. 6.53 France Millau bridge upon completion.

6.3.4 Construction Safety Identification Bridge construction is a complex and dynamic system, with the construction phase of the advance, the main structure of gradually increasing structural resistance power and the structural response is time-dependent, its boundary condition and structural system with changing process of construction. Under normal circumstances, the most dangerous stage often occurs during the process of construction. So that during the bridge construction, you must be ensure that each application stages of security. In the conceptual design should be pay attention to in the construction of four kinds of extreme conditions: 1. each construction stage of bridge structure’s ability to resist wind damage and flooding accidents; 2. the stress state in the control section of the most unfavourable construction phase; 3. the displacement of the cantilever end state; 4. the structural stability of the construction phase. Paying particular attention to floods and typhoons in the conceptual design, ship and other unsafe impact on structures. In General, within sunk pier foundations before flooding beyond the design flood water level. Actual projects upstream flood crest early arrival, construction equipment does not feet factor caused the accident are many examples of such accidents. Will also encounter a similar situation in the bridge, that can not be ignored due to an accident the consequences. In upper structure construction is also possible accidents resulting in significant financial losses. To bridge this concept should be considered in the design. Concept design should also focus on constraint pouring of large and complex structures, the most disadvantaged, cables and pre-stressed cantilever construction stage pull, system conversion and other stages, designed to leave in safety. Conceptual design phase, also through the construction phase to determine the bridge during the construction phase of the security risk assessment.

6.4 ESTIMATION OF BRIDGE STRUCTURE AND RECOGNITION OF ADVANCE Design of bridge structure is: development of structure member sizes, through the calculations to verify the safety and legitimacy, then adjust the original estimate to optimize the structure of alternate process. Advances in computer technology and software, putting us on a size of bridge structures that have been identified are essential accurate analysis possible. However, when we begin conceptual design, the size of these structures must be based. Meter personnel to develop. Early size should be within a reasonable range, otherwise it would gut the entire design. The bridge’s advanced nature is the embodiment of technological progress, but also guarantee the competitiveness of the important guarantee. Bridge’s advance, must begin at the concept design stage. Therefore, during the conceptual design phase, estimation of main stress components of the stress state of the bridge, and prepare its size appears to be particularly is very important.

6.4.1 The Estimation Method of Bridge Structures Estimation of bridge structure is in the case of component dimensions unknown, using a simple method to estimate the size of its main component, and pile stress. Therefore, you must explicitly load status, structure, construction of a bridge method and boundary conditions. Loads are diverse in the bridges, but during the conceptual design phase are estimated dead load (weight), the live loads (cars, people) role. Statically indeterminate structures should also be considered generalised loading effects such as temperature, bearing displacement. Dead load has been built according to the structure and architecture experience to estimate dead load can be determined early. Live load can be reduced to distributed load, will be analyse the most disadvantageous position as an important section. For some of the load bearing structure or structures, live load reduction turn into dead load multiplied by a scale factor, merged with the dead load analysis. Estimates, the calculation mode to try to simplify the structure, spatial plane and complex structure simplification, while also taking into account the effects of construction process on structure loading. Following a single-span suspension bridge, for example, indicates that structure estimation methods. Example 6.11. Design a 1000 m programme for steel box girder of suspension bridge main span, height-span ratio is one-tenth, the live load for road-I level, the two-way sixlane. as shown in Fig. 6.54. Estimated dead load, live load and size of main stress components of the bridge under the internal forces.

Fig. 6.54 Scheme of steel box girder suspension bridge with main span of 1000 m. The main component of this bridge are: main cables, slings, main tower, steel box girder, after determination of main cable of anchorage design loads can also be also be determined.

1. Loading (a) Constant Load According to the established six-lane suspension bridge with steel box girder, assume that the width of the bridge is 34 m (taking into account the reserve and emergency parking lane), beam height 3.5 m. Steel box girder and suspenders weight is assumed to be 500 kg/m2, which can be used to estimate their weight load is: 500 × 34 ÷ 100 = 170 kN/m. Set weight of bridge deck pavement and crash bars around 50 kN/m.

(b) Live Loads According to specifications, six-lane traffic loads through vertical and horizontal reduction, and consider improving the eccentric load factor 1.15, then the concentrated live loads for 6 × 360 × 0.55 × 0.93 × 1.15 = 1270 (kN), uniformly distributed load of 37.35 kN/m. Loads can be adjusted according to the actual situation as above, as a basis for estimation.

2. Estimation Analysis (a) Estimation of Main Cables The main cable is the main load-bearing components of the bridge, dead load borne by the main cables of the construction phase, bridge with stiffening beam to share, but in longspan bridges, the stiffening girder of sharing part is negligible. Main cable curve approximation for the parabolic line cable horizontal force (two cables together, the same below) as follows:

Maximum force of main cable (at the top) is:

In the formula: l =

main span;

gd =

per linear meter weight of slings, stiffening and paving;

gc =

cable per linear meter of weight;

q =

uniform live load;

P =

focal live load;

f =

rise of the main cable;

φ =

saddles bridge main cables and horizontal angles.

Stress capacity of cable material is γc is located = 78.5 kN/m3, cable material design strength σs = 1670 MPa, factor of safety γ0 = 2.0 (project value at 2.0~2.5), the gc to γcAc = γc γ0 Tm/σs in place, can be found across primary horizontal force of the cable as follows:

Maximum force of main cable (at the top) is:

From which the main cables area can be deducted :

In accordance with the principles across the horizontal force of the main cable of the same approximate, using Ta = Hm/cos φa side span cables can be further evaluated the great pulling, where φa is the saddles edge across the angle and the horizontal line of the main cable. Across the main cable curve is a catenary, estimates still put aside curve approximation. Side span of la = 300 m, loose saddle point to control point of the main cable saddles of a vertical distance h = 140 m, side spans rise fa ≈ 5.152 m, then:

from which the main cables area can be deducted:

(b) Sling Estimation Spacing for hangers developed for 15 m, 2 pieces on each side. Sling maximum internal forces occur when the load is shown in Fig. 6.55. Concentrated load P born by the 30 d d stiffening girder and may be viewed as uniform load within this range , where d is the stiffening beam height. At the maximum Internal forces the hanger bears the cable within

the spacing range with length of λ, stiffening and weight gd paving, uniformly distributed live load q and concentrated live loads such as

. As the bridge has two cable facades,

and each sling consists of 2 cables, so the load value is one-fourth of full-bridge load. Maximum internal force of Th is:

If Derrick safety factors γ0 = 3.0, the area can be deducted as follows:

Fig. 6.55 Maximum internal force of hangers loads.

(c) Estimation of Main Tower At constant load, horizontal force at the top of the main cable is balanced, the tower only vertical forces generated, whose value is as follows:

Under the live loads, vertical force is:

Fig. 6.56 Tower top displacement under live load model. Due to the little impact of tower top displacement on main cable, if first assuming fixed on the top, then under the live loads across the main cable horizontal force increment is

. Under live loads resistance of main tower can be ignored

under rigidity, this tension increment will be determined by cross the elastic elongation of the main cable to the resistance, as shown in Fig. 6.56. Set top displacement as

. In the formula, Eeq is cable of

equivalent elastic modulus, calculated by the Ernst equation get

Aa is the area of side span of cable from the side maximum force Ta to get

=

504571 mm2. From thin one can work out tower top displacement:

If tower vertical cross section moment of inertia It =300 m4, total height of the tower from the bottom surface of the ht = 180 m, C50, concrete is used, main tower of bottom bending moment weight is negligible, the bending moment at the end of may, according to calculation mode of a cantilever beam subjected to forced displacement as:

(d) Estimation of Main Beam Set the moment of inertia of the beam I = 3 m4, A = 3 m3, Professor of internal force of girder can follow Brandon in 1941, equivalent beam method estimates the equivalent diagram of the beam is shown in Fig. 6.57. Where Hd is under dead load cable tension, Hl is loading the additional tension of the main cable, g is the dead load, q(x) is the live load intensity (including concentrated loads). The method is based on the line deflection theory

derives, which ignores the load cable tension on vertical load provided by the resistance.

Fig. 6.57 Sketch of equivalent beam method. Below using live loads on the main span as an example, calculate the main beam bending moment. For ease of calculation, will treat the live load as uniform live load. Thus in Fig. 6.57, q = 38.27 kN/m, g = gb + γc Ac = 257.61 kN/m, Hd =

= 322012kN.

And Hl is unknown here, cannot be solved by equivalent beam method, therefore needs to be supplemented by a main cable compatibility equations. Since the horizontal projection of the total length of the main cable is constant, it is easy to deduct cable compatible equations as follows:

In the formula: η = stiffening girder deflection φ = stiffening angles. η, φ can be obtained by the fundamental solution of the bending beam, full span of bending beam load basic solutions as shown in Table 6.11. Table 6.11 Fundamental solution for bending simple support beam. Legend

Deflection η(ξ)

Angle φ(ξ)

Bending moment

Note: Combining Table 6.11 and main cable compatibility equation, after a simple iteration Hl and η can be obtained, resulting in stiffening beam bending moment. The steps are as follows: 1. Assumed that the initial value of Hl, according to precision requirements step ΔHl. 2. To determine the value of Hl, is given in Table 6.11 η(ξ), φ(ξ) formula η and φ.

3. Simpson quadrature formula is used to calculate two integral equations compatibility, compatible function f(Hl). 4. Use Hl iteration value is calculated:

In the formula: Hl current value of; Hl, i = Hl, i + 1 = Hl New iteration of the values. 5. Repeat steps (b)~(d) until f(Hl, i) fully close to 0, satisfy the accuracy requirements, get the Hl and η which is the theoretical value. 6. Using mid-span bending moment calculation formulas in Table 6.11 to obtain stiffening beam bending moment. The Iterative process of this case is shown in Table 6.12, calculation formula step size set as ΔHl = 100 kN. Table 6.12 The iterative process of equivalent beam method. i Hl, i (kN) 1

f(Hl, i)

f(Hl, i + ΔHl)

Hl, i + 1(kN)

10000.0

30.27

–5.980128

–5.980111

44354.3

2. 44354.3

2.78

–8.933259E–02

–8. 931536E–02

44873.0

3. 44873.0

2.37

2.505165E–05

4. 228345E–05

44872. 9

Min (kN.m)

4421.8

The iterative process can be seen is Table 6.12, convergence is very fast. Finally stiffening beams bending moment is calculated as 4421.8 kN·m. Final estimates of this bridge is shown in Table 6.13. Table 6.13 Component dimensions and load. Components

The main cable

Main span area (mm2)

Dimension Side span area (mm2)

Load —

Main span pulling force (kN)

Side span pulling force (kN)

479102

504571

—

479102

504571

Area

—

—

Pulling force (kN)

—

Hanger rod

Cable tower

Stiffening beam

(mm2) 1813

—

—

1813

—

Total height (m)

Corss-section moment of inertia (m4)

—

Tower top displacement (mm)

Tower bottom bending moments (kN.m)

180

300

—

180

300

Beam height (m)

Area (m2)

Corss-section moment of inertia (m4)

Main span bending moments (kN·m)

—

3.5

3

3

3.5

—

6.4.2 The Rational Scale of Conventional Bridge Conventional bridge (mainly beam bridges, arch bridges, cable-stayed and suspension bridge) dimensions are typically determined by comparing with existing similar designs, so to speak, it is both an empirical formula and the results of design optimisation.

1. The Pre-stressed Concrete Beam Bridge Set the pre-stressed concrete beam bridge main span as L, beam height h, the high beams of a reasonable range is: Simply supported girder bridge with Bridge with uniformed height continuous beam

, common

Bridge with un-uniformed height continuous beam Continuous rigid frame For a railway bridge or road and bridge in soft soil areas or large temperature difference between the environment, h value should be set at the maximum. Table 6.14, Table 6.15 give beam height or plane thickness in part of the simply supported uniformed cross-section beam, as well as beam height in variable cross-section continuous beam and continuous rigid frame. Table 6.14 Simple support uniformed cross-section beam height or slab thickness Span Section Load beam (m) form 10 Hollow Highway-grade-I,

Height or slab thickness (cm) 60

Note

h/L

Pre-stressed

1/17

slab

Highway-grade-II

concrete plate

13

Hollow slab

Highway-grade-I, Highway-grade-II

70

Pre-stressed concrete plate

1/19

16

Hollow slab

Highway-grade-I, Highway-grade-II

80

Pre-stressed concrete plate

1/20

20

Hollow slab

Highway-grade-I, Highway-grade-II

95

Pre-stressed concrete plate

1/21

20

T-beam Highway-grade-I, Highway-grade-II

150

Pre-stressed concrete plate

1/13

25

T-beam Highway-grade-I, Highway-grade-II

170

Pre-stressed concrete plate

1/15

30

T-beam Highway-grade-I, Highway-grade-II

200

Pre-stressed concrete plate

1/15

35

T-beam Highway-grade-I, Highway-grade-II

230

Pre-stressed concrete plate

1/15

40

T-beam Highway-grade-I, Highway-grade-II

250

Pre-stressed concrete plate

1/16

Table 6.15 Beam height in variable cross-section continuous beam and continuous rigid frame bridge. Span (m)

Section form

30 + 50 + Single-box dual30 Chamber

Bridge Beam height width (m) Notes (m) Fulcrum Across 8.50 2.80 1.50 1982, continuous beam

h/L Fulcrum Across 1/18 1/34

47 + 3 × 70 + 47

Double-box dual-Chamber

21.0

4.00

2.00 1979, continuous beam

1/18

1/35

59 + 7 × 90 + 59

Double-box sibgle-Chamber

24.0

5.40

3.00 1983, continuous beam

1/17

1/30

70 + 94 + Single-box 70 single-Chamber

12.0

5.00

2.00 1985, continuous beam

1/19

1/47

70 + 4 × Single-box 100 + 70 single-Chamber

13.0

5.50

2.20 1995, continuous beam

1/18

1/46

80 + 110 + Five-box single80 Chamber

24.0

5.50

2.70 1983, continuous beam

1/20

1/41

75 + 7 × Single-box 120 + 75 sibgleChamber

18.5

6.50

2.60 1993, continuous beam

1/19

1/46

70 + 2 × Double-box 125 + 70 sibgle-Chamber

31.0

6.80

2.50 1993, continuous beam

1/18

1/50

85 + 154 + Single-box 85 single-Chamber

11.0

8.50

2.80 1991, continuous beam

1/18

1/55

65 + 125 + Single-box 180 + 110 single-Chamber

15.0

10.00

3.00 1988, continuous rigid frame

1/18

1/60

162.5 + 3 Single-box × 245 + single-Chamber 162.5

19.5

13.0

4.10 1995, continuous rigid frame

1/19

1/60

150 + 270 Double-box + 150 sibgle-Chamber

31.0

14.8

5.0

1/18

1/54

2000, continuous rigid frame

2. Arch Bridge Listed in Tables 6.16 and 6.17 are rib arch height and height-span ratio in rib arch and box arch. Table 6.16 Arch cross-section area in reinforced concrete arch bridge. Span Arch cross-section Notes (m) (cm) 30 Height 90, width 85 H-shaped double-rib, rib spacing 4.95 m (1/8) 40

Height 90, width 60 Rectangular three-rib, ribs spacing 4 m (1/5)

50

Height 120, width 80 (1/5)

H-shaped double-rib, rib spacing 5 m

60

Height 140, width 90 (1/6)

H-shaped double-rib, rib spacing 5 m

65

Height 160.1, wide Rectangular double-rib, ribs spacing 5 m, width variable 164 (1/5) section arch width 221.7 cm

Note: Are the ratio of height to span. Table 6.17 Arch ring thickness in reinforced concrete arch bridge. Span (m) Arch ring thickness (cm) 30 91 (1/8) Box width 132 cm

Notes

60

130 (1/7)

Box width 130 cm

92

160 (1/10)

Box width 159 cm

100

160 (1/6)

Box width 130 cm

146

250 (1/4)

Box width 1050 cm (single-box three-chamber)

Note: Are the ratio of height to span.

3. Cable-stayed Bridge As for two-span cable-stayed bridge with single tower, side-to-across ratio is usually 0.5~0.8, with the majority being 0.6~0.7. For twin towers three-span cable-stayed bridge, side-across ratio is 0.3~0.5, with the majority being 0.4. Tower height above the deck and the cross-length ratio is typically between 1/4~1/7, mostly about 0.25. Beam height and main span-length ratio in early thin cable systems is generally 1/5~1/70, in dense cable system generally 1/70~1/200. Table 6.18 lists some of the main dimensions of cable-stayed bridges. Table 6.18 Dimensions of cable-stayed bridge. Span Tower (m) height (m)

Beam height (m)

Sidecross tatio

Bridge type

230

113

4.0

0.870

Single tower single-cable-plane, concrete box beams, built-in 1988

288

56.4

2.4 (boxes)

0.474

Double tower double cable plane, double box girders built-in 1987

400

91

2.78

0.450

Double tower double cable plane, concrete box beams, built-in 1995

450

78.3

4.0

0.368

Double tower single cable plane, steel box girders built-in 1987

465

94.3

2.315

0.393

Canada, double tower double cable plane, H-shaped steel beams and concrete deck girder, built-in 1987

510

131

4.0

0.498

Japan, double tower single cable plane, flat steel box girders built-in 1995

590

136

3.5

0.492

Japan, double tower double cable plane, flat steel box girders built-in 1995

602

144

856

152

890

175

2.96 3.00 (steel) 3.05 (concrete) 2.7

0.404

Double tower double cable plane, steel box-girder and concrete composite beam, built-in 1993

0.417

France, double tower double cable plane, composite beams, on each side there is 191 m and 337 m smallspan concrete continuous girders connected with main beam , built-in 1995

0.360, 0.303

Japan, double tower double cable plane, flat steel box girders built-in 1999

Note: 1. Unless otherwise indicated herein are our bridges. 2. Side-across ratio with Two numbers indicates that cross-span on two sides are different.

4. Suspension Bridge Completed suspension bridges, side-span ratio is mostly between 0.2~0.3, United States George Washington Bridge has the smallest side to span ratio of 0.174, whereas the largest side-span ratio is the Akashi Kaikyo Bridge of 0.482. The vertical cross-ratio of suspension bridges is 1/9~1/12, heavier suspension bridges adapt bigger vertical cross ratio in order to limit the increase of forces, such as the great belt East bridge, vertical cross-ratio is 1/9; box lighter beam may have small vertical cross-ratio to increase the stiffness of suspension bridge. Bosphorus bridge vertical cross-ratio is 1/12; self-anchored suspension bridge has greater vertical cross-ratio than ground-Anchored suspension bridge, generally about 1/5. Table 6.19 lists some of the main dimensions of cable-stayed bridges. Table 6.19 Major dimensions of cable-stayed bridge. Span Tower Beam Side- Main Main (m) height height cross- beam beam (m) (m) ratio diameter vertical(mm) cross ratio 300 104.6 300

94.4

12

0.417

467

3.17 0.468

119.0 570 and 8.90 117.37

Bridge type

1/5

Korea, three-span steel truss selfanchored suspension bridges, double traffic deck

1/6

Japan, three span self-anchored suspension bridge, built-in 1990

0.20

762

1/9.85

Japan, three-span steel truss steel tower, upper and lower deck multiple transport system, built-in 1993

770 135.85 9.00 0.325

626

1/10.14

Japan, three-span steel truss steel tower, built-in 1983

about 876 136

12.5 0.377

840

1/10.68

Japan, three-span steel truss steel tower, road-railroad dual function, built-in 1985

888 147.55

3.0

0.340, 0.392

687

1/10.5

Japan, single-span steel box girder concrete tower, built-in 1997

900

3.0

0.25, 0.283

560

1/10.5

Japan, single-span steel box girder concrete tower, built-in 1996

1280 210.41 7.62 0.268

924

1/8.94

Japan, three-span steel truss steel tower, built-in 1937

1100

1/ 11.0

Japan, single-span steel box girder concrete tower, road-railroad dual function, built-in 1999

0.223, 0.243

864

1/10.5

Single-span steel box girder concrete tower, built-in 1999

1991 282.8. 14.0 0.482

1120

1/10.0

Japan, three-span steel truss steel tower, built-in 1998

128

1377 201.4 7.643 0.218 183, 186

1385

3.02

Note: 1. Main cable vertical-span ratio is based on cross data. 2. The tower height is from the surface of base to the top of the tower. 3. Side-across ratio with two numbers indicates that the side span on two sides are different.

6.4.3 Conventional Bridge Materials Index As with conventional bridge component scales, material consumption and economic indicators are also vary within a certain range, beyond which a design may be innovative, advanced, and also can be dangerous and wasteful. Conceptual design phase, one should have an objective assessment of the design’s economic indicators and compare it with that of the conventional bridges. Tables 6.20 and 6.21 list conventional bridge materials index

1. Beam Bridge Table 6.20 Simply-supported girder bridge materials index. Span (m) 13

Cross-section Hole-shaped hollow plate

Materials index per square metre of deck Concrete High-strength steel Bars 3 2 2 (m /m ) (kg/m ) (kg/m2) 0.53 — 89. 4

20

Hollow plate

0.738

25.6

21.5

16

T-shaped

0.29

—

82

20

T-shaped

0.34

—

84

Table 6.21 Pre-stressed concrete T-shaped beam materials indicator (1983 final drawings). Span (m)

Crosssection

Materials index per square metre of deck Concrete PC steel products Ordinary steels (m3/m2) (kg/m2) (kg/m2) 0.38 14 15

25

T-shaped

30

T-shaped

0.41

15.7

50. 7

35

T-shaped

0.46

19.1

52.3

40

T-shaped

0.49

22.4

53.4

50

T-shaped

0.4

28.7

49.4

62

T-shaped

0.56

44.6

72.4

Note: The table does not include decks, the number of crash barrier or railing and walkways. The 50 m and 62 m span data are from individual bridge, not blueprint. Table 6.22 Girder bridge upper part structures materials index. Materials index per square metre of deck Built year and construction Span (m) Cross-section Concrete PreOrdinary methods steel (m3/m2) stressing steel (kg/m2) (kg/m2) 11.5 + 30 Single-box 0.38 17.7 66 1975, bracket assembly + 11.5 multiChamber 41 + 2 × Multiple T40 + 41 shaped beam 19 × 40

Multiple Tshaped beam

30 + 50 + Single-box 30 dual-chamber

0.5

20

75

1978, simple support followed by continuous continuity

0.564

19

58.9

1998, simply-supported girder precasting and installation

0.59

24

57.2

1982 cantilever

42.5 + 3 × 54 + 42.5

Multiple Tshaped beam

0.53

30.5

64.6

1984, simple support followed by continuous continuity

48 + 3 × Double-box 60 + 48 singlechamber

0.58

35.9

44.2

1983, cantilever

9 × 60

Double-box singlechamber

0.72

29.2

61.9

1983, pusher

47 + 3 × Double-box 70 + 47 doublechamber

0.63

24.7

70

1979, cantilever

73.3 + 3 × 90 + 73.3

Double-box singlechamber

0.58

33

118

1984 , floating crane installation

59 + 7 × Double-box 90 + 59 singlechamber

0.83

49.3

92.6

Around 1985, cantilever

36 + 58 + Single-box 90 + 58 singlechamber

0.87

30.7

94.7

2003, cantilever, continuous rigid frame

Note: Unless otherwise indicated herein are all continuous beam.

2. Arch Bridge Table 6.23 Reinforced concrete arch bridge superstructure materials index. Clear span (m)

Materials index per square metre of deck of arch

40

Bars (kg/m2) 113.3

Concrete (m3/m2) 0.76

50

181.2

0.85

60

152

1

Note: This table is converted from “The highway bridge and culvert/m clear span of the arch bridge design manual”, calculate area is the arch area of the ventral surface of the horizontal projection, so the indicators are greater that the results of full-bridge-area calculations. Table 6.24 Box arch bridge upper part structures materials index. Clear span (m)

Materials index per square metre of deck of arch Bars (kg/m2)

Concrete (m3/m2)

30

8.1

0.31

60

19.4

0.65

66

19.8

0.45

92

30

0.63

100

30.6

0.53

Note: This table is converted from “The highway bridge and culvert/m clear span of the arch bridge design manual”, calculate area is the arch area of the ventral surface of the horizontal projection, so the indicators are greater that the results of full-bridge-area calculations.

3. Cable-stayed Bridge Table 6.25 Cable-stayed bridge superstructure materials index.

Main span (m)

Main structure, materials

Concrete box 230 girders, concrete single tower Double-box steel 288 girders, concrete dual-towers Steel-concrete composite beam, 465 concrete dualtower Flat steel box girders, steel twin 510 towers

Materials index per square metre of deck Concrete Ordinary Stayed 3 2 (m / m ) steel (kg/m2) cable Upper Lower Upper Lower (kg/ 2 part part part part m )

Notes

Built in 1988 0.98

1.52 179.6 122.6 111.9 Built in 1987

—

0.19

—

1.18 400.1 78.2

20.5

0.29 188.1 68.8

Canada, built-in 1987, lower part contains tower 50.5 column only, does not include foundation

—

Japan, built-in 1995, lower part contains tower 510.8 348.3 67.1 column only, does not include foundation

Note: The construction volume of main tower is part of the lower part construction. All bridges not specified otherwise are cable-stayed bridges in China.

4. Suspension bridge

Table 6.26 Cable-stayed bridge superstructure materials index.

Main span (m)

Main structure, materials

Three-span, steel truss, 570 steel tower

Three-span, steel truss, 770 steel tower

Three-span, steel truss, 570 steel tower

Single-span steel box 900 girder, concrete tower Three-span, 1280 steel truss, steel tower Three-span, steel truss, 1991 steel tower

Materials index per square metre of deck Concrete Ordinary Stayed (m3/ m2) steel (kg/m2) cable Upper Lower Upper Lower (kg/ 2 part part part part m )

—

—

—

—

Notes

—

Japan, built-in 1993, twodech bridge, lower part indicators 1008.3 610.2 360.6 do not include foundations, and anchorage, but steel consumption data only

—

495.7

Japan, built in 1983, lower indices lower part indicators 203.5 do not include foundations, and anchorage, but only steel consumption data

—

Japan, built-in 1985, twodech bridge, lower part indicators 611.3 166.8 283.7 do not include foundations, and anchorage, but only steel consumption data

4.83

412.7

171

—

Built-in 1985, steel consumption data in tower, 267.2 anchorage unavailable

United States, built-in 1937 —

—

—

498.1 778.8 429.7

—

Japan, built-in 1998, foundation, anchorage steel 648.2 360.1 432.2 consumption data, unavailable, lower part steel indicators are only for the tower

Note: The construction volume of main tower and anchorage is part of the lower part construction. All bridges not specified otherwise are cable-stayed bridges in China.

6.4.4 Identifying Advances Any actions with thorough thought during construction to increase security, lower costs, improve and beautify the structure and environment, improve structure durability and environmental design, or through the introduction of new materials, new technology and new equipment to simplify and shorten the process of construction, overcoming difficulties that cannot be solved by conventional methods are all advances. In contrast, raise costs, increase the risk of work for the sake of innovation should be regarded as backward. identification of advance must start from the concept design. Security is an eternal topic, pose a security risk has two major factors: natural and man-made disasters. Natural disasters are mainly seismic, wind, mudslides, floods and snow disaster and so on. Man-made disasters include overloaded, traffic accident, collision, etc. In order to withstand the earthquake disasters, ensuring great structural safety under seismic forces, Greece bridge Rion at conceptual design stage base isolation is used, placing the steel caissons on gravel cushion, allowing relative slip between the Foundation, which guarantees the safety of tower columns.

Fig. 6.58 Facade layout of three arch bridges (size: mm) (a) Thrust steel arch bridge (b) Dead load thrust-free prestressed concrete arch bridge, (c) Thrust of reinforced concrete arch bridge. “Economy” is a relative concept, economy at stake of security, be could not attend. In the mid-1990s, many bridges are built very economical, but these bridges low safety factor, ability to withstand overload is also low, cannot be said to be advanced. Similarly, materials indications listed in the previous section lists reflect bridge economic performance from a certain angle. A bridge with real advances in the economy can be reflected in the land system, material, functional structures, construction and other aspects. In downtown Kunshan Lou Jiang adjacent three newly built arch bridges, main span is around 40 m, as shown in Fig. 6.58. Fig. 6.58(a) is a thrust steel arch bridge, the ratio of

height to span 1/10.3, the main bridge span 44.87 m; Fig. 6.58(b) is a bridge of constant load without thrust pre-stress concrete arch bridge with a main span 36 m; Fig. 6.58(c) is thrust of reinforced concrete arch bridge, with a height-span ratio of 1/9. Kunshan is a soft soil area, bridge programme is not economical. But in order to beautify the city bridges, arch bridges is also an option. On soft ground, in order to overcome the horizontal thrust base will take a large economic cost. And horizontal thrust and structures are related. Fig. 6.58(a) thrust for the bridge arch, using steel arch bridge, light weight, relatively small horizontal thrust. Fig. 6.58(b) bridge constant load without thrust, only horizontal force live load and temperature. Fig. 6.58(c) bridge with large weight has the largest basic horizontal thrust. Therefore, from conceptual design stage we can decide which economic b > a > c of three bridges, three economic indicators listed in Table 6.27 illustrates the point. Table 6.27 Construction cost comparison of three arch bridges. Economic efficiency

a

Cost per square meter (USD/m2) 1.029

b

0.602

Superior

c

1.111

Poor

Programme

Average

Improving and beautifying the structure can also reflect the bridge’s advance. In the concept of the United States Oakland Bay Bridge, in order to satisfy residents taste for single-column pylon and the demand that the bridge can immediately restore traffic functionality after the quake, structure of multi-column shear tower was proposed. The Tower look like a single tower structure Fig. 6.59 is a single-column and portal bridge tower scheme selection.

Fig. 6.59 Single-column tower and gantry bridge scheme selection. Beam bridge construction can also embody its advanced nature. France Millau bridge incremental launching construction adapted to local conditions is an example. Improve the durability of the structure can also reflect its advance. Stonecutters Bridge in Hong Kong achieves the theoretical design life of 120 years, in the choice of materials, structural design, sacrificing protection, dehumidification systems, maintenance equipment, special considerations have been made. First of all, the bridge concrete tower with a high strength grade concrete, water/cement ratio was 0.35, added fly ash and 15 L/ m3 35% nitrous inhibitors of calcium, and stirrups and outermost vertical reinforcement uses stainless steel and, secondly, due to the lower part of the tower structure long

immersion in high-chlorine environments, protective layer of thickened more than 60 mm; and, third, tower top section steel enclosures were used as sacrificial protection, in order to prevent the air from the chloride ions on corrosion of the tower four, in order to prevent rusting, the main beam not only go through layers of paint to protect, has also set up dehumidification system inside the box the last check maintenance to guarantee the durability of the structure has a very important significance, therefore, Stonecutters Island Bridge tower, both inside and outside of main girder installation maintenance equipment, such as tower top set the hanger deck has the following settings maintenance platform in the lower part of the tower [Fig. 6.60(a)], set inside a box girder of repairing the shuttle [Fig. 6.60(b)], externally mounted portable maintenance hanger [Fig. 6.60(c)], and can also be installed on the cable maintenance vehicle [Fig. 6.60(d)]. All in all, finds bridge’s advance, must start, from concept design concept design principles. After completion of the bridge temporary summed up the “innovation” generally does not mean that advanced.

Fig. 6.60 Durability of stonecutters bridge maintenance facility (a) main column bottom detection platform; (b) main welded connection shuttle repair; (c) maintenance under the main beam hangers; (d) cables repair vehicle.

6.5 IMPORTANT MECHANICAL CALCULATION IN CONCEPT DESIGN PHASE During the conceptual design phase, the main purpose of structure analysis is to verify whether the establishment, including strength and stiffness (distortion or image stabilisation qualitative) fatigue of overall control meet code requirements, simplified methods or empirical formula is often used to estimate. But when confronted with complex structure, numerical methods are used. Numerical model is crucial in determining whether numerical analysis is correct.

6.5.1 General Method for Structure Analysis Structure analysis purpose is mainly to effect structural change as the structure of responses. These responses at the structural level include displacement and stability of enclosed, at the component level includes force and stress, and so on. Structural analysis mainly consists of solutions analytical, numerical analysis method and semi-analytical method. Analytical method generates ease to-use analysis models through simplifying actual structure, established the relationship equations between the mechanical values , and finding the answer via., analytical solution. Numerical analysis is discretisation of complex differential equations with boundary value problems, and obtain approximate solutions using algebraic equations. Commonly used numerical analyses are divided into two categories: represented by the finite difference method and represented by finite element method. Semi-analytical method is by introducing parsing functions obtained from analytical method, in combination with numerical analysis method. Relative to finite element method it requires less computation work. Finite strip method is often used in semianalytical method. Conceptual design, structural analysis is designed to ensure that the programme is viable. So you can use a simplified analytical method (estimation) or a simple model of the finite element method.

6.5.2 Strength Calculation Strength-test is the assurances for structure and components to meet the ultimate and serviceability limit. Ultimate loading limit states corresponds to structures or structural elements to achieve the maximum load capacity or to not fit to continue bearing load without deformation. When a structure or structural component appears when one of the following States, the ultimate limit State should have been reached: 1. The entire structure or portion of a structure as a rigid body lost balance (capsizing); 2. Damage to the components or connections because of the stress exceeds the material

strength limit (including fatigue), or due to excessive deformation and unfit to continue bearing load; 3. Structure transformed into mobile; 4. The structure or structure lose stability; 5. Foundation lose bearing capacity and gets damaged. Serviceability limit states correspond to structures or structural elements to achieve the normal use or durability of a provision limiting value. When a structure or structural component appears one of the following states, the ultimate limit state should have been exceeded: 1. Affect normal use or the appearance of deformation; 2. Partial damage affecting the normal use or durability (including fractures); 3. Vibration affecting the normal use; 4. Other specific status that affect normal use, such as relatively large settlement. Through analysis of structure, each component can be obtained under the most adverse combination of responses. Usually on structural components according to load bearing limit state, followed by calculation of deformation, crack width, anti-crack, etc., based on serviceability limit State. Bridge design specifications of components for ultimate limit state calculation using the following formula: In the formula: γ0 = The importance factor of bridge structure; S = Effect of composite design values; R = Design value of bearing; fd, ad = Material strength and geometrical parameters of the designed value. The above formula is a basic expression , giving in detail the bridge bending, compression, tension, torsion, punching shear, local pressure component calculation method of bearing capacity design values, no longer listed here. During the conceptual design phase, because there are a lot of options, each type of bridge layout, structure is not stable, this can only be preliminary calculations. For example, for a continuous beam bridge, at the concept design stage, because you haven’t configured the general reinforcement or pre-stressing reinforcement, and therefore cannot check the structural strength and can only be computed structures, previous work experience, preliminary judge whether or not the section size may be reinforcing success. Therefore, the conceptual design stage of structural strength check is mainly holding structure size is appropriate.

6.5.3 Rigidity and Stability Calculation

Stiffness is the object’s ability to resist deformation under force. Stiffness calculation corresponds to specification in the serviceability limit state requirements for the deflection under load and span ratio. During the conceptual design phase checking stiffness is very important. Calculation by finite element method, you can easily structural deformation curve and find the maximum structural displacement value. Some basic structure can also be based on the simple theory of deformation and calculation formula estimation of maximum displacement structure. For example, the simple architecture of several sections such as maximum displacement calculated as follows.

1. Simply Supported Beam Mid-span deflection under a concentrated force: Full uniform mid-span deflection under load:

2. Cantilever Beam Mid-span deflection under a concentrated force: Full uniform mid-span deflection under load:

3. Simply Supported at one end, Consolidation Beams at the Other end (Akin to Continuous Girder Side Span) Full uniform deflection under load: f = 0.00541

(at a distance from simple-support

end 0.422l).

4. Fixed end Beam (Akin to Continuous Beam of the Cross) Mid-span deflection under a concentrated force: Full uniform mid-span deflection under load:

.

Comparing with control code for modification one can determine whether the structural rigidity of the structure meet the requirements. For example, the highway reinforced concrete and pre-stressed concrete bridge design code (JTG D62—2004) provides as follows: reinforced and pre-stressed concrete long-term deflection of the flexural members, after long-term deflection of eliminating structural weight, warping the maximum deflection of primary beam should not be more than 1/600 of calculating span, cantilever length not exceeding 1/300. The highway cable stayed bridge design rules (JTG/TD65-01-2007) states: main beam lane loading (no impact) under maximum vertical deflection of concrete beam bridge shall not be more than l/500, steel beams and

composite beams in the main hole using steel beams shall not be more than l/400. The highway cable bridge design code (approval) in the provision of: stiffening girder of suspension bridge by vehicle load (regardless of the impact) of the maximum vertical deflection should not be greater than the span of the 1/250 and fiftieth ~ 1/300; in high winds (deck car-free) maximum lateral displacement should not be greater than the span under the influence of 1/150. Stability includes two aspects: static stability, including stability and regional stability as a whole; wind-induced stability, including flutter instability and static wind instability and so on. Static forc, structural stability of cable-stayed bridges, arch bridges and other issues are more prominent, thin-walled structures such as thin-walled steel box girder, bridge tower local stability is more prominent. During the conceptual design phase primarily concerned with the overall stability of finite element method can be easier to first class stability analysis of structures and stability safety factor meets the requirements for testing. Local stability in terms of rods stability ensured by limiting slenderness ratio, stability of stiffened plate structure measures adopted as assurance. On mechanics, for large-span bridge at conceptual design stage only preliminary estimates according to the formula, the highway bridge specification for design of wind resistance (JTG/T D60-01-2004) are detailed in the static wind stability, galloping, flutter stability test calculation formulas and specific requirements.

6.5.4 Dynamic Characteristics Calculation The inherent dynamic properties of structures mainly refers to the natural frequencies, mode shapes, damping, etc. They depend on the quality structure and rigidity, quality and distribution, support conditions, and other factors. Structure dynamic analysis is the basis of calculation of wind and earthquake resistance of structures. In addition, bridge live load impact co-efficient associated with the structure of the fundamental frequency; for specialpurpose bridge, footbridge, its fundamental frequency there are certain requirements. Therefore, is necessary to perform structural dynamic characteristics calculation. During the conceptual design phase, dynamic characteristics of bridge structure can be directly estimated using the approximate formulas. Refer to the existing bridge specification and related research results, bridge the fundamental frequency estimation formulas are as follows.

1. Beam bridge (a) Simply Supported Beam

In the formula: l = Structure of calculating span length (m); E = Elastic modulus of structure (N/m2);

Ic = Cross-section moment of inertia of the cross section (m4); mc = Structure mass per unit length in the (kg/m), when converted to gravity calculations, unit N.s2/m2; G = Structure span meter structure gravity (N/m); g = The gravitational acceleration g = 9.81m/s2.

(b) Continuous Beam Bridge

When calculating the impact of continuous beam caused when the positive bending moment and shear effects by f1; negative effect is calculated using f2.

2. Arch Bridge

When the main arches for such section or other arch bridges (such as truss arch and rigid frame arch, and so on):

In the formula: f = ratio of height to span arch bridges. When arch for arch bridge with variable cross section at:

In the formula: ri = co-efficients can be determined according to the following formula: ri = Ri × n + Ti, where n is the arch thickness variation coefficient, Ri, Ti values may be found in Table 6.28.

Table 6.28 Arch Bridge natural frequency calculation parameter. i Ri

1 3.7

2 34.3

3 16.3

4 364

5 1955

Ti

1.7

15.7

0.15

–30

–88

3. Cable-stayed Bridge

(a) Vertical Bending Frequency of the Twin Towers of Cable-stayed Bridge Cable-stayed bridges without auxiliary piers: f1 = 110/l. Cable-stayed bridges with auxiliary piers: f1 = 150/l. In the formula: l = main span cable-stayed bridge span (m); f1 = vertical bending frequency (Hz).

(b) Twin-tower Cable-stayed Bridge Base Reverse Frequency

In the formula: C = empirical co-efficients, according to Table 6.29. Table 6.29 Twin Tower cable-stayed bridge base frequency calculation parameters. Cable facade Parallel cable

Inclined plane

Shape of main girder cross-section Open

Steel bridge Concrete bridge 10 9

Half-open

12

12

Closed

17

14

Open

12

11

Half-Open

14

12

Closed

21

17

4. Suspension Bridge (a) The Anti-symmetric Vertical Bending Frequency in Single Span Simple Supported Suspension Bridge

In the formula: f1 = antisymmetric vertical bending frequency (Hz); l = main span cable-stayed bridge span (m); EI = stiffening girder vertical bending stiffness (N.m2); Hg = constant horizontal force of main cable under load (N); m = deck and the mass per unit length of the rope (kg/m), m = md + 2mc; md = floor system mass per unit length (kg/m); single main cable mass per unit length (kg/m).

mc =

(b) When the main span more than 500 m, the suspension of the antisymmetric vertical bending frequency

In the formula: f = main cables vertical height (m).

(c) Vertical Bending Frequency in mid-span of Simple Supported Suspension Bridge

In the formula: Ec, Ac = the main cable of the elastic modulus (MPa), crosssectional area (m2).

(d) Skew-symmetric Reverse Base Frequency in mid-span Simple Supported Suspension Bridge

In the formula: EIω, and GId = restrained torsional stiffness (N.m4) and free torsional stiffness (N.m2) of closed box beam restrained torsional stiffness can be ignored; r = stiffening girder section radius (m); Bc = centre distance of the main cable (m).

(e) Symmetry Reverse base Frequency in Suspension Bridge

6.6 MODELING METHOD 6.6.1 Method for Model Selection Bridge structural analysis must be based on analysis and requirements, select suitable numerical analysis model and structure the dynamic abstraction, simplifies, and discrete, and based on program requirements, the discretized structure with the corresponding computer language statements, such as data files, describe them. Rational and accurate modeling and numerical simulation of bridge structural analysis is the key to success.

1. The Plane Model and Spatial Model Force main bridge structure in the vertical plane, and transverse dimensions is vertical small, so the general line bridges or flat and curved bridge inconspicuous simplified into flat structure in the vertical plane, model was called model established at this time. In the two-dimensional plane, finite element model of nodes in general only the DX, DY, RZ, three degrees of freedom. If the bridge is located within a clear plane curve, the transverse dimensions or components relative to the vertical must not be ignored, or structure under a large transverse loads (such as wind load, earthquake load, and so on), and planar structure is simplified as it does not reflect the structure of space, in which case in three dimensions space calculation model, called the spatial model. In three dimensions, a node usually has 6 degrees of freedom, namely, DX, DY DZ RX RY RZ. Thus, plane models and model selection of main space is based on characteristics of the structure itself. Under normal circumstances, using space model can be achieved than plane stress state is closer to the actual structure of the model structure in response, but due to space model for data entry, programs, data processing and other links are far more complicated than flat-panel models, so you must the relation of the trade-off between accuracy and workload. Because in the conceptual design phase one is typically concerned with the overall structure of mechanical behaviour there is no need to get very accurate results, so simpler plane model is used as much as possible.

2. Unit Type Selection By geometric characteristics and element types, structural model can generally be divided into frames (“line” structure), plate and shell structures (“surface” structure) and entity structures (“body”). Truss component is characterised by scaling in one direction than the other two parties to scale, truss rods, beams, cables and other wire unit, such as lengths much greater than the height and width of the beam section. Plate and shell structures is characterised by a scale much smaller than the other two directions of scale, as a flat platelike objects called plate structures, if surface shape is called a shell, plate and shell elements, respectively. Entity structure refers to the three directions of scale at about the same levels of structure, corresponding to solid elements. In the conceptual design phase, due to high precision requirements the calculation result is not, in general, one can use framed structures. If rod components are not subject to bending moment, use rod element or cable element (can only sustain tension); if subjected to bending moment, beam element is used. When beam unit length is greater

than 15 times of section feature dimensions, commonly known as slender beams, one can ignore the effect of shear deformation. With the upgrading of computer processing speeds, at the concept design stage, for geometry more complex structures one can also consider adopting shell or solid elements to build more elaborate finite element model. It must be noted that inside is a truss element model results from the shell or solid models can be the result of stress and strain, such as demand forces more difficult.

6.6.2 Geometric Description Geometric description of a task is to describe a real bridge structure in finite element calculation of node, element, provide node position, and to determine how to connect unit between nodes. Through the positioning of node provides structure position information, described by the unit knot extension of frame component. Architecture modeling is the process of a logical process. The first step is to choose a reasonable simplification of modeling mode. At conceptual design stage if the choice of plane frame models, spatial effect of live load transverse distribution co-efficient and coefficient of uneven load can be used to express; to calculate space loading (wind load, earthquake load, etc.) under the action of static response, generally using space truss model, as shown in Fig. 6.61. In Space truss model, simulation is a key technology for main girder. Closed box beam free torsional stiffness can adopt the single main beam model; with separated half-open section of box girders, especially for free torsion stiffness with solid edge beam of plate opening section, double girder models can be used; halfopen the main beam section or open the main beam section three-beam model can be used. The second step of modeling is the discretization of the structure, nodes, unit systems. In the finite element analysis, proper discretization of the model is the key to economical and reliable structural analysis. Different unit size analysis sometimes has a great influence the accuracy of the results, which must balance the unit number and the model efficiency, models usually have to sacrifice high accuracy model analysis of the cost in time and the overall efficiency of the model. Analyst must determine whether a subdivision unit necessary based on engineering judgement.

Fig. 6.61 Space truss calculation model (a) girder bridge (b) cable-stayed bridge. For framed structures, a unit corresponds to two end nodes, of nodes and cells boils

down to determine node location, in general the following principles should be followed: 1. the structural anchor should set the node; 2. in order to deal with the relationship between structure and discrete model, in accordance with the construction process, phasing in natural settings node; 3. longer natural block should be appropriately sub-divided; 4. the pre-stressed cable-endpoint sections should generally set the node; 5. section should set the node where the focus on internal forces and displacements; 6. at supporting parts node should be set.

6.6.3 Materials and Sectional Properties To receive the correct structure, one of the most important factors is determining structural elements and section properties of the material. Material properties elastic modulus, Poisson’s ratio, density, cross-section area, bending moment of inertia and torsional moment of inertia are considered. Structure calculation of bridge structure is built on the theory of homogeneous material, actual materials and section features can be used. Theory of material properties have values, more precise measured data can also be obtained on a test. Section property can be calculated using section dimension. In the linear model, and section properties of the material are generally the same, but in dealing with material non-linearity problems need material special treatment or section properties. For non-linear materials only through testing or the actual detailed theoretical analysis to the material properties can be simplified inelastic model to simulate the expected component behaviour. According to the complexity of material properties change, you can use bilinear or a much broader linear material models. If degradation of materials considered in the analysis, you can use the Takeda model. For non-homogeneous material, sometimes by changing the section properties to consider their non-linear properties. Such as reinforced concrete, solid object, you may need to modify the section properties: elastic analysis, if the goal is to strength, concern only calculation of knot, as long as the relative stiffness of the various components is correct you can; when you target the displacements and deformations, each member calculation of cross-section must be accurate, and beyond a certain deformation when the cracks in the concrete, you must also modify the section properties to reflect the effective stiffness of structure.

6.6.4 Boundary Conditions Another key step is the correct description of the structural analysis of successful systems outside the constraints, boundary conditions. Boundary conditions include force boundary conditions and displacement boundary conditions. For the conceptual design stage of the overall structural truss unit mode type, normally only displacement constraint conditions

exist, under bridge’s practical constraints can easily determine its finite element model type of boundary conditions. When determining the boundary conditions certain construction assumptions are usually needed. For example, in static force Analysis boundary conditions are often described using simple supported rigid (fixed, hinged, rolling moving or sliding), without consideration of deformation sub-structure and foundations. However, for the need to take into account certain static analysis of ground displacement (such as considering the slow displacement of suspension bridge anchorage) and dynamic analysis (such as seismic response analysis), describing the deformation is very heavy, Non-linear spring/ damper model can be established at this time (Fig. 6.62). Structural engineer and geological engineers can work closely together correctly determining the nature of soil spring and sometimes need to pass set up a small model or manual checking of the required parameters is acceptable.

Fig. 6.62 Non-linear spring/damper model.

6.6.5 Quality When calculating the dynamic characteristics of structure should be given quality, mainly refers to the components of the translational mass and moment of inertia. Translation quality of centralised or distributed approach, and the moment of inertia is way depending on the simulation of the floor system is different and can be automatically form or according to the actual sections of the mass distribution calculations input.

6.6.6 Loads Bridge structures need to withstand various loads, such as temporary loads, dead loads, live loads, wind, any temperature and load. These loads consist of a series of load exerted on the structure model of express or analog, each load included a series of concentrated loads (section point loading) or distributed load. Range relative to the extension unit can use smaller loads concentrated loads simulation, and vice versa with a distributed load simulation. Dead load refers to the weight of the structure, the size according to the size and density of the material and the acceleration of gravity is calculated. General description

the distributed load, but sometimes also attach some concentrated loads, such as truss continuous girder beam weight is concentrated in the model force simulation. Temporary construction loads on the structure has been built mainly of temporary stacking loads, and hanging baskets, and so on. Interim stacking load can be simulated based on equivalent in the form of concentrated or distributed load. Simulation of hanging basket is relatively complex. General cantilever hanging baskets can be fixed with a virtual rod unit and structure has been built-in several equivalent concentration on simulated basket moves, you can fold the unit at this stage and concentrated force dismounted to move before the next stage of the unit and focus. Fore-cable-stayed bridge basket required to simulate the tension in its construction and process value calculation method can be used to simulate. Live load can be directly illustrated using the standard load calculation, and record transverse, longitudinal reduction factor. Static wind load on a structure shapes, wind speed and the Pontic of bridge site structure related to the height of the load. When calculate one can refer to code for design of highway bridge wind (JTG/T D60-01-2004), the estimation formula of critical wind speed of flutter. For important large-span structures, first through wind tunnel tests to determine its major components of the three-factor (curve), then calculate the corresponding equivalent static wind loads on structures. Flexible structures and sometimes even structural posture change causes changes in angle of attack of the wind effect of static wind loading. Other static loads, such as ship and ice loads, and also calculate the equivalent load applied to the corresponding position in the model. In some cases, especially in high seismic intensity area, many dynamic load-controlled bridge design parameters. At this point, understanding dynamic loads of the nature of the responses of bridges under such loads is very important. In the districts of high intensity, Thong common multi-modal response spectrum analysis to calculate the dynamic response of bridges. In this case, usually with a given structural damping periods and under acceleration, velocity and displacement relationship between response spectrum load. In some cases, especially for complex bridge structures, and time history analysis method is usually used when needed at the border when applying a group ride on the nodes load (usually expressed as time or time-acceleration-displacement curve). Example 6.12. According to the conceptual design, shown in Fig. 6.63, and full-bridge (156 + 180 + 300) m + 1400 m + (300 + 180 + 156) m of 7-span continuous structures. main beam is made of flat steel box girder, beam height 4.5 m, the full width 41 m (including wind mouth). Pylons uses “A” shaped concrete towers, set the beam at the bottom anchor, set the lower beam girder. Tower height is 357 m deck above 287 m, the tower is a hollow rectangular section. Cable total 38 × 4 × 2 = 304, specifications for PES7-211~313(1770 MPa), single cable maximum length of about 750 m. Floating structural system for the whole system, and try to model this structure.

Fig. 6.63 General layout scheme of cable-stayed bridge with a main span of 1400 m (size: m) (a) programme general arrangement; (b) pylon arrangement; (c) girder sections. According to this knowledge, can be modeled according to the following steps for this solution: 1. The choice of plane and spatial model: Conceptual design for similar configurations of cable-stayed bridge in Planar structures, but large-span bridge, in transverse direction (lateral) loads of established controls, so using spatial models. 2. Unit type selection: Using truss structures, and the selection of tower column of main girder beam elements, cable select space beam element. 3. Description: Main beam and column have access to all the nodes in the corresponding section of the tower at the centroid of the girder set the principles of the nodes is: beams, on end, cable cranes, tower junction set node, insert a niche between adjacent points; the main tower sets the node’s principles that is: Tower, bottom set, beams, cables anchoring points are the endpoints node, the tower columns and beams a long rod is properly sub-divided so that the unit length has differ; cable setting the node’s principles are: both ends of the cable are set the node and with segmented rods method test taking into account non-linear effects of cables SAG, so

each of these cables are inserted at the dividing point 7 nodes. Full bridge element and node the connection information is as follows: along its axis of beam, towers, cable connection between adjacent nodes as a unit, cable section corresponds to the lower point and main beam increased rigidity beam element, namely the main girder of single-beam mode “fish bone beams” model. 4. And section properties of the material: The main girders, cables for steel components, pylon for the concrete components, elastic modulus of the material is already known. Geometry calculation of sectional properties according to the corresponding section. Beam elements needed to calculate the area and around three axes: Moment of inertia, the main beam, the main tower in the typical cross-section is shown in Table 6.30, typical between each cross-section curve can be approximated by a straight line interpolation; Element need only enter the cross-sectional area, area corresponding to each cable as shown in Fig. 6.64.

Table 6.30 Typical cross-section geometry parameter. Site

Area (m2)

Main girder section A

1.7029

In-plane bending moment of inertia (m4) 5.8241

Out of plane bending moment of inertia (m4) 220.8435

Torsional moment of inertia (m4) 21.8092

Main girder section B

1.9817

7.0609

248.0076

25.4121

Main girder section C

2.4034

8.3907

318.8833

31.2312

Main girder section D

2.9100

10.2898

392.9832

38.20563

Tower top

85.512

528.403

902.353

1 090.466

Bifurcation of 25.458 the main tower

68.340

400.500

212.310

Beams in the main tower

35.575

133.444

669.258

395.867

Pylon beams under

57.343

664.348

2515.169

1774.659

Bottom of main tower

66.300

1155.722

3579.702

2892.310

Fig. 6.64 General layout scheme of cable-stayed bridge with a main span of 1400 m (size: m) 5. The boundary conditions: Combined effects of ignoring upper and lower parts of the structure, nodes at the bottom of Tower column for consolidation of constraint; main girder for floating junction structure constraint only two end nodes and the auxiliary piers at the vertical displacement of the node. 6. Quality: All elements can be directly determined by the area and density. But beams, floor system of main beams and cables sheath does not participate in force, such as quality of components with specific quality elements. 7. Loads: In addition to deadweight, a cable-stayed bridge under live load and static wind load, thermal load and bearing modification and so on. Functions that can be provided in accordance with the procedures directly imported or calculate the equivalent load according to specification, separately as multiple load simulation. Finally, the numerical model is shown in Fig. 6.65. After description of the model Data based on analysis program numerical formatting, analysis will be carried out through computers.

Fig. 6.65 Overall structural analysis model (half-bridge).

REVIEW QUESTIONS 1. For the selected type of bridge structures based on design conditions in order to determine a reasonable system? 2. Why during the conceptual design phase to construction problems? Determining bridge construction program and what are the main factors to consider? 3. Where several advantages determined the bridge program? 4. In a 180 m design is a three-span beam bridge on the river, the conceptual design process of determining design parameter of continuous beam.

REFERENCES [1] Brandon Lee. Stability and Vibration of Bridge Structures. Beijing: China Railway Publishing House, 1992. [2] Deng. Several Design Concepts of the New Bridge in Chongqing//proceedings of the 17th National Conference on Bridges. Beijing: People’s Transportation Press, 2006. [3] Deng. City Bridge Innovation//Proceedings of the 18th National Conference on Bridges. Beijing: People’s Communications Press, 2008. [4] Xiang Haifan. The Main Technological Innovations in World’s Bridge Development. Guangxi Traffic Technology, 2003 (5). [5] Xiang Haifan. Conceptual Design of Large-span Bridge Problems//Proceedings of the 2004 National Conference on Bridges. Beijing: People China Communications Press, 2004. [6] Xiang Haifan. Chinese and Foreign Comparison of Technological Innovation in the New Bridges//Proceedings of the 17th National Conference on Bridges. Beijing: People China Communications Press, 2006. [7] Xiang Haifan. 60 Years of Modern Bridge Engineering//Proceedings of the 18th National Conference on Bridges. Beijing: people’s Communication and Publication Press, 2008. [8] Xiang Haifan. Reflection on Chinese Economic Problems of Bridge. Bridge, 2010. 3. [9] Fan Lichu. Bridge Engineering. Beijing: People’s Communications Press, 2001. [10] Xu Zhihao, Huang Jianbo. Stonecutters Bridge, Durability, Maintenance, and Safety//17th National Bridge Conference Papers China Communications Press, 2008. [11] Wang Fumin, Xu Wei. Study on Structural System of Main Bridge of Chongqing Chaotianmen Yangtze River. Road Traffic Technology, 2005 (7): 23-28. [12] Xiao Rucheng, Chen Hong, Wei Leyong. Research, Optimization and Innovation of the Bridge Structure. Journal of Civil Engineering, 2008 (6). [13] Xiao Rucheng. Tongji University: Bridge Systems (Lecture Notes). [14] Xiao Rucheng. Bridge Structural Analysis and Program Systems. Beijing: People’s Communications Press, 2002. [15] Xiao Rucheng, Sun bin. -Meter Scale Cable-stayed Bridge System. The bridge, 2009 (1). [16] Jacques Combault. The Rion-Antirion Bridge-When a Dream Becomes Reality. IABSE Workshop, Shanghai, 2009. [17] Michel Virlogeux, Claude Servant, Jean-Marie, et al. Millau Viaduct, France Structural Engineering International, 2005,1(4). 4-7. [18] Wai-Fah Chen, Lian Duan. Bridge Engineering Handbook. CRC Press, 1999.

[19] Miao Jiawu. Study on the Design theory of Super Long Span Cable-stayed Bridges. Shanghai: Tongji University Department of Bridge Engineering, 2006. [20] The Sun bin. Ultra-Meter Scale Cable-stayed Bridge System. Shanghai: Tongji University Department of Bridge Engineering, 2008. [21] The Bridge Design Committee for the Preparation of the Data Sheet. Bridge Design Data Handbook. Beijing: People’s Communication, 2005.

SOLVING NEW PROBLEM IN THE CONCEPTUAL DESIGN A good bridge engineer should be try to make your own design work reasonable, including maximum possible meet the requirements, try to adapt the natural conditions of bridgesite, minimise construction costs, and bring beauty to bridges. To achieve these goals, we must continue to break through the existing technical limit. Bridge design and structure selection cannot be separated from some key details of the bridge idea. Sometimes innovative bridges programme, structural systems depends on a new frame details, the invention of the new method, as well as the application of new materials and technologies. Conversely, innovative structural details, innovative methods, new materials, new technology research are driven by the constant pursuit of a more rational structure. In this chapter, starting from the analysing and achieving a more rational structure, introduced innovative structural details, method, new material and how new technology of bridge design is generated based on the special needs.

7.1 TECHNICAL SUPPORT OF REALIZATION OF INNOVATIVE DESIGN IDEAS Bridge engineer continuously challenge the limits in design for the bridge structure meet the requirements or to make the structure suitable. According to different bridges, these limits may be greater span, higher carrying capacity, more economic and more resistant longer, more beautiful, more resistance to extreme events, and many other aspects. To achieve these objectives, in addition to the bridge engineer rich experience in engineering and mechanics of ingenious ideas, reasonable knowledge structure system, it also requires the following specific technical safeguards. First of all, innovation in critical structural details. The overall bridge structure is made up of different components, different components in structure plays a different role. When structure when the overall breakthrough for structural requirements increased, but not structures all the details of the design points. Overall innovation ultimately materializes in key construction details, some successful solve critical structural problems are sometimes so that the structure’s overall performance is greatly improved. Secondly, the innovative construction method and corresponding equipment guarantee. In addition to the ingenious design of bridge structure, construction technology is the key to success. High quality bridge design requires a high level of construction technology to be realized. The progress in bridge construction technology offers a flexible and powerful tool, as well as increased span, improved structure and the use of material provided sufficient conditions, in some cases, bridge designs of innovation depends entirely on the innovative construction method. While innovative methods must have the appropriate equipment to achieve, and sometimes equipment development determines the success or failure of the method. High precision application work cannot be completed by human hand-operated, there must be precise control of construction equipment, construction must be rely on automation, smart large equipment. Application of advanced materials and high-tech innovative bridge design requirements. Construction technology of modern bridge exhibition can be said to be result of engineering material advances. Development of modern smelting technology provides high strength steel, which is born reinforced concrete and pre-stressed concrete. Over more than 100 years, the achievements of modern bridge engineering is based on steel and concrete implementation. Modern materials has created a large number of advanced materials other than steel or concrete, these strong materials high unit volume light weight, durability, but the application also has some advanced material in civil engineering technology and economic barriers. Modern bridge engineers design bridges, is no longer a traditional apprentice imitating the master model, but using systems engineering knowledge to create. Therefore, the timely application of high-tech innovation can be greatly boost structure innovation in the design of bridge. Finally, the complex bridge construction key process of technological innovation is the safeguard to implementing the design. In the complex hybrid or a special bridge construction process, process of bridge-building engineers often encounter before without problems, in response to these needs in the design and construction of special studies, the successful resolution of these problems on the construction of the bridge play a key role,

and solutions also provide ideas for similar bridges construction in the future. Successful solutions will have an impact bridge construction technology in the future development of new constructs described earlier in detail, construction methods and materials is via., a bridge, the engineers creative daring the attempt, but proved to be more social and economic benefit, and become a bridge technical safeguards.

7.2 IMPROVEMENT OF STRUCTURE AND PROPERTIES OF STRUCTURAL DETAILS Overall structure is made up of numerous details structure. Modern bridge design is achieved through mechanical knowledge function as a bridge to the technical requirements, from the traditional mode of operation of the apprentice legend. Therefore, engineers can use the knowledge to create a structure that was never designed. In particular the application of the computer, so mechanics can be parts available to engineers, so they can be calculated completely by means of mechanical devise never before imagined a unique bridge scheme. But mechanical engineering abstract theoretical knowledge in practice, when applied to the design of new bridges must restore entity structure. For example, the mechanical bridge is supported only in a simple hinge joint or hinge point of the swing, and bridge abutment you must have a certain bearing strength and can meet the displacement requirements of different components of the entity. If an agent is only designed bridges beam structural system, ignoring details such as the support structure will not be able to bridge that is consistent with mechanical system design. And structural details are also changed with the development of bridge. Early bearing of bridge using steel bearing force for clear advantages, can well meet the requirements of bearing and deformation, but the high cost of production and maintenance of steel bearing. Alongwith the awareness of the mechanical characteristics of the structure and development of material industry, there has been a rubber support. Rubber bearing the same to meet the force requirements, has a certain durability, but manufacturing and maintenance costs dramatically, so soon is the bridge application. While rubber support also provides flexible support condition, reasonable force to provide new means for a structure, so in order to get a different force structure effect of rubber bearings and different types are derived. It can be seen from above the development of bridge support, structural details are necessary to achieve the conception design, at the same time, based on the innovational design of mechanical theory is also promoting advances in structural details.

7.2.1 Innovation of Structural Details Innovation of structural details from the structure of the requirements according to the characteristics of bridge design method, primarily through mechanical model of structural measures outlined by the design of the bridge. Construction and replacement of the structure also on structural details of design proposed new requirements. To sum up several aspects include the following:

1. Reasonable Force Structure Requirements Varied Boundary Conditions Boundary conditions are important components of force calculation of bridge structure models, the same structure in different border makes great a change in structure of the force. For example, as it is a single-span beam bridge, simply supported beams with

single-hole-shaped frame bridge moment distribution is totally different. Simply supported beam produced only positive moment, and single frame girder is at the same time produce positive or negative bending moment bending moment. Bridges on the border generally in addition to supporting role, must also be able to adapt to a certain displacement. In order to adapt to the above requirements, will require innovative design. Especially for complex structures or large bridges, requirements under different operating conditions, using different boundary conditions can also be receive better mechanical performance, so raises can be designed in different working under the conditions of different requirements for connecting effects support member.

2. Fully Utilize Material Characteristics of Structure Components Bridge structural artifacts bear force such as tension, compression, bending and bending can be decomposed into tension and compression area. Among the commonly used building materials, steel both tension and compression, but the price is high, long-term maintenance costs and high resistance of concrete high compressive strength and low tensile strength, but cheap. Therefore, if the two materials combine to form composite structures can have large economic benefits. The bridge engineer with a broad scope for innovation.

3. Reliable Connections between the Different Components and Different Materials Reliable connection between bridge components is key to ensure the normal use of the bridge, these connection parts often bear a great deal of force, for example, tower column of main girder and cable connections, how to guarantee the reliability of connection is also a challenge to bridge engineer. For the same reason using combined structure, connections between different material structures bear a great deal of stress, how to guarantee connection under high stress conditions reliable, is also one of the design challenges.

4. Meeting the Dynamic Needs of Disaster Equipment Bridge over the natural disaster conditions, will produce devastating damage, where the vibration generated by external factors will have dynamic amplification, so that internal forces of structures subjected to far much larger than static, reduction or structure designed to isolate vibration of continuous effort one of the direction of the force.

5. Improving Construction Required by Structure Durability Bridge to reach the design life, must carry out the necessary maintenance. Due to component life expectancy varies, if necessary, to replacement of some components. In bridge design one should take into full account the possible actions in the future, reserved on the structure of future replacement support measures.

7.2.2 Boundary Conditions Structure Meeting the Requirement of Different Force Requirements

In order to meet the bearing and deformation under different loading conditions, supports and telescopic component needs to be set. The most common such component are the bridge bearings and expansion joints. In addition, in order to achieve some special support structure and deformation, depending on construction of reality for innovative design. Equivalent bearing, meet special activity direction of deformation, in different operating conditions can be adjusted boundary condition is one of several ways.

1. The Equivalent Bearing Condition In exceptional circumstances, had simple support conditions is not easy to achieve, or after long-term operation of the bridge will pose a security risk, can be equivalent to the mechanic design equivalent conditions. Former Yugoslavia (now Croatia) in the KRK bridge (7.1) is a bridge crossing the Adriatic Sea to mainland and the island of KRK, dual-use pipe concrete arch bridge, builtin 1980. Full bridge by span 390 m (mainland to island, KRK-I) and 244 m (St Koh Kho Khao to Krk, KRK-II) consists of two reinforced concrete deck arch bridge, the two bridges are 235 m apart, connected with a 96 m long highway on Koh Kho Khao. Deck width is 11.4 m, under the bridge deck laid oil pipelines, water pipes and industrial piping, a total of 17. Arch is a single box three rooms section, with units from the ends of pre-cast segmental cantilever until closure. To coordinate two bridges arch line, and not much higher than arch bridge II and lower road profile, it must place the 390 m bridge’s arch I at below sea level. Adriatic sea is highly corrosive, leaching having a serious affect on the durability of the arch in the sea. Therefore, equivalent to the mechanical design of this bridge, arch, the original force of arches under vertical load and functional separation of the horizontal thrust, the vertical force borne by hinged struts and arch ring and the horizontal load consolidation of horizontal Struts and Arch ring passed to the mountain. Due to the assumed vertical load of the vertical struts and arch ring hinged and the hinge is set above the water surface and avoids the risk of water erosion prone to cracking of arch, and because section strong horizontal bar and consolidation of arch ring, play a role in non-hinge arch.

Fig. 7.1 KRK bridge (a) KRK bridge layout; (b) KRK-1 bridge arch.

2. Meet the Requirements of Special Activity Direction of Deformation Structure In bridge, you typically need to set expansion joints, usually in the setting expansion joints are hinged. For example, the beam and the adjacent junctions of main girder or mainbeams at the articulated hinge. Sometimes, however, in order to improve the rigidity of the structure, mechanics theory hope can only be freely and no hinge at the expansion joints of beam, you could pass the bending moment, which broke the previous making joints in the frame requirements. Such as the construction of multi-tower cable-stayed bridge to span a wide surface, in order to improve the rigidity of the structure, main beam of hope is the continuum and consolidation of girders and pylons. However, this poses a problem, after so many years under the action of temperature difference effect the beam vertically retractable tower column constraint, which would have a huge moment in the towers, at the same time causes additional tension or pressure in the main beam. In order to solve this problem, the best main beam can be freely, but the hinge does not reduce bending stiffness, therefore, German Professor Schiliesh raised the sliding beam structure envisaged to achieve that function, as shown in Fig. 7.2.

Fig. 7.2 Retractable passing moment of structure.

Fig. 7.3 Hinge passing elastic bending moment. Figure 7.3 is another assumption, shown above is usually cross-hinge method, shown below, is both a retractable flexible hinge of the passing moment. In Croatia, Franjo Tudjman, Dubrovnik Bridge (Fig. 7.4), is a composite girder cablestayed bridge in collaboration with the connection of pre-stressed concrete rigid frame bridge, built in 2001, bridges total length 481 m, which combines a beam bridge part 337 m, pre-stressed concrete box-girder frame section 147 m, a main span of 304.05 m, is the largest span in the world alone multi-tower cable-stayed bridge composite cable-stayed bridge with pre-stressed concrete rigid frame bridge with box section connection point on the use of the above slide fixed beam structure, effectively improve the stiffness of the cable-stayed bridge with rigid frame bridge section and at the same time allowed between two bridge girders vertical scaling.

Fig. 7.4 Franjo Tudjman Bridge.

3. Adjustable Boundary Condition—Position Limiting Device In long cable-stayed bridge or suspension bridge design, the forms of tower and main beam column connection include floating, articulated, rigid etc., bridge span is smaller a form generally selected according to specific design conditions. But for large-span cable-

stayed bridge, or Span cable-stayed bridge, hoping to improve the stiffness of structures under live loads or wind, which want the main girder and pylon hinge, in small earthquakes loads of girder and tower column of main girder on seismic force evenly spread over several towers. However, upon articulation, the main beam under the longterm temperature effects of lengthening and shortening will make the towers bear a great deal of bending moments, so using a floating system is more reasonable. This requires under different conditions different boundary conditions in order to achieve better loading state. According to the above request, the lock is set in between the tower and the main beam damping device of the ideas put forward. Fig. 7.5 is the principle of viscous damping devices. Viscous damper works with a small hole in piston moving within a viscous liquidfilled pipes. When the piston movement speed, there is resistance and—slow movement offers very little resistance. Application of this principle can be implemented in different conditions requirements of different boundary conditions. Live load or deformation under wind action is faster transient deformation of damper produces a great deal of resistance of main girder and the tower is similar to the hinge between the columns or piers, year-round temperature disparity effect distortion were slow, so resistance is very small, it’s like sliding between the main beams and columns or piers.

Fig. 7.5 Viscous damper construction principle. Damper’s damping force through viscous liquid of characteristic physical characteristics and pistons small holes to adjust, damping size matches the natural vibration characteristic of bridges, structural vibration dampers can also consume energy to vibration control role. China’s Su Tong bridge main span is 1088 m of super long-span cable-stayed bridge design set a maximum displacement limit damper when displacement damper of smaller working principle is similar to the above, but when the displacement of more than 750 mm, the damper spring steel sheet will work, flexible connections, limiting power of upto 10000 kN, elastic stiffness for the 100 MN/m. Fig. 7.6 is the layout of Su Tong bridge damper. Greece’s Rion-Antirion Bridge across Greece city and boluo ran sub-peninsula, between the Gulf of Corinth, was a 286 m + 3 × 560 m + 286 m span continuous girder

cable-stayed bridge of four towers (Fig. 7.7), the main beam length of 2252 m, is the world’s longest main girder of cable-stayed bridge, completed in 2004. Sensitivity, and building on the strong seismic belt, in order to accommodate the live load, temperature, wind loads and degeneration under seismic effects, floating in the whole system of main girders with tower, girder and pier between cleverly arranged joining condition. In design, pier and beam, beam locally increased small stringer, to decorate the connection of pierbeam damping device. In order to ensure stability against wind and reduce operations due to live load and temperature in vertical and horizontal displacements, each tower is equipped with a four linkage between dampers allow for it about 1000 kN, along the bridge to the limit 1.6 m, transverse nearly motionless. When strong earthquake occurs, damp damage beam movement can be connected to the tower of four damper under the influence have been greatly eased, displacement up to ± 1.3 m. Both ends of the main beam and bridge junction, under the live loads, vertical displacement can be up to 2.5 m, beam supports with high 14 m, can withstand the vertical load and longitudinal displacement of the beam of steel frame, between steel frame and main girder dynamic dampers were installed. Fig. 7.8 illustrates the damper of the bridge signalled. Above are specifically designed according to the specific requirements for bridge border some examples of components, these components have in common point is, by means of special construction, makes the overall structure of the force status more reasonable and reliable, in design played a key role.

7.2.3 Innovative Construction Composition Utilising material strength is an effective way to save construction costs. From the microstructure of material damage consists only pull, compressive and shear. In general, materials with high tensile and compression strength of unit price is relatively high, such as steel high compression strength materials with low tensile strength and are relatively inexpensive, such as stone and concrete. If use completely steel can make bridge structure light, but the price is high. And if built entirely out of concrete bridges, although the material prices are low, but in addition to basic compression arch bridges, no other types of bridges can be built. Therefore, in the tension zone of steel at the same time in the compression zone concrete, is a bridge set up low cost compromises, which formed a composite structure. Fig. 7.9 is reinforced concrete beam shape and perspective, reinforced glass is shown in Fig. 7.10.

Fig. 7.6 Layout of Su Tong bridge damper (unit: cm). Composite structure of reinforced concrete and pre-stressed concrete is the most basic, their invention is the modern civil engineering exhibition of the most important achievements. Steel bar tensile, compression of concrete, and also protect re-bar. Reinforced concrete and pre-stressed concrete. Main weaknesses are the big weight of the concrete, it is difficult to fully control the crack of concrete construction site require large equipment and more artificial, and long duration. Fig. 7.11 shows the serious corrosion of steel bar in concrete has lost the protection of function. In order to overcome the defects of reinforced concrete and pre-stressed concrete structure, built entirely of steel tension only in compression zone built with concrete, commonly referred to as steel and concrete composite structure is formed. As some of the sections using the steel structure, so Widget reduction in weight, in the crack-prone location is in steel, avoiding concrete cracks cannot totally control problems erection of light steel structures part can also save the concrete construction of the bracket or large lifting equipment. Therefore, composite structure bridge engineers increasingly with a large number of innovations. Composite structures can be combined into composite section structure and architecture. Former members within a section built with different materials, which built structures in different sectors with different materials.

Fig. 7.7 Rion-antirion bridge base deflection (a) Rion-antirion Bridge shape (b) Seismic changes front and rear axle position within possible terrain. Application of composite bridge there are still some hurdles to jump, mainly the following issues: 1. concrete creep and shrinkage strain led to stress between steel and concrete in large weight distribution; 2. need a reliable connection between steel and concrete; 3. complicated technology and high cost, we must fully cost competitive advantage. In Europe, America and Japan for many years efforts have been made, composite structure in bridges already have a wide range of applications, while also the corresponding industry standards and specifications. In contrast, composite structure bridges in China has just started, there is no industry chain, currently do not have design specification.

1. The Combined Cross-section Structure Composite section with the most intuitive principle is steel and concrete structure in tension zone, so you can play steel good tension performance of steel, good compression performance of concrete. Early years, part of composite section beam with small span steel girders of many smaller beams, so you need to set more reinforced ribs, increases the complexity of construction. In order to reduce the cost of composite section beams, simplifying structure is a direct route. The current trends is the use of large I-steel to minimise the stiffener and

horizontal linkages, while the beam section directly by steel rolling shape, which greatly reduce the workload of bridge construction site, although the steel consuming, but overall effectiveness is still high. A narrower bridges (10~12 m wide) may use either a larger Ibeams, only a small number of horizontal linkages. Fig. 7.12 shows the composite section beams, two steel girders formed by large I-steel from a split in the middle of the web, carefully designed cutting line connection between steel beam and concrete, and significant cost savings.

Fig. 7.8 Rion-Antirion Bridge damper schematic drawing.

Fig. 7.9 Reinforced concrete hollow slab beam shape and internal reinforcement. Over a wide bridge, in order to increase the torsional stiffness of the bridge, there has been a combination of box-section beams, usually composed of groove consisting of steel beams and concrete roof. Bridge of Donghai bridge over main navigation 420 m for longspan cable-stayed bridge, in order to resist the dominated by container truck load of eccentric loads, using channel section of main girder box beams (see as shown in Fig. 7.13). If it is a continuous beam, in order to resist the pivot plate pressure caused by negative bending moment stresses at the pier near the base plate can be poured concrete in order to improve the stiffness of composite beam smaller, roof and floor beams can also be built with concrete, webs of steel structures, steel webs can effectively avoid webs easy to crack under tensile stress of concrete problems. Top and bottom setting can be the same as in concrete beam in the concrete pre-stressing tendons, to resist bending tensile stress. If you need to layout curved pre-stressing, can take the form of externally pre-stressed. Fig. 7.14 is France’s La Ferte Saint-Aubin bridge, Web is made of 12 mm thick steel plate. In addition to simple-supported beam, beam in the other bridge types is likely to take different directions in different sectors of the moment, such as continuous beam across sectors bear the positive moment, while the middle pier near Liang Duancheng charged moment, which made it possible for both upper and lower beam flange pulling force. Prevention of crack in the tension zone of the concrete in tension becomes the key to the design. Solution to this problem is in the concrete pre-stressed plate. Pre-stressing in

several different ways, direct approach within the board or boards by pre-stressed reinforced, after bent steel beams can also be poured concrete slab and then release the Pre-flex pre-stressed indirect approaches.

Fig. 7.10 Reinforcements in reinforced glass works only after cracks have occurred.

Fig. 7.11 The serious corrosion of concrete has lost it protection of steel bars.

Fig. 7.12 New composite section beam, Germany.

Fig. 7.13 Donghai cable-stayed bridge main girder cross section at main navigation span (unit: cm).

Fig. 7.14 France’s La Ferte Saint-Aubin bridge. However a greater shrinkage and creep of concrete, if the direct placement of concrete in the compression zone, started by a force, coagulation soils can bear the stress. However, over time, larger shrinkage and creep of concrete (contract value of approximately 310~529 μ, the creep co-efficient value of approximately 1.28~3.9), this results in a crosssection stress redistribution between the steel and concrete. Compressive stress of concrete will be transferred to the compressive flange of steel girders, which will make the beam flange in compression zone yield. This is the reinforced concrete need to address one of the problems of composite section beams.

Reduce the shrinkage and creep of concrete is one way to solve this problem. Thus, compression zone of concrete slabs, pre-fabricated stored for more than 6 months after, then erected on a steel beam, after watering or watering hole after using shear studs and beams connected. During storage the shrinkage of concrete have completed most, meanwhile, loaded due to age-long concrete total SEO variables will also be reduced (smaller values of the creep coefficient). Fig. 7.15 shows a composite girder cable-stayed bridge of main girder erection process. Concrete bridge decks was built on top of main beam, connecting with steel beam through post-casting gap. In addition, erecting steel girders of steel beams can also take advantage of characteristics of light weight and easy to set up, bridge erection is relatively easy to set up steel beam erection of concrete plate bracket, saves the construction cost. Fig. 7.16 shows a Switzerland composite continuous beam bridge (Vaux Viaduct) construction process, ranging through the valleys of the bridge part is 62 m + 130 m + 16 m + 130 m + 62 m + 45 m un-uniformed span continuous beam, light variable-height steel girders set to the bridge using incremental launching method , on top of which pre-fabricated concrete bridge deck pavement was then installed. Because it is a continuous beam, stretching in the middle pier top of concrete has longitudinal pre-stressing to resist the negative moments pre-stressed concrete slabs and steel beams stretching before you connect. Between steel and less concrete due to shrinkage and creep of concrete stress redistribution is the another way, through the gauge steel can withstand shear and longitudinal freely, without impeding the shrinkage and creep of concrete, eliminating stress distributions. Corrugated webs of beams under this is the design of the product.

Fig. 7.15 Composite girder cable-stayed bridge main girder erection process. Figure 7.17 is the France Cognac bridge. It is a continuous box girder bridge, the top and bottom was pre-stressed concrete, and webs were converted wave shape steel web plate. Because quality steel hummocky, with almost no longitudinal stiffness, but can take on shear, it exerted on the beam all by in vivo and in vitro on pre-stressed concrete, and long-term creep will not be cause between steel and concrete, should re-distribution of gravity. In addition, the transverse stiffness of corrugated webs than steel, so it can be without stiffener, drastically reduces the effect work intensity.

Fig. 7.16 Switzerland Vaux Viaduct (size: m) (a) General arrangement; (b) Steel beam push process; (c) Cross-section.

Fig. 7.17 France Cognac bridge. Built-in 1987, France Maupre bridge is also a continuous beam bridge with box girders with corrugated webs, so long as 324.5 m, max. clear span 53.55 m. The lower edge of the bridge to cancel a concrete slab, two corrugated webs close to a piece of

concrete filled steel tube to form a triangle box girder. Waveform similar constraints on the concrete roof of the web role is very small, while steel tube on the bottom plate can take triangle box girder torsional capacity enhancement, as shown in Fig. 7.18.

Fig. 7.18 Maupre bridge, France (size: m).

Fig. 7.19 Boulonnais viaduct, France. Figure 7.19 shows Boulonnais viaduct in France, built in 1998, made up of three overpasses, are continuous girder with variable height, combination span is 44.5 m + 5 × 77 m + 44.5 m, 52.5 m + 2 × 77 m + 52.5 m, 44.5 m + 3 × 77 m + 93.5 m + 5 × 110 m + 93.5 m + 3 × 77 m + 44.5 m. Girder steel pole is used to link concrete roof and floor of the composite section beams, pre-cast segmental cantilever method construction, roof and floor is equipped with prestressing of concrete, generally equipped with externally prestressed. Equivalent to abdomen plate slanting steel pole can play the role of shear and longitudinal no compressive stiffness, all applied to pre-stressed concrete, concrete creep and shrinkage of soil does not produce stress re-distribution.

Fig. 7.20 Öresund Bridge (size: m). Is a commonly used form of an overloaded bridge with large span truss beam, in order to be able to bear overload can also use steel truss and concrete composite beam. Fig. 7.20 shows the Denmark and Sweden between which the resund bridge, is a highway-railway dual-purpose bridge, the main bridge of 490 m cable-stayed bridge with multi-span continuous girder of approach span 140 m span. Main girder of cable-stayed bridge and

continuous girder of approach spans are all used steel trusses concrete slab composite section. Steel industry is one of the major forces driving the development of composite structure, together with engineers, they produce suitable for shaped steel beams of composite section beams and accessories, thus greatly lowering the cost of steel parts manufacturing. For example, the wave plates, large beams and so on. As shown in Fig. 7.21 Japan’s engineers worked with Mills to develop specialised in the production of composite beams of steel, such as steel pipe, grooved girder. By contrast, there are no steel mills in China to develop such product.

Fig. 7.21 Composite beams of steel (a) pipe; (b) u-channel steel. In addition to the composite section beam, pillar can also be use the composite section. Main steel casing filled with concrete piers cross-section. The advantages are: on the one hand, column surface plate can effectively resist tensile stress to prevent cracking of concrete on the other, steel housings can be used as scaffolds and templates, save on construction costs. Fig. 7.22 is the towers of the Akashi bridge and selection programme, which section is divided into many compartments of the steel casing filled with concrete to form a composite section. Most of cable-stayed bridge tower for eccentric compression member, can be built with concrete, but at the top of the tower cable anchorage area, in addition to vertical under the pressure, but also bear the main span and side spans of cable horizontal force on the pull. This concrete tower columns, use negative, there are two ways to take the level of tension. One is the main span and side spans of cable pylon cross, horizontal tension transformed into compression, the benefits of doing so are tower anchorage zone of volume can be reduced, unfavourable place is the primary span and side spans of cable transverse does not meet at a single point, towers assumed local torque and bolt-head is exposed. Another way of dealing with is the use of hollow towers, inclined cable anchorage in the transverse direction of towers and walls. Advantage to this is the main side spans of cable anchor fixed on the same plane, bridge overall reasonable strength, disadvantage is, ask for installed in the tower stayed, poor construction, the Tower post jamb to bear pulling force. Resist the pull of the tower within the walls, there are two methods: one is the tower walls arranged in circumferential pre-stressed, the parties law pre-stressing loss in the tower there is the risk of cracking and another method is the use of steel and concrete composite sections, borne by the concrete vertical pressure, inflict horizontal force on steel.

Fig. 7.22 Towers of the Akashi bridge and selection programme (size: mm) (a) Combination of tower column cross-section formed schematics; (b) Akashi bridge tower selection scheme details.

Fig. 7.23 Nromandie bridge, France pylon anchorage zone of tectonic (elevation units: m; dimensions unit: mm). Figure 7.23 shows the Nromandie bridge, France pylon anchorage zone structure. The main span of the bridge is 856 m, embedded in the concrete wall undertake longitudinal tension of steel anchor box, the vertical force passing through shear studs to tower on a concrete, towers and concrete in the transverse direction is divided into two pieces of steel anchor box and tower configurations within circumferential pre-stressing of concrete to cover of steel anchor box passed over by shear studs vertical pull. Figure 7.24 is Rion-Antirion Bridge bridge pylon anchorage zone structure, its construction principle are the same as Nromandie bridge. Figure 7.25 shows China’s Su Tong bridge constructed of steel anchor box, full of steel anchor box embedded in a closed hollow concrete towers columns, analysis showed

that, due to the rigidity of steel anchor box is not infinite, under the action of horizontal forces of cable-stayed, transverse to the tower wall side will produce a horizontal force, under the most unfavourable conditions reach the level of concrete cracking, for overcoming the cracking of concrete failure profit impact tower configuration with more conventional bars in concrete walls to spread the crack, crack width control in a certain fan within the surrounding.

Fig. 7.24 Rion-Antirion Bridge damper schematic drawing.

Fig. 7.25 Of Su-Tong bridge of steel anchor box structure. Figure 7.26 is Hong Kong Ting Kau Bridge pylon anchorage zone, being a 4-cableplane cable-stayed bridge, steel-anchor-box symmetric protrude from concrete outside of the towers, horizontal force entirely shouldered by the steel-anchor-box while the concrete bear vertical force. Because steel anchor box is on the outside of the tower, so after using manufactured on the sides, lifting craft, erection of steel anchor box in place, reperfusion tower anchorage of steel anchor box of concrete, assisted by tensioned circumferential pre-stressed beams. The design is to use the outer steel tubes confinement on concrete-filled steel tube to form triaxial compressive stress of concrete, thereby increasing the compressive strength of concrete. Concrete-filled steel tube, first in foreign countries have been proposed, but due to the confinement of the outer tube the mechanism is not clear, so not many examples of engineering applications. In current engineering practice in China, concrete-filled steel tube arch bridges are widely used, mainly due to the construction of facilities. Pipe has lighter weight in the process of assembling arch and high tolerance for tensile or compressive stress (high tolerance). Eliminating the arch, so there are some economy. Often arch design of concrete-filled steel tube arch bridge does not take into account the confinement of concrete-filled steel tube effect, but simply as a general section design of the conversion, even carrying capacity limit state is not considering the effect of pipe, consider only the compressive strength of concrete.

Fig. 7.26 The Hong Kong Ting Kau Bridge pylon anchorage zone of tectonic (size: m) (a) Pylon anchorage zone profile; (b) Pylon anchorage zone of cross-sectional; (c) Pylon anchorage zone of longitudinal and transverse section; (d) Steel-anchor-box. In addition to forming of steel and concrete composite section outside and other tensile properties of materials can also be combined with a concrete section. Fig. 7.27 shows the Brazil of a form of composite section beams and concrete log bridge, bridge of long-span 12 m. Fig. 7.28 shows the connection structure of wood and concrete. As Brazil is rich in wood, it is a bold attempt.

Fig. 7.27 Timber-concrete composite beam (unit: m) (a) Bridge deck cross-section; (b) Deck top.

2. Combination of Architecture Structure of the different sections with different materials, can achieve weight reduction, cost savings, speed of construction purposes. Figure 7.29 is the layout of vertical and cross-section of the bridge of France Normandy bridge. Main span 856 m span of was the world’s large cable-stayed bridge across the Seine river, straddling the river, a condition of small-span bridge, so the side span of cable-stayed bridge and the main from the towers out of 116 m concrete span section, middle main span of steel box girder. This reduces cross-main beam weight (beam 9 t/m, if we adopt the concrete beam 45 t/m), save cable costs, while reducing the side span length, not only saves the cost side, more auxiliary supporting piers also greatly increases the stiffness of the main span. To section integration one side span concrete beam and steel box girder of main span is selected the same shape.

Fig. 7.28 Wood and concrete coupling construction (unit: mm).

Fig. 7.29 The layout of vertical and cross-section of Normandy bridge, France. Chongqing shibanpo Yangtze river double-line bridge of shibanpo Changjiang River Bridge in old in order to coordinate needs to build 330 m of main span continuous rigid frame bridge. Large-span pre-stressed concrete continuous rigid-frame bridge, due to the

weight of main girder set degree, will produce a great deal of bending moments and shear forces, previous bridge built, there have been many cracks. In order to avoid these problems, Mr Man-Chung Tang in the cross-section of steel beam scheme span weight sets in due to the decrease of 330 m master looked back only the equivalent of 270 m of long span continuous rigid-frame span bending moment of pre-stressed concrete continuous rigid frame and the 270 m long-span pre-stressed concrete continuous rigid frame is built of precedents, so programme set up as shown in Fig. 7.30. Chongqing caiyuanba Yangtze River Bridge Is a span of 88 m + 102 m + 420 m + 102 m + 88 m supporting system arch bridge, due to terrain features, has selected a span across the main channel of the programme. Side span on river banks and in shallow water area, reducing the span can reduce costs, and eliminates side pillars, aesthetic values. In order to balance the weight of the main span of the bridge above the main arch with steel box section, below the side spans and bridge main span arch using concrete cross-section, as shown in Fig. 7.31.

Fig. 7.30 Changjiang Shibanpo River Bridge double-line bridge (a) Main spans 330 m; (b)

Of steel beams and reinforced concrete beams load distribution map; (c) The cross beam lifting system schematics; (d) Across the beam of the lifting process.

Fig. 7.31 Caiyuanba Yangtze River Bridge (a) general arrangement; (b) rendering.

7.2.4 Structural Connections between Different Interface 1. Force on the Connection Requirements Neither composite section structure nor the combination of architecture, must be connected between different materials. How to apply different material together is the key to form a uniform cross-section or structure. For composite beams, different materials need transmission mainly is the shear force and bending moment of composite architecture needs to be passed between different materials. Connections between different materials typically weaknesses in the structure, apart from satisfying the normal stiffness and strength requirements, fatigue is often the design control factors, as well as to construct designed also to ease of construction. Transmission of forces between different materials is not enough to rely solely on adhesion between material, you must take certain measures, which measures increase the connection area, increase mechanical pre-stressed occlusal function, and so on.

2. Composite Section Member Mainly Based on Transfer of Shear Joint Structure In the composite section member, with transfer of shear between concrete and steel, uses connections with stud connections, steel connections, steel connections, perforated steel plate connections. Stud connection is widely used in the steel and concrete composite beams in the form of its principle of operation is vertically welded in the tension zone of steel plate shear studs on concrete adhesive, in addition to the bond between the concrete and shear studs, there are mechanical forces. When the number of shear studs enough, failure mainly around shear studs, concrete is crushed, as concrete, strength that could cut nail. When the bond between concrete and steel plate failure, shear transfer depends entirely on shear studs, so in between steel and concrete there is a slip, also known as the flexible connection, as shown in Fig. 7.32(a) shown below.

Rebar connecting through steel plates welded bent into various shapes of reinforcing steel bar and concrete form of connection, when steel-tired gauge length is long enough, the bond between reinforcing steel bar and concrete enough to make steel and concrete work. The strength of the connection depends on in between steel and steel plate welding strength and yield strength of rebar. Reinforced connections are well suited to bridge construction site operations steel bending in the form of a ring, spiral-shaped, as in Fig. 7.32(c) shown below. Steel connection in steel channels and angles, such as welding on steel and concrete with the connection, it works with the same principle as that of shear studs. Due to steel and steel plate stiffness of connection, even in the absence of bond between steel and concrete, steel plate and mix slip between the concrete is very small, so called rigid connection, as shown in Fig. 7.32(b) shown below.

Fig. 7.32 Connector structure (a) Cylinder head Stud connectors (b) Grooved steel connectors (c) bent steel connectors. Perforated plate is the use of steel concrete between steel and concrete in the hole forces a new connection forms along the steel beam vertical connecting plates can be set through holes on steel, can also do not set through steel bars. This connection is first proposed by Leonhardt and others in 1987, Japan got a lot of research and applications. Study shows that holes in the mix concrete has great dowel action and its ultimate destruction is the hole in the shear failure of reinforced concrete, and are not subject to the effects of fatigue. At present, specification is basically not open cell provide for the shear capacity of steel plate calculated basically based on test an empirical formula.

Fig. 7.33 Shows the shear plate and concrete bolted connections with perforated sheet.

3. The Passing Combination of Bending Moment and Shear Force Structure of Connection Points Structure Combined system of structural connections between components of different materials,

transfer request is complicated, passing some major moments, some to transfer of shear to be passing moments. Connections between different components the construction convenience is a major factor must be taken into account in the design of these factors. Resistance of shear connections can still use the above forms, bridge of steel-concrete composite joints many openings plate form, in addition to passing moments, to be configured in the concrete and steel members connections pre or pre stressed bars.

Fig. 7.34 Shibanpo bridge of steel-concrete composite connection point (size unit: mm) (a) steel and concrete connecting structures; (b) in the connection section of perforated steel plate (c) connect steel beams install. Chongqing Shibanpo bridge of steel-concrete composite joints made of perforated steel plate connections structure with pre-stressed joint. Because in the middle-section of steel beam from a major, if the steel beams cantilevered cast-suspended in the air and concrete connection, a long time, the operation is difficult. Steel beam end connection section is separate from the main production, fixed on a concrete cantilever and hoisting of steel girders in place connect directly with welding, so that after hoisting into place the

field connection workload has been greatly reduced, ensuring the safety and quality of construction. Fig. 7.34 is slate slope construction and connection of steel beams of the bridge connecting hole on plate. Perforated steel embedded in concrete connections steel beam connections with perforated steel plate welded and tensioned, main hoisting of steel girders in place welded to steel beam connections.

Fig. 7.35 Nanjing Changjiang third bridge tower connection parts. Nanjing Changjiang third bridge tower following sections of bridge deck concrete towers and steel towers above deck. Connecting parts mainly transmit axial force, in order to make the junction shape smooth, general connection with flanges structures is not used, instead axial force was transformed into shear force through perforated plates connecting steel columns and concrete pylon. Fig. 7.35 shows the connecting point structure. In building structures and steel bridges, based on different loading behaviour, can be combined with reinforced concrete column and steel beam, Fig. 7.36 shows the construction of a pre-stressed bolt connection, which greatly reduces the workload of the field.

Fig. 7.36 Pre-stressed bolt connection structure.

4. Innovation in Making the Connection with a Simplified Structure Connection structure between the different materials is difficult in bridge construction and durability locally, so that an attached structure simplified, stress clearly is effective for improving connection reliability pathways. Pylon cable-stayed bridges mostly built of concrete, which can give full play to concrete good strength characteristics, usually towers on either side of the cable-stayed for while anchoring at the tower, rather than is continuous across the towers, mainly because the cable is thicker, small radius cannot be used through the tower. Pylon pylon is the anchoring problem in addition to bear vertical force, also bear the horizontal force, the same tower requires a larger size to decorate when two anchorages and tensioning.

Fig. 7.37 Glass City Skyway main Bridge facades (unit: mm).

Fig. 7.38 Glass City Skyway main bridge tower facades and cross-section (unit: m). Located in the United States city of Toledo, Ohio, Glass across the Maumee river City Skyway Bridge is a two-span 186.69 m single-cable-plane cable-stayed bridge with single tower, bridge width reaches 38.814 m, as shown in Fig. 7.37. In order to make the bridge a new landmark of the city, and aesthetic requirements bridge scheme is one of the main factors to be considered when, so choose a simple, single-cable multi-tower cable-stayed bridge. Due to large, cable forces of cable-stayed, the maximum cable required 156 root 7Ø5 steel wire Fig. 7.38. If the pylon anchorage cable on both sides, the giant large horizontal force would make the Tower size increased a lot. To solve this problem, the design continuously through the pylon of cable-stayed bridge saddles, saddle structure as in Fig. 7.39. Saddle consists of a series of small diameter 25 mm stainless steel tubes, each pipe through a steel wire, all the small pipe wrapped in a big stainless steel tube closed at both ends, filling in the casing strength 34.5 MPa cement slurries, as strand completely in

parallel through the tower, successfully resolved the hawser asks not bending with small radius problem. Due to this critical structures, towers using solid cross-section tower size was greatly reduced, and because tower anchorage zone stress is very small, the reinforcement is greatly simplified. Simple anchoring provides conditions for the area is decorated with glass towers.

7.2.5 Structural Measures to Mitigate Failure 1. Reduce Failure Requirements and Approaches Special loads such as seismic, wind, ship collision with power amplification of common features, but the probability is very small. If bridge is fully equipped with the ability to resist these load of peaks, bridges need to be designed to be very powerful, which will make the project cost greatly increased. How small the price conditions enabling bridges to resist these little probability of special loads, bridge design is not off the pursuit of the objectives. Appropriate structural measures to be taken, you can reduce the load of these power amplification causing the destruction of the bridge.

Fig. 7.39 Glass City Skyway main Bridge facades (unit: mm). Effect of cyclic loads on the bridge is mainly reflected in the vibration caused by fatigue and dynamic amplification sides. Dynamic role in addition to loads itself with relations, also associated with the natural frequency of the structure. When the structure of the natural vibration frequency cyclic loading of frequencies or frequency multiplier with the outside world came near, the resonance structure occurs, power amplification is more obvious, and even dynamic instability. Therefore, the reduction of dynamic characteristics of the destruction of the bridge from the following two aspects: one is to change the structure of vibration characteristics, so that it is not easy for the outer resonance excitation effect; the second is increase passivation measures, reduce the destruction of the dynamic load capacity.

2. Change the Structure Vibration Characteristics of Structures For relatively light structure or structures are prone to periodic external vibration under load, may be controlled by design factors. Most likely vibration of cables of cable-stayed bridge is bridge members. There are two factors causing vibrations of cable-stayed: one is the parametric oscillation, and second, the vortex-induced vibration under the action of wind and rain.

Fig. 7.40 Principles of the parametric vibration of cables. Fig. 7.40 is basic principles of parametric vibration. When cable’s main beam vertical bending vibration transverse vibration period and cycle close, cable vibration will be more obvious. In the Normandy bridge design, because the primary beam span upto 856 m, bending vibration period of 4.0 s, the longest cable vibration period of 4.5 s, parametric vibration of cables in order to prevent, in the cable is designed for connecting cable Fig. 7.41. Due to the cable settings, will be the longest natural period of vibration of the cable, down from 1.25 s, other cable, which effectively prevents the parametric vibration of cables.

Fig. 7.41 Normandy bridge cable.

3. Energy Dissipation Damping (Earthquake) Construction

Damping will be eliminate the vibration energy and, therefore, increased damping to reduce vibrations caused by knots effective measure to frame failure. Increase the damping is the most direct way to set the dampers, and stayed increased cable damper design has become a usual cable vibration reduction measures. Simple damping is to fill rubber damping material between the cable and the girder sleeve through which the cable runs. Currently focused on the design of hydraulic damper in cable has been widely, hydraulic damper of damping ratio can be set as desired. Fig. 7.42 is a hydraulic damper and its installation on the cable.

Fig. 7.42 Hydraulic damper (a) hydraulic dampers; (b) position on damper in cable. If yield would also eliminate the vibration of structure, in the traditional concept of structure is not allowed to succumb, even under the earthquake forces as well. But if fruit intends to make some minor component at design time in the strong earthquake occurred while yielding to remove earthquake input of energy, you can protect the main structure, and these secondary structures after earthquake can be replaced. This is a design under the performance-based seismic design idea. New East San Francisco Bay Bridge is to replace the existing San Francisco East Bay Bridge self-anchored suspension bridge, east of the existing bridge is a steel truss bridge, the 1989, San Francisco earthquake partially damaged it, according to estimates, the bridge could not meet a future anti-earthquake requirements, and reinforcement of cost is very high, so to build a new Bay Bridge. East San Francisco Bay Bridge Fig. 7.43 is a single-tower self-anchored suspension bridges, with the main span of 385 m Bridge is based on conditions across the deepwater channel decision, due to the aesthetic requirements of the local population, they do not want portal pylon, but single-column. Huge deck suspended on a single column, in the earthquake zone pylon seismic requirements it is difficult to foot, so designer Mr Man-Chung Tang limited destruction dissipation solution. The whole tower is divided into four branches, and shear plate connection between each other. Battened usually tower of limbs even as a whole so that they work together to resist the live load moments. And under strong earthquake forces, these panels will surrender, to the Council the role of protecting the main structure of full bridge was destroyed, as shown in Fig. 7.44.

Fig. 7.43 The new San Francisco Bay Bridge East Facade layout (size: m).

Fig. 7.44 East San Francisco Bay Bridge Tower columns with shear keys (size unit: mm) (a) Tower column cross-section; (b) Cross-section diagram of bridge; (c) Finite element simulation of the shear yield. Canada Confederation Bridge was built-in the North Atlantic Winter sea ice, ice floes in spring alongwith the currents hit the pier, to prevent crashed ice bridge becomes the key to bridge design. Resist ice impact directly through strengthening the piers, but it will greatly increased. Designers through thematic studies and designed the ice structure. Ice shield is set in sea-level location on the pier slope, when ice floes rammed into a pier at

sheet lifted, under the action of gravity, crushed ice, eliminating the impact of ice energy, as shown in Fig. 7.45. This is a unique example of a design of energy dissipation.

Fig. 7.45 Confederation Bridge ice shield working principle.

7.2.6 Structural Measures Ensuring Structure Durability Durability is an important parameter for evaluating structural design, life span is 100 years of bridge design, bridge master structure must meet this requirement, generally cannot be replaced in the design life. But in the bridge structure exposure to nature, while also experiencing the repeated actions of vehicle loads, how to guarantee the durability of bridge engineering a big problem. Bridges the widespread use of outside material, in addition to concrete, steel corrosion (especially the corrosion of high strength steel), issues such as the aging of rubber from the material itself is not easy to solve, enhanced durability generally use two methods: one is to enhance the protection measure; the second is on long-term protection of members, reserve replacement measures in the structural service life period. Now common in bridge-free guarantees durability throughout the lifecycle and requires multiple replacements of components are: high strength steel cables, suspenders, rubber or steel made of timber supports, expansion joints, and so on. Durability of building materials cannot yet be predicted at present, this requires that in the course of shall carry out regular checks of bridges, especially those known vulnerable component, must be regularly checked. Therefore, in bridge design examinations, operations, space should be reserved in the course, wearing component construction, inspection, can be replaced.

1. The Corrosion of the Reinforcement Measures Corrosion is the weak point of durability of reinforced concrete structures, particularly chloride ion permeability rather serious situations, such as environment of the marine environment and the northern winter road salt, corrosion in these environments is essential. Corrosion protection there are at present several ideas: the first is to strengthen the protection of concrete, and the other is in steel add extra protection protective measures, the third is to improve resistance to corrosion of the steel itself. Rebar is mainly chloride ion corrosion reinforcement in the environment, to the reinforced concrete blocks to chloride ion penetration, time increased chloride ion penetration into the steel becomes effective means of protecting reinforcing steel bar. There are two steps to achieve the above objectives: Is to increase the thickness of the concrete cover, and the other is the compactness of concrete. National specification for

reinforced concrete protective layer thickness generally determined depending on the structure of the office environment, for example, in reinforcement protection layer thickness of bridge design specifications according to the reinforcement category, component in the structure determines the location and structure of the office environment, I kind of superstructure of main reinforcement protection layer thickness in the environment is 30 mm, while in the III, IV class environment of substructure reinforcement protection layer thickness of 60 mm. Under the environment of salt in the ocean or the North, with the exception of thickened layer, but also called for greater strength of concrete to improve its compactness. In the East China Sea Bridge, bridge construction of bridge pier and splash zone maximum thickness of concrete cover for 70 mm, for because it is a cast-concrete, concrete cover thickness 90 mm, add slag and superplasticizer using high density compaction of marine concrete with chloride ion penetration to slow speed. In the rebar can be increased with additional protective measures are: added rust inhibitor in concrete, rebar added corrosion-resistant coating, reinforced implementation of cathodic protection. Add a rust inhibitor in concrete, can form a passivation layer of protective film on the steel surface, thus effectively blocking to prevent erosion by Harmful ions on the steel bar. Inhibitor is relatively cheap, the operation is simple, just mixing in concrete, has been widely used in China. Tidal zone pile caps of Hangzhou Bay Bridge and piers of the splash zone areas as a mixed-type inhibitor additional measures to guarantee the durability of concrete structures. Increased corrosion protection coating on the surface of the steel is also an effective reinforcement of protection measures Shi, widely used epoxy-coated surface by electrostatic spray bars, abroad, starting from in the 1970, of the 20th century bridge is already in widespread use in the marine environment. Our country has been able to produce epoxy resin coated steel bar, and the enactment of production standards, some application in port engineering. Application of epoxy resin coated steel bar key is in the process of shipping, processing, assembling not to damage the steel surface coating. If the local coating is damaged, it accelerates corrosion of the tear, hence, damage must be repaired on site, increases the difficulty of construction. In the splash zone of Hangzhou Bay Bridge Piers cast-concrete epoxy resins used in coatings reinforcement, practice has shown that, under China’s construction technology, easily damaged coating application is difficult. Cathodic protection by effectively the establishment of an external anode, turning the bar into a cathode to prevent loss of iron, in order to achieve corrosion protection. External anode can lower than that of steel materials, or realized by impressed current. Hangzhou Bay Bridge bearing platform of main piers, the tidal zone and the splash zone to try impressed current cathodic protection measures have been adopted to ensure RC 100 years without being eroded, and the entire system imported from abroad. Protective measures, the third is to improve resistance to corrosion of the steel itself. Stainless steel main alloy constituents of chromium and nickel, has a high chemical stability in oxidizing medium to generate a dense tough film. When the chromium content of more than 11.7%, can make the whole gold electrode potential of significantly improved, so as to effectively prevent the further oxidation of the alloy. Currently not in concrete structure stainless steel rebar is austenitic steel and duplex stainless steel, the chemical composition and mechanical properties as shown in Table 7.1.

Table 7.1 Chemical composition and mechanical properties of common stainless steel reinforcement of the concrete. Steel grade 304 304L

Mechanical properties Cr Ni Mo C N (max) 19 9.5 0.08 19 10

Chemical composition (%) Tensile strength Yield strength Elongation rate (MPa) (MPa) (%) 584 240 55

0.03

550

296

55

316

17 12 2.5 0.08

584

240

60

316L

17 12 2.5 0.03

536

296

55

2205

22 5

721

508

30

3

0.03 0.14

Application of stainless steel reinforced concrete was as early as 1937~1941, year construction-project is Mexico Yucatan Progresso Harbour project, 2100 m length of reinforced concrete piles with sea water corrosion of type 304 stainless steel to resist serious. Projects put into use 40 years later no related news was heard in 1970, testing began on the corrosion research, which lasted 20 years, results show that its corrosion resistance performance is good. The project services for more than 60 years, without much maintenance, so stainless steel was widely used notices. Stainless steel application problems mainly in the areas of: stainless steel smooth surface, and the behaviour of the concrete was wrong, so need more anchorage length; stainless steel electrode potential is high, if mixed with carbon steel use will accelerate carbon steel corrosion, therefore, when used in the two structures must be electrically isolated; more important is high prices, increase in engineering material costs. In recent years, abroad to study the properties of stainless steel reinforced concrete, studies have shown that material prices increased despite an increase in one-off costs, however, due to low maintenance costs, total life cost was still better than the steel reinforced concrete structure. AO Shi Kanshi, connecting Hong Kong and deep Hong Kong section of the Shenzhen Western Corridor in Western bridge, use about 1250t stainless steel type 316 and type 2205 bars as the lower part of the bridge’s Pier Outer layer of reinforcement, Stonecutters Bridge in Hong Kong using type 304 stainless steel wire as the lower part of the tower’s outer steel to ensure bridge 120 years of service life. In mainland China there is no use of stainless steel reinforced concrete in bridge records.

2. Ease of Construction Ultimately to be achieved through the construction of bridge design, construction quality depends to a large extent on the ease of construction, must fully take into account the difficulty of construction of complex components to ensure reliable operation. Construction technology of inclined cable fully reflects the ease of application development requirements. Early parallel wires of cable-stayed bridges in applying on-site production, wire wears into the PE sleeve anchor head is installed, completion of cable

tensioning sleeve grouting cement slurry. Because on-site production, pouring cement in hard dense near the anchor head, causing cable durability is greatly reduced. Some of our cable-stayed operating for 10 years or so, only had to replace the bridge cables. In order to solve the problem of construction of cable-stayed, Japan engineers invented the hot extrusion PE sleeve, semi-parallel wire cables. On the factory floor by hot-extruding PE sleeve wrap in wire, so quality of wire corrosion greatly improved. In order to facilitate transport from factory to construction site of cable, parallel wire twisted 7°, make cables in elastic modulus case of not more than the amount, you can pan in the roller. This cable has become mainstream. After further increases as bridge of long-span, inclined cable diameter and weight increased significantly, even if it is difficult to transport in the roller. In order to solve this problem, France freyssinet company has invented a single-unit parallel tensioning steel strand cables. PE sleeve is first installed in the cable position and comes with PE wrapping the steel strands one-by-one, into the scene PE sleeve and pull and then filling in the sleeve preservative, antiseptic liquid can be replaced during operation. This not only solves the problem of transport and long cable tension, and improved anti-corrosive measures, than the early filling water mud corrosion reliability is greatly increased. Fig. 7.46 for the construction of Qingzhou Minjiang bridge in the cable. Forming technology of post-tensioned, pre-stressed pipe to improve ease of application examples. Pullout difficult extubation process, and pipe friction losses, and thus, invented the process of formation of metal corrugated pipe, pre-stressing pipeline construction difficulty is greatly reduced. Easily leakage of metal corrugated pipe plugging, to reduce the reliability of pre-stressed and piping grout is not easy compacting. In order to solve these problems, plastic corrugated pipe was invented. Plastic corrugated pipe heat welding long pipe except at the ends, completely sealed and this will be greatly reduce the problem of pipeline leakage, but also makes it possible to vacuum mud.

3. Ease of Inspection Bridge component is not yet quantified the relationship between influencing factors and durability, so used to periodically check necessary measures to ensure durable security. Durability is the main controlling factor for the bridge components, such as steel components, cable anchor head, base, telescopic devices, must be checked frequently, so that should be considered when designing the future convenience of checks, reserved check condition. For steel girder bridge, in order to facilitate corrosion inspection and using stage additional coatings, conditions should be set up in the breast can be moved check the platform. Figure 7.47 is the Hong Kong Ting Kau Bridge cable connection to the steel-concrete composite girder structure. Cable through the ear plate of steel and steel beam connections anchor layout above deck, exposed to make inspection engineers can directly see the anchor, but also easy to check operation.

Fig. 7.46 The construction of Qingzhou Minjiang cable bridge.

Fig. 7.47 Stay cable bridge with steel-concrete composite main Beam coupling construction. Early concrete cable-stayed bridge cable, tie-bar arch bridge suspender using prestressed anchor head first method of protection, anchor embedded in concrete. However, as some cable-stayed bridge and tie-bar arch bridge suspender rust accident happened, cables and cranes rod corrosion check of a great importance. Operation found buried in concrete in the anchor head is difficult to check, thus, the designed cables or lifting anchor head is exposed and protection sleeve design, protective cover removable for easy checking. Figure 7.48 for the Ting Kau Bridge, Tsing Yi Bridge section, beam of cable-stayed bridge with steel hinge, for ease of maintenance, support week edge design are taken into account in the operating room.

Fig. 7.48 Ting Kau Bridge, Tsing Yi Bridge side profiles (unit: m).

4. Replacement Measures Expected component needs to be replaced during use must be set aside for replacement measures, apart from the detachable component itself, but also to reserve replacement operation of points and space. Cables and Suspender cable supported bridges due to fatigue and corrosion problems, you must in the use of a certain number of years after the replacement, so in addition to cable replacement must be considered in the design of bringing mechanical problems, would also like to reserve some operational measures. Fig. 7.49 is Runyang bridge hang Sola Panel, set on plate for use temporary suspender suspenders bolt holes.

Fig. 7.49 Runyang bridge Crane Sola Panel. Rubber bearing for bridge life-cycle components must be replaced, (JTG D62-2004 of reinforced concrete and pre-stressed concrete bridge design regulations D62-2004) 9.6.6 requires that, when using rubber bearings, and pier between the breast and bearing

replacement should be reserved to the desired position and space. This requirements are generally achieved by setting a certain altitude bearing pads stone. Rubber bearing thickness is generally only a few centimeters to more than 10 cm2, pier capping beam top surface usually sets the support cushion stone to spread the concentrated force of the support and levelling supports to the base. Early design bridge beam pads stone height 10~15 cm only, only clearance between the top of piers and abutments and breast 10~20 cm, unable to place jacks, with other temporary support to point beam replacement bearings must be jacked up. In order to facilitate future replacement bearings should be top of coping and bottom surface of the beam reservation placed between beams held up the Jack of the space, which can be easily realised through the raised seat cushion stone height, usually beams gap bottom top of the coping above 50 cm.

7.3 INNOVATIVE CONSTRUCTION METHOD AND CORRESPONDING EQUIPMENT Modern bridge construction technology of progress but the advances in design theory and engineering materials, but also relies heavily on construction technology progress. Best bridge designs should make full use of the existing state of the art construction techniques, as well as the progress of construction technology in turn can also promote technological progress of bridge design, bridge engineers to come up with a brilliant plan. The progress in bridge construction technology on the main steps in the construction equipment, it is difficult to imagine relying on manual operations can build a modern bridge. Therefore, as a bridge designer, you should understand the most advanced construction methods and the appropriate equipment.

7.3.1 Driving Force Behind Method of Innovation Innovation method of invention is always to achieve certain ends, when innovation brings significant benefits are other engineering mode limitation, thus forming various type of mature technology. In the area of today’s bridge-building, technique innovation is as follows power.

1. Adaptation and Building Bridges Span More Build a bridge of long-span bridge builders is always striving for goals. When the span to a certain extent, previously formed mature technology will not be able to complete the task, therefore, the pursuit of a long-span bridge construction process is the biggest driving force of innovation.

2. Adapt to the Special Circumstances of Construction Social development calling for greater room for development, as well as communication between people and people, towns and cities and towns also increased, need to bridge had previously encountered in the environment. Constantly in the new environment under the condition of bridges, is a bridge engineer challenging, and sometimes requires a completely different technology. For example, in the construction of the bridge in marine environment, and across the river bridge, there is no land as a base for building a bridge, and need to use ships as the main tool. In cities, for example the construction of viaduct, does not affect the existing traffic within the city, you must operate in the narrow space, a lot of process cannot be adapted under normal conditions.

3. Improve Construction Speed, Reduce Human Resource Costs With the improvement of transportation requirements, in order to improve the prevailing conditions, bridge road, the proportion is considerably improved, this required built super long bridge, and even all the road construction on the bridge. Such as high-speed rail, in order to reduce the damage of foundation subsidence in soft basic foundation area to replace the bridge embankment, this requires the construction of dozens of even hundreds

of kilometers of bridges. In super-long bridges construction, structure is not complicated, but to bridge construction to be completed within a certain duration becomes the key of course, in accordance with traditional methods of construction can take full flowering, doing so while it is possible to achieve that goal, but will result in human and equipment costs increase significantly. Therefore, through process improvements to achieve increased speed of construction has become an inevitable requirement.

4. Improve the Reliability of Construction Quality Improving construction quality is another goal of bridge builders, which is bridge construction method for improved direct power. Good construction method is simple and reliable, quality can be guaranteed. Imagine in very difficult conditions in construction, or in process of non-often complex situations, it is very difficult to guarantee the quality. Innovative bridge construction mainly in two aspects: one is to improve the construction of bridge in the structure, arrangement; the second is development of specialised equipment, mechanised, large-scale, automated, intelligent development trends of bridge construction is equipment.

7.3.2 New Technology of Bridge Erection Adapted to Special Requirements Bridge erection environment is the main factor affecting the bridge erection technology of, which set up process is sometimes a bridge-building success the key to this section presents specific examples to illustrate the influence of bridge construction method of the bridge program.

1. Ideas for Special Bridge Erection the Erection Process Is a kind of self-anchored cable-stayed bridge cable-supported bridge, the advantage of stiffness of cable, cable-amount of horizontal force to the primary beam outside prestressed and combined with the cantilever construction technique, so modern cable-stayed bridge in more than 50 years become of long-span bridges strong competitive bridge, currently the world’s largest long-span cable-stayed bridge span exceeds 1000 m, Master of bridge design Denmark’s Professor Niels J. Gimsing’s idea of 5000 m long span cablestayed bridge. However, increasing self-anchorage cable in bridge span but had a negative factor. With the increase of long-span girder under the horizontal force is increased, eventually beam compression capability and image stabilisation qualitative further increased span constraint. In order to overcome this disadvantage, Gimsing, Professor idea 5000 m for long-span cable-stayed bridge on the Bill partially anchored cable-stayed bridge, as shown in Fig. 7.50. Using some anchor side main beam level pressure can be reduced, but not decreased across the tower at the root of the main beam level pressure, need to span sections in setting horizontal cables welded connection pressure distribution from the roots crosssection to the cross-section. At bridge completion phase this is a good idea, but the traditional cantilever construction technology of large-span cable-stayed bridges are used,

yet before the closure of main girders, to pass all the dead load of the horizontal force to the main section near Liang Tagen. This makes cross-level recovery is not installed front, beam is broken. In order to solve this problem, Gimsing in conceiving and devising this programme, a professor at the same time, proposed in the span middle and around the pylon-girder construction method for installation at the same time, across horizontal cables can be installed at the same time, as shown in Fig. 7.51. You can see from this example, bridge in bridge design and construction technology of relationships.

Fig. 7.50 Partially anchored cable-stayed bridge with intermediate horizontal cables.

Fig. 7.51 Process idea to first erect span in the middle.

2. Ideas for Special Bridge Erection the Erection Process Bridge construction environment on the erection of the bridge there is a restriction, and optional erection process restricted bridge program ideas. This section describes several of the ingenious design to adapt to environmental conditions of building the bridge and the construction method. Across eastern Canada Northhumberland Strait Confederation Bridge Jian Qiao, is located in a natural environment, the biggest obstacle has a long winter, sea ice most of the time in a year, and cross-channel bridge a total length of 12.9 km. How to hold effective construction within a year, built the bridge within the limited annual, becomes the key to bridge construction. Bridge scheme uses multiple-span beam bridge, divided into three sections. West approach for 14 holes standard long-span continuous beam of 93 m bridge, cross-channel part 43-hole standard 250 m with hanging hole rigid-frame bridge with long span, East approach span to 7 hole standard long-span continuous beam bridge of 93 m. Full-bridge uses fully assembled construction technology, approach as on land and in

shallow water, and limited capacity of lifting equipment, the use of bridge girder erection machine segmental construction, while 43-hole-by-holes and assembling construction of cross-sea bridge, the large floating crane “Swan,” used in the construction of hoisting the most large lifting quality 7500t. Construction of the bridge is the main feature of the bridge pier foundation, including all components are used, including the assembly of pre-fabricated construction technology, components pre-fabricated in the factory, the west shore of the prefabricated, pre-cast steam curing, insure uninterrupted during the cold winter. In order to make the base and piers using the installation process, designed using underwater foundation programme, is also the basis of pre-fabricated expanded by floating crane floating transported to the bridge, placed directly on the sea-bed. In order to expand the foundation level, expanding the bottom surface of the base is set three blocks. Figure 7.52 is disecting views of bridges pre-cast components. Expansion base was mainly used in the construction of land bridges, and the bridge because the environment element assembling process must be used, so the geological conditions of spread foundation under the water, is a bold idea. In order to piers pre-cast completely, the pier and the base is divided into two sections of pre-fabricated, using tooth-shaped tenon joints, avoiding the wet joint assembly, simplifies the assembly process. While the main beam is divided into only two cantilevers and weigh upto 7,500t 1,200t of hanging two large paragraphs complete set equipment, greatly simplifies the assembly process. Of course that are inseparable from the large lifting equipment.

Fig. 7.52 Confederation Bridge (a) lifting of main block division; (b) West approach of lifting pieces divided; (c) hoisting the east approach spans of segmented.

Fig. 7.53 Rion-antirion Bridge (size: m) (a) river section (b) pylon structure (c) infrastructure. Foregoing Greece for 4 towers connected across Rion-Antirion bridge cable-stayed bridge, bridge is located in water depths of 65 m. In such deep water bridge base is a technical challenge. Commonly used scheme for large-scale deep water bridge foundation or the open caisson foundation of pile, but construction works of the foundation in such a deep sea water is very difficult. Therefore, the foundation uses the innovative design of this bridge and under the sea construction of large foundation. Undersea site is soft foundation of bridge site, in order to enhance bearing capacity and to broaden the base of foundation intensive short break into piles, each base consists of 250, (25~30 m long) steel pipe piles, within 7~8 m, as shown in Fig. 7.53. Such a large expansion is located to the bottom of the process is a bold and innovative ideas. Used floating under water sinking craft. 90 m diameter, expansion chassis is designed to be separated into many compartments sealed hollow box, box at the coast stratified placement within the excavation dry dock, dry dock can be poured two base chassis. When you finish pouring the pier at the bottom of section, bring water in the dry dock, the chassis can emerge, dragged into the sea. Dry dock once again closed after pouring two pier foundations chassis. Continue pouring the piers on floating on the sea bottom, high piers at the same time, the chassis underneath due to the weight of the piers over the sea floor. When high piers reach to a certain height, floating in the waters of spread foundation and was towed to pier—the pier continued to pour concrete. When the pier to board after a pier height, infusion in the chassis and the basis of hollow pier, sea piers to the effect of gravity located under pile reinforced seabed. At this point, the foundations and piers built entirely, you can continue up bridge tower in construction. Fig. 7.54 shows in dry dock in the pouring of the foundation and completion of prefabricated base being dragged out of dry dock.

Fig. 7.54 Rion-Antirion bridge Foundation construction (a) Dry docking base chassis; (b) Based chassis out of dry dock. As China’s economic development and technological progress to build the bridge, construction of bridge over the sea requirement has become reality. In our country in recent years building Donghai bridge, Hangzhou Bay Cross-Sea Bridge, the island project in Zhoushan Jintang bridge, Qingdao haiwan bridge and a number of cross-Sea Bridge. These bridges across dozens of kilometers of distance on the sea, no land construction, erection method of bridge beam design of the most important factors to be considered. These cross-sea bridges across the shallow water or mud flat, little depth, in addition to the navigation needs set outside the large-span bridge, the remaining bridge were determined by the economy and duration, economy and duration depends mainly on the erection process and equipment capacity. East China Sea Bridge was built-in China’s first cross-Sea Bridge a total length of 32.5 km. Full bridge in addition to the two main navigation span stayed-cable three auxiliary navigation opening bridge, using cantilever construction continuous girder bridge with variable cross-section, but rest all used the height of continuous beam bridge of bridge spans. Deep sea Part is a 70 m long-span continuous beam using monolithic construction technology of hoisting, simple support into continuous erection. Shallow Ford parts is a 50 m long-span continuous beam using movable frame hole-by-hole in situ process set up. Hangzhou Bay Bridge is the world’s longest sea-crossing bridge, full length 36 km, the two main navigation span cable-stayed bridge, North Channel size 448 m, navigable span South 318 m, and the remaining 30~80 m span continuous girder of bridge spans. Deep part with 70 m span sea part is a 70 m long-span continuous beam using monolithic construction technology of hoisting, simple support into continuous erection. Shallow sections dominated by 50 m long-span continuous beam using shift formwork lifting holeby-hole (beam girder) in process and beaches part dominated by 30 m long-span continuous beam. Island project in Zhoushan Jintang bridge is 26.54 km, 620 m steel girder cable-stayed bridge of main navigation span for span east navigable Kong Wei 216 m span prestressed continuous rigid-frame and navigation span 156 m span continuous girders in the west, the majority of non-navigable spans of 60~70 m continuous beam, using full span pre-cast hoisting erection process. In order to guarantee period, several bridges are used in this installation process. Because the water is not very deep, use of driven pile foundation. Had intended to use pre-

cast pre-stressed concrete pipe piles for Donghai bridge Fig. 7.55(a), but after some time it was found that prestressed concrete pipe pile head could be easily crushed, thereafter only steel pipe piles were used. Two other bridge was used to break into steel tube pile bases Fig. 7.55(c). Steel bottom sealing concrete of pile construction technology, is only one onsite placement of full-bridge construction pieces. Piers precast hoisting technology of watering down the seam and pile connection Figs. 7.55(b), (d). Superstructure of continuous beam effects lifting or moving die carrier cast uses technology, to accommodate construction of water over long distances. The deep water area, you can use large floating cranes, floating cranes of lifting capacity of 2,500 t, therefore, constructed using the 60~70 m long-span continuous beam, 70 m lifting the quality of whole hole 2180t Figs. 7.55(e), (f). Inaccessible to large ships in shallow water, we must use the already built piers erection of main girder. Uses 50 m long-span continuous girder of Hangzhou Bay Bridge, box girders with large girder transport vehicle has been set up on the deck of transported to the bridge using erector erection Figs. 7.55(g), (h). 50 m continuous girders of Donghai bridge using the moving die carrier cast new construction technology. Due to the number of number of main girders, piers, during the process of prefabricated steel banding used pre-fabricated in the workshop, whole casting process, makes efficient use of templates is greatly increased.

Fig. 7.55 Donghai bridge and Bay Bridge assembling process. (a) Pre-stressed concrete pipe piles for Donghai bridge; (b) Donghai bridge precast concrete piers within the field; (c) Steel pipe piles of Hangzhou Bay sea-crossing bridge; (d) Hangzhou Bay cross-sea bridge pier and pile Cap docking; (e) Prefabricated at the bar as a whole into the mold of

the Hangzhou Bay Bridge; (f) 70 m spans of Donghai bridge girder integral lifting; (g) Box girder of Hangzhou Bay Bridge from the ground onto decks; (h) Hangzhou bay Bridge 1,600t bridge girders. Massive construction of railway passenger dedicated line, design speed of 200~350 km/h, rail ride quality is very high, when completed should consider not only the situation, while also taking into account the long-term deformation results. Therefore, requires a long-term commitment and total not more than 30 mm of deflection, and the 20 m range of uneven settlement not exceeding 20 mm. Such a high demand for soft soil foundation and roadbed filling height exceeds the 5 m section is unable to achieve, so these sections needed to bridge road design, which increase the proportion of railway bridges in passenger dedicated lines in length, average total route length of bridge 36%. Using bridge instead of road bridge generally do not require long span, span size depends on the cost of the superstructure and substructure cost balance, also depend on the time, equipment, capacity, and other factors. Track extensive use of bridge construction period will become the main controlling factor for the construction of passenger, fast bridge becomes a problem that must be solved. Increasing the speed of bridge erection methods there are several. One is framing a comprehensive workers, this approach requires a lot of support, templates, and human, and cannot turnover. II is the use of large precast technology this requires fast and efficient precast plant, as well as large girder erecting equipment. In order to solve this problem, in railway-related research and after a long exploration in engineering units, develop criteria for passenger bridges in China were—32 m, 24 m, 20 m, span post-tensioning method pre-stressed concrete simply supported box beam Fig. 7.56. Three kinds of standard double-track box beam with long span 899t, 699t, 562t, respectively, using the whole construction technology of pre-cast hoisting, transport, in order to achieve the goal of rapid construction. Primarily in pre-cast box beams prefabricated in the factory, through the beam girder approach transport to beam, then through the erection of bridge girder erection machine. Set of process of pre-fabricated, transport, installation and operation process as well as the equipment required.

Fig. 7.56 Passenger dedicated line 32 m double line box girder cross-section (unit: cm) (a) Cross-section; (b) Pivot section.

Fig. 7.57 Segmental assembly (a) MSS segmental process diagram; (b) Assembled in the box girder segments; (c) Assembled after the completion of box girders; (d) United States New Roosevelt Bridge section connecting the alveolar. Viaduct is a form of using bridge instead of road bridge, also built on the land bridge, but in most cases were of short and medium span bridges. Viaduct on the original roadbuilding, bridges while maintaining traffic flow on existing roads, construction site became one of the important factors controlling the bridge construction. Pre-fabricated lifting is one way to solve space problems, on structure in pre-fabricated in the factory on the outskirts of the city, transport to the night-time traffic in smaller times of bridge crane loading. Large viaducts have greater width and weight, full span transport is impossible within the urban area. Early trestle used longitudinally parting methods, such as hollow slabs or t-beams, a piece on a girder bridge by lateral ties after, if the Shanghai inner ring viaduct is basically take the form of hollow plate and t-shaped beam. Practice: using fabricated hollow panels, weak bridge horizontal linkages, prone to bridge longitudinal crack, instead of t-beams, easy lateral during transport. Box-girder of the landscape as a whole is good, but the city will not be the whole set up. One approach is the use of full space supports in situ, doing covers, time consuming and inefficient. Another approach is to use a horizontal parting of the ways pre-cast segmental. Segmental assembly mounted on large movable scaffold, pre-cast segmental transportation to the site temporarily supported on brackets, all sections install in place, with tendons into the whole. As shown in Fig. 7.57(a), (b), (c). In order to ensure the reliable segment connections, segmental sets can occlude each other tooth and section after section of the front end with back-end of the previous segment as a template and even pre-fabricated continued, as in Fig. 7.57(d) shown below. Construction technology of large-span cable-stayed cantilever, while its system is also particularly suitable for cantilever construction, it is a cable-stayed bridge to get an

important factor in promoting. In certain cases, however, erection of other methods, such as pushing makes it well adapted to land condition. Completed in 2004, France Millau Viaduct, needs across the Tarn River Valley, connecting both sides of the highlands, in the valley, for soft soil foundation, basis in order to reduce the workload, select 8-span cable-stayed bridge scheme, span into 204 m + 6 × 342 m + 204 m, due to the high bridge pier using taliang DUN consolidation system, as shown in Fig. 7.58. This bridge with a large span across the Valley, high, very high and pier (2 pier of 245 m, 3 high pier of bridge deck pavement of bridge deck of high 230 m), cantilever erection difficulties, you need to set the lifting so much so, boldly using pushinstallation technology of main beam, girder in place before you install pylons and cables. The main beam, for adapting to the incremental launching construction, used single-cableplane with small base width (only 4 m) inverted trapezoidal cross section, and bridge deck width of 32.05 m (Including wind up), at the intersection of bottom and inclined plate set longitudinal clapboard to support push reaction forces in the process, as shown in Fig. 7.59.

Fig. 7.58 Facade of the Millau Viaduct set (size: m). Pushing from both ends of the bridge, between the 2nd and 3rd pier closure. In order to reduce the girder moments in the process of thrusting the two measures: first, in addition to 2, outside the closure between the 3rd pier-span, each set up a temporary pier; the second is close to push the top forward side pylons installed, follow the main beam push, tension on each tower 6 to cable, as shown in Fig. 7.60(a). Of course in front of thrusting beams also usually set the steel truss girders. In order to reduce friction in the process of thrusting on the pier horizontal force a pier while the thrust of the synchronised launching technology, with the exception of side span outside the temporary pier installed a push on Jack, all the remaining bridge DUN is installed on two jacks, all jacks through the computer control system of control to ensure the synchronisation job. In addition to the first segment more complex, took 3 days to push things, remaining on average 5 days pushing a span (171 m).

Fig. 7.59 Cross-sectional arrangement of the Millau Viaduct (size: m). Deck above the bridge tower of steel box-section, high 88.92 m, 800 t, by flatbed truck from pushing the main beam delivery to each a pier location, the ultimate bearing capacity of the girder was a real test. Tower is straight through a temporary tower bar lifting towers on bifurcation, bifurcation point is raised later when, under the action of gravity and natural vertical towers, (see Fig. 7.60(b).

Fig. 7.60 Construction of the Millau Viaduct (a) Pushing the Millau Viaduct girder in; (b) On the tower is straight in the course of construction. Can be seen from the examples described above, in order to adapt to different environments to build the bridge, flexible mounting method must be used, not what approach to what type of bridge is mechanically. In exceptional cases, possible mounting methods, in turn also affect bridges set design scheme. Therefore, good bridge engineers must master the technical principles in different contexts in order to work out alone and practical design and construction program.

7.3.3 Equipment of New Bridge Erection Technology Manual handling ability is limited, but cannot guarantee the quality, so large, complex, high quality of bridge construction rely advanced construction equipment. Construction equipment usage has following purposes: the first is carrying large objects into the air, which would require large lifting capacity, long-distance lifting cranes; second, increasing operational efficiency, the use of mechanical equipment can greatly improve labour efficiency, and impossibly long intense labour of the workforce; the third is improving

accuracy, manual operation is affected by skills, attitudes, and the use of automated equipment operation ensures that each time the error levels remain stable; and, finally, use equipment to detect structural parameters that cannot be directly observed by humans, lots of testing equipment help engineers to check the quality of construction.

1. Large-scale Bridge Construction Equipment The most direct goal of using machinery and equipment is maximisation, as human carrying capacity is very limited, it’s hard to imagine a modern bridge construction relies on manual handling of large structures on the site. Large power equipment is used, not only help workers lifting large structures, sometimes even changing the mode of construction, affect the design. Heavy lifting, pile driving, transport equipment are representatives of this type of equipment. Construction of sea bridge as described earlier in this chapter, while also achieving rapid construction without land support using large load distribution construction technology becomes the most ideal construction methods. Large segments would require large lifting equipment, lifting capacity, lift height are critical to these devices.

Fig. 7.61 Confederation bridge main part parameters (size: m). Canada Confederation Bridge used complete assembling technology from base to the upper structure, the largest component is 250 m span t-type rigid frame cantilever section, 192 m in length, weighs 7,500t. Figure 7.61 is the bridge’s 250 m rigid span erection part parameters. The erection of the bridge using a unique lifting ship “Swan” (SVANEN), as shown in Fig. 7.62. “Swan” was specially built-in 1990, for the erection of Denmark West Sea Bridge set of lifting, transportation bridges of large own floating crane can lift caissons, piers, main beam and various artifacts. At first, design of lifting capacity of 6500t, lifting height 48.5 m. Between 1994~1995, it was reformed for hoisting Canada Confederation bridge, the maximum lifting capacity reached 8700t (including enclosed hanging beams), maximum lifting height 76 m, as shown in Fig. 7.63(a). In order to hoist pier, the hull was designed as catamaran, length is 102.8 m, the full width of 71.8 m, ship shape deep 6 m, draft of 4.5 m, able to work under 15 m/s conditions of high wind speeds, wave 1 m, as shown in Fig. 7.62. The biggest feature of the ship is to bring large bridge component without cooperation from other barges.

Fig. 7.62 Ship “Swan” (SVANEN). In 1997, the ship was hoisted out resund link between Denmark and Sweden, with the main span of the bridge being 490 m it is road-railroaddual purpose cable-stayed bridge with approach spans span 140 m, as shown in Fig. 7.63(b). Main bridge girders of approach spans are used ceiling the floor is concrete, webs of steel truss composite beam. As a result of the “Swan”, the main bridge with long segmental, bridge hoisting the hole. They built the sea-crossing bridge of Donghai bridge in China in 2002, also facing a large floating crane lifting requirements, when water transportation can be found on the market can be used in the construction of bridge crane, the largest lifting tonnage of 2,500t. It is the original ministry of transportation salvage and rescue Bureau of Shanghai’s “strong” number, captain 100 m, 38 m, 9 m, 1981 years from Japan’s Aichi shipyard was constructed by turning multipurpose crane, as shown in Fig. 7.64(a). If the leased foreign large-tonnage crane, daily rent is upto 10 Million. In accordance with the natural condition of bridge of Donghai Bridge based high cost, should be appropriate to increase the span of bridge hole to achieve a higher economic indicators. But considering the lifting capacity of 2,500t limit, the Sham Shui Po non-navigable spans of 70 m. One 70 m hole of box girder weighs about 2,000t, and lifting auxiliary spreader can be controlled in the range of 2,500t.

Fig. 7.63 “Swan” at of lifting work (a) Confederation Bridge erection; (b) Cresund in hoisting Bridge approach bridge. During the course of construction of Donghai bridge, designed and built the “four airlines to forge ahead” and “little Swan”, and two large floating crane, are dedicated to marine construction crane. CCCC’s “four sail endeavour” has jib crane, with lifting capacity of 2,600t, 100 m in length, width 41 m, 7.6 m in depth, its most prominent feature is the lifting heights of upto

80 m, as shown in Fig. 7.64(b), box girder cable-stayed bridge at main navigation span of Donghai bridge “The four airlines to forge ahead” was lifting. The floating crane with “strong” number only has a lifting capability, must have a beam barges together. Iron bridge Engineering Bureau for 70 m box girders of Donghai bridge erection construction of “little Swan” crane ship, using a “Swan” design ideas, you can beam lifted themselves after, don’t need to beam barges together. Disadvantage of doing so is that the floating crane to transport contains the main beam navigation in bridge longer in length, floating crane used less efficiently. “Little Swan” lifting capacity of 2,500t, maximum lifting height 41 m, wide 7 m, as shown in Fig. 7.65 (a). In order to set up district 70 m of box girder of Hangzhou Bay Bridge high pier, built iron bridge Engineering Bureau a “floating crane. “Day one”, also is lifting one floating crane, lifting capacity of 3,000t, the maximum lifting height upto 53 m. On the bridge erection is complete it can also be converted into a jib crane for other hydraulic lifting operations. Due to “day one” construction, during the construction of the Shanghai Yangtze River tunnel and bridge, bridge using steel-concrete composite beam of long span 105 m, quality 2350t, saving foundation price, achieved better economic results, as shown in Fig. 7.65(b).

Fig. 7.64 The large floating cranes “strong” and “four sail endeavour” (a) “vigorously” in the East China Sea Bridge erection; (b) “four airlines to forge ahead” in the Jintang bridge erection.

Fig. 7.65 The large floating cranes “little Swan” and “day one” (a) “little Swan” in lifting 70 m box girders of Donghai bridge; (b) “day” in the Shanghai Yangtze River tunnel and bridge erection 105 m box beam. Long span bridge was built on the water, in order to guarantee period, use of driven pile foundation. Built-in China in the East China Sea Bridge of Hangzhou Gulf bridge cross-Sea Bridge, due to the bridge’s long, tight, in addition to several main navigation channel bridge piers using basically the basis of a bored pile into steel pipe foundation. Hangzhou Bay Bridge, a total of 1.5 m, 1.6 m diameter steel 5144 pipe piles, maximum

depth of 88 m, such a large number of large steel pipe pile must have big effective pile driving equipment to complete. Piling on the water must be done with the pile driver, in order to build offshore long bridge and coastal Marina, China has built several of the world’s most advanced driving boats in recent years. Common characteristics of these floating pile driver is: pile high, 90 m above, can sink into the 80 m the length of the pile diameter, the biggest pile diameter 2.0~3.0 m, flexible operation, could eat into raking piles and higher productivity, as a result of automatic hydraulic control device, every boat sinking 10~15. In the absence of measuring marks to determine where piling on the water, usually real-time GPS positioning system is equipped. Haili 801 turn pile frame, precision 60 mm, is currently one of the world’s most advanced large pile driver. Table 7.2 is the largest parameters of the largest pole ship. Fig. 7.66 shows the two different types of floating pile driver. Table 7.2 China’s biggest pile driver parameters (unit: m). Ship names

Length Shape- Pile Sinkable pile Sinkable Diameter Enterprises width depth high length pile

Three navigation pile 15

72.1

27

5.2

93.5

80

2.0

Navigation bureau three

Three navigation pile 16

72.1

27

5.2

93.5

80

2.0

Navigation bureau three

Three navigation pile 18

72.6

28

5.2

93.5

80

2.0

Navigation bureau one

Guangdong pile 8

70.5

28

5.2

93.5

80

2.0

Navigation bureau four

80

30

6.0

95 (Rotary)

80

2.5

Navigation bureau two

Three navigation pile 18

71.7

27

5.2

95

80

3.0

Navigation bureau three

Haiwei 951

66.6

27

5.2

95

82

2.5

Bridge bureau

Haili 801

Massive bridge assembly construction on land again at a large bridging equipment, however, due to limitations of transportation road conditions, no big equipment may be used for maritime transport, so also has limited land mass assembled construction the span of the bridge. China’s massive construction of railway passenger dedicated line by lifting simply supported girder, formed a 32 m, 24 m, 20 m, standard beam forms. Weight is 32 m long-

span double-line box girders, 900t beam girder approach on transport, saving construction pavement. This process, when required during the construction of 900 t Erector, 900t beam carrier, 900t or 450t spar three essential for large equipment.

Fig. 7.66 Large pile driver (a) three air 15th; (b) Hai Li, No. 801. Beam girder erection of hole-by-hole method is not a new technology, pre-fabricated bridges have also been used in the past. However, because the primary beam horizontal slice, the weight of each beam is relatively small, even if 50 m-span T-beams, lifting weight does not exceed 250t, therefore, bridge girder erection machine lifting capacity required is small. Meanwhile, pre-cast beam transport in the already-built bridge will not break through the bridge’s load, no special treatment in deck paving of temporary rail, beam carrier formed by several temporary group of railway axles. But for the entire hole set girder weighs greatly increased, these 32 m long span box girder weighing 900 t. This lifting capacity requirements for bridge girder erection machine greatly improved, moreover, beam has been set up on the beam transport, its weight far beyond the future use of loads must use special transportation beam motor on beam spread over a wider area. Liang Ti from the pre-fabrication to beam transportation truck also need large removable hanger—The gantry. Bridge building machine is a means to expand the already built piers and girders, a hole-by-hole bridge equipment. In order to be able to set up completed bridge across the span, generally long main beam of bridge erecting machine must be no more than two holes. The difference between setting up all full hole and erection of pre-cast beams is that in order for erection of girder bridge girder erecting machine through the bridge girder erection machine in the hind legs, the legs must be entirely outside the beam width, or retractable. Assembled width is much smaller than the width of the beam, it is easy to cross the bridge girder erection machine and made the design of bridge girder erecting machine very simple as that. In order to improve the efficiency of bridging, advanced bridge girder erecting machine using the hydraulic control system. Advanced embodiment of bridge girder erection machine in terms of its light weight and ease of operation.

Fig. 7.67 Bridge machine structure diagram (a) DF900 non-guiding-beam bridge girder erecting machine (b) DF900D guiding-beam bridge girder erecting machine (c) transporting-erecting-in-one bridge girder erecting machine. Italy’s Nicola is the world’s leader in the production of bridge girder erecting machine, after the digestion and absorption of recent years, our country has production and erection of monolithic erecting machine. According to the characteristics of China’s construction of passenger dedicated lines, these erector is also supported to varying degrees improvement, make the operation more convenient. For example, using beam transportation truck TRANS-bridge-tunnel machine, Erector, erector bi-directional bridging technology are manufacturer improvements and inventions in China. Current monolithic erecting machine comes in three forms, namely without Liang Shi, Liang Shi, and integrated transportation and erection. Fig. 7.67 are no guiding-beam bridge girder erecting machine DF900, guiding-beam bridge girder erecting machine DF900D and Italy nicola-transporting-erecting-in-one bridge machine structure diagram, they are all used in the Chinese passenger dedicated lines. Beam carrier’s main functions are: delivery of prefabricated box girder by bridge girder erecting machine and is responsible for feeding of pre-fabricated box girder

erecting machine, within the transitions can be checked when erecting machine long distances. Because of openings since major, currently most advanced beam transportation truck with rubber-tyred, in order to increase and beam transportation road contact area increases. In addition, wheel type beam carrier operations greater freedom, without the preset orbit, as shown in Fig. 7.68.

Fig. 7.68 The box beam operating at prefabrication site (a) Main girders of Donghai bridge in orbit transfers and (b) Wheeled girder of Hangzhou Bay Bridge. Full span pre-cast and hoisting construction of porous Longbridge is the duration of the programme is born out of control factors of condition of building the bridge, although the full time limit, but the demand for heavy equipment. In the construction of Chinese passenger dedicated line, through comparative analysis are as follows inspection, construction of a main beam pre-casting yard complete with girder, bridge equipment, one-way bridge length of 10 km of the economy. Super pre-fabricated plant can be built in the middle of line, after finishing erecting a bridge girder the erection machine transport back to the beam direction to start the opposite direction. The economic length of double Erection is 20 km.

2. Automated in situ Bridge-construction Equipment Erection of monolithic process mentioned above, fast speed, high efficiency, suitable for construction of super long bridge, but requires large transportation equipment and prefabricated, assembled or concrete on the bridge directly is the way to solve this problem. Previous in situ bridge assembling or concrete casting used scaffolds and templates in general, to improve transport efficiency of bracket, mobile scaffold and shuttering were invented and used. MSS is a template or scaffold or bracket combined with mobile devices, done using a template and bracket in one cross, afterward it does not require complete disintegration, instead using mobile device it is transferred to another cross and can be assembled instantly, thereby improving efficiency. Mobile support only needs to provide segmental beams assembled with stand, movable frame in addition to removable brackets also want with a group put together by the template. Mobile scaffold and shuttering of advantage is that a good chunk of the automatic control of hydraulic equipment, so that bracket, template, moving to group together shorten the process, while ensuring the quality of the template. Main components of the mobile frame or formwork is coasted between the piers of the main beam, according to the support pouring or assembling bridge mode is divided into the upper deck and lower deck. The girders of upper deck type mobile bracket moves along the cross bridge fixed to piers, the concrete girder to be erected is placed on top

surface of supporting beam, as shown in Fig. 7.69. Through-type mobile bracket girder moves along the completed concrete beam, on the bridge to be poured (assembled) , and through the legs on top of the pier, as shown in Fig. 7.70. Deck bearing stents benefits are that beam to be poured (assembled) is on the top of mobile frame, with large hands-on space; on the contrary, benefits of through good mobile stand is that stent placement (assembled) is on top of beam, not restricted by the clearance under the bridge, bridge operations are affected by the interference of mobile frame.

Fig. 7.69 Working diagram of deck-bearing type movable frame. Using mobile formwork on-site pouring good beams, and girders framing finished pouring quality is basically the same, but due to require binding reinforcement on the mold and cured concrete, long duration, for construction of a cellular beam normally takes 12~15 days, so efficiency is quite low. Girders assembled using mobile frame segmental generally requires dry joints, stretching and external pre-stressed girder to join together, the wholeness of the completed beam is not as good as beams using casting placement. Therefore, choice of dedicated-passenger railway in China complete set mounted or movable frame construction technology of on-site pouring. Bridge using technology of segmental has higher efficiency than using the shuttering method, Shanghai-Shanghai Min Lu viaduct, using a movable frame construction technology of segmental, after the craft skill, every three days can be installed in a hole 30 m long span box the end of circular beam, as shown in Fig. 7.71. Movable frame bridge construction cannot only for straight line construction through eccentric wedge change paragraph or section by section of the template can also be construction of curve bridge, Norway produced by NRS shuttering minimum radius 75 m construction of the viaduct.

Fig. 7.70 Working diagram of Through-type movable form frame (units: m). The former Transportation Ministry first highway construction company build the 4th bridge in Mosul, Iraq, with the Federal Republic of Germany PZ company–developed Switzerland–provided movable form frame. Using this device, in 1990, built the first bridge in China movable frame construction of pre-stressed concrete continuous beam bridge—gaoji Strait Bridge in Xiamen. Gaoji Strait Bridge full length is 2070 m, made up of multi-span continuous girder of long span of 45 m. Since then, construction equipment manufacturers have done a lot of research and development in China, China had to create all kinds of mobile scaffold and shuttering, but relies on imports of key high-precision hydraulic equipment. These MSS are erecting beam bearing units, thus, creating span movable frame girder of bridge bearing capacity restrictions now, shuttering to construction of main girder of the largest span is 60 m over this span, movable frame girder sections greatly increased. Multiple-span beam with large span bridge can take advantage of mobile scaffold to assemble, but must be combined with other bridge construction technology the role of Mobile supports is only to transport segment so to reduce the mobile frame weight. Fig. 7.72 is China’s Zhongtie major research of large-span mobile 96 m long-span continuous beam bridge adopts cantilever segmental construction technique, remove boot supports transport of box girder sections.

Fig. 7.71 Deck-type mobile bracket of the Shanghai-Shanghai Min Lu viaduct segmental box beam.

3. High-quality Concrete Formwork Concrete templates are basic civil engineering construction equipment, determining the appearance and quality of components and templates-intensive, in engineering cost account for a large proportion. Previously (before in the 1970, of the 20th century) the most often used was a natural wood-mode, with los repetitive use (no more than 5 times), and high resource consumption, abroad have long used alternative materials to build templates. Currently widely used are glued wood template, glue bamboo, steel, composite templates, engineering plastic application templates are at exploring stage.

Fig. 7.72 China’s zhongtie major research of large-span mobile (unit : m). Steel high strength, good rigidity and flatness, widely used in engineering. But the high cost of steel formwork, not easy to change re-used, so in need of mass production of pre-cast plant to use more. In order to overcome this shortcoming, assembled steel framework was invented, but the seams of assembled steel framework is difficult to handle and, therefore, relatively poor surface quality of concrete. Glulam template is the currently used template, it has hardened layer on the surface, there is a certain air suction, and seams easy to deal with and therefore produced better surface quality of concrete structures. Both sides of Glulam templates can be used, and reusedfor upto 30~50 times. In the 1980, of the 20th century the introduction of glued wood mold production technology, but the relatively poor quality of the domestic bond template, some re-use can reach no more than 10 times. Bamboo production is large in China, in the 1980, of the 20th century in China invented a glue bamboo template, properties and glulam is similar to or better than wood-mode, repeat number can be more than 30 times, and has been widely applied, can now be exported to foreign countries.

Template’s surface physical properties directly affect the quality of production of concrete components, concrete is vibrated and condensation to release a certain amount of water and gas in the process, it will form bubbles and tiny grooves on the surface of the concrete, thus affecting the concrete the compactness of the surface, reducing the role of reinforced protection. In order to solve this problem, Japanese engineers invented in 1985, production a controlled permeability formwork (Controlled Permeability Formwork, known as CPF). The surfaces have permeability for water and airy, which can be in the newly poured concrete to drain excess free water and air, greatly improved performance. Since then, the Europe, Denmark, Germany and the United Kingdom have been produced using this template. Starting from Hangzhou Bay Cross-Sea Bridge in China, in order to high durability of the bridge piers, try using permeable formwork, good results have been achieved.

Fig. 7.73 CPF work schematic diagram. Permeable formwork is made in ordinary templates by pasting a layer of permeable formwork on cloth formed. Permeable formwork cloth generally consists of raw materials such as polypropylene special handling, varying periods of formation of filaments of polypropylene fibers, via., hot spinning processes and surface prepared from special secondary roller handle. Structure can be divided into upper, middle-tier, and centre. Surface and intermediate layers are formed by fine 17~115 dtex, 110~313 dtex fiber composition, its diameter is 1~10 μm and 4~15 μm; adhesive layer and pasted the template, consisting of fine fiber 212~414 dtex, the aperture is 10~30 μm, has water- and air-permeability and retains moisture. Due to the small surface pores of permeable formwork cloth, equivalent aperture D95 composite structure is much less than 30 μm, you can spilling water and cement and cementitious materials to be stranded in a flooded template inside of the concrete surface, makes the structure surface hardened into a dense layer of hydrated calcium silicate-rich layers, so you can to effectively reduce cellular concrete surface, pockmarked face. Also, this water formwork cloth with water retention, improves concrete curing quality. Fig. 7.73 is permeable formwork structure schematic drawing. Currently permeable formwork materials in China is still at an experimental stage of production, and imported products are still lags behind. Template is assembled at the construction site is more labour-intensive processes, templates in conjunction with stents increase the production efficiency effective method.

Therefore, a variety of ingenious flexible formwork system is widely used, its fundamental component is a steel-frame glued wood mold. Japan and Europe and the United States is currently widespread use of these composite templates, instead of steel, template support system from the original group together into small blocks of hydraulic automatic contraction device. Fig. 7.74 is the overall external formwork of box girders of Hangzhou Bay Bridge and collapsible overall internal model.

Fig. 7.74 Hangzhou bay bridge overall template (a) Outside the box girder of Hangzhou Bay Cross-Sea Bridge model (b) Hangzhou Bay Bridge shrinkage overall IMC.

7.3.4 Detection Equipment for Bridge Erection Early in the design and construction, to ward off a variety of uncontrollable factors, it required a higher safety factor. With the development of engineering technique, bridge design safety factor becomes more and more rational, so as to make the structure more lithe, more saving and longer span. Therefore, quality control of the construction process becomes the key to bridges built. Various parameters and accurate detection of bridges in terms of quality are the necessary means of control. Parameters that are commonly used in the construction of bridge location, shape, stress, and so on. Regarding these arguments, there were corresponding test equipment, but most of the hand-operated, low efficiency and poor operating conditions and low accuracy cannot be comprehensive, observation. Currently testing equipment for the construction of the bridge was largely digitized, allowing for remote detection.

1. Test Equipment for Location and Shape The position and shape of bridge construction is the most basic control data, early main optical telescope measuring instruments, including water associate and theodolite. Measured data are subject to complex measuring and calculating, thus time consuming and error-prone. At present, these two compliance measurement tool has been included with microcomputer combination of calculation of total station instrument functions, automatic total stations can also automatically set goals greatly improves the efficiency and accuracy. Application of laser technology in the measurement makes the component location and shape measurement accuracy greatly improved, and are commonly used in large bridges beam box beam pre-fabricated factory, bringing the precast segmental box girder to mmlevel accuracy.

Wide-range application of Global Positioning System GPS position measurement, built a bridge over wide surface measurements of productivity and greatly improved. Using GPS, and horizontal position can reach millimeter precision, elevation can achieve centimeter-level accuracy.

2. Stress Testing Equipment Direct indicators of internal force is the force structure, load can directly reflect the present state, especially for statically indeterminate structures. Early force measuring devices required sensors to be embedded in the component in general. For example, the cable tension to pressure-measuring sensor embedded in under the bolt head, counteracting force to pressure measurement sensors embedded in bearing down. In this way, high equipment costs, and cannot be replaced. In response to this situation, the random vibration test method of cable tension of cable-stayed and devices have been invented, as long as the measured fundamental frequency of vibration of cable-stayed access to cable tension, can be measured at any time. With the advent of steel wire cable, because there are gaps between the casing and steel strand, it is not easy to measure the whole length of cable’s frequency and, therefore, magnetic flux, cable tension measuring devices have been invented. Through the force of cable-stayed solenoid effect of magnetic flux conversion cable, got rid of the vibration characteristics of difficult measurement obstacles.

3. Strain Gauge Testing Equipment Strain is the local reaction of structure to force, its monitoring is a traditional measure. Early monitoring of stress used variable, but characteristics of the strain gauge readings with time drift is not conducive to long-term monitoring of the construction process. Therefore, VW sensor was invented, which uses embedded sensors in measuring of pipe vibration on steel base frequency to conversion of the strain sensor. Due to the lower steel relaxation rate, and generally keeping the apparent drift strain readings for more than a year. At present, the fiber bragg grating sensors are being explored. Fiber grating sensor using fiber bragg grating in the deformed by the spectral changes of principle, measuring estimated spectrum change of variables. Theory of fiber bragg grating strain sensor drift is small, and can be more than one sensor measurement series, so for large strain distribution measurement and monitoring of micro-cracks in concrete structure is very effective. Therefore, this very broad prospects for application of fiber bragg grating sensors.

7.4 APPLICATIONS OF ADVANCED MATERIALS AND HIGH-TECH 7.4.1 Application Requirements of New Materials and HighTech Advances in materials engineering and high-tech itself and various use requirements are closely related. Bridge builders continue to pursue larger spans, better durability, lower the cost of these promote the application of new materials and technologies in Engineering investigation. Application of new materials and new techniques in engineering, in turn, contributed to raising the level of bridge design and construction. Material is the basis for construction, modern advances in materials industry to fundamentally change the system of engineering structures and concepts. With the development of modern materials, there have been a lot better materials, but from a price/ performance perspective, there is best suited for steel and concrete bridges, to replace the two materials have a long research path. Civil engineering materials research is to improve the properties of steel and concrete. With the development of science and technology, there have been a number of high technology, knowledge of new technologies, are defined as high-tech, this is one classes on the latest scientific research achievements applying transformation. High and new technology was quickly applied to all walks of life, have made great economic benefits. Application of information technology in building the bridge, the bridge construction has been developing by leaps and bounds.

7.4.2 High Performance Steel (HPS) Steel is the result of modern smelting technology, is one of the most important influence on modern engineering structure materials. From the 1980s, high-performance steel products has been gradually popularised. High Performance Steel (HPS) application is from High-Strength Steel (HSS) began. With research and development of high performance steel, currently in structural steels material called high performance in the field usually contains the following aspects: high strength, weldability, weather resistance, shock-resistance, mutation profiles.

1. High Strength Steel Using high strength steel from structural design point of view has distinct advantages, it can reduce the dimensions of the structural components, thus reducing low weight, increased span. High strength steel as early as after World War II were tried for bridge construction. Japan in the 1950, of the 20th century will be the yield strength of the steel of 500 MPa and 600 MPa for construction of the bridge, 60’s the steel with yield strength of 800 MPa. Akashi Kaikyo Bridge on stiffening girder of 800 MPa steel is used, made to reduce weight of good results.

In Europe, the bridge with a yield strength of HSS usually between 460~690 MPa. After heat treatment of 16 mm S960QL steel, nominal yield strength up to 960 MPa. United States began using HSS and weathering steel in bridge engineering (such as bridge, completed in 1977, the new river valley). prior to HPS research and development, there are 4 grades of steel for bridges: 250, 345 (345S, 345W), 485 (485W), 690(690W), numbers in code represents the minimum yield strength, the unit is MPa,W on behalf of the types of steel have weather-resistant properties. The most common bridge steel is 345W. Steel bridges made of high strength low alloy structural steel, mainly 16 Mnq and Q345q series-steel, in special bridge supplied by agreement. On the Jiujiang Yangtze River Bridge, the 15MnVNq produced by angang steel on the Yangtze River Bridge in Wuhu, mining 14 MnNbq steel manufactured by the Wuhan iron and steel (thickness ≤ 16 mm yield strength ≥ 370 MPa); the Lupu bridge, Pu steel reference as Germany DIN EN standard S355N steel (thickness ≤ 16 mm yield strength ≥ 355 MPa). Promulgated in 2000 national standard of the structural steel for bridges (GB/T 714-2000), provides Q345q, Q370q, Q420q (containing three of C, D, E rating) series-steel (thickness ≤ yield strength ≥ 345MPa, respectively 16 mm, 370 MPa, 420 MPa). Early high strength steel, high strength, but poor solderability, need to be pre-heated welding, to bring quality and cost control difficulty, so applications are difficult.

2. High Weldability Steels In the 1990, with the development of smelting technology, while maintaining high strength requirements for structural steel, but also have ease of processing (mainly weldability), weather and so on, become a High Performance Steel (HPS). Improving the performance is through modifications rolling process of steel chemical composition and heat treatment method. Effect of heat treatment on Crystal structures of steel has great, Oh the United States and Japan has developed in the fine control of heat treatment technology in cold rolling process in Europe is called quenching and tempering (called Q&T) technology, in the United States and Japan called Thermally Controlled Processing (TMCP) technology to produce while maintaining high strength and easy welding of fine grain structural steels resistance and high toughness. Respectively in the 1990, of the 20th century, America and Japan have developed high-performance structural steel standards, including on weld pre-heating temperature requirements a at 50°C the following, for example, United States HPS485W requirements of steel: thickness of weld pre-heat temperature at 60 mm only 20°C, 60 mm will be 50 degrees centigrade. Ordinary steel weld preheating temperature of 100~120 degrees centigrade. High solderability is also reflected in the different strength of steel can be welded, which makes structural engineers design concept completely changed. In the past it can be used with different strength levels in the structure of steel, but in different components, this is called a hybrid design (Mixed Design). If used in the main beam of a component, or a different type of steel, it is called a Hybrid Design (or translated as “confounding”). Hybrid design is characterised: according to the force structure configuration model

(generally not more than two) of steel, in order to give full play to material properties, economical benefits. Located in United States, Tennessee, Martin, R. (Martin Creek) bridge, opened in February 1998, to 2 × 71.78 m two-span continuous girder bridge, the roadway width of 8.53 m, horizontal layout 3 contiguous pieces of shaped beam, girder spacing 3.2 m. Original design used 345W steel, after support from FHWA, using HPS 485W for bridge design. In re-design, intermediate HPS 485W was used in pivot near the beam, span beam using hybrid design, which all transverse webs and connect the 345W. Final result: girder steel consumption by 24.2%, costs reduced by 10.6%. Weight considerably reduced because the primary beam, apparently transport, erection and lower construction cost savings.

3. Corrosion Resistant Steel With high atmospheric corrosion-resistant property (weathering), is one of the characteristic of HPS. Due to atmospheric corrosion resistance, omission or partial omission of painting of steel bridges can be significantly reduced maintenance costs in service period, achieving better overall economic benefit. In the United States, has 45% using weathering steel bridges. Weathering steels contain certain amounts of copper in steel, chromium and nickel alloys, their solid steel surface oxide layer, preventing steel step continued to internal corrosion, play a role in weathering. Normal weathering steel only in the case of low salt content in the air, and early rust on the surface of weathering steel and sometimes affect the appearance of the structure. Japan is in most parts of the marine environment and the winter salt non-slip, high salt content in the air and, therefore, ineffective use of normal weathering steel, so less used in bridge construction. To solve this problem, Japan steel works has been developed in the coastal environment of atmospheric corrosion resistant steel and weathering steel is developed early corrosion resistant coating to prevent formation of oxide layer on the surface of weathering steel in the process of rust off.

4. Low Yield Point Steel (Earthquake-resistant Steel) The general concept of seismic design of structures is by means of calculation and analysis of design and construction measures under the “strong column-weak beam”, “weak strong shear bending”, “strengthening connections weak members” principle, when the structure column and beam structure when subjected to seismic action in some parts of the plastic deformation and absorb seismic energy in order to achieve the required seismic performance of “minor earthquakes are not bad, repairable in the earthquake, earthquake fail” three levels of security requirements. However, in the 1994, United States California’s Northridge earthquake and the 1995, Japan’s Kobe earthquake damage survey, found conventional principle design of welded steel frame beam-column connections of steel building near the region widespread destruction. Although this damage not cause steel-frame buildings to collapse, there is no personal injury due to damage of steel frame joints, but the owner and the insurance company for inspection and repair complex pay lots of fees. Therefore, as a new method for solving such problems, set in the building seismic control device (example the damper)

“structural seismic control” studies began to be developed. Fig. 7.75(a) is expressed in conventional buildings under earthquake action beam ends of plastic hinge absorb seismic energy, while Fig. 7.75(b) is artificially set at specific areas consumption can absorb seismic energy, both on the principle of shared features, but it is a different design concept.

Fig. 7.75 Comparison of energy absorbing plastic hinges and seismic control device (a) Beam plastic hinges to absorb seismic energy; (b) Energy dissipation devices absorb seismic energy. After 10 years of research, Japan Nippon Steel company LYP100, LYP235 (yield strength of 100MPa and 235MPa) two low-yield-point steel, steels compared to conventional steel with lower yield strength and resistance to Rachyan, and yield-point margin of error smaller, has better extension and low cycle fatigue resistance properties.

5. Vertical Steel Plates with Variable Thickness (LP) Steel plate thickness along its length changing (Longitudinally Profiled Plate, referred to as LP steel) is hot when changing the thickness of the slab length. Webs and bottom plate of continuous box girder bridge across the different locations often need to change the thickness, if the thickness of steel plate, to achieve this purpose it is necessary to use different thickness sheet steel stitching, welding and material waste. Using variable thickness steel can reduce the number of welding structure and reduce the weight of the structure. In Japan all high performance structural steels can be rolled vertical thickness. Fig. 7.76 shows the schematic diagram of a LP plate production process and cost savings.

Fig. 7.76 LP steel schematic drawing (unit: mm) (a) LP steel production process; (b) LP plate cost reduction.

6. Other Features of High Performance Steel High performance steel in addition to these characteristics, according to a variety of structural features, you can also achieve some special performances, such as: Fire resistance, fatigue resistance, toughness at low temperature, special shapes, etc. In the 1990, of the 20th century, the high-performance steel products in the world wide range of attention, more and more applications will affect engineers design concepts. In addition to applications in civil engineering, high-performance steel products in other areas where there are more and more applications, so all over the world have invested heavily in the research and development of high performance steel. In 1997, Japan invested 10 yen, started the “super steel” research project, the goal was developed over 10 years strength equivalent to twice times the super steel for iron and steel (including 800 MPa easily welded steel, fatigue and delayed fracture resistance and failure 1,500 MPa class ultra high strength steels, heat-resisting steel for ultra supercritical pressure power generating equipment and beach area using weathering steel, etc.). In 1998, China has started in the national key basic research development plan “a new generation of steel materials for key basic research” “973 Program”. The ultimate goal of the study was a significant increase in Chinese steel output over 60% of carbon steels, low alloy steels, and the strength and life of structural steel, to produce a new generation of steel prototypes. Some specific objectives are: yield strength of carbon structural steel high to 400 MPa, low alloy yield strength of 800 MPa, yield strength of alloy structural steel 1,500 MPa, also the service life of steel 1 time. Domestic steel mills also applies to new steel bridges are being developed.

7.4.3 High-performance Concrete (HPC) Traditional concrete is extended from late 19th century, 20th century human civilisation and made a great contribution. Development of China’s economy is undergoing a period of rapid growth and construction is unprecedented in scale, in China in 2007, cement production reached 13.200 milliont, almost half of world cement concrete output of 7 billiont. However, the cement is high energy-consuming, resource-friendly products, improve efficiency in the use of concrete, not only on the construction itself has boost also contribute to socio-economic development. Therefore, in the development process, increase per unit of volume of a strong becomes a goal to strive for engineering and technical personnel, the development of high-performance concrete is from the beginning of high-strength concrete.

Fig. 7.77 Concrete development process schematic drawing. Early concrete strength depends mainly on improvement of cement strength grade and reduce mixing water consumption of concrete realisation. Water content reduction in the amount leads to significant reductions of the work, which is hard to operate at construction site. In 1986, Norway engineers first developed admixture in concrete with Silica fume on concrete strength, impermeability and resistance to chloride diffusion enhancement. In 1990, the United States rates first coined the term high-performance concrete (High Performance Concrete, called HPC), defined as having high strength, durability, highworkability concrete. To focus on these targets a different aspect of research in Europe, Japan and other countries, makes high-performance concrete application is rapidly advancing. Fig. 7.77 is described by Chinese academician Wu Zhongwei concrete development process. The objective is achieved through high performance concrete adding superplasticizer and implemented active fine admixture. Active fine admixture ground granulated slag and fly ash, silica fume, high quality, fine zeolite powder and development of rice husk ash, and so on. Such as fly ash, slag and silica fume admixture in began in the 1950, of the 20th century, however, owing to lack of grinding fineness, did not play an active role. To the above material, greatly improves the density of the concrete, thereby increasing the strength, durability and impermeability of the concrete, while increasing the work performance. To increase the concrete tensile capacity in recent years, adding fiber concrete material to be studied extensively.

1. High Strength Concrete High strength concrete is widely used in the construction of high-rise buildings and bridges. At present in the construction of bridge engineering C60 concrete has been more widely used in the bridge construction site, C80 concrete abroad already have lots of applications, C100 concrete also has experimental applications in foreign countries. High performance concrete with compressive strength under 150 MPa can consist of a fine admixture cement + active + reducer + sand + ground stone tie in together. Due to the active fine admixture and superplasticizer admixture, the slump can be reached 27 cm, making it work can be improved dramatically, can achieve a pump and self-leveling. High strength and Ultra High Performance Concrete (UHPC) is entirely the activity is made of cement + admixture + this carefully superplasticizer mix together, compressive strength up to 200 MPa. From Norway began in the 1970, of the 20th century research on ultrafine silica powder, 50 MPa, compressive strength of concrete slump 120 mm normal strength

concrete, by 1990, the slump 270 mm, 100 MPa, compressive strength and high performance concrete.

2. The Self-leveling Concrete Also known as self-compacting concrete vibration-free self-leveling concrete is a kind of high performance concrete with low water-binder ratio, usually mixed with a lot of powder coal ash, slag. Japan Tokyo University first developed the self-leveling concrete, concrete cement on each side only 114 kg, 71% per cent of total amount of cementitious material with slag, fly ash, in mixture added with high efficiency water reducing agent and expansive agent, thickening agent, mix with wrap sand technology, it is more complicated. Later development of vibration-free concrete cement-principal cementitious materials and mixing a number of mineral admixtures, adding superplasticizer and thickening agents such as phthalate, such as acrylamide. Vibration-free concrete can improve construction speed, reduce labor intensity and save on vibrating machinery and electric power consumption and eliminate noise pollution. This amount of powder and fine aggregate in concrete more need to find ways to suppress shrinkage of concrete, is the focus of research. Self-leveling concrete slump 230~270 mm, Development is greater than 550 mm (upto 700~800 mm).

3. For Fiber-reinforced Concrete By means of high efficiency water reducing agent, activated ultrafine admixtures can significantly improve the compressive properties of concrete, but the tensile strength of modified good is not evident, and improve cracking resistance and tensile strength of concrete is one of the research efforts in the direction of high performance concrete. To concrete mixing a quantity of fiber is one of the methods to improve the tensile strength of concrete, are widely studied. Mix fiber in concrete with steel fibers, synthetic fibers. Various fibers improve tensile strength of concrete key parameters under study, for example, steel fiber shape, size, etc. Constructability of fiber mix is the focus of research these factors. Through the fiberreinforced concrete tensile strength of upto 10 MPa. If the concrete on bridge design, alter our concrete design concepts. There are a lot of practical engineering where steel fiber was Added to the concrete bridge deck pavement, however, because of steel fiber-reinforced mechanism is not used in full, crack resistance of concrete tensile strength only as a reserve.

4. Other Properties of High Performance Concrete High performance concrete in other performance improvements are under study, these studies will be overcome the existence of ordinary concrete weaknesses so that concrete can be more widely applied in various fields of civil engineering. Table 7.3 shows some features of high performance concrete. Table 7.3 Performance range of HPC.

Feature

Code

Feature

Code

Feature

Code

Bonding with hardened concrete absorbs energy

AD Poor absorbency

EA High strength/density ratio (high strength light weight)

High wear resistance

AR Early strength

ES

Corrosion protection

CP High modulus

EM Low permeability

IMP

CS Wash erosion resistance

WSH

Resistance to chemical CR High compressive corrosion resistance strength Toughness

DUC High flexural strength (modulus of rupture)

Durability

DUR High tensile strength

High workability and cohesion

S/D

WRK

MOR Volume stability

VS

TS

Table 7.4 shows the places of application requirements of HPC performance codes shown in Table 7.3. Table 7.4 Performance requirements of the application of high performance concrete. Application site

N/E*

Performance requirements

Architectural pillars

E

WRK, CS, EM, PTD**

Post-tensioning plate

N

CS, EM

Base

N

CS

Floor

E

CP, DUP, AR, S/D

Long span concrete bridge

E

EM, S/D

Cold weather construction

N

ES

Chemical and foodprocessing plants

N

IMP, CR, AR

Fast completion of Segmental construction construction

N

WRK, ES, MOR

Hazardous waste storage

N

IMP, DUR

Parking lot

E

CP, DUR

E

ES, MOR

Structure

Bridge

Main

Road surface Road surface grand con-

Pavement

struction Repair

E

WRK, ES

Heavy traffic area

E

AR

N

WRK, CS, MOR, ES, S/D

Urgent Repair

E

WRK, ES

Underwater

N

WSH

Long Time

N

DUR, CS, AD

Use of Fibrous concrete

N

EA, AD

Public health structures

N

IMP, DUR

Earthquake

N

EA, WRK

N

EA, TA, CS

N

VS, CP, CS, EM

N

CS, TS, EM, DUR

Secondary Offshore structures Float

E

CS

Relief structure

N

EA, TS, CS

Tunnel

N

IMP, ES, CS, TS, DUR

Pre-cast/prestressed concrete

Fix

Military structures

Military structure

New traffic system High-speed rail, Maglev Gravity

Special

Lunar concrete

WRK

Automatic construction

WRK

Note: *N: new development, E: existing, ** a predictable deformation development over time. High performance concrete mix slag, fly ash, silica fume, active fine admixture could save a lot of cement, thus saving energy, also known as the green concrete, has broad application prospects in the future. Concrete performance will affect bridge design ideas.

7.4.4 Fiber Reinforced Polymer (FRP) Fiber reinforced composite (fiber reinforced polymer/plastic, FRP for short) is composed of fibrous materials and substrates proportionally mixing and through a certain formation of composite high-performance materials. This material came into use in the 1940, in the world of aviation, aerospace, shipbuilding, automotive, chemical, medicine and machinery are widely applied in the field. In recent years, the FRP with its advantages of high strength, light weight, corrosion resistance, began to be applied in civil and building

engineering structural and attracts the engineering sector’s great attention. In Engineering structures oftern used are mainly carbon fiber FRP (carbon fiber), fiberglass (glass fiber) and aramid fiber (aramid fiber) reinforced resin matrix, respectively referred to as CFRP, AFRP and GFRP. Table 7.5 the three types of fibers and the mechanical properties comparison with steel and aluminum. As can be seen from Table 7.5, fibrous material strength (tensile strength/weight) 20~50 times that of steel, high-strength lightweight performance is outstanding; carbon fiber modulus (tensile modulus/weight) 5~10 times that of steel, aramid fiber modulus for steel sheets 2~3 times, modulus of fiberglass and steel. Simply looking at specific strength and modulus alone, actual projects with carbon fiber material works achieve best results, but carbon fibre elongation is very small, they sometimes need to be mixed with other fibers, with the idea better overall performance. Table 7.5 Comparison of typical fiber axial direction mechanical properties with that of steel, aluminum.

Material type E Glass Fiber

Coefficient Tensile Young’s of thermal Specific Specific Relative Extension strength modulus expansion intensity modulus density rate (%) (GPa) (GPa) (GPa) (GPa) (10–6/°C) 2.55 3.5 74 5.0 4.8 1.37 29

S, R

2.49

4.9

84

2.9

5.7

1.97

34

M

2.89

3.5

110

5.7

3.2

1.21

38

AR

2.70

3.2

73.1

6.5

4.4

1.19

27

C

2.52

3.3

68.9

6.3

4.8

1.31

27

Standard type (T300)

1.75

3.5

235

–0.41

1.5

2.00

134

High strength (T800H)

1.81

5.6

300

–0.56

1.7

3.09

166

1.88

4.0

485

–0.6

0.8

2.13

213

ExtremeHigh model (P120)

2.18

2.2

830

–1.4

0.3

1.01

381

Kelvar 49

1.44

3.6

125

–2.0

2.5

2.50

87

1.45

2.9

165

–3.6

1.3

2.00

114

Carbon Fiber High models (M50J)

Aramid Fiber Kelvar

149 Steel

HM-50

1.39

3.1

77

–0.1

4.2

2.23

55

HRB400 Steel bars

7.8

0.42

206

12

18

0.05

26

High strength steel wire

7.8

1.86

200

12

3.5

0.24

26

2.7

0.63

74

22

3.0

0.23

27

Aluminum

1. Preparation Technology of FRP Products Preparation of moulding is the premise of FRP fiber and matrix in working together. Mechanical properties of FRP relies heavily on preparation technology, so one must be taken into account in the design the preparation technology of FRP structures. Products obtained by different preparation forms differ greatly. Application of FRP in structures Engineering’s products mainly include: the sheet of material (fiber cloth and plates), reinforcement materials and Suo Cai, mesh bar and grille, pultrusion, winding, molding profiles and profiles such as hand lay-up. Fiber cloth is the most widely used form. It consists of a continuous filament woven together, usually of unidirectional fiber cloth, so that do not infiltrate the resin before use. Current fabric mainly used in structural engineering, with resin paste surface after the invasion. FRP panels are fiber through layers in the factory shop, infiltration, curing the resin prepared from preformed, paste it in the construction or mechanical anchors fixed on the surface. FRP tendons is a one-way process (pultrusion), unidirectional fibers and resin molding rods may be on the table surface processed to increase its bonding with concrete. FRP cable is long, continuous fiber braid, then use a small amount of resin moist curing or without resin and cords made of FRP products. FRP reinforcement materials and cable materials in the reinforced concrete structure instead of reinforcement and prestressing tendons, can also be used for large-span cable-supported structures, tensioned structure and cable structures. Long fiber bundles woven in accordance with certain spacing perpendicular, and infiltrated with resin curing FRP grid materials can form FRP grating. FRP grid material substitute reinforcement mesh, three-dimensional FRP reinforcement cage alternative. FRP grating can be directly used as a floor or structure made of sandwich panels and other components. Pultrusion is the fiber or fabric through continuous feeding Creel, through the resin tank impregnated fibres, and wearing a thermal after the mold to pull bodies, can be made into a continuous FRP products accordingly. Pultrusion produces cross-sectional shape complex mixed continuous profiles, because of pultruded fiber along the axis, and is high in fiber, have very good mechanical properties, can be used directly as for loadbearing

elements, force can also be combined with other materials. But the lower transverse strength and shear strength of pultruded profiles. FRP winding profiles were continuous fibers or fabrics impregnated resin, clinging to core-mould according to certain rules (or lining of bile), and then after curing to form in order to annular fibers oriented profiles, a common form of tubes, tanks, spheres, etc. In engineering structure, FRP winding Canal filling can be used as a column, concrete piles, beams, component properties can be superior to concrete-filled steel tube. Moulded profiles are pre-impregnated resin fiber or pressurised heating curing fabric into the tool made of FRP material. Profile of this technology to produce accurate, smooth surface, stable quality, but usually low in fiber mechanical properties is poor. For some large or complex-shaped profiles, normal temperature and low pressure is generally used contact moulding process, low pressure at room temperature, or under no pressure formed a type of sticky with resin fibers and fabrics, used to manual operation is complete, so called hand lay-up. This method can produce complicated shapes, fibers lay out arbitrary and large sizes of FRP products, product quality is stable.

2. The Performance Characteristics of FRP Very high strength, that is commonly referred to as lightweight and high strength, so using FRP materials to reduce the structural weight. In bridge engineering, or FRP composite structures using FRP structure as a bridge superstructure can limit span greatly increases. Good corrosion resistance, acids, alkalis, chloride, and FRP can long-term use in a damp environment, which the traditional structural materials cannot compare with very suitable for designing. FRP artificial material, you can shop with different fiber, fiber content, and chen Fang to design a variety of strength, modulus of elasticity and specific performance requirements for FRP product. FRP products are easy to shape, shapes can be designed. Good elastic properties, stress-strain curve is close to linear elastic, in restitution after large deformation, plasticity deformation and structural deformation recovery after accidental overload. FRP products are suitable for production in a factory, transported to the site, installation of industrialised construction process, to ensure project quality and labour efficiency and building industrialisation. FRP itself contains mainly fiber conductive ability is related to the stress applied to it, by detecting certain fibers conductivity degree of stress can be deducted, therefore, FRP material will automatically detect the smart widget.

3. FRP Application in Bridge Engineering FRP high strength light weight makes it from the date of birth as the study subject by engineers on how to apply to construction works. In bridge engineering A variety of attempts have been conducted, including bridge strengthening, FRP tendons instead of directly using FRP reinforcement and prestressing tendons or FRP composite structure bridges.

Paste in concrete structures using FRP surface to improve the bearing capacity of most of the current application of FRP bridge condition. Concrete piers strengthened with FRP winding through concrete to improve strength and deformation capacity of concrete and the shear capacity of high pier, this is the most effective re-habilitation method of FRP reinforced concrete. Beam and plate tension sides pasting FRP sheet can be improve their bending strength and cracks can be effectively controlled, passive force due to FRP, reinforcement efficiency is not high. Wrapped with FRP beams, beams shear strength can be improved, but there is also strength of FRP application low-efficiency problem, generally only using the strength of FRP 20%~40%. Fiber volume content in FRP reinforcement could reach 60%, has the advantages of light weight, high strength, weight about one-fifth of the ordinary steel, strong 6 times the ordinary steel, corrosion resistance and fatigue resistance, low relaxation, nonmagnetic, and so on. With FRP tendons instead of steel makes good Use of its corrosion resistance, avoiding corrosion on the structural damage, reduce structural maintenance costs; FRP cable used as a suspended rope slings and cables of the cable-stayed bridge, and tendons in pre-stressed concrete bridge. Due to high strength and light weight, the direct use of FRP profiles to build bridges with good prospects, countries around the world conducted a lot of research on cable, up to now, completely made of FRP bridge limited to footbridges. 1982, in Miyun County, Beijing, China lay-up process of GFRP honeycomb beam, built a bridge, spans 20.7 m, width 9.2 m, is the world’s first FRP road bridges. In 1992, the United Kingdom of Aberfeldy in Scotland built up a whole structure of FRP cable-stayed pedestrian bridge, long 113 m, main span of 63 m, width 2.2 m, double tower double cable plane cablestayed system, a-shaped pylon. Towers, beams and decking and handrails of a box-shaped cross-section of GFRP pultruded, AFRP cables of cable-stayed, coated with polyethylene protection, some connected to metal connections. The total cost of $ 200,000, for traditional wooden, concrete and steel cable-stayed bridge or half the cost of the steel truss bridge, and at least 20 years from dimension fix the bridge’s success greatly promoted the study of FRP bridge. In 2002, Japan’s Maeda proposed using FRP to build 5000 m longspan suspension bridge scheme Tower, qiaosuo and bridges are FRP, and static and dynamic analysis of the programme proposed for application of FRP bridge opened up a bright future. FRP bridge as a whole in addition to, build a deck with FRP and FRP composite member is being a hot spot, as shown in Fig. 7.78. Decks are vulnerable to erosion, especially in the northern regions winter road salt non-slip, corrosion of the deck is more severe, good corrosion resistance of FRP, made decks can greatly improve performance, save maintenance cost.

Fig. 7.78 FRP bridge deck (a) FRP honeycomb sandwich deck; (b) FRP-concrete composite deck.

4. Application of FRP in Bridge Engineering Problems and Solutions FRP has the above excellent structural performance, but there is still a number of obstacles, problems all over the world an unremitting exploration, some have found a solution. FRP products is usually anisotropic, high strength and elastic modulus of along fiber direction, perpendicular to the fiber direction, strength and Young’s modulus are low. Due to the anisotropy of FRP, on the mechanical properties are different from traditional structural materials, stretch warp phenomenon, which will increase the difficulty and design of FRP structures. Compared with steel, the majority of FRP products due to the small cross-sectional area, have low rigidity. Therefore, the design of FRP structures usually is controlled by the deformation. The current solution is accomplished through the design of FRP members section and rationally, and combinations of materials such as concrete and using deformation of prestressed methods such as control structures, to compensate insufficient rigidity. FRP materials shear strength, tensile strength and interlaminar shear strength between layers are just 5%~20% of tensile strength, while metal shear strength is 50% of its tensile strength, which makes connection of FRP components a prominent problem. Current solutions are riveting, bolting and bonding, but no matter what kind of connection, connecting parts are likely to be the weak part of the entire Widget. In structural design of FRP, therefore, on the one hand you want to minimise connect, on the other hand, you want to take the connection design. Figure 7.79 are the FRP anchor and connection types that have been developed. Compare with concrete, poor fire performance of FRP material in general, mainly because most of the resin at high temperatures would soft, resin the softening temperature is reached (usually 70 degrees or so) will be greatly reduce the mechanical properties,

reach the glass transition temperature (usually about 300°C) behaviour will occur when you shift. Current solution is mixed with fire retardant FRP resin material, at the same time fire prevention at the surface and improve its fire resistant properties.

Fig. 7.79 FRP materials connection form (size unit: mm) (a) Bonded FRP reinforcement type anchor; (b) Wedge bonding FRP reinforcement type anchor; (c) Bonding FRP profile form. In addition, fatigue resistance, durability of the FRP has not yet mature theory and experience, need further study. Finally, the economics is the question concerned by all engineers and users. Only seen from the material price, FRP structure and compared with reinforced concrete structure is not competitive, but due to light weight, and taking into account the corrosion resistance of FRP materials lower maintenance costs arising from using FRP materials, the overall economic efficiency is deserving attention. Given that the FRP is at an early stage, the cost is high, as the volume of applications increased, the price of FRP products produced on a larger scale will be greatly decrease. Case study of concrete structures strengthened with CFRP and its price from the initial 2000 yuan/m2, is reduced to at present about 500 Yuan/m2, is a good example.

7.4.5 Role of IT Technology in Promoting Bridge-building In all high-tech, the role of IT technology in bridge-building is obvious. IT technology in bridge engineering starts from Numerical calculation, with the development of IT technology, visual, multimedia, network technologies are quickly applied to the construction of bridge engineering.

1. Numerical Techniques Promoting Effect on Bridge Engineering Bridge structure mechanics is complex, structural calculations is the key for the design of bridges. Traditional mechanics can be provide analytical solutions read clearly, but for complex and time-consuming effort, and in many cases cannot be solved, emergence of the finite element method allows engineers freed from structural calculations and finite element calculation is the basis of other information technology applications. Now solving complex mechanical problems in bridge engineering is mainly reflected in high solve statically indeterminate structure, non-linear problem solving, mechanics

problem solving etc. The solution to higher order of statical structures provides the basic means for the development of bridge type. Cable-stayed bridges are higher order of statical structures, its development embodies the role of computing. The most important development trend of cable-stayed bridge is from the earlier thin cables system to the current system of dense cables, cable-stayed bridges span has grown from 200 m level to the 1000 meter scale over the decades, this is inseparable from the increase in calculation capacity. Traditional bridge design analysis simplified the bridges into planar structure, this limits the bridge type development. With the popularity of structure calculation, space system bridge program has been growing, particularly in urban landscape bridge in the city. The solution to hyperstatic problem makes it possible to structure fine analysation. The current bridge design specifications is based on the concept of beams and columns, and correction factor of spatial problems, often through a variety of methods into a simple beam force calculation, calculate the average result is based on the beam-column cross section spatial peak load. The problem of this is waste, and in some cases, failure to cover peak, resulting in accidents. Fine analysing designs is based directly on spacial stress, problems from average stress design can be avoided, at the same time it saves material. Non-linear question is mainly manifested in two aspects of geometry and material, particularly in the case of large span and load carrying capacity. In the traditional nonlinear problems are solves using differential equations, but solutions cannot be found in many cases. By finite element iterative calculation, non-linear problems have been solved. Calculation method of nonlinear problems plays a very important role in promoting development of large-span bridges, cable-supported bridges. Self-anchored suspension bridge development benefits from finite element non-linear analysis methods. Traditional suspension bridge is based on the pre-sumption that main beam being suspended on main cable, the girders at the construction stage are completely hanging in the main cable, making construction processes simple, also enable the suspension bridge span more than 1000 m without computers. While the main cables of self-anchored suspension bridge is anchored on the main beam, girder by boom pushes overall hanging on the main cable, construction phase the main cables would have to work with the main beam. Non-linear large displacement problems with the entire construction process, if there are no non-linear finite element calculations, it is hard to imagine the reinforced concrete girder self anchored suspension bridge could be built successfully. Implementation of finite element method for material non-linear analysis, allows engineers to analyse bridges from beginning of loading to collapse the whole process, this technology will be promote the safety of bridge design values is more reasonable. Dynamic problem-solving is the difficulty point in calculation of classical mechanics, it tends to associate power with power amplifier in bridge design static problem solving converting approach, it is difficult to reflect the actual situation. By using dynamic numerical simulation based on finite element method, the whole process of bridge vibration under the external excitation can be reflected. Through analysing the data of the bridge response to seismic, wind, vehicle, one can better grasp the dynamic performance of bridges, and most reaction ever to pass the test of these structures otherwise is timeconsuming and costly. During bridge program planning, one can be calculated by

numerical analysis of structural dynamic response, until the final stage when test is carried out, this leads to significant savings in manpower and material resources and project selection can be carried out on a large scale.

2. Environmental Factors to Simulate Actual Working State Calculation of Bridge Design Approach Bridges work under natural conditions, classical mechanics needs to abstraction and standardisation of external action can be take place. With the development of computer technology, nature has gradually digitized simulation of various external factors, and effect on bridges and structures closer to the real situation. Currently wind, fluid flow, temperature field and main force are the main factors affecting bridge, can be dealt by digital simulation, and can substantially reduce design costs.

3. The Visualisation Technology Transforms the Bridge Design from Abstract Thought into Virtual Operating With the development of computer technology, in the 1990, of the 20th century, the era of ordinary computer into a graphical user interface, visualisation technologies in all fields of engineering construction began to develop from the early visualisation of two-dimensional visible until now. Visualisation of virtual digital world helps people to visualise the concept of real world image, so that people can be simulated in the virtual world real objects. Applications of this technology in civil engineering, enables designers to imagine visually design the structure. Combination of visualisation and finite element calculation techniques, enabling engineers completely in three-dimensional graphic model and output manifested by our understanding of physical concepts, such as stress, deformation of shape, greatly improving working efficiency. In the 1980, when the continuous rigid-frame bridge luoxi bridge with a span of 180 m was analysed on the middle pier top No. 0 for space stress, finite element software did not have visualisation, classification units to be constructed on the drawings are solid structures are divided into small pieces, and compute node position output result is artificial to draw stress contour lines. Such an analysis took more than 1 year. In 2008, in Zhoushan island-connecting project 216 m long-span continuous rigidframe bridge in Jintang bridge No. 0 space stress analysis, finite element software has achieved a visual modeling and results output, calculation of the same size, no more than 1 month, the efficiency increased by more than 10 times. Visualisation technology enables designers in structural design, you can easily build bridges or their local members of three-dimensional images, drawing only threedimensional images are projected onto a two-dimensional drawing. This technology greatly facilitates the implementation of complex structure design of structure design from the original abstract ideas into the ideas and the outcome of the interaction.

4. Networking Technologies Enable Remote Monitoring Bridge Construction Extensive comparison of bridge construction in the past, construction and design is often

disassociated, ensures the quality of bridge construction monitoring data cannot be instant analysis, resulting in quality problems of bridge construction. As the technology of computer network and digital sensor signal development of remote control of bridge construction possible. In recent years, various sensor signals the progressive realisation of analog-digital conversion, digital signals can be easily through computer networks instant transmission. the sensor or measuring instrument embedded in the structure transmit data in real time from the construction site to the office computer engineers, engineers can compare estimates of rates and design, judge bridges the site conditions, in the event of deviations can be adjusted promptly inform site. Construction monitoring technology in the past 30 years have made sufficient progress, thanks to the structural development in computing technology, you can use computers to simulate the entire construction before the bridge construction drive second, thanks to the sensors and the development of network technology, makes it possible to remote real time measurement.

7.5 CHOOSING RESEARCH TOPICS IN COMPLEX BRIDGE CONSTRUCTION WORK Bridge-building and development of science and technology progress alongwith engineering, every bridge engineer in bridge engineering foster innovative concepts in the construction of the project, in the construction of large bridges in China tend to earmark some of the money to fund scientific and technological innovation, bridge recognised by peers in the world are those making break through in different ways. The most direct and simple break through indicator of bridge construction is the size of bridge-building, span, large scale, large span often reflects the level of bridge construction. However, the size does not mean everything, many of the projects themselves are relatively small, and does not require large-span. Bridge construction technology breakthroughs should be reflected in larger span, more economical and faster construction period, and many other aspects. Building a bridge and where to make break through reflect bridge engineer vision and ability.

7.5.1 The Purpose and Necessity of Research Project In bridge design and construction process, in order to meet the special conditions of building the bridge to reach higher quality standards, technical requirements, some would point to the current bridge design and construction there is no theoretical and empirical research on, and development of innovative technologies. Often one or several key breakthroughs can help more difficult projects complete successfully, so that projects achieve higher economic efficiency and some new technology can be made a demonstration for future projects with social benefits. This work has gone beyond the normal bridges design and requires special studies. Some large foreign complex bridge projects have some the key issues studied years prior to the bridge being built special study on the issue, the success of these key issues and sometimes determines the success or failure of bridge program. Thematic studies in the construction of large bridges have two purposes. First, solve new problems in the construction. Complex conditions of building the bridge or the special requirements of building the bridge often exceeds technology and experience, case studies is required to ensure the successful completion of the bridge. For example, the construction of bridges in coastal areas, long sex will become critical to the success of, China’s first cross-sea bridge Donghai bridge in bridge design in the process of coagulation soil, steel and other construction materials durability problems in the marine environment for a number of case studies, culminating in selection, mixing ratio, processing technology, anti-corrosion measures proposed technical procedures to ensure measures. Similar coastal environments, Zhoushan island project in xihoumen suspension is the span of 1650 m suspension bridge and wind resistance will become the success or failure of critical issues, conducted a special study finally using the middle groove 6 m box-steel box girder stiffened girder of this special plan. Second, to obtain building experience for similar bridges. Technological progress of bridge construction is built on a large number of projects on the basis of practice, during

the course of a bridge built, ways to solve specific problems, and after summarising the formation theory and method of enterprise in order to enhance its ability to compete, if extended to other similar projects, can also get very good social benefits. Therefore, some prospect of technology combined with the engineering special studies, forming monographic study on theories, techniques and methods become another primary purpose. Chinese government from the central to the local, thematic studies on promising strong support, in addition to engineering construction set owners to provide funding, government back to work with a certain amount of subsidies. Currently used in bridge design and construction of theory, technology and engineering methods are formed this way. For example, in China’s first railway passenger line on Qinhuangdao-Shenyang passenger dedicated railway line construction process, on land speed bridge type, prefabricated technology of erecting bridge, bridging technology, equipment and other special studies on a number of key issues, the results for our large-scale construction of passenger dedicated line provided technical support. Again, the bridge of Donghai bridge erection technology of thematic research offers for our other cross-sea bridge construction experience.

7.5.2 Choosing Research Contents Research content should adapt to the level of scientific and technological development of bridge-building, and commensurate with the needs. At present, the hot issue of bridge construction are mainly the following several aspects: The application of new structural systems. Structure adaptability to complex environmental conditions. Forms of complex details. A new working method and corresponding equipment. The application of new materials and technologies. The durability. The rapid development of China is in bridge-building phase, due to the different levels of economic development, peak of bridge construction in foreign countries 30 years earlier, so the bridge can be a lot of foreign experience for reference in our country. However, our country and abroad the same, different natural conditions of the construction, so we cannot copy the technology. For example, a country with a large population, with a development of the traffic surge in overall level width of building bridges in China than abroad, which make foreign developed bridge knot system is not necessarily suited to China’s national conditions, design theories are not necessarily suitable lagging research in China results in quality problems in wide bridges. However, the large population of China has the advantage of low labour costs, China’s construction, Labour costs account for about project cost 25% ~30% and 60% ~70% of foreign labour cost of the total project cost, therefore, drive to solve the problem in the construction of mentality and the focus is different. Raising the level of science and technology in order to improve the bridge construction, our country at all levels of Government in the construction of the bridge has

promotional value, can improve the industry competition ability research projects were funded. On bridge engineering research funding in recent years is the highest national technical support program. National science and technology support program is to implement the outline of the national medium-and long-term program for scientific and technological development (2006–2020) (Hereinafter referred to as the program), mainly for national economic and social development needs, is focusing on major economic and Social Development Department technical problems, and was established on the basis of national scientific and technological plans of national science and technology plan. Supporting programme, mainly the implementation of the platform for point and its priority theme in the area of mission, to major public technical and industrial generic technology research focuses on development and application of the model, and major construction projects and major equipment development, strengthening of integrated innovation and the introduction of secondary innovation, with a focus on involving global major technical issues of sex, trans-industry, trans-regional, focused on overcoming a number of key technologies, break through the bottlenecks and improve our industrial competitiveness, providing support to the coordinated development of economy and society in China. States currently funding mainly for bridge engineering research is set in large complex bridge construction project, requiring in bridge construction at the same time, address the common problems of similar bridges, enhance the competitiveness of the industry as a whole. Currently national science and technology support included in bridge-building case studies were funded through three bridges, they are: Su-Tong Yangtze river highway bridge and Zhoushan Island West Hou bridge of Taizhou Changjiang river highway bridge. Funded research is as follows. Su Tong bridge technology supporting plan research overall objectives: make meter scale long span cable-stayed bridges breakthrough to improve cable-stayed bridge construction techniques. There are six sub-topics: 1000 meter scale cable-stayed bridge technology standards and essential structure and properties; Long cable production, erection and vibration reduction technology research and demonstration; Erection of large-span steel box girder and its control technology research and demonstration; Monitoring and control technology research of 300 m cable tower; Deep water pile foundation construction and erosion protection for complete integration technology; Construction management for large complex traffic engineering and safety disaster reduction technology. Xihoumen bridge technology supporting plan research overall objectives are: realization of construction technology of super long-span suspension bridges in our country catch up with the world advanced level. There are six sub-topics: Cross-sea mega size steel box girder of long span suspension bridge structure

characteristics and technical standards; Cross-sea queen size steel box girder of long span suspension bridge wind key technologies; Key material for large-span suspension bridge cable system; Mega size complete technology of steel box girder of long-span suspension bridge split; Cross-sea mega size steel box girder of long span suspension bridges study and demonstration of key technologies; Meag size steel box girder of long span suspension bridge with key technologies of monitoring and management. Science supported planning of Taizhou Changjiang overall objectives to: promote continuous-span suspension bridge design technology. A total of three sub-topics: Multi-tower continuous span suspended cable structures characteristics; Multi-tower continuous span suspension bridge middle tower key technology research; Flexibility of large span continuous bridge track structure characteristics and key techniques of pavement.

7.5.3 Research Technique and Method Most technical route and method of bridge engineering research may use two types of methods: theoretical analysis and experimental research. Theoretical analysis usually uses two means: analytical and numerical analysis. Analytical method is traditional, with strong concept, but many problems are hard to find answer using this method, for example, the most commonly used many of the mechanical behaviour of beam with variable cross-section would be difficult to analytically solve. Numerical analysis employs the finite element method. In theory, all current mechanical problems can be solved with finite element method, however, finite element calculation for a particular structure at a time, to get results, a lot of work. Therefore, at present many studies use the combination of analytical solution and numerical analysis, to structure the purpose of conceptual clarity and ability to solve practical problems. For problem whose mechanism is not completely understood the empirical method must be used. Experimental studies in engineering have two purposes: first, exploratory testing, the other is a confirmatory test. Experimental studies of physical connections is not clear structural problem, access to analytical or numerical analysis of constitutive relation of software needed, often requires a large series of tests. Confirmatory test is a new structure, new technologies and so on before the actual application authentication. There are some particularly complex structure, process, although in theory has been to suggest that programmes were established, however, due to physical works high cost the project is not allowed to fail and, therefore, require scale or full size prior to the implementation of verification tests to detect design problems not thought through in design. For example, a cable-stayed bridge cable tower anchorage zone of cable-stayed, stress and complex production processes, sutong bridge constructed with steel anchor box

for the first time in the country, although the design of theoretical calculations have pledged to set up, but in order to ensure bridge construction site safe, sectional model test of anchorage zone, a theoretical analysis is to validate the design indeed, the second is verifying the reliability of construction technology.

REVIEW QUESTIONS 1. What is innovation in bridge structural details ? Where can structural details of innovation start? 2. What drives the application of advanced construction technology, construction equipment? From where come the innovation of construction technology and equipment?

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CONCEPTUAL DESIGN OF URBAN BRIDGE In this chapter, I would like to speak with you about a recent hot topic: the conceptual design of urban bridge. Before starting this topic, a couple of interesting phenomena may stimulate some of your thoughts. These things take place on bridge designer, you may also be familiar with.

(a) The Most Beautiful Bridge The end of 20th century, International Association for bridge and engineering organised the “20 century world’s most beautiful bridge” selection, from more than 100 countries over 1000 bridges 15 were awarded the “the 20th century most beautiful bridges in the world” title. One the top is Switzerland engineer R. Maillart’s Salginatobel bridge Fig. 8.1, a sickle-bearing arch; the second is a United States engineer J. Strauss’ United States famous San Francisco’s Golden Gate Bridge Fig. 8.2; the third is France Engineer J. Muller’s single cable concrete cable-stayed bridge—Brotonne bridge Fig. 8.3. Neither of these first three has the largest span in the bridge, special the Salginatobel bridge whose span is only 90 m, built-in 1930, this fully shows that bridge aesthetic evaluation is not determined by its span size. So, what is the standard to measure a bridge aesthetic? How to display the beauty of the city bridges?

Fig. 8.1 Salginatobel bridge (Switzerland).

Fig. 8.2 The Golden Gate Bridge (United States).

Fig. 8.3 Brotonne bridge (France). The Millennium footbridge when the world entered a new era, all the way to build a bridge to mark the dawn of the new millennium, it is not a co-incidence. At this stage, monumental construction of the highway bridge and the railway bridge is no longer the center of attention, they gave and human relations are closely related to the footbridge Figs. 8.4~8.6. This shift reflects on the “sustainability” continue to strengthen that concerns people and people’s desire for healthier lifestyles. In this wave of pedestrian bridges, the interesting thing is that design working group includes architects, engineers, artists, as well as landscape and environmental experts, have now joined the ranks of the bridge design, and historically, the bridge design was under the Project Professional’s realm. Meanwhile, some excellent, avantgarde engineering also began to focus more on bridge aesthetics and artistry, and explore innovations in bridge structures, beautiful design ideas throughout the design process, and not just be limited to the traditional pattern of engineering.

Fig. 8.4 Gaicimode Millennium Bridge (United Kingdom).

Fig. 8.5 The Royal Victoria Dock bridge (United Kingdom).

Fig. 8.6 Sufeilinuo footbridge (France).

(b) Sea-River Bridge In recent years, cities around the world started renovating the landscape, creating city river bridge culture to show city charm, urban river bridge landscape has become a shining point of the urban landscape in urban development have an increasingly important

location. Beginning in 2003, Tianjin out of Haihe economic development overall plan, it has been the past five year, has achieved great successes in its infrastructure construction. Among them, the bridge construction is one of the highlights of haihe development, has completed the order represented a number of excellent works of dagu bridge Figs. 8.7, 8.8, for the entire river landscape considerably. Attention on Tianjin 5 years of bridge-building, whether it is modified by strengthening of existing bridges or the implementation of a new bridge, conceptual design of system analysis of urban bridges provides good material.

Fig. 8.7 Reconstruction of the haihe River Bridge—Northampton bridge.

Fig. 8.8 Haihe River new bridge of dagu bridge.

(c) National bridge Conference In May 2006, the convening of the 17th National Conference on bridges in Chongqing City, on the theme “strengthening innovation, improve the quality, attention to aesthetics” and “Western bridge”. In May 2008, to “reinforce innovation, attention to aesthetics” as the theme of the 18th state Bridge Symposium held in Tianjin. The annual bridge conference held in Tianjin, Tianjin in recent years, mainly due to “strengthening new, focused on aesthetics, “outstanding achievement in bridge-building, in particular, won the 2006. World of dagu bridge Youjin Feige international awards, a good example of academic exchanges. Two bridges meetings listed “renovation” and “aesthetic” as the theme of the meeting, the two concepts become the mainstream of design of new bridges. We found that, unlike in previous years national bridge conference compared to twice in this annual meeting, the participating experts and scholars on the “city of bridges” to give more clearance note, receive papers covering bridges also enriched the contents of many of the city.

8.1 THE CONCEPTS OF URBAN BRIDGES 8.1.1 The Definition of Urban Bridges In the initial stages of bridge design, how to use conceptual design to construct reasonable overall arrangement? How to level up from the basic concepts to understand bridge design and construction? How to use the new technology, new technology, new design concept to the design and construction of bridge? As mentioned in the above questions, in the preceding seven chapters, we bridge the conceptual design, bridge aesthetic, innovative thinking, and an in-depth discussion of topics such as structural concept, hoping for future practical work and research offer some help. This chapter is: the conceptual design of urban bridge. First of all, if you’re a bridge engineer, may wish to consider this question: when you have received one or several bridges designing tasks, road and rail bridges and bridges, would the conditions be different. Difference in Owner’s project requirements, respectively. Throughout the design process, you begin to design cut changes accordingly. If you are not clear on the road and rail bridges and bridges of the city in the process of design and construction of otherness, concept being very fuzzy, this chapter may be of interest to you. So, what exactly is bridge? As its name suggests, usually refers to the city limits of urban bridge built across the river, across the river, cross-sea beam bridges, overpasses and pedestrian bridges. The load of urban bridge design standards (CJJ 77-98) city bridges known as: “Urban construction, reconstruction of permanent bridges and elevated highways structure as well as other constructions.” In the beginning of this chapter, “the haihe River Bridge” for example, by collecting a lot of data, summed up this type of municipal bridge’s main features are: 1. Key aspects of bridge aesthetics in bridge construction, each bridge to become a beautiful scenic line, as for one aspect of the city, became a symbol of the city. Dagu bridge in, for example, it won the world famous bridge awards—receive the folling evaluation: “the imagination and innovation of dagu bridge in Tianjin, China, in bridge engineering have made distinguished achievement, and became a local landmark.” 2. Bridge in the central area of the city, bridges scales in the appropriate range, the span of the bridge is more modest. 3. The bridge structure is extremely complex, and challenge to the structural design. Such as the Tianjin Haihe River Bridge in Bengbu, space antisymmetric network structure and vertical and horizontal arch structure, and complex stress. 4. The complex loads on bridges, under the influence of high-rise building in the city, uncertain direction and high wind speeds, decorative objects various, decorative load heavy. For example, Northampton, bridge, bridges with decorations, and have some loadings of structures. 5. The bridge tends to be thin, mostly steel for the main beam and larger flexibility.

The five points above, as certain characteristics of the Haihe River Bridge, many of these areas is common for city bridge. But the characteristics of urban bridge do not exist the so-called unification, for each city’s bridge, things could have been different, even for the same two bridges in the city, their requirements are sometimes quite different. Therefore, we cannot pass the limited character of urban bridge features a nearcomprehensive summary. It is Not hard to find urban bridge with highway bridge beam in bridge aesthetic requirements, environmental conditions and other aspects, the difference is obvious, but a successful bridge must meet “safety, utility, economy and beauty” four demands, which requirements are the same for all bridges. Previously involved concepts and theories, and apply equally to city bridges, so no attention is here, focusing on the characteristic of urban bridges talking about several points while, as a bridge (all types) continuation of conceptual design and additions. In order to differentiate from road and rail bridges, the contents of the chapter, using narrower concept of urban bridge, especially in urban centers bustling bridges, bridges aims to solve inner-city traffic, spanning medium, in the range of appropriate scales bridge, which we often refer to the “urban landscape bridge”. Here we treat “urban bridge” as a separate section to discuss, because in recent years, “city bridge beam” landscape “very high frequencies of terms such as, it seems that all the bridge engineers talking about” beautiful “everyone in the speaking of “innovation” and the topics concentrated on the large component on top of the bridge. These days, for almost all of urban bridge construction industry owner require “landscape design”. In fact, the “landscape design of the urban bridge” that is in itself is a statement of the layman design is a process of discovering, analysing and solving problems, city bridge design is a blend of structure engineering and architectural aesthetic thought in creative thinking process, there is no peeling of the bridge design called the “landscape design. Structural engineering and architectural aesthetics combined with the topic in 7. Section 5 will form a more exhaustive discussion. The beginning of this chapter “National symposium on bridge” referred to in the country, “bridge aesthetics” received more and more attention, this is a very welcome, but still want to see, not all of the owners and designers can truly understand the construction of bridges in cities reasonable use of “aesthetics” and “innovation”. There are some bridges, decorated with a very pompous, very economic and there are individual bridge work, for different purposes, “innovations”, but makes for a weird and unreasonably bridge, which reduces the value of the bridge, these demand our vigilance. In this chapter we want to solve the problem: How is the process of conceptual design of urban bridge like? In which we encounter design problems, and how should we respond? We’ll start off city bridges development history.

8.1.2 Historical Evolution of Urban Bridge Since time immemorial, the bridge is witnessing a transformation of human nature, making history, it reflects the human conquest of nature, also reflects the on human nature return; bridge is not only to create beautiful works of art, buildings full of wonder. It adds to nature beautiful melodies, but also with its different style to demonstrate and give specific beauty and arts; bridge is the cultural landscape is closely related to people’s lives, it is human nature, to modern civilisation and the United States better ties with the future.

Marx said: “people cannot be allowed to change history”, they had “in a direct encounter, established, from the past inherited condition” to create. So, who will have a more profound and thorough understanding of history, who are more likely to succeed work foundation. Conversely, if only to look beyond ideology and in the present, not to mention future-oriented, I’m afraid even now is uncertain. In fact, great time to have a great sense of history, a great designer must also have great historical meaning. Therefore, today’s design students learn to appreciate the historical achievements, and learn to apply it in the contemporary setting. We have to study the city bridge, first thing to analyse is its history. We know that rivers are cradles of human civilisation, mentioned in the history textbooks of the cradles of human civilisation, is the world’s accepted, they are the Euphrates and Tigris and Euphrates river valleys, the Ganges river, the Nile river and the Yellow river. Together with the Development of civilisations, urban bridge across a river’s history can be traced back to the earliest urban civilisation development and bridge beam since ancient times and people’s daily life are inseparable, famous qingming Shang he Tu Fig. 8.9 is the Testimony of ancient Chinese bridge-side commercial prosperity. This diagram depicts the qingming Festival the Northern Song capital of Bianjing (now Kaifeng) East point inside and outside the door and the Bian river bustling scene on both sides.

Fig. 8.9 Hong Qiao (the qingming, local). Chinese ancient bridges, stone and wooden materials have built thousands of stone arch bridge wooden bridge, Shiliang bridge, wooden beams bridge, wonderful, still rendered architectural achievements of ancient Chinese bridges is universally acknowledged. For instance, the Sui first year of Yianye (605) Zhaozhou bridge is an arch bridge above the fold-open small arches, known as the “international landmark of wood engineering”; founded Jin Mingchang three years (1192 ad) Wanping Lugou bridge in Beijing, Shi Liang Qiao, for a total of 11 Hole, the stone railing on the deck head, carved hundreds of stone lions, shapes and more numerous little lion in the lion who, legend, from now no one has been able to count how many lions are there on the Marco Polo Bridge. This bridge is not only a national cultural relics protection in 1991, have been listed as world culture heritage. Wooden bridges built in the 4th century AD have been recorded, existing in Guangxi, Sanjiang Dong autonomous Cheng Yang Yongji bridge, is a 4-hole wooden cantilever bridge with 5 piers, whose 5 piers are built with laminated bridge Pavilion and corridor through the bridge, the bridge Pavilion Balance, architectural decorative art features combined with the bridge, is the first bridge in the ancient and modern history of bridge building in China art examples in conjunction with bridge function.

In this section, through fragments of narrative history of urban bridge which can help us to understand the design of municipal bridges change the course of history. Attention is needed that when we read history, to have a sense of the times and a sense of realism, Rather than simply knowing a few historical facts. Because history has it’s objectivity, but every era has its own of new issues, new social situation, and hope that through history to look for new answers. In this fast-changing time, we need to understand history from a new perspective. We look forward to the historical changes of urban bridges analysis, find some inspiration.

1. Pre-18th Century Urban Bridge Before 18th century bridges all over the world mainly made of natural wood, stone construction: wooden bridge destroyed, pre-18th century wooden bridge to this has gone away, only descendants according to the painting or repairing the original to see them face, such as the above “Qingming Riverside picture”; the durability of the stone is better, we might as well take a few surviving ancient stone bridge, for example, recall that period of history.

(a) China’s Southern Stone Arch Bridge Bridges are special, because they are cultural integration; bridge were told through the ages, because they contain the calendar the vicissitudes of history; a bridge across time and space, because they embody a regional style. Bridges in ancient China have always been connected closely to arts and culture , as says in a poem: Night mooring by Maple Bridge relay Moonset Wu Ti Frost all over the sky, Jiangfeng for sleeping. An interlude, Midnight bells to passenger ships. Maple bridge was first built in the Tang dynasty in a poem, Hanshan Temple in Suzhou city, Jiangsu Province, North of Maple Bay, now Suzhou can see that bridges. Bai Juyi’s poem: “the South is good, old everyone knows scenery; the flaming river, Spring Green river waves grow as blue. Cannot Yi Jiang South?”, unconscious thoughts lead to people’s picturesque south, and can reflect the style charm of the historic riverside town are that most floats a few ancient bridges, water, household. South China is abundant in bridges, Guangxu of Shaoxing Fu cheng Qu road records, when Lu Xun’s hometown of Shaoxing city had 229 bridges, averaged 31 per square kilometer bridge density of is 45 times higher of Venice in Europe. Although these are small bridges beam bridge, Shaoxing, but varied, and political skills, which are adapted to the wooden beams of the Xiaojiang river Bridge, wooden arch bridge, adapted to Jiang Dahe along the Boardwalk, then develops to a girder bridge, semi-circular arch, horseshoe-shaped arch, oval stone arch bridge, and even into today’s advanced world of catenary arch bridge arch structure, constitute an extremely complete family of old bridge, bridge and ancient China economic development, the epitome of evolution. And the poem “bright moonlight 24 bridge” to describe the Yangzhou bridge, visible in ancient China

bridge building boom scene.

Fig. 8.10 Bridge-river-family (Zhou). Southern China Bridge is not only found in poetry and prose, and are available in among the many paintings. Fig. 8.10 three painting in Chinese ink, depicting an old town —Zhou Zhuang of small bridges, flowing water, and people’s home. 24 stone bridge across a narrow straight on the river, formed Zhouzhuang, a beautiful landscape, and Chinese-American paintings chen Yifei has to double as the background, creation famous paintings of the hometown memories, bridge of Zhouzhuang fame into even greater, popular at home and abroad. China’s Yangtze River Bridge (as mentioned above, Zhouzhuang, Shaoxing, Suzhou and Yangzhou, the bridge, as shown in Fig. 8.11), although will be regarded as the true meaning of “city of bridges”, but they are an epitome of ancient bridges, evolution and economic development, set out China’s rich history and culture, in many places worthy of our reference. First of all, at the time, bridges serve pedestrians or Bullock carts and carriages. Without the modern bridge construction design, you could only use simple tools, manual work, teach skills by experience, actual housing architecture and the designer of the bridge craftsman. We might call this process is called “local design”, then design and construction are inextricably linked. But in modern times society, the construction of a bridge for the most common, requires a series of professionally-designed bridge itself is made up of several structural engineers regiment designed to bridge decoration done by architect, bridge crossing by road designers and lead to the design, the road network grounds for professional designers for drainage, road and bridge location arranged by town planners, and these designers are likely to have never participated in the production of these artifacts. So can separating design from construction produce better design? This is a debatable topic. Secondly, the Jiangnan bridge is popular, generally civil building, myself, unlike today’s bridge owned by somebody. Rivers and footbridge, stranded, met Qiao bridge, trade, culture is created by the mass of the bridge. Therefore, the water bridge is a simple subject, stationary, it was used, it was celebrated, it was described with poetry and painting, film and television performances, story …… Something about these and bridge, bridge cultural accumulation process is why bridge the infinite vitality. Popular culture is a multi-functional integrated culture, it is the entity matter and the spontaneous product of abstract ideas. In contrast, modern the utilitarianism of the bridge too thick, especially after the industrial revolution, the bridge is treated as a mass production of “industrial production” To meet the transport needs and bridge construction general lack of humanism and culture.

Fig. 8.11 Southern China Bridges (a) Maple (Suzhou); (b) Stone arch bridge (Shaoxing); (c) Bridge (Zhou); (d) wutingqiao (Yangzhou).

(b) In Europe in the Middle Ages the City Bridge In the world, in Paris and London, for example, rapid development of two cities starting from the 12th century, their common feature is built around the ancient old river to organise its urban development, bridges and the city main streets, town squares, as well as important public buildings, to shape the key elements of the new metropolis, city bridge has also ushered in a relatively stable development opportunities. In the era of roman rule in Paris, Seine by East-West and North-South trunk road cut, built-in the interchange four major bridges: transform bridge (Pont au Change), Notre Dame bridge (Pont Notre Dame), close, St bridge (Pont Saint-Michel) and the bridge (Petit Pont). These four bridges located in a region with high density of buildings and people, coupled with the city’s geographical, administrative and religious influences, making it they have unparalleled status and value. Bridges are characterised by: River crossing construction is basically completely blend with its surroundings, the bridge there are houses and shops, architectural style and houses around the same, seems to be completely unrelated with the river. Such bridges in the middle ages an extremely common, Called the “living bridge”, Venice’s famous Rialto Bridge Fig. 8.12 is the representative of such bridges. This style is to bring the bridge into environmental manipulation to the max, as you wander through the city streets, wander through the bridge of time, can fail to feel its presence. This to us contemporary designers are inspiring, true, bridge is an important node of the traffic system, functionally road system spanning barrier tool for city bridge, but, in fact, it is part of the cultural landscape of the city, and not specific, not isolated from the bridge in the city outside the city, but to consider it as a part of the human living environment.

Fig. 8.12 The Rialto Bridge (Venice).

2. Near-modern City Bridges (a) Near-modern Time World-wide Urban Bridges The 1760, industrial revolution changed the world. First European industrialisation, mechanisation and production industry is one of the main characteristics of industrialisation, it necessitates a more effective means of transport and transport systems. Between 1883~1885, the automobile was invented, in the 1920, of the 20th century, Germany, and Italy led the rise of the highway-building craze, 30 European countries built many roads and bridges , United States followed suit. Industrialisation pursues mass production and high efficiency, and does not tolerate any “non-economic” operation, as an element in the landscape image of the bridge architecture requirements are considered to be “uneconomic”, and thus is not desirable, which even continues until today. Relative to roads and bridges, some of the urban bridges of that era, due to decoration of its special significance and be strong to ensure the architectural heritage of the bridge, which is the fashion of its representative works in United Kingdom London Tower Bridge and France’s Alexandria III bridge. We here in United Kingdom London Tower Bridge Fig. 8.13, for example, to see bridge construction works of art of the 19th century, Pont Alexander III bridge will tell you in the decorative section.

Fig. 8.13 Tower Bridge in London (United Kingdom).

Tower Bridge is the first bridge from mental arithmetic on the River Thames. Its designer was the London architects Horace Jones and Wolfe Barry. The bridge was originally designed to establish a principle: new bridge must be integrated into the surrounding environment, so that the old palace and adjacent to the “London” maintain the harmony of stone castle, Tower Bridge hence got its name. Designer use rebel bridge was designed so that it reflected in the environment of conflict beautiful, but kept the echoes on the environment. Tower Bridge is a double layer of dual-use Bridge, lower level is a bascule bridge, upper level is fixed footbridge Within one month of the initial navigation, Tower Bridge opening or closing a total 655 times, it also alludes to the Thames at that time flourishing. The construction of this bridge meaning has gone far beyond its functional needs, but it has been recognised as enjoying London City and the River Thames best place for scenery, the bridge itself into the local environment, became classics in the history of the bridge. Represented by the beautiful Tower Bridge and Pont Alexandre III bridge, urban bridge is not a brief appearance in modern bridge engineering history. With the growing deterioration of the urban environment of industrialisation, people start to care about living environment, build the new landscape of thought of nature conservation-oriented. In 1863, United States officially presented the landscape designers and landscape design represented by Olmsted, landscape design courses was offered in 1900, in Harvard. Bridge as an artificial landscape elements, judging from the sense of Visual beauty, also received attention. In 1936, fulici·laianghate and Kaer·shexitele of Germany jointly published the bridge shape, according to his request, the 1978, International bridge engineering society created the “structural engineering aesthetics” task force, to the attention of the world to promote bridge aesthetics, 1984 book bridge publication of architecture and style. Japan starting in 1930s-40s and the 80s, published the “Guide to aesthetic bridge design”, “bridge modeling” and other writings. New bridge aesthetics is gradually taking shape, broadens the design idea to generally raise the level of bridge construction and design, emerge and can be comparable with the predecessor bridge design and innovative newbridge laid the Foundation of. Modern bridge image features can be summarised as follows: simple, slender, smooth, bright; respect for the natural environment, pay attention to the overall effect; remarkable creative effect; detailed delicacy, modest decoration.

(b) The Development of Modern Chinese Urban Bridge Since reform and opening up, advance the urbanisation process and building a well-off society in China, infrastructure construction of China development by leaps and bounds, size around urban bridge construction has made rapid development, showing construction boom of urban bridge. Here, only few mega-cities in China as an example to explain China’s bridge history and today.

• Beijing Development and Evolution of Urban Bridges Beijing’s urban area, although not wide, deep rivers, but as the capital of China’s city

construction started early, traffic large bridge main complex of overpass bridge, across the city line, light rail viaduct, and is very good for easing Beijing’s busy urban transport. With the construction of ring road in Beijing and other cities, rapid development of traffic engineering, construction of urban bridge both in terms of size and quality is impressive. I will cite several bridges: built-in 1986, over the Yongding river daning reservoir the yongding River Bridge, 1120 m, is Beijing’s longest river-crossing bridge, the project won the national quality engineering AG in 1991, Beijing Guang an men used pre-stressed concrete, reinforced concrete and other forms of interchange and supports different bridge, bridge area of about 21000 m2, a breakthrough in structural design of special-shaped slab; completed in 2001, North Beijing city ring road, all 147 bridges, bridge area of 485,000 m2; in October, 2003 designed to complete the ring road of Beijing has interchange 55 seats, of which 12 large interchange, Bridge 11, line 259 bridges and bridge area of 694,000 m2. At the end of 2007, Beijing has built a variety of interchange over more than 400, but said China’s largest number. In recent years in Beijing area in the city of new type of bridge design and construction, have made the leap-style development: for example, Beijing BeijingChengde highway in Beijing success in Chaobai river built a cable stayed bridge with low pylon; built internally in qinghe bridge line Subway Line 5 a curved cable stayed bridge; in the Changping District of South Central bridge built Asia’s first self-anchored suspension bridge. In the design concept also has a new improvement, in construction of urban bridge the application of new materials, new technology, new technology has taken a solid step forward.

• Shanghai Development and Evolution of Urban Bridges Talking about Shanghai’s urban construction will naturally link to a few big names: Nanpu bridge and Yangpu bridge. In 1970s–80s, Shanghai in large-span bridge construction has been at the forefront of domestic, such as the construction of 1982, Shanghai China’s first cable-stayed bridge in Hongkong—MaoHarbour Bridge. At Shanghai railway station after construction of cable-stayed bridges—near Shanghai hengfeng Lu bridge. In the 1990s, the Shanghai Huangpu river has built a world-class city bridges, nanpu bridge and Yangpu bridge, Xupu bridge and Lupu bridge, and so on.

• Development and Evolution of Tianjin Urban Bridges Tianjin is located in the North China plain, Bohai Sea coast, Haihe river system downstream of the river confluence to the sea, commonly known as Tianjin as “nine rivers converge”, Canal-dense, well-developed, in the North of China, history is the construction of a bridge across a river upto the city of Tianjin. Up to 1948, urban area a total of 72 bridges across the river, of which: 6 steel bridges, reinforced concrete bridge 19, Woodbridge 46, brick bridge 1, however, the Haihe river, North Canal and South Canal, Ziya river, xinkai 5 major rivers in the urban areas of rivers with a length of 38 km consists of only 12 bridges, urban river 14 km only 4 of the Haihe River Bridge, and the majority of major bridge projects contracted by foreign companies, technology held in the hands of foreigners. Among them, the gold steel bridges, Jintang bridge, Jiefang bridge, and the bridge of Jinhua 4 for open-type steel bridge, with the exception of Jiefang bridge

which was still open in the 1960s, others have been replaced by fixed bridges, due to the river of Tianjin, little bridges, railway, resulting in the river crossing Difficulty, railroad difficulty, causing serious consequences for urban traffic. Table 8.1 1965~2004 Tianjin Haihe River Bridge. S. Project name No. 1. Northampton bridge

Length Bridge type (m) 97 Span 24 m + 45 m + 24 m hanging cantilever prestressed concrete girder bridge

Year built 1973

2. The Lion Bridge (widened)

97.60 long-span 24 m + 45 m + 24 m prestressed concrete continuous box girder bridge

1974 (1995)

3. Guang Hua bridge

156.87 Hanging cantilever prestressed concrete girder bridge

1977

4. Square bridge

102.94 Hanging cantilever prestressed concrete girder bridge

1982

5. Big bright bridges

113.30 Length 28.5 m + 53.0 m + 28.5 m

1983

6. Thrifty bridge

71.1 Long-span 5 × 14.1 m reinforced concrete T-beam bridge

1985

7. Outer ring road haihe River bridge

266

1987

8. Liuzhuang bridge reconstruction project

The span 4 × 20 m + 3 × 35 m + 4 × 20 m

115.89 Span 32 m + 71.85 m + 12.04 m

9. Bridge reconstruction project

466

Upper main span 25 m + 101 m + 25 m concrete-filled steel tubular arch bridge in

10. Tianjin Tanggu haihe bridge project (singleTower cable-stayed bridge)

2660 Main span 310 m + 3 × 48 m + 46 m steel (main span) concrete (side) of hybrid cable-stayed bridge with single tower

1991 1996

2001

In 1949, after the liberation of Tianjin, with the development of Tianjin’s economic self-reliance built a massive bridge Table 8.1. Especially since the 1980s after the introduction of reform and opening up, great changes have taken place in bridge construction on the technology and scale. In order to improve urban transport in order to meet the needs of economic construction, Tianjin has newly built and re-built many important bridges. Especially in the Haihe river in Tianjin, gradually building the Lion Bridge, North Andover Plaza bridge, chifeng light bridge and the Guanghua bridge. These are all concrete bridge, built-in the 1970, of the 20th century and 80 respectively. Old

bridge renovation project including the 1991, Liu Zhuangqiao and King Kong Bridge in 1996. Tianjin haihe bridges mostly built before in the mid 1980, of the 20th century on, more Jintang bridge, built in 1906, Jiefang bridge, built in 1927. Due to the existing bridge built for a long time, limited to the political and economic condition, its simple structure and low load, and due to the settlement of the business for many years, most no longer meets planning navigation requirements as well as Haihe economic development consistent with the objectives, in particular, highlight the landscape design requirements. For the penetration of these issues to be resolved at the end , existing bridges need to be rebuilt or reconstructed. As the river of nine rivers converge, has given birth to this beautiful city and formed and continues to be enriched its culture, history and cultural heritage. For connecting the city of Tianjin Haihe River Bridge construction pioneer leagues has become the natural places of great players. Silent love of the Haihe River, witnessing the history of bridge construction of Tianjin. From the late 19th century, on the Haihe river in Tianjin began building various bridges. Bridge structure evolved from the original forms into meeting the needs of urban development and function. From the design concept, the bridge construction is no longer content merely to function, but constant attention to coordination with the urban landscape. Construction of the Haihe River Bridge, one must take full account of the city’s master plan, and look at haihe economic development closely, and with a new design creating a modern city environment. Tianjin Haihe economic development, Tianjin Haihe bridge planned to form a complete set of system. According to the current construction of Haihe River Bridge, can be divided into the following two categories: Both the re-construction of the old bridge of the Haihe river, including retrofit and bridge repair and reinforcement of concrete bridges; Concrete bridge reconstruction include: Lion Bridge, Guanghua bridge and North bridge, bridge of light; Open repair and reinforcement of the bridge include: Jintang bridge, Jiefang bridge. The new bridge on the river, including: Dagu bridge and Fenghua, Chifeng, Bengbu bridge, Ji Zhaoqiao bridge, and so on.

8.2 CONCEPTUAL DESIGN OF URBAN BRIDGE— GENERAL DESCRIPTION Unlike most products, the architecture presents space while being felt as an entire environment. Design tasks are comprehensive and specific, it has both shaped and invisible, and this makes things complicated. In order to create an effective building, designers need to process spatial form with three interrelated functions: use, material relating to the activities and the symbolic needs. Requirement for designers is to group multiple properties of a building together, in order to meet these requirements, and the collection should be optimized. T. y. Lin, “the concept and system structure” We might as well apply this concept to the design of urban bridge with this interpretation: urban bridges is a structure, while itself produces an environment, which is an integral part of the urban landscape. Bridge design process is about the overall concept , and detailed local, it not only in structural engineering, but also in architectural aesthetics, which puts the ideas into a complex systematic engineering of bridge design. In order to complete a good piece of work, the designer must bridge structure with three interrelated functions: functions, constraints and aesthetic requirements. Bridge designer is required to use structural and architectural aesthetics and other means to meet these three requirements, and optimize it, i.e., a bridge’s indicators of “safety, utility, economy and beauty” are optimal. Thus, to form a good design solution, you need to use advanced design ideas and new technologies, new processes, and fully understand concept and system structure, and not only can accurately calculate and analyze a given structure and components. Today, only in accordance with a program training designers does not go far enough, because the very fast pace of development in the world today, because no one wants to be left behind. Students of architectural or structural design can not only learn a few traditional skills and be done, on the contrary, they must be taught to appreciate and use new technology, the best method is to use innovations in design. Designs are a process of discovering problem, problem analysis and problem-solving process, design form is one of the results of this process, it does not exist outside this process independently and therefore they cannot be indulged in “forms”. If you will only rely on the specification, design manuals, computer programs used by traditional design, especially in integrated computer program comprehensive application today, learned college as they get older can lead to the loss of learned concepts, let alone innovate designs. In this chapter, we try to think in terms of analysis and creation of urban bridge design activities, is because the thinking of the world completeness and depth of the grip is unmatched by anything else. Perhaps the same designer of the bridge varies, but thinking is the subject reflects the object of relatively stable forms, depending on the value objective of designers, psychological characteristics and cultural traditions, knowledge structure and professional basis. During the course of the conceptual design of urban bridge, design thinking is exactly what we need the most. Construction of the bridge, is closely related to socio-economic development; throughout the history of bridges in the world, is an ancient bridge outstanding practicality

to focus on aesthetic effects of modern as well as contemporary bridges and landscape history of the transition with the surrounding environment. In this case, an increasing number of newly built bridge highlights the features of the new bridge, structure diversification, focusing on the surrounding environment coordination has become the development trend of the new bridge. In recent years, urban bridge has received more and more attention, it is due to the construction of bridges in the city, reflecting the more styling variety, more attention to expressions of landscape. Therefore, at conceptual design of urban bridge how to apply advanced design idea, what ideas, become the primary issue facing a bridge designer. What we say here “concept design”, refers to the bridge design’s initial conception stage, overall layout of how to set up layout, how to carry out the overall concept of the process. At this stage, bridge designer must have knowledge and hard work, meticulous, use deduction and conscious, positive towards advice of the partners and owners. any decision on bridge structure in conceptual design phase will have the rational, economic, aesthetic effects on bridge structure. We perform “concept design” with the ultimate goal being to provide the most complete and efficient technical solutions, but in general design phase, should grasp the overall design concept of avoiding ideas received numerous details of the disturbance. In fact, whether you can distinguish the fundamental elements from many details is an important factor dertermining if he could successfully complete the design. A case study of dagu bridge in Tianjin Haihe river, at the start of the design, we must first understand the design requirements, can be summarised as follows: Functional requirements: bi-directional 6 traffic lanes, 4 m wide sidewalks on each side. Restrictions: maximum permissible longitudinal gradient of bridge deck 3.5%; Under the bridge navigation clearance requirements limit the maximum height of main span beams shall not exceed 1.3 m; Cannot be set in the Haihe River Bridge, determines the span of dagu bridge is 106 m; For soft foundation of bridge site. Landscape: landscape on the Haihe river with a special sign on the building. Function, the restrictive conditions and landscape aspects, covering almost all bridge design requirements, designers is the concept of rational use of structure and aesthetics, in meeting the above requirements based on the finished design tasks, and try to achieve “security, utility, economy and beauty” optimal configuration. Dagu bridge is built, not only strengthened the Haihe river transport links, and became part of Tianjin City landscape, and thus by virtue of its excellent design and landscape, becomes when landmark buildings. So, designers is how to do it? I think that to successfully complete a design work, science must be and intuition and deduction and induction are perfectly combined to design around it. Indeed, for any design, regardless of how perfect the theory, based on ideas of how mature, inevitably there will be numerous subjective concept design, as a bridge designer, you will always have the opportunity to structure their own unique ideas into practical projects to, and may also melt into the idea of art and aesthetics, and achieve the combination of art and technology, this is the charm of design. Scientists could very

well do their job without having to care about how artists think; the artist may or may not need theories of the scientists will be able to creations, but is not so simple for designers, they have to pay attention to scientific and artistic effects. Here, although it is not possible only through text drove home for the conceptual design of urban bridge, but this is not going to give talk about some vague concept, but how to deeply explore issues in structural engineering and architecture learn two ways to carry out the conceptual design of urban bridge.

8.3 CONCEPTUAL DESIGN OF URBAN BRIDGE— STRUCTURE AND ENGINEERING In the bridge design process, many advanced design ideas are often through conceptual design to materialize. Want to finish any good works, cannot be fully implemented in accordance with an established procedure. We emphasise that a bridge engineer’s main tasks are under certain qualifying conditions, apply concepts to design the structure of the programme as a whole, creatively to achieve optimal structures to meet the requirements of owners. The following content, largely through explain the structure of urban bridge engineering unique places, to further elaborate the ideas of conceptual design, as well as how to troubleshoot creative use of urban bridge design.

8.3.1 Choice of Urban Bridge Style There are several types of urban bridge: urban city pedestrian bridges, overpasses, viaducts and bridges, this kind of bridge concept and characteristics of design point of view, relative to the road and bridge of urban bridge is obviously special nature. However, our common design tasks, tend to be some of the more common jump or cross-river bridge, these general bridges exist in cities and rural area. So, for general bridge in the city, how during the conceptual design phase, that is, i.e., general design stage, to form the best design solutions to meet the functional and aesthetic needs? We simply Comb through a design process, when we received a design task, starting with early work usually manifested in gathering information and compiling feasibility study report and then the familiar conceptual design, preliminary design, construction drawing design. So, at a time when sufficient information is gathered, we entered a phase of general layout design. At the time, we must start from the functional requirements, technical conditions, ecological environmental protection, visual images, viewing conditions and other aspects of the co-ordination, we immediately faced the task of bridge scheme selection.

1. Basic Bridge and its Development Characteristics We take a look at, exactly what are the forms of bridges: 1. according to the purpose, there are a road bridge, a railway bridge, the road-railway bridge, bridge, pedestrian bridges, aqueducts, as well as other special bridges beam (such as through the pipes, cables, etc.). 2. by the main materials: wooden, steel bridges, masonry bridges, reinforced concrete and pre-stressed reinforced concrete bridge. 3. according to the structure, warping, arch, bridge, cable-supported bridge (suspension bridges and cable-stayed bridge) systems. 4. by the cross form: fixed bridge, a bascule bridge, floating, submersible bridge etc. In these four classifications, classification of structural systems for designers is the most important, and bridge engineering design process, its soul is in the organisation of

structures. The previous 3.3 (bridge type and applicability of the foundation), we have compared the shape of bridge structures with detailed description, here is only for simple review.

(a) The Form of the Basic Structure of Modern Bridge Beam bridge: Beam bridge bear pre-dominantly vertical loads which produce bending moments and shear forces, the basic forms include plate girders, box beams and girders. Arch bridge: Arch bridge is a bearing structure with compression arch or arches as the main components , its basic structure include non-hinge arch and single-hinge arch and double-hinged arch, generally span less than 200 m or 300 m. The cable-supported Bridge: The original suspension bridge after a lengthy development process and evolved into today’s cable-supported bridge of the most basic structural forms of suspension bridges. Relative to the other basic bridge forms, suspension bridge spanning the most, generally upto 1500 m.

(b) Characteristics of Modern Bridge Structure Development Bridge in its development process in three categories new form have emerged based on the basic forms, and alongwith the winning elimination of inferior quality, natural selection, survival of the fittest rules. Material development as a precondition for development, has always run through the bridge structure the development process all the time.

• Development of Beam Bridge Introducing pre-stress is the most important element in concrete bridges development, and the knowledge of premature damage due to salt damage of concrete materials, neutralisation. Alkali-aggregate reaction, freezing and thawing, and other dameges, “the concrete maintenance free” is a thing of the past, we were forced to begin research on a variety of measures to prolong the service life of concrete bridge deck.

• Development of Arch Bridge In the development process of Arch Bridge, two-hinged arch, single-hinged arch soon exited the competition stage, hingeless arch with better use performance and stress performance get more attention. The beginning of 20th century, there has been a tie-bar offset thrust of arch tied arch bridge, which can be either geological conditions for thrust arch bridge, which greatly expand the scope of application of the arch. Similarly, arch bridge has a certain applicable span.

• Development of Suspension Bridge Suspension bridge development is mainly reflected in span increasing, and this process is credited with the following research: theory of computation march wind tunnel test on wind-resistant stability of theoretical research and technological advances; stable development of high strength steel wire. To date, the completed suspension bridge with the maximum span is Japan stone bridge, 1991 m. Messina Strait bridge under

construction in Italy has a span of 3300 m.

• Cable-stayed Bridge Cantilever construction of cable-stayed bridges due to the suit, tower shape and the shape diversify their tall beautiful model, various parts reasonable strength, quickly spread the word to come out, this is also the most successful in the history of bridge structure models. So far the built cable-stayed bridge with the largest Span length is China’s Su Tong Yangtze River Bridge, a main span of 1088 m, exceeds 1000 m.

• Beam, Arch and Cable Combined System In the history of the bridge, people never gave up on the rational use of the mechanical properties of beams, arches, cables, seeking greater span, and achieve better economic performance and innovation. Such as beam-arch composite, cable-tower-beam, even cable-arch-beam composite, and so on. Today, dozens of such bridges have been built around the world, spanning between the abilities of continuous beam bridge with cablestayed bridge, and can be mixed beams (cross-beams for the PC beam intermediate supports) to extend its span. The representing bridges including Japan mucengchuan bridge (hybrid, long 160 m + 3 × 275 m + 160 m), China’s Wuhu Yangtze River Bridge (steel truss girders, span 180 m + 360 m + 180 m).

• Novel Bridge Structure 1. cable-stayed bridge without backstays, arched bridge pylon, sailing pylon of cablestayed bridges, curves and broken line pylon of cable-stayed bridges, bridge tower positionedon the side of a curved cable-stayed bridges, cable surface arrangement of cable-stayed bridges and cable-stayed arch bridge; 2. single rib oblique arched bridges, latticed arch bridges, arch bridge without spandrel, fish-shaped arch, Arch Butterfly arch and lattice configuration and petal-shaped connection system, straight, arched bridges, flat space, rotate to arch, the arch shell bridge and fish-shaped truss bridge; 3. curved bridge tower suspension bridge, suspension bridge with curved cable layout, suspension bridge, suspension bridge and arch combination system; 4. bionic bridge: fish-shaped bridge, swan bridge, bridge of shells, butterflies, dinosaurs and the Sun and the arch of the bridge, and so on.

2. Traditional Bridge Type Selection Earlier, we give a general illustration on selection of bridge type, you can choose the old form, or you can select a new form, select the base type, or you can select a derived type. However, when in the face of the specific design problems, which one to choose is not a simple task. We try to seek answers from textbooks, in many traditional textbooks, bridge type selection method is often described like this First of all, carefully determine the bridge span, especially the span of the main span. Bridge engineering conditions, such as topography, terrain, geology, water text, navigation (or line), may have their own span requirements, should be based on the maximum span as

required by various factors must meet the designed main span. This should be based on design for long-span must be met, according to adjustment of upper and lower parts of the economy as a whole selection of bridge span, and according to the to select the type of bridge. The smaller the span, the more options, and vice-versa. Then, implement the “safety, utility, economy and beauty” principle, according to different conditions of bridge span, select the appropriate bridge type, from the point of view, and continuous system of pre-stressed concrete bridge should be preferred, and the design process as far as possible the use of new technologies, new materials and new techniques. Traditional bridge type selection, can be summarised as follows: the span selected for the pilot, backed by four principles, sound bridge programme selection. This idea, ingrained in almost all the bridges in the designer’s head, guides us to design. May be you didn’t notice, this modern, industrial design and its appearance is only two hundred or three hundred years ago something, maybe you never doubted the correctness of this bridge type selection, and even as a designer, you do not fully understand the true meaning of this option. Engineer’s approach is generally motivated by economics, practical considerations, generally receive the design has a very strict time limit, as in today’s society when the bridge became a mass product, engineer work tends to be limited to a standard procedure, and will bring them to find readymade solutions. About 100 years ago or 80 years ago, bridges slowly become industrialised, with advances in engineering, bridge more and more possession and control, community lost interest in the bridge, construction of the bridge is no longer a risky business. After the second world war, people had to re-build road and rail networks after the war, and later developed into our modern transportation systems in large industrial bridge engineers become anonymous partner. Since reform and opening up, China’s construction of the bridge has undergone a never before process of rapid development, bridge construction are impressive in terms of its scale and the number, form a thriving scene. In such a large bridge construction, formed a mature set of bridge design and construction technology for simply-supported girder bridge and continuous girder bridge, continuous rigid-frame bridge, x-style arch bridge, bridge of concrete-filled steel tube arch bridge type, such as developing very quickly, almost every classic bridge all land in China is furiously copying, in this process, the choices and the importance of appearance, usually lag behind practical consideration. Nowadays people are fully aware of all the artificial, the cultural landscape is formed by relying on technological progress has its advantages and disadvantages. Germany master qiaoge·xilasi structure: “design today, only a functional purpose, doesn’t care about the overall effect. Most to be proud of, especially after the industrial revolution in the 1960, of the 20th century, including many name loud, for which our eyes shiny structures, today has been monotonous and awkward structure in place. At that time, a bridge across the streets and a railroad the bridge, in terms of materials or forms are not the same, a city bridge with a broad rural bridge is often different. Now all the bridges are similar to simple, clumsy, drab box-shaped components constitute the primary beam consists of precast elements or, beam is equipped with vertical and horizontal blocks, beams supported on a flat base. In long-span variable depth beams. The upper structure applies to all types

of piers and are interchangeable. “Production of this factory, the bulk of the bridge, on a highway, appeared to be relatively affordable, but if it is in the city is terrible, as if the whole city was packed with stands one track, match-box-like skyscrapers, bark beetles of the technological advances become eroded people’s living environment, the whole city landscape slowly become alienated, eventually forming the environmentally indifferent city. Therefore, we rejected in the city similar to simple quantification production of bridges, this doesn’t mean that they should pursue bridge forms of quirky and weird, but that buildings and structures, our consumer resource consumption at the expense of constructed living space, we want to work with city bridge is closely related to our daily life can be reflected history and culture, rather than an industrial product. City bridge due to its regional restrictions, more medium and small span across line across the river bridge, bridge types to choose from more flexibility in the design of the structure also provides a larger space. Here, we present a view that: “the city of bridges beam bridge type selection is more than just a traffic problem, cannot and highway bridges for mass production and cannot be rigidly fixed or mechanical way of thinking, but using a more flexible design to create a more reasonable characteristics better suited to urban environments structure parameters.” In contrast, traditional bridge type selection thinking has its drawbacks, it’s really easy to understand, because, “the bridge type selection” statement in itself limits the designer’s thinking, we do a bridge is designed to be organised structure to overcome obstacles, hard at the concept design stage in beam bridges, arch bridges, Suo Fuqiao, choosing one of the bridges, they will amount to “form”, and put into the habitual thinking, resulting in monotony of the bridge form. In the dilemma in the planning principles and authors mentioned Ritter: “Problem-solving skills a lot, one solution is don’t be too quick to be restricted to a certain range.” In the UK architects bulaien·laosen, also mentioned in the monographs of the design thinking: “designer constraints relative to other sources of constraints flexible (designer constraint refers to the habitual thinking in the design process itself, such as constraint). If constraint caused too much difficulty, or difficult to achieve, the designer can be freely adjusted or reformulated constraints. Design students often did not recognize realize the simple truth, tend to think it should cost a lot of intelligence in an attempt to resolve many self-inflicted that could not be overcome. Designers need to acquire skills, is able to use a critical eye to evaluate and analyse their own design restraint.” So, in our design of urban bridge, to review the applicability of traditional bridge type selection.

3. Urban Bridge Structure Design City bridge span is small, if only technically, to implement it across a city bridge features in the works highly developed today, it is relatively easy to do, because our predecessors left a lot of off-the-shelf solutions, in this days a lot of the design sector, even in large quantities using standard image to complete the design. In the field of bridge design, there is such a saying, is a new bridge design, at least a decade to get out because the bridge complex, to various forms of bridges do come here, accumulating enough experience, about a decade’s time. With today’s highly developed computer-aided technology, many early designers of the bridge involved had the feeling that bridge is so easy to do, because the calculation of the structure of bridges with large engineering software is not difficult.

As a designer of bridges, what are we doing? Is the accumulation of various forms of bridges, is a readymade analysis and calculation of structures? Today, many bridge engineers design look too simple. Design is a process of discovering, analysing and solving problems. Some structural engineers may be calculated reinforcement design for main girder. In practice, however, to say the least, the process is almost entirely mechanical: use one or some formulas, in drawing up the size (textbook in the proposed rule a decision) into the, value generation beams subjected to loading in, needed much reinforcement even came out, and this is our concrete structure design course at university have learned. This process is the essence of “computing” instead of “analysis”, in fact, does not call it “design”, although these powers in the detail ties frame processing is necessary. Specific details are different, conceptual design of bridges, in a structural conception of first-order paragraphs is the best design ideas. City bridge, the owners and the public often has a relatively high standard of requirements and, therefore, our expectations for its is not confined to arrive at a solution, but was more of an aesthetic, humanistic, urban taste as well as cultural and historical heritage, and so on. Karl Kraus said: “the artist is the only solution that will have people to challenge.” Bridge Master Dr. Man-Chung Tang also said: “the bridge is an art. Art is flexible and engineering also flexible. To meet the established functional requirements of the bridge, one can have a lot of different choices in appearance, structure. This flexibility gives engineers the creation and the new space. Because engineers rely on, not just the scientific truth, more important is to implement and use the scientific truth of wisdom and the experience accumulated in the practice of engineering. Engineering guidelines are not a matter of right or wrong, but rather can or cannot. “Obviously, in urban bridge design ideas using structural art concept is very important. In the first article, referred to in the general layout of the city bridges is located the timing, the use of traditional bridge type selection is abusive, which tends to make the design process flow in programming and design work tends to be “form”, so how can we deal with it? How do you achieve structural art? We try to make the following views: In conceptual design of bridges in the city, the design idea is: the bridge pattern is determined by “need”. In city bridge design process, explore each due to the specific design of “ demand” caused by design problems and solutions and reflecting the specific characteristics of the bridge, and originality of design. Actually referred to here is the design of the “common sense”, rather than a profound thing. Because the design can be interpreted as: “Design is a particular condition, meeting the needs of all genuine best practices”. Design Needless to say is a very complex maybe that “design” seems too general outlines the definition of. First, the “specific conditions” refers to the designer constraints limiting conditions encountered during the design process, concern asked problem is, in many cases, these constraints are limiting conditions is not clear. Secondly, all “real demand” does not enumerate out early in the design stage, not all design issues are for specific purposes. Again, the “best practice” is often difficult to determine, the success of the design results, very little can be done in a setting of standards to adhere to our way of thinking about the question: since the classic bridge-tied our design thinking, we might as well go

back to bridging the last step is “design” from the original “requirements” set out to craft our structure, we need to is a kind of “structure of thinking”, rather than a series of models. In sculpture, for example, if it is a factory production of stone lions, it is charged its just a product, but from the hands of masters, and carved into their feelings for the recreation can become a work of art. The design concept that “Bridge structure form is decided by” “need” is not the negation of traditional bridge type selection method, on the contrary, it they are interlinked. However, engineers have to bridge some understanding of how choices are one-sided, used according to bridge span to select the type of bridge, but, in fact, never had any articles point out that, for a functional set of bridges, what kind of bridge type is best suited. Bridges in the form depends primarily on the number of “needs”, namely: construction cost, construction materials, transport, worker technical, aesthetic and other factors. Bridge is in the form of the ever-changing and basic form of warping, arched bridges, cable-stayed bridge, suspension bridge, but the bridge option is not is select from one of these bridge types, then apply some classic bridge and be done, we need to open our minds, not only bridge in the form of ever-changing, why should we get bogged down in “form”, we can according to organisation frame form to meet the actual needs. During the process of our knowledge, to learn how to “in” and “out”, can we have a critical distance, the independent thinking. On bridge form selection, “entry” refers to is that our predecessors left the classic bridge, carefully studied analysis of mechanical characteristics of fully understanding these bridge, applicability and functionality advantages; “ Get out of the” is referring to, from a bystander point of view, from a large scale to measure the accumulation of history, a classic bridge. Many of those world class bridge works today still have remarkable features, but this is only in the knowledge level, unable to graft it onto that bridge today. However, we can try to transform yourself into the role of bridge master, exploring them when designing bridges when thinking, design work is definitely not plagiarism imitations of them, there is no question that, and so on, repeated exercises our ability to think, to form their own structure of thinking, utilizing today’s designs, is the right way to learn. How to use mechanical concepts in design of urban bridge, forming excellent structure, the bridge will be reflected in what the kind of structure, will be discussed in the next section.

3. Urban Bridge Structure Characteristics At the beginning of this chapter, I cited “Millennium footbridge” example, built to mark the new Millennium Memorial Bridge, it was focus from big-span highway bridge, moved to more closely related to humans on the pedestrian bridge, and use a very flexible construction technique, done plenty of bridge works of artistic value. Similarly, in recent years, its urban bridge modeling concepts such as variety, emphasis on landscape, reflecting the characteristics of many different from traditional bridges. Germany architecture master Douglas said: “each compatible with the ultimate goal of building were filed and, therefore, each engaged in structural design engineer is an inventor. Scientists found that what was already there, and engineers are always inventing new things. But very regrettably, many engineers rarely or never use them. “ In the previous

section, we talked about the bridge’s structural design, is to tell you, city bridge design to its specific objectives in order to meet the needs of all aspects of this design idea will lead us to be the kind of structure? The content that is discussed in this section.

(a) The Development Direction of Urban Bridges For architects, and implementation is often the biggest challenge of building height, longspan under specific conditions but bridge’s first challenge, like the height of skyscrapers, load history is that the growing length of the bridge. In the 20th century of large-span bridges landmark buildings are: 1. A main span of 1991, m of Japan Akashi Kaikyo Bridge, the steel suspension bridge (advanced technology of deep water Foundation, advanced technology, super cable design, structure control technology); 2. A main span of 1624 m of Denmark the sea with Bridge, the steel suspension bridge (advanced technology and advanced design of deep-water Foundation construction technology. 3. Cross 890 m of Japan more luoqiao, steel cable-stayed bridge (side span for concrete structures); 4. Cross 856 m of France the Normandy bridge, steel cable-stayed bridge (side span for concrete structures, hybrid cable-stayed bridge, advanced pyramid structures, towers and girder construction side by example, using structural control technologies, welded box-section). In the last decade of the 20th century, we have witnessed more than a few record span bridge construction, each of them is a sign of progress of bridge engineering. In China, in the years late in the 1990, of the 20th century and the 21st century began, China bridge both in scale and pace, have made a spectacular achievement. Today, China remained the world’s record of longest bridges: Donghai bridge is the longest cross-sea bridge. Meanwhile, we should also see, China is in the midst of reform and opening up economic takeoff stage of development and infrastructure advances, although the scale and pace of the construction of the bridge in the world is the leading, But that doesn’t mean China bridge technology to achieve world class standards, our most developed in the 1960, of the 20th century, the creation of new materials, new technology and new structure, we just got done with people decades ago have already done. For world records, Chinese-American doctor of man-Chung Tang was said long ago: “I don’t think we should spend extra money to Genesis records, and great efforts should be made to design beautiful, technologically advanced bridge. Break the world record does not make sense, and is a beautiful bridges, high quality is always excellent achievements of the monument.” In the wake of modernism, bridges has appeared in two: the first is bridges and complex advanced modern technology links and tend to bring bridge to engineering Kingdom bridge another tendency is viewed as a system of cultural meaning, the bridge beam shapes generated as a result of the cultural connotation of the ingenious interpretations to explain the significance of structural form, the pursuit of cultural performances and continuation. In terms of engineering, developed almost all the innovation in raw technology that China, as a developing country lags behind developed

countries in the process of technology development and need further efforts to shorten the gap in culture, due to the developed infrastructure is complete, scale and pace of the construction of the bridge has reached a stable development stage, bridge designers began to focus more on the bridge of cultural understanding, Spain engineer Santiago caratera watts is particularly prominent in this area. In China, is now at a stage of rapid development infrastructure, and so-called “food will often eat, and then for the United States; clothing will often warm, and then seek Hali; Chang an Habitat will then seek music,” Chinese bridge on building size and number and taken get extraordinary results, but beautiful bridge lags utility requirements, this is determined by the economic and social conditions in China. In his book, published in 1991, the global bridge aesthetics, mentioned in the view: Bridge configuration should be designed under the maximum visual attraction to bear its loads. Some prominent bridge engineers and architects in the book of words very enlightening for us: “The validity of performance and aesthetic structure so closely together, which is more difficult to determine in some sheer beautiful bridge and touch us in the creative impulses behind in structural engineering, whether it is dynamic or static structure of abstract aesthetics thought.” —De Miranda (Italy) “As was the case as each crafts, a beautiful bridge of many aesthetic characteristics are represented in the form, to say that in the bridge designer of bridges could be granted in the form of a beautiful. Process for both sensitivity and technical capacity require form, because it does not do so, he cannot guarantee the realization of thought.” —Revelo (Mexico) “In this regard, however, must be emphasised depending on project requirements, but with less changes or decorating attempts to improve appearance is set method of bridge and should be condemned in the strong wording. Only developed into a general idea of the main aesthetic design department in order to achieve kick-butt design. Therefore, there must be a full involvement of the architect, this, from the time envisaged by the basic forms are to begin.” —Liebenberg (South Africa). Many writers argue that the global bridge aesthetics and bridge shape should not be in the form of load effects, regardless of its shape, while bridge shape should not be in the form of appearance, regardless of bridge load effect. Instead, the two main objectives and appearance, is not out to combine together, thus the choice of a certain specific forms of bridges from the design evolution and come, alternating and continuous consideration forms the design process in the functionality and appearance of the effect of two aspects of decision-making. Finally, at least in the designer’s comments, two aspects of the design optimisation and thus will show up. Functionality and appearance of both determining form, bridge designers to ignore one or the other major goals, to be built in the wrong place at the wrong time, the wrong bridge. As Dr man-Chung Tang has mentioned: “beauty is not added on the structure of the decorations, but the philosophy throughout the design process. Function of a beautiful bridge should be natural, with simple structure,

innovative design, and the environment harmony.”

(b) Design Requirements and Structure Characteristics of Urban Bridges Mentioned earlier, the bridge as a tool of cultural expression, bridge of plastic art is a kind of urban bridges trend, this thought is represented by Spain engineer and architect Santiago. Calatrava. We are here as a case study of the architect’s life and works, to experience the cutting edge concepts in the design of urban bridge design thought. Santiago Calatrava is one of the most well-known and innovative architects, his voice and elegant and rich in the humanistic spirit generation of structural form, as well as controversial architect. He has a dual identity of engineers and architects, they are able to form and structure as a whole into account, resulting in a unique work, which works like a dynamic abstract sculptures, which he won the “poet of structure,” said. He designed bridges, world-famous for its sheer elegance of structure formation dynamics, showing the technique rational logic that can be rendered in the United States, and as the tie beyond the law of gravity and the structure. Because of his architect and engineer dual role, he has accurate grasp on the interaction between structural and architectural aesthetics. We use the master’s works, to share experience of modern urban bridge structure.

Fig. 8.14 The alamillo bridge.

• Alamillo Bridge (Fig. 8.14) The bridge was built-in 1992, is located in Seville, Spain, across the Guadalquivir River, asymmetric, road inclined tower cable-stayed bridge without backstays, with sidewalks. It design is a bold, innovative, and the structure, architecture and sculpture merge into one. This bridge is the world’s first large-span without back stay cable-stayed bridge. Alamillo cable-stayed bridges overthrew the basic principle of achieving steady state balance through symmetry structure reaching balance in imbalance, obtaining the stable function of in instability, from deriving static dynamic image, not a sculpture but better than sculpture, as a levy geese coming into people’s minds, nurture the movement in a blink. This was Calatrava is often used, he often places the structure forces the focus outside the structure, which under structure is static, stable, but always presented or fly or fall trends, leading to a strong sense of tension and inference. This approach are reflected in his work Europe Bridge Fig. 8.15, Millennium bridge, Ladeweisa bridge Fig. 8.16.

Fig. 8.15 The European Bridge.

Fig. 8.16 Ladeweisa pedestrian bridge.

• Barcelona Expo bridge (Bach de Roda-Felipe II Bridge) ( Fig. 8.17) In 1984, Calatrava bridge is designed for the Barcelona Olympics, and in the design of the bridge, he adopted dissimilation and shaped policy. Arch bridge span 52 m bridge deck width of 25.8 m, the main arch ribs by the auxiliary arch enhanced ability to resist twisting and overturning of bridge. Auxiliary tilt inward arch ribs, short ribs connect to the main arch ribs and shoulder next to the sidewalk and step load. Ladder attached to the auxiliary arch, a natural product. Calatrava classic for this idea is that broke through horizontal linkages to resolve their two main arch ring of arch bridge stability of ask title law, and reflected in the symmetry of the whole bridge component of the master-slave relationship. Thus it can be seen by Santiago Calatrava bridges design of multifunctional form, integrated and coordinated approach. This programme has been successful in structural and cultural levels. The bridge created a recognised integrated aesthetics, sculpture and engineering characteristics of Calatrava style, meanwhile, also proves that karat lavoie the bridges works printed on the chic structure label.

• Milwaukee Footbridge (Fig. 8.18) This bridge was built-in 2001, is located in United States, Wisconsin, Milwaukee Art Museum on one side with a main span of 73 m, as the leaning tower of cable-stayed bridges, Calatrava is in the United States’s first work. The construction of this bridge is to connect the same was designed by Calatrava quadracci Pavilion with a local main road,

the Lincoln Memorial drive. The building to direct people’s attention to the new building up straight on the Gallery’s main entrance. Cable-supported bridge in bridge forms the traditional vertical pylons, to draw out a striking entrance box. Due to the master of Calatrava on the load-bearing concrete structures, the white material of concrete pylons vividly underscores the forceful and strong temperament, all of a sudden the whole building character and inventory hold out. In 2001, by the United States on the times magazine’s annual design list, Milwaukee Art Museum, were cited as the top. This bridge and art gallery received the 2004, International Association for bridge and structural engineering with outstanding structure Award.

Fig. 8.17 Barcelona Expo bridge.

Fig. 8.18 Milwaukee footbridge.

• Alameda Bridge (Fig. 8.19) In Spain Valencia Alameda Bridge also present unfinished state, and giving the instability feeling. Bridges completed in between 1991-1995, deck include the 130 m of highway bridge surface and overhanging a pedestrian path. The oblique arch with an inclination of 70°, vaulting from the deck 14 m, main girder of steel box beam, arch steel boxes with a main span 130 m rise 14 m, overall length: 163 m, main beam 2.54 m, the width of 26.0 m. In cross section, oblique arches in bridges one side of the body, suspended walkways through its tilt balance bridge torque. Alameda Bridge used the suspension pick structure characteristics of arches within the law lined with sturdy steel tilt rod gives a sense of stability. The bridge and other bridges designed by Kara terraba are white, diffused sunlight makes suspender line in continuous changing shadows and give it vitality.

Although the bridge has no Majesty spectacular vehemence, but its fresh, balanced structure shows the kind of gritty temperament. At this point, Calatrava arch-beam treatment preferences are revealed.

Fig. 8.19 Alameda Bridge.

(c) Training of Structure Thinking United Kingdom bulaien laosen in his book the design of famous architect thinking (How Design Think) said: “my experience in both teaching and research, convinced me of two things: First, all of us capable of designing and, secondly, through learning that we can better design. Indeed, as to how to do bridge design, probably it cannot be defined by the master or authoritative writings , because there is none of the so called standard and the standard answer to that question. All we can do is through learning and practice improve our understanding of the design and to make “better design”. For the design of urban bridge, we would like to make a point here, in order to help people to deepen understanding of urban bridge design process, it is: “structure the train of thought”, which is going to help you better achieve an important way of urban bridge structure design. Moreover, the “structure thinking” and design are alike, we can all learn and continuously improved through training. Just as Edward: “treat thinking as a skill, not a gift, it is the first step of continuously improving one’s thinking.” Earlier, we mentioned that the landscape of urban landscape bridge due to its high specification needed bridge engineer in the design structural art, rather than merely rely on mechanical codes, manuals and computer design. So, how do we specific design projects, reflect the diversity of structure, and to meet specific aspects of design needs? The answer is that we need to apply “structural thinking,” will design and structure organisation scheme to establish a link between, and the said the structure was not there, it may only appear in the designer’s mind at a certain time, that is, original design works. Here we are not talking about hanging in and hanging of esoteric theory, in simple terms, is in the analysis of this problem, ask bridge structure design for questions, problem-solving process, we need not only learn knowledge, but also applying “knot structure-thinking” to build our system of bridge structure, the development of our ideas, and ultimately seeks to meet project-specific design standard, rather than a copy of an existing structure. The so-called “structure of thinking” is not a new concept, refers to the creation of structural form using design thinking. Design in all its forms, must include the exact and

fuzzy two different ideas, requires systematic and chaos of intuition and reset method of thinking, requires imaginative thinking and accurate calculation of integrated. In other words, is to learn how to design science and consciousness, deductive and inductive organically together. How to use in design of “structures”, it is a very complicated and delicate skill, it would just like us to learn flute and table tennis, although almost all are all trained to to learn, but it takes practice to do. Concepts of urban landscape bridge structure of the design is a creative design, need a rich imagination, and in the overall design filled with unknown factors in the process, some designers, created may be a burden, but for others speaking, they may feel that it is very exciting. Germany bridge master as a bridge engineer, described his creative process: “naturally, you will have some unconscious thought, it is because something is stored in your memory inspiration occasionally emerges. But generally speaking, happy is hard work; field exploration, thinking and painting sketches, evaluating design plan, identify advantages. A sketch after another, not satisfied with the reverse designs, fighting with it, new programmes, to consult with others, sweat, until the final solution from the many choices in implementing them. The more difficult a task, the greater the opportunity that you can come up with some unique solutions. As time goes by, you will develop a certain degree of design strategy. First solve the most difficult problems in a complex task, but using the most simple way possible, so that other unresolved issues will become less difficult issues, and finally you’ll be able to put forward a comprehensive and coherent solution design scheme. However, our engineers are not there simply to seek to satisfy, and not just to promote technological progress to the top, we are within a short time to live on the Earth, making human life more pleasant.” If you frequently experience urban landscape bridge conceptual design process, it is not difficult to understand the hardships of the creative process. In most of the time, when we do not see The things we require, we may feel frustrated, in the conceptual design of the structure of the process, we are going to learn could substitute with firm confidence disappointed—I know it was already on the path of realisation, is what we are learning in practice the growing “structure of thinking” ability gives us that confidence.

8.3.3 Urban Bridge Structure Characteristics 1. Design ad Construction Difficulty in Urban Bridge Design At the beginning of this chapter, we talked about the topic of Haihe River Bridge, with the advancement of landscape construction of the Haihe River, alongwith the improvement of urban traffic, gradually a group of river-crossing bridges were built on the river. In this section, through the introduction of Haihe bridge design and construction difficulties, we try to understand issues related to the design and construction of urban bridge. According to the overall policy of Haihe construction of Tianjin about Dagu bridge construction begins at home and abroad are invited to most famous civil engineering consulting firms to participate in the design and tender. Table 8.2 Famous foreign consulting companies participating in new bridge design and tendering upto date. Table 8.2 Famous design firm involved in the Haihe River new bridge design.

Bridge name Dagu bridge

Foreign consulting firms involved in the design United Statest. y. Lin International (t. y. LIN International

Chifeng bridge

United Kingdom Hyder Consulting Limited

Bengbu bridge

France Mark Mimram Ingenierie

Fenghua bridge

France Mark Mimram Ingenierie

Fumin bridge

United Kingdom Halcrow Consulting Limited

Auspicious bridge

United Kingdom Hyder Consulting Limited

These world famous design companies participate in the Haihe river new bridge design, making Haihe River new bridge able to fully integrate current development trends of bridge, borrowing world intellectual resources, establish a culture, and pursuing high technology. Meanwhile, we also emphasise great importance to innovation in design and construction, through the continuation of new bridges in Haihe River culture, highlight the economic development in Tianjin. Width of the Tianjin Haihe river is generally around 100 meters, as span are small, and navigation standards are not high, so most of the various types of bridges are consider a bridge over the river. Starting from selecting your new bridge of dagu bridge in bridge and structural characteristics as shown in Table 8.3. Table 8.3 Structure feature highlights of the newly built haihe River bridge. Bridge Arrangement name of bridge span (m) Dagu bridge

Bridge forms and basic features

Three spans On both sides the main arch rings decumbent in opposite of: 24 + 106 direction, main arch ring size, tilt angle are asymmetry. Sling + 24 space layout, full bridge consists of four cable planes.

Fenghua Three-span: Tied arch bridge. Three spatial arrangement of arch form three bridge 56 + 138 + groups of vierendeel, each group of vierendeel arch with three 56 triangle connected with the “Blade”. Full-bridge has six Slingcable-plane, each group of vierendeel arch features two cable planes, with the exception of two pairs of vierendeel arch outside the inner Sling crossing arrangement, all other Sling are arranged in parallel. Bengbu Seven cross: Arch-beam composite structure bridges. Antisymmetric flexible bridge 27 + 12.63 + arches on both sides and the middle lane group of rigid box 35.37 + 42 + girder and intermediate supports are also anti-symmetric layout. 35.37 + Composition of the main arch also consists of smaller arch ribs, 12.63 + 27 arch ribs are connected by transverse arch ribs, each form of arch rib using space warps.

Fenghua Three-span: Special cable-stayed bridge, uses the streamline form enclosed bridge 120 + 55 + curved steel box girder in main beam. Main tower is located in 40 the inside of the curve of oblique, structurally separated from the main bridge. Pylon cable is positioned behind main tower to balance the horizontal force of main tower. Main span and side span are asymmetrical, main span use fan-shaped arrangement, side with thin rope system. Fumin bridge

Four spans Single-tower self-anchored suspension bridge. Main span cable of : 160 + 13 is space cable, tilt hanging rod is set in the main beam from the + 37 + 20 middle to both sides of the. Sidewalks located beneath the main beam.

(a) Design and Construction Innovations of Dagu Bridge Dagu bridge in Tianjin (8.20) use open, non-symmetric space arch design, breaking the previous two-dimensional arch bridge structures from flat surface of the three-dimensional structure of two-dimension to space. Dagu bridge design philosophy is “Sun Moon arch”, constructed by two asymmetrical arch, Arch rings arch high 39 m facing east to symbolise the Sun; little arch high arch 19 m to the west, a symbol of the Moon, predicts bright future of Tianjin as the Moon and Sun. Total bridge length 154 m, as a three-span continuous girder system, unique design, modern and fully represents the current bridge development trend, that is safe to use and beautiful landscape, technological innovation, and the economy sensibility.

Fig. 8.20 Dagu bridge in Tianjin. In terms of landscape, the bridge is a very nice and in harmony with the local environment of the bridge; in terms of structural mechanics, it makes full use of bridge lateral rigidity and vertical stiffness of arched, making this look extremely slim structure can also resist Tianjin area strong earthquake. It is a three-span continuous tied arch bridge, bridge spans are: 24 m + 106 m + 24 m, bridge, 154 m. Bridge arch crosses over the river, side arch provide adequate space for two sides under roads and Riverfront hydrophilic platform. Sidewalks and landscape design of trails for pedestrians and provides a resting and viewing platform.

In the whole process of Dagu bridge construction system switch is the key to completion of bridge, novel structure requires in this phase of construction to be innovative. Practice proves, the entire set of system construction technology to be practical. It increases the accuracy of the positioning of the bridge structure, accelerate the pace of construction, guarantees the safety of construction process for smooth and completing the works played an important role in quality, but also for the future of such bridges provides valuable experience for reference. The design mainly has following several aspects and construction innovations: general procedures for mechanical calculation and analysis of applicability of bridge structure; steel weldability study on small space; low alloy steel thick plate welding performance of different types of steel welding performance; inverted trapezoidal arch moulding process; study on installation technology of steel box arch ribs; asymmetry of the Suspender tension control process.

(b) Design and Construction Innovations of Fenghua Bridge Fenghua, Tianjin Haihe River Bridge Fig. 8.21 is located in Fenghua road, Hexi District, Tianjin Hedong District, and connected a bridge across the river, was designed by Mr. Makemanlang, founder of the France makemanlang design engineering firm. Fenghua river on both sides of the bridge and the coastal strip garden connected due to the surrounding landscape, and will attract a lot of visitors and, therefore, when Mr Makemanlang in bridge design to avoid pure traffic function of bridge design, but rather from the function of urban bridges and from landscaping standards to select bridge form. To this end, the Fenghua bridge structure is three-span arch structure, span is 56 m + 138 m + 56 m, hole 138 m across the river. Main span arch is 32.5 m in height, side-span arch 20 m, upstream sidewalk bridge are fully linked, downstream sidewalks on both sides connected, from coast to coast, on both sides of the Park connected. Each arch of the bridge formed by three independent arch, main span and side spans the Middle arch is located between the lanes on both sides, lateral arch is located at a carriageway and scenic trails and sidewalks in between. Each separate arch formed by the three box-section steel tube arch, box-section steel tube arch of curve, box roof arch, between steel pipe arch consists of several different forms of metal leaf-shaped piece connected to the network. Three of the same cross alone state set between the arch of wind connections, to ensure lateral stability of arch structure. Main span arch and lateral side arches hang from the bar in 4 m, others are 2 m. Deck system formed by the longitudinal beam and steel deck, side pedestrian bridge consisting of steel beams and concrete composition. Its main design application difficulties are:

Fig. 8.21 Fenghua bridge. Spatial structural analysis of special-shaped arch; Super thick steel plate welding technology research; Hyperboloid steel arch rib and petal structure fabrication; Sliding pan on steel deck erection technology; Space diagonal steel arch with variable cross-section of installation; Steel arch closure process; Construction technology of new tensions in suspenders.

(c) Design and Construction Innovations of Bengbu Bridge Tianjin Haihe River Bengbu Bridge Fig. 8.22 used in the design of a girder and arch combination system. The total length of the bridge 192 m, flat against the structure parameters A thin single-room of steel box beam in along the bridge has a double point, respectively (parts of the bridge abutments, strut position and diagonal brace parts), point (v-shaped piers in parts), point (v-shaped piers in parts), double (Raking parts, strut position and abutment areas) supported even continued beam wing through a number of bridges are cantilever beam, transverse arch, V-shape piers of components and auxiliary bridge made up of vertical and horizontal beam structure multi-point support, connection, and consists of three spatial distortions on both sides of the longitudinal arch and the corresponding transverse arch even and reticular arches withstand the external part of the passed to the lower base of arch.

Fig. 8.22 Bengbu bridge. Bengbu bridge is anti-symmetric spatial distortion mesh arch structure. Commonly

regulations simply increase or decrease the stiffness can be improved to some extent loading condition of the structure, and for this kind of beam and Arch (Generalized arch) system, in whole or in part under the influence of external load rigidity and internal force distribution problem, it takes should be carefully weighed and studied. This bridge and the bridge has been built in the past, stress characteristics of huge difference, unable to bridge design has been built through learning from other experiences full control and design information on structures, so we devoted to the study of the bridge. Design concept of this bridge novel, even with conventional bridge design concepts, and manifested in the following aspects: Main structure consists of box girder of the bridge with the lattice arch consists of small box girder sections, structure of the unique network-shape arch bridge is never use a principal stress structures. Design first starting from the landscape dimensions of the selected components, which greatly increases the difficulty of structural design and workload. Load bars under tension and compression transform into bridge design support structure (1st, 6th Pier). Used in the bridge configuration is a hinged components in order to meet the need of force structure (2nd and 5th Pier). Special “V”-shaped structure Pier design (3rd and 4th Pier). Due to the prominent landscape of this bridge, bridge structure fully into account aesthetic requirements. This bridge, such as linear, sectional dimensions of space hormone directly affects the aesthetic effect through optimized calculations and research necessary to solve the difficulties of the structure to meet traffic requirements, and full attention to appearance, so as to ensure uniformity in its effects and appearance features, rich in Tianjin urban image, Ascension Day Tianjin’s status, which greatly promoted the economic development the Haihe River.

2. Improvement of Existing Urban Bridge Tianjin’s development, especially in more than a century, is working closely with the development of the Haihe river, also accompanied the Haihe river development. Tianjin Haihe river have been completed on existing bridges, witnessed the Tianjin culture, history and the progress of humanity. Because sea bridge over the river’s low density, is far from meeting the needs of urban development, so in terms of Haihe river bridge continues to show the beauty Li’s rich historical and cultural point of view, or continue to divert the busy traffic in the city’s point of view, require Haihe river bridge. However, because of the bridge construction days earlier, is confined to the settlement of the standards as well as many years of operating, such as element, now Tianjin has been unable to meet the growing demand. These factors not only are unable to satisfy traffic under the bridge, bridge traffic and load standards improve using features such as new requirements, at the same time, demand more and more of an urban landscape of urban development element, so must deal with problems of existing bridges, according to the overall plan calls for each of the reform of the existing bridge.

(a) The Lion Bridge Lion Grove Bridge name derived from the “lion” names. Existing lion bridge built-in two: 1974, construction of pre-stressed reinforcement concrete bridges, bridge width 24.6 m, the layout of the roadway and sidewalks on the bridge. Upper structure is a three-span simply supported single arm hang hole structure 24 m + 45 m + 24 m bridge, hanging length is 8 m. Piers, abutments with reinforced concrete piles. Under the original bridge, 1994 tours on each side to build a new bridge, Shinbashi Bridge 9.3 m. Shinbashi bridge superstructure shapes with the same old bridge and structure for the three span variable cross-section pre-stressed concrete continual box-girder span is 25.2 m + 45 m + 25.2 m. New and old bridge substructure for reinforcing steel bar pier concrete entities, with bored pile foundation in the lower part. To comprehensive tests showed the Lion Bridge, the bridge continues to meet load standards and existing regulatory requirements, you can still in order to continue using it. But because the river navigable standard, lion bridge could no longer meet the current navigation requirements, must be of high bridge range is increased by 1.271 m. Because the Lion Bridge has a unique cultural and landscape values, to dismantle it would be a pity. After overall carefully researched and repeatedly demonstrated, decided to conduct an overall rising, at the same time, in accordance with the landscape requirement to haihe bridge area decoration. Transformation after Lion Bridge sculpture 4 magnificent Crouching Lion, with the bronze lions of bridge railing look different form the unique style of stately traditional Chinese culture. Fig. 8.23 respectively, Lion Bridge in the rebuilding process and after reconstruction.

(b) North Bridge North Bridge (Fig. 8.24), built in 1973, the main bridge consists of three spans, long-span 24 m + 45 m + 24 m, width 24.6 m bridge laid on the roadway and sidewalks. Superstructures for simple single cantilever girder pre-stressed concrete box girder with variable cross section with a hanging beam, suspension beam length: 8 m, weight set at the side abutment. Substructure with bored pile foundation, round-end-column bridge piers, hat bridge.

Fig. 8.23 Before and after the transformation of the Lion Bridge. Tests on the first of the bridge showed that Northampton bridge suspension beam are unable to meet the existing load requirements, you need to thoroughly replacement. Meanwhile, Northampton bridge of cantilever beam brackets must also be reinforced. According to the planning requirement of Haihe River Bridge, on the North onkyo alterations include the following:

Fig. 8.24 North Bridge. 1. Widening: widening part is on the Haihe River bridge downstream steel bridge and re do two width 9 m, newly-widened bridge span arrangement consistent with the existing bridge; 2. Equally in order to meet the existing navigation requirements of the Haihe River, North Bridge will also be to be the overall rise, lifting height of 1.55 m; 3. North Onkyo landscape decoration mainly borrowed from the Western classical style of the Pont Alexandre III in Paris, France, bridgehead statue-production with western classical forms and learn Chinese traditional theme, Green Dragon, white tiger, rosefinch, Xuanwu meaning North, South, East and West the Quartet peace; piers statue embossed front decorative bronze dragon, delicately on the plinth for four different dance Dragon Lady; sidewalk and non-motor vehicle road surfaces as Granite paving; Rails in the form of elegant vase forms and the use of stone for its characteristics; bridge head consists 4 bridgehead fortress of 20 m in height, highlighting its ancient dignified features. Transformed the landscape of Northampton bridge features can be summarized as “European style Han rhythm”.

8.4 CONCEPTUAL DESIGN OF URBAN BRIDGE— STRUCTURE AND ENGINEERING—THE ARCHITECTURAL AESTHETICS When Germany bridge master qiaoge·xilasi was asked in an interview: “what is an engineer in the eyes of the art of architecture?” He replied: “that process it is the natural or urban environment can be like dealing with the function and construction of social responsibility as sensitive creative design. A friendly, holistic solution suitable for all purposes, including their appearance is also very beautiful feeling. Architecture is the ultimate goal, comments ensue. “The designer wants to stress is, the beauty of bridges art values and bridging functions are equally important. An excellent bridge designs should be the science, technology and culture the result of combining art and should adapt to the various aspects of the project requirement, while the demand for architectural aesthetics, two of the more important point is: in harmony with the environment and an attractive appearance. Dr man-Chung Tang once said that “a successful bridge design must be natural, simple, innovative, coordinated with the surrounding environment, and get along well. “He was once quoted in Merriam-Webster’s Dictionary of” civilisation “definition of” using science and technology to achieve the comfort and convenience of modern “to describe the United States important concept in building design. The bridge structure is concerned, “safety leaps” provides “convenience”, and beautiful environment makes one feel “comfortable”. Therefore, Man-Chung Tang stressed the importance of bridge aesthetics in terms of quality of life. He thought bridge are public buildings was decorating the environment one of the most important structures. History of mankind are to improve the quality of life. Beauty is a very important part of quality of life! Therefore, the bridge should not neglect the beautiful. Professor qiaoge·xilasi and Dr man-Chung Tang, although we are doing the structural origins of bridge engineers, but they do not exclude introduces the idea of architecture aesthetics in bridge design. Instead, they’re very big on bridge aesthetics, their works can be seen in the many of the design elements of the building. Early city bridge, due to the lack of material and technical, generic bridge design with practicality, Liang Duo mark design and use of precast construction, in order to achieve high performance and short of goals, choices and the importance of appearance, often behind such pragmatic considerations. Today, the bridge has a more and more important role in urban space, we hope the city bridge not only as a tool to cross, but other buildings, reflecting the quality of urban life, interpreting in a way or value, become part of people’s lives. As bridge designers of the new era, we can’t force their way of thinking in the field of architecture, also want to try architecture some thinking into the field of bridge design, creating both works of art and architectural design of the structure. Modern architecture, is a design imported from western thought since reform and opening up, all along, the domestic construction sector there are several trends: 1. Irrational tendencies. In teaching, the teachers will be sporadic and emotional

experience through different building types similar problems (such as functions, forms and norms) repetition of the exercise in order to “language, but not explained” way to teach in practice, people rely on talent, “perception”, with the sudden “inspired” created around themselves “feel” for evaluation. 2. Art trend. Inherited from the 19th century Beaux “bandage” system, academic background in China formed under a set of “fine arts building” concept. From the perspective of advancement of the design and evaluation of, the “beauty” concept significance based knowledge construction of knowledge, theory, “style and genre” is the main tool, the focus is still on “forms”. 3. The gap between theory and practice. Most of the architectural theory at the abstract level, with the text, the theory itself is logical demonstrated, the lack of effective ways to put it into practice; architectural practice multi stays on the perceptual experience of specific projects, it is difficult to methodological level, refine, validate and promote. Domestic architecture of the level there is a considerable gap with the European powers, several tendencies of the above, the domestic construction sector common problem in columns. We should pay attention to when using architectural philosophy, not blindly to the Builder, but should be directed at specific problems of rational thought, after all, in the field of bridge using architectural aesthetics, at the international level is still at an initial stage.

8.4.1 In Harmony with the Environment We start by looking at an example—Italy bridge of Sighs, as shown in Fig. 8.25.

Fig. 8.25 Italy bridge of sighs. “When the Sunset bell rings, I want you kiss under the bridge at sunset”—In the film “the sunset bridge” the most classic dialogues of love, has been popular around the world, the two main characters of the film it was standing in on the bridge of sighs in Venice. Also here into Europe and young people to the lovers expressed their love in the most romantic of places. But if the origin of the name of the bridge of sighs is not romantic. The bridge of sighs was built-in 1600, the style early Baroque style, the Bridge House, the upper dome cover closed tightly, only to Canal two openwork carving small side window. The bridge fully illustrates the meaning of “connection”, it connects tokary Palace next to

the Governor’s mansion and old prison dungeons in the middle ages, when the prisoners at the Governor’s mansion after the trial, criminals will be brought to the Dungeon, and may have thus to be gone forever. Only one bridge away, but can be described as between heaven and hell. These dying prisoners, after which beautiful marble bridge, through the side of the bridge window to see beautiful water scenery, will not help and groaned, the bridge of sighs hence the name. Through the “bridge of sighs” in this case, we may wish to explore the deep: essentially, the bridge was designed to between the two points (tokary Palace next to the Governor’s mansion and old prison dungeons in the middle ages) to provide access to bridge the natural and artificial obstacles (the Canal between two buildings). Bridge Designer is not just building a building, its soul is how to use ingenious structures that link the meaning perfectly into the environment, so that it not only provides a new processes, new viewpoints and experiences through time, and forming new place and in shaping the landscape. Therefore, the bridges of the city and the urban environment are inseparable, it, town squares and main streets and other urban architecture, into the cultural landscape of the city as a whole, is part of people’s daily life.

(a) The city’s Landscape City is an integral part of human civilisation, cities along with the development and progress of human civilisation. The impergium, humans started to settle; accompanying commercial development, development, urban civilisation began to spread. In fact the impergium, cities appear and role in the military defence and sacrificial ceremony, does not have the production function, it’s just a consumer centre. At that time the City Planning Board model is very small, because the surrounding countryside provides surplus grain is not much. Each city and its control in rural areas, forming a small unit, the relative closed and self-sufficient. Scholars generally believe that cities are the result of industrial and commercial development in the true sense. As of the 13th century mediterranean Coast, places like Milan, Venice, Paris, is an important commercial and trade Center; Venice, which during the boom, the population exceeded 200,000. After the industrial revolution, and greatly speeds up the process of urbanisation as farmers continue to flock to the new industrial centres, urban growth was unprecedented . To the eve of the first world war, United Kingdom and the United States, and Germany and France and other Western countries, most people have been living in the city. This is not only a symbol of abundance, and is a symbol of civilisation. According to the Chinese Academy of social sciences, according to city blue book published on July 29, 2010, as of 2009, China’s urbanization rate was 46.6%, the town’s population reached 6.200 million, urbanization scale ranks the first in the world. This report, titled China urban development report of blue skin demonstrates, the 1996-2005, the urban population every year in China more than 20; 2006-2009 year increase the town’s population is approximately 1 to 5 million people. By the end of 2009, China’s total urban population was the United States population (two times), even higher than the total size of the 27-nation bloc’s population of one-fourth. The blue book is expected, for some time to come, China’s urbanisation process will remain in a period of rapid progress,

by 2015 the urbanisation rate will reach around 52%, by 2030 65% or so. In the rapid development of urbanisation in China and even the whole world today, understanding further insight into the urban environment, it becomes very necessary. In the famous TV series beijingers in New York, a classic line, had this to say: “If you love someone, send him to New York, for it’s heaven if you hate someone, send him to New York, for it’s hell.” It is clear that urban environment complex, let us not analyzed the city’s concepts from the fields of philosophy, this is not the focus of this chapter. We are here concerned the city as a place to live, many of us work, and it really gives us a kind of environment? These urban bridge design concepts and how close liaison?

(b) Coordinating and Urban Landscape and Urban Bridge Previously mentioned the global bridge aesthetics, a book, in this book, 24 of the world’s prominent bridge engineers and architects, from 16 countries selected representative bridges, shared their experience on bridge design aesthetics, comments and suggestions. They summarised that in the conception and design of bridge the main principles to be followed are “unity of the location of the bridge and the bridge” and the application of “the presenting form of the structure”. “The structural form” is discussed in articles in structural engineering, above, and “bridges and bridge unity “is the central idea of this section. Bridge location refers to the “landscape”, “City”, “city space”, “ring state” “scenic area”, “the bridge and the environment do not” noise” and “harmony” and “complementary”, “enhance”, “protect”, “side-by-side etc.”. Experts in the book are cited: “We must pay attention to the balance of nature and landscape to interfere as little as possible to form a bridge for us. As long as the bridge construction is Close to spectacular natural beauty, this is especially important.” —Von Olnhausen (Sweden) “We think that the bridge must be combined with its local environment, landscape or city views, particularly when it comes to size relationships and the proportion of occasions. In the past decades due to the heavy concrete blocks were placed in the old Center of the city had caused many mistakes … … Often, with deep, heavy girder of longspan bridges will undermine the lovely valley views or city”—Leonhardt (Germany) “With boundary node of this property, is another aspect of importance of bridges exist in space. That is to say, a bridge the function not only as a thoroughfare, and is a place for people to meet each other … … Space and form design of the bridge, also turned up consider bridges in urban space as a unique meeting place of this aspect of human culture.” —Nakamura (Japan) “When we think about at the location of the bridge and its relationship to the environment, configurations and colours of the temples and palaces available as an example to investigation. For example, a temple or palace of the city sights are built high walls, decorated in red, green or yellow glazed tiles. This deals with the contrasting backgrounds, showing temples, palaces, the existence of different and important. In the same way, some large-scale modern steel bridge designer bridges has been painted with

bold colors. However, most of the bridges are designed and decorated with your local environment Association Harmony complement each other.” —Tang (China) “The bridge should never be considered unrelated to its surroundings. Therefore, a bridge must be designed to complement each other with their setting environment and Harmony exists.” —Menn (Switzerland) City bridge, the city/bridge, city bridge concept, closely related to the city’s overall philosophy. Bridge should fit in the local environment, as well as the history and culture of the city, unique style, and so on, require bridges to echo the urban environment, reflecting the high urban quality.

(c) City Bridges in the River Landscape At the beginning of this chapter, we mentioned the topic of rapid development of Haihe River Bridge construction, economic development for bridge construction to provide strong powerful protection, harmony with the environment of the new bridge is also able to stimulate economic growth. Going across the city like Tianjin Haihe River rivers, its bridge-building of the whole landscape is very noticeable. Haihe River Bridge construction, Tianjin will become a global and strategic and historic works. Construction of Haihe River Bridge, to capitalise on advantages of the bridge, Haihe River economic belt formed effect, thus boost the city’s economic and social development is of great significance and importance. Coincidentally, at the national level, with the process of urbanisation, in order to adapt to the development trend of urban landscape renovation, urban traffic development needs, many cities have also started to landscape planning of urban River Bridge renovation, such as the Shanghai Suzhou River bridgescape governance, Guilin, “two rivers and four lakes” landscape renovation of bridges and so on. Bridge is the city’s business card, is condensed and carrier of geographical and cultural history of the city. Landscape of urban bridge not only needs to comply with technical and aesthetic characteristics, but also display features, embodying regional characteristics into the cultural identity. Urbanisation, art, human culture is urban landscape meets the general landscape of three major characteristics. River bridges are part of the urban landscape of the city, by the in its waterfront properties/in waterfront personality, organisation of urban space environment of urban environment and urban activities play an irreplaceable role.

• Waterfront Space Properties River Bridge across the surface of the city, connecting the two sides of traffic as the main function, which combines the different blocks of the city as a whole, provides the basis for people perceiving the city’s overall intent. Bridges are often marked cross-hair in the direction to the river crossing, with the city roads connected urban traffic network. People walk on the deck and fast driving vehicles and surface ships navigating under the bridge joint formation of transportation flows, showing the bridge’s dynamic landscape features,

reflect the waterfront of the most productive in urban bridgescape.

• The Urban Landscape Features City River Bridge, town squares and main streets and major public buildings became part of urban elements, the style should be consistent with the city’s overall style. Bridge design both as an independent building design as well as road landscape in its entirety, an entire section of water features, part of the street environment as a whole, with its surrounding environment, the built environment and cultural landscape harmoniously.

• Geographical Culture Characteristics Each city is unique in the world, has a unique history and culture. Bridge as a special kind of knot frame, long considered a symbol of economic and cultural. It tells you more about the history of changes and the evolution of the times, reflects the different age architectural features, contains a wealth of culture.

• Night Landscape Aesthetics Characteristics Bridge pattern in the city’s strategic position in the night view of the bridge became an important component of urban lighting. Waterfront of bridges site, its expansive vision is the expression focus of the urban landscape, night view of the bridge city night view of depth and space layer play an important role.

8.4.2 Construction Techniques After entering in the 1980, of the 20th century, bridges as the main cultural and architectural landscape, obtaining increasing attention. Bridge’s two main line is particularly evident in the development of: innovation of large-span structures are emerging on the one hand, are the big traffic load in North America and the Pacific region, especially China, and on the Spain architects in San Diego Yage Kalatelawa (Santiago Calatrava), France Marc Mimum, and the Chinese-American Pei (Pei Ieoh Ming), architect, United Kingdom by Wilkinson Eyre, Ove Arup company, France, Dietmar Feichtinger division of Spain of the engineer Leonardo Fernandez Troyano, works as a model, is absorbing in bridge design construction approach, designed many bridges as art. These bridges are often small scale of urban bridge, or a some artistic atmosphere footbridge. Environmental Designer, product designer and graphic designer needed vocational skills may be the most important space, form, line and colour and mechanism, and so on. Similarly, for urban bridge, apart from satisfying beyond technical feasibility, there is another very important factor is its aesthetic value. Because city bridge not only to meet its required function, it is always in sight. The achieving of aesthetic value, in many cases requires the power of the architect by using effective techniques to beautify the bridges, such as the below are listed several bridges.

(a) The Aspiration Bridge This bridge is an impressive, delicate and bold designs, a high place in Floral Street in

Covent Garden bright, shiny footbridge, across from the new building of the Royal Ballet School and the Royal Opera House link for dancers direct before. Revolving bridge shape, square 23 door frame made of aluminum girders, adjacent to each gantry rotation, then install glass to become. The bridge opened in 2003, as shown in Fig. 8.26.

Fig. 8.26 Aspiration Bridge in London.

(b) United Kingdom Butterfly Bridge United Kingdom Butterfly bridge Fig. 8.27 is using modern programme material and the design. Original butterfly double Arch truss bridge design on the new bridge with high arching parabola forms of reproduction, this parabola is composed of a single ring, hollow steel tubes form. Arches on both sides of the point, upward-sloping constitutes upto open shapes. Two Vault between water distance is 16 m, look like the wings of a butterfly. This modeling buildings have a certain vitality, as if stuck in the flooded low the mechanical insects on the ground. This, coupled with the nearby bridge beam Parallels, making this perfect combination of new bridge and the surrounding environment.

Fig. 8.27 United Kingdom Butterfly bridge.

(c) The United Kingdom’s Millennium Bridge Over the Lankaisitelun River United Kingdom Millennium Bridge on the Lankaisitelun river Fig. 8.28 “Y”-shaped railway viaduct piers and connects with the North Bank of the river. It makes both sides of the river between Lancaster and morecambe walking and bicycling all very convenient. This twin mast cable-stayed structure using the south better geographical conditions and at the same time awakens sleeping memories, people seemed to enjoy the 17 and 18th

century, when the pier was crowded with ships. Bridge passageway extending into the terminal, adding navigation the image, you can also play a reinforcing role and prevents the mast swings. In making use of architectural aesthetics of urban bridge model design, and structural design compared, often of a more large uncertainties. In fact, for the architectural design of the bridge is not a so-called absolute standard that can be quantified, in the design process, most of the time we are unable to determine exactly to what extent an issue is fully resolved. Generally speaking, the designers end a design for two reasons: one is that time has run out, and second, they think it is no longer necessary to have a design problem studied further more. Bridge design in urban landscape, however, we had to hastily because former junction beam architectural design process, there are many designs and sometimes regrets. The causes of these issues are , the urban landscape bridge was built building design, is often the goal is unclear, including design issues would also need to be proactive to discover. Clearly, “judge when to conclude its work” is an important bridge designers, but this seems to only find itself through practice. Fizzled out design problems is very unreasonable, and the other extreme is that problem at design at the beginning of Ming dynasty practice, later also tend to bring a lot of misleading, in this argument about “traditional bridge type selection alternative thinking “are mentioned.

Fig. 8.28 United Kingdom River Lune Millennium Bridge.

8.4.3 Bridge Decoration 1. The Knowledge of Urban Bridges Decoration The Pont Alexandre III in Paris Fig. 8.29 and Notre Dame bridge Fig. 8.30 are very famous, from the aspect of structure, that two bridges there is almost no difference, they are steel deck-arch bridge, the structure forms are similar, but in appearance, it seems as if there is a big difference between the two arch bridge, the reason is that they adopt a different style of decoration, so as in a completely different visual effects.

Fig. 8.29 Pont Alexandre III (Paris). At the time, heavy is a stylish decoration of the urban bridge, especially the Pont Alexandre III, the bridge is decorated very heavy, sumptuous, Royal style came to prominence. Bridges North and South ends of the four pylons erected on the pier, the tower a bronze Pegasus rose, symbolising the goddess conquers Pegasus; Bridge vaults sculptor George Lei Xipeng work; bridge the lamp is made of Cupids holding on, meaning the image construction of bridge decorative theme; on the bridge’s steel skeleton outside the bars of gold is a gorgeous flower-shaped sculpture, garland pair of beautiful ladies looming; bridge lights installed on a bronze sculpture lights and lamps next to the candle holder hugs, forever as festive. Two columns on the left bank of the bridge represented on the Renaissance and Louis 14 of france signs on two pillars on the right bank have symbolic sign of ancient Italy and modern French. At the entrance from both ends of the bridge column there are symbols of the Seine with the moral of the decorations of the Neva river. All in all, this bridge decorative technique used to perfection, its decoration is meant to convey a certain meaning and emotion, namely: praising former Russia and France’s friendship.

Fig. 8.30 Notre Dame bridge (Paris). To decorate the bridge has a very long history. As society changes, bridges decoration has undergone since time immemorial Jane single, simple to fussy pile and finely crafted before the 18th century, from the 19th century, abandoning decoration to the early 21st century form of functionalism generation, decoration of reason such a development process. Second half of the 20th century, bridge sector have no bridges, decorative, displaying is the number in front of people without any “traditional” ingredients, just to meet the functional requirements of the bridge, although the solution some looming transportation issues, but did not take into account bridge landscape. The so-called bridge decorative refers to non-necessary for the function and design of bridge structures, but additional, improved bridge art image measures collectively. Highway bridge, due to its zone pedestrian with few tourists, mainly to meet transport function it is generally not necessary to do unnecessary decoration, simple nature is as good a city bridge, due to mostly medium and small span, and high aesthetic requirements, in order to make the bridge more harmonious with the surrounding environment, it is appropriate to add decoration.

2. Principles of Decorative Design of Urban Bridge In the external decoration of the urban bridge, generally should be guided by the following principles.

(a) Do not Decorate for the Sake of Decoration Modern bridge architectural decoration are not symbols of power, not a mark of wealth, not fake vulgar display, nor nostalgia retro-decadence, but socially positive spirit in the pursuit of the ideal, is the memory of history and culture and develop the successor, is an effort to establish social perfection. Modern bridge architectural design should be decorative, not ornamental, must be in the bridge coordinate functions on the basis of full consideration of its practical value, taking into account their artistry, building society and nature, and harmony, in order to improve the people’s quality of life, to contribute to the promotion of social progress.

(b) The Green Decoration and Economic Constraints Modern bridge architectural design should promote “green” principles, namely natural priority, people-oriented, optimization of landscape as a whole, conservation of resources and energy. Under the economic conditions, and at a minimum cost, maximum results are achieved.

(c) Decorative Symbols Decorative performance will inevitably affect people’s mental, and influence is limited by people understanding, so people understand are important restrictions of decorative design, decoration design creations, using those for the public to understand and familiar symbols, more capacity easy to be accepted and loved. Meanwhile, giving new meaning to the old symbols, thus allowing it to update and develop.

(d) Regional and Democracy Modern bridge architectural design must pay attention to ethnic and regional characteristics, correctly reflect the national style and local characteristics.

(e) Harmony Between Features and the Environment, Unity of Variability and Integration Bridge design and decoration should be distinctive, but restricted its features should be in harmony with the environment, and the environment, interrelation. “Highlighting” is the decoration makes bridge-building image is reinforced, prominent in the environment; “ Tumor suppressor” is a decorative bridges beam fusion of architecture and environment. Fusion is divided into two categories: assimilation or comparison, the former is a common integration with the environment, directly integrated in environment which is integration with the environment, namely, self-expression, and environmental interdependence, formed an indivisible whole. Change and unity, including changes in individual and groups of unity and change and unity, which refers to the partial and whole relationship is the unity of different local treatment method in the overall unity of style, whereas the latter refers to groups of individuals and groups in relation, it is unification of multiple individual style.

(f) Tradition and Modernity Modern bridge architectural design should consider how to express a cultural tradition with modern technologies and materials; how to use traditional technologies art adapted to modern bridge architectural features, reflecting the modern life. Key is to find the combination of tradition and modernity, to find the true genus in China the national decorative design, and which conforms to the spirit of modern society.

(g) Simplicity and Luxury Different Zeitgeist created a different style of architectural decoration, luxury, rule was once a period of ancient popular décor modern bridge design with simple, slender style as tone, the decorative style is predominantly minimalist. Simplicity is not simply in form, but also refers to outside of the component containing a common understanding, characterised by free imagination of uncertainty, so as to expand the connotation of the decorative and value. Even in specific cases, and require luxury decorating design style nor should be simple and rustic, and when should be given in accordance with spiritual connotations.

(h) Strictly Control and Raise the Standard Bar Modern bridge architectural design decorative items should be tightly controlled and content, should not pretentious and banal, not to thick made, high standard of design and decoration should be conducted and decorated with exquisite craft.

3. Functionality of Decorative Design of Urban Bridge Bridge decoration is a secondary part of bridge attached to bridge body to participate in and strengthen the bridge landscape, while also can also have a bit of accessibility, as reflected in:

(a) Decoration on the Main Structure of the Bridge has a Protective Effect Such as: surface paint rust-proof steel surface coating and finishes can prevent rain water and poisonous gases on the corrosion of concrete flowers engineered stone veneer of Pier and abutment can prevent water, mud, ice, erosion and so on.

(b) Decorations can make up for Local Defects in Bridges of body Image For example: bridgehead buildings make up the bridge the monotonous level image; honeycomb, pockmarked face, templates, seam, reinforced gel top concrete tables unavoidable construction defects can be covered through shows that decoration, so that they could with a beautiful image like this in front of other people.

(c) Decorations can be used to Adjust the Bridge body Proportions, Scale For example: use shadow or painted in different shades of colour change too much height or physical area of visual perception and week surrounding environment of colour can be adjusted to its sense of scale, and so on.

(d) Decoration can be used as “Visual exchange point” has Weakened the Role of Bridge and Bridge Differences Example: difference between great bridge and bridge joints easily shaped points, destroying smoothly and continuously, built on the main bridge and bridge approach between the bridgeheads, move horizontally so that people’s attention is transformed into vertical movement, weakening the main and bridge the differences.

(e) Decorative Sign Recognition Function, Become the image of Cities or Regions on Behalf of Road or Bridge, “Critical” Sign Bridge structural limitations restrict the morphological changes of bridge-building, by crafting decorations, so that people can clearly know bridges, discriminating bridge terminal, mood in favour of regulating traffic and traffic safety. Such as the Wuhan Yangtze River Bridge, South beijing Yangtze River bridgehead of different shapes have become recognized Bridge as well as the city’s symbol.

(f) Decoration can Build Shelter Space Environment Bridge gallery building not only the characteristic shape of the bridge was constructed, and providing the actual service function for pedestrians and to prevent water intrusion erodes wooden beams.

(g) Bridges can be Beautified to the Spirit Realm by Decoration The Pont Alexandre III, represented on the two columns on the left bank of the Renaissance period and Louis 14 France logo, right france signs on two pillars on the right bank have symbolic sign of ancient Italy and modern French. At both ends of the bridge entrance to the post respectively, features the Seine and moral of the decorations of the Neva river, a symbol of the former Russia and France between friendship.

(h) Decorating can Extend and Strengthen the Bridge Space and time Exhibition and Beautify the Bight Environment Like bridge landscape lighting at night, not only make it night or day, you can enjoy the artistic image of the bridge, and improved the city image of the city, showing social progress, improve people’s lives.

8.5 CONCEPTUAL DESIGN OF URBAN BRIDGE— STRUCTURE ENGINEERING IN COMBINATION WITH ARCHITECTURAL AESTHETICS United Kingdom architect bulaien·laosen monograph in design thinking, the authors summarised the design model as shown in Fig. 8.31. In his view, design is a process of discovering, analysing and solving problems, and from design issues to resolve path to the programme, requiring analysis, synthesis, evaluation of complex intertwined with the process of thought.

Fig. 8.31 The design process. We know that design goal is rarely a single design problem in the majority of cases with multiple and interacting. United States architect Philip Johnson (Philip Johnson) has found that: some people think some chairs are beautiful, it is because it is comfortable to sit while others thought, chairs were comfortable, it is because they look very pretty. In this light, both visual and ergonomic chair design is very important. Geometry of a chair leg and making way to express definitely not just spatial problems, it also has to meet the following requirements: it must be stable and have a certain bearing force it wants to ensure the chair stacking chair legs can bite each other; it requires the designer to chair the overall vision on the vision. Designer a chair cannot be stacked and visual stability, support, and other issues considered separately, because all these account problems must be resolved through the same programme at the same time. In addition, designers have to consider many other common sense issues, such as the construction costs, the practicality of manufacturing technology, materials, finished products and durability of the node, and so on. Therefore, in the design, it is often necessary to a comprehensive solution to meet all your requirements. Then the natural consequence is that being a “good design”, you will comprehensive reflection of all the problem; to make a “good designers”, they must possess the ability to integrate and digest. All attempts to define the design process as a set of logical operations concluded, there are all kinds of lack of can’t tell you what steps a city bridge design through, how to do it. However, through some study, we find: urban design bridge is in some sense, is the creative application of structural engineering and the construction of aesthetic ideas, two thought mastery, to guide us through the design.

REFERENCES [1] Martin Pearce, Lichade Qiaobusen. Bridge Construction. Dalian: Dalian University of Technology Press, 2003. [2] Wanghuiping. Discussion on Treatment of City River Bridgescape/territory/in Proceedings of the 17th National Conference on Bridges. Beijing: People’s China Communications Press, 2006. [3] Wang Xiaolan. Interpretation of Architectural Culture in Books—Bridge. Beijing: China Renmin University Press, 2007. [4] Wang Yingliang, Gao Zongyu. Bridge Design in Europe and America. Beijing: China Railway Publishing House, 2008. [5] Bulaien·laosen. Design thinking. Beijing: China Waterpower Press, 2007. [6] Chen Airong, Cheng Yong, Qian feng. Bridge Design. Beijing: People’s Communications Press, 2005. [7] Teng Jiajun, Shen Ping. Modern bridge Architectural Design. Beijing: People’s Communications Press, 2008. [8] T. Y. Lin. Concept and System Structure. Gao Liren, Translated. Beijing: China Architecture and Building Press, 1999. [9] Yin Delan. Deng, and bridge—China article. Beijing: Tsinghua University Press, 2006. [10] World Architecture, 2009.

INDEX A Aerodynamic measures 258, 272 Aerodynamic testing 192 Aesthetic design 76 Air curtain 151 Alkali-aggregate reaction 493 Amplitude 264, 268 Analytical method 341, 472 Anchor group 11 Anisotropic 465 Anti-collision facilities 297 Anti-seismic design 19 Anti-seismic tower 14 Arch bridge 126, 216, 314, 318 Arch system 337 Asphalt concrete pavement 30 Asymmetric arrangement 82 Auto pneumatic caisson 153 Auxiliary pier 84 Axle vibration model 20

B Backwards analysis 16 Bar stable formula 19 Beam end corner 111 Bedrock 241 Bell foundation 159 Bending moment 380 Bending stiffness 338 Bending torque 324 Bound voyage 121 Boundary conditions 382, 390 Breakthrough 223 Bridge construction 47 Bridge design 224 Bridge pylon 86 Bridge scheme 188 Bridge seismic damage 275 Bridge span 108 Bridge tunnel 193 Bridge-axis 114

Brooklyn bridge 4

C Cable 239 Cable casing system 26 Cable construction line 335 Cable plane 88 Cable pylon 404 Cable stayed bridge 193 Cable tower model 304 Cables vibration control 269 Cable-stayed 289 Cable-stayed bridge 26, 27, 72, 81, 132, 140, 161, 236, 313, 327, 464 Cable-stayed suspension bridge 137 Caisson 144, 150 Caisson foundation 145 Cantilever casting method 15 Capital investment 179 Carbon fiber 13 Cast in situ 349 Channel high level 293 Circular caisson 229 Collision avoidance 39 Column base 153 Composite 306 Composite cable-stayed bridge 394 Composite design 374 Composite foundation 29, 156 Composite girder 200 Concept design 188, 353 Conceptual design 54, 55 Conceptual design phase 380 Concrete cover 422 Concrete pylon 173 Consolidation 241 Constant load 333 Constant load + live load 333 Construction preparation 344 Construction technology 141 Continuous girder 128, 322 Continuous girder bridge 349 Continuous rigid frame bridge 247 Continuous wall 151 Controlled permeability formwork 449 Corrosion 421 Corrosion resistant steel 454

Corrosion-resistant 454 Cracking resistance 458 Creep 401 Creep co-efficient 400 Creep effects 348 Critical loads 341 Critical wind speed 265

D Damper device 33 Damping force 394 Dead load 383 Deck 245 Deck system 317 Deck-bearing type movable 446 Deflection theory 4 Derricks stiffness 337 Design concept 48, 304 Design earthquake 202 Design parameters 331 Design problems 222 Disaster prevention design 252 Discretization 380 Double spherical aseismic bearing 286 Double-wall steel cofferdam 154 Drawbridge 190 Drilling-and-blasting 150 Dual-tower cable stayed bridge 194 Durability 465 Durability of concrete 300 Durability problem 20 Durable materials 307 Dywidag anchor 11

E Earthquake damage 275 Earthquakes 102, 273 East huntington bridge 86 Elastic sliding bearing 285 Elastic supports 319 Energy dissipation 297 Energy dissipation system 285 Expansion joints 278

F Facade 82

Fatigue resistance 465 Fiber cloth 462 Fiber grating sensor 451 Fiber reinforced concrete 209, 210, 458 Fiber reinforced polymer 460 Finite difference method 373 Finite element analysis 18, 380 Finite element method 373, 466 Flexible structures 278 Floating protective system 297, 298 Flutter control 269 Footbridge 5 Force base 317 Force-bearing structure 69 Freedom of navigation 121 Freezing and thawing 493 Friction pendulum bearings 286 FRP resin material 465

G Gantry tower 202 Geological exploration 45 Geology 98 Geometric characteristics 380 Geometric description 380 Girder bridge 169 Girder foundation 319 Global positioning system 451 Glue bamboo template 449 Glulam template 448 Grating sensors 451

H Height-span ratio 135 High performance concrete 11, 456 High performance steel 11, 163, 452 High strength steel 209, 452 Hingeless arch 339 Horizontal alignment 115 Hot extrusion PE sleeve 424 Hydrogeological conditions 156

I Impact anchorages 291 Impact force 293 In situ method 347

Incremental launching 208 Incremental launching construction method 208 Inland navigation standard 119 Innovation 70 Intelligent monitoring devices 52 Iterative calculation 466

J Jib crane 440

K Knot frame stiffness 302 Knowledge economy 53

L Laminated rubber bearing 284 Landscape architects 113 Landscape effect 334 Large-span cable-stayed bridge 315 Laser technology 451 Lateral movement 345 Launching construction method 351 Limit states 374 Live load 108, 110, 333, 383 Live load deflection 197 Lock-coil 11 Longitudinal and lateral movement 238 Longitudinal stiffness 110, 401 Low tower cable-stayed 140 Lower deck 219

M Main beam girder 88 Mass damper passive control 20 Master girder 239 Maximum amplitude 273 Middle deck 219 Mid-span deflection 375 Mineral composition 98 Modulus of elasticity 463 Monitoring technology 468 Mounting rack technology 334 Movable frame construction 447 Multi-tower cable-stayed bridge 313

N

Natural conditions 91 Natural frequency 268 Natural science foundation 52 Natural vibration 418 Navigable holes 80 Navigation bridge 38 Navigation requirements 290 Neural network control technology 30 Non-linear materials 381 Non-linear problem 466 Numerical analysis 373, 472

O Open caisson 146, 174, 175 Overturning moment 327

P Parabolic steel arches 244 Parallel wire beam 263 Parametric oscillation 418 Pedestrian bridges 492 PHC pipe pile 148 Pier 239 Pier bearing platform 297 Pier foundation 32 Piers 260 Pile bent diaphragm 161 Pile foundation 148 Pile hammer equipment 148 Piles 144 Pneumatic caisson 151 Pneumatic controls 272 Post-tensioned cable-system 241 Post-tensioned pre-stressing steel 242 Post-tensioning prestressed concrete 200 Pre-cast 156 Pre-cast hoisting 435 Precise geometry control 33 Pre-fabricated base 156 Pre-fabricated units 211 Pre-fabrication 306 Pre-stressed concrete 350, 396 Pre-stressed concrete beam 359 Pre-stressed concrete girder 302 Pre-stressed plate 400 Proportional beauty 68

Pylon 140 Pylon foundations 229

Q Quenching and tempering 453

R Rain-wind induced vibration 268 Rebar connecting 413 Redundant design 305 Reinforced concrete 462 Reinforced earth 159 Relative displacements 278 Resonance 268, 418 Richter scale 202 Rigid frame bridge 128, 394 Rigid-frame structure 324 Rigidly connected 326 River bed 92 River regime 91 River regime analysis 234 Road construction 90 Rubber bearing 390 Rubber damper 272

S Scaffolding 182 Seamless connectivity 320 Secondary pier 197 Sediment conditions 92 Segmental assembly 436 Seismic intensity 103 Seismic performance 317 Self-anchored 467 Self-anchored suspension bridge 138 Self-compacting concrete 457 Semi-active 269 Semi-active damper 269 Sensor signals 468 Service life 309 Shantou bay bridge 27 Shear key 326, 327 Shear plate 419 Shield protection system 298 Ship collision 144 Ship collision force 289

Ship domain theory 120 Ship-colliding fortification 287 Shrinkage 401 Sink box 144 Soft soil 316, 371 Soil sinks 174 Space truss 241 Special conditions 246 Split box deck 14 Standard gauge 108 Static response 380 Steel box girder 169 Steel deck 13 Steel pylon 228 Steel truss composite beams 201 Steel truss girder 241 Steel-concrete composite girder 195 Stiffening girder 200 Strong column-weak beam 454 Structural durability measures 309 Structural features 252 Structural seismic control 454 Structure analysis 373 Structure bearing 347 Structure durability 299 Stud connection 412 Studs enough 412 Super long span cable-supported bridge 329 Suspender cables 319 Suspension 87 Suspension bridge 81, 133, 27, 42, 44, 289

T Technical innovation 90, 223 Technological innovation 141 Technology 306 Tectonic movement 160 Tectonic stress 273 Tensile strength 458 Terrain conditions 87 Tied arch bridge 2 Torsional stiffness 380 Tower anchorage 196 Tower elastic fixation 233 Transient deformation 394 Triaxial compressive stress 407

Truss component 380 Twin towers 233 Two-tier structure 219

U Ultra high performance concrete 457 Ultrafine admixtures 458 Upper deck 219

V Vertical alignments 115 Vertical deflection 110 Viaducts 436 Vibration control 269, 394 Virtual digital world 467 Virtual reality 52 Viscous damper 394 Vortex frequency 268 Vortex-excited resonance 268 Vortex-induced vibration 264, 418 Vortex-induced vibration control 272

W Warping 142 Water anchorage 32 Water level 94 Wind characteristics 254 Wind induced disasters 256 Wind load 198, 383 Wind resistance 225 Wind stability 88 Wind tunnel testing 226 Wind vortex 135 Wind-induced vibration 225, 264 Wind-resistance 253, 257

Y Yield strength 413, 453