Construction and Design of Prestressed Concrete Segmental Bridges

Construction and Design

of Prestressed Concrete Segmental Bridges

Walter Podolny, Jr., Ph.D., P.E. Bridgc Division

()Hicc Ellgineering

h'dcr;ti II iglll\'d Y :\d millisl ratioll

L' .S. Depart illenl 01 Tr;lIls[Jortalioll

or

Jean M. Muller (:llaillll;11I (lilhe Board

Figg alld ),[uJkr Ellgincers, [Ill.

BR1T"

LEM".

-9 AUG 1982 82/19656

A Wiley-Intersdence Publication

John Wiley & Sons

New York

Chichester

Brisbane

Toronto

Singapore

Copyright

©

1982 by john Wiley & Sons, Inc.

All rights reserved. Published simuhaneollsly in Canada. Reproduction or translation of any part of this work beyond that permitted by Section 107 or 108 of the 1976 United States Copyright Act without the permission of the copyright owner is unlawful. Requests for permission or further information should be addressed to the Permissions Department. john Wilt·)' & Sons, Inc Library of Congress Cataloging in Publication Data:

Podoln)', Walter. Construction and design of prestressed concrete segmental bridges. (Wiley series of practical construction guides ISSN 0271-6011) "A Wiley-Interscience publication." Includes index. I. Bridges, Concrete-Design and construction. 2. Prestressed concrete construction. I. Muller, jean M. II. Title. III. Series. 81-13025 AACR2

TG355.P63 624.2 ISBN 0·471-05658-8

Printed in the United States of America 10 9

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Series Preface

The Wiley Series of Practical Construction Guides provides the working constructor with up-to-date information that can help to increase the job profit margin. These guidebooks. which are scaled mainly for practice, but include the necessary theory and design. should aid a construction con­ tractor in approaching I\ork problems I\'it h more knowledgeable confidence, The guides should be useful also to engineers. architects. planners. specification writers. project managers, superin­ tendents, materials and equipment manufacturers and, the source of all these callings, instructors and their students. Construction in the United States alone will reach $250 billion a year in the early I980s. In all nations, the business of building will continue to grow at a phenomenal rate, because the population proliferation demands !1('I\ living. I\'orking. and recreational facilities. This construction will have to be more substantial. thus demanding a more

professional performance from the contractor. Be­ fore science and technology had seriously affected the ideas, job plans, financing, and erection of structures, most contractors developed their know-how by field trial-and-error. Wheels, small and large, were constantly being reinvented in all St'C(ors. bccause there ,\as no interchange of knmdedge. The current complexity of cOlIStru{'­ tion. even in more rural areas, has revealed a dear need for more proficient. professional methods and tools in both practice and learning, Because construction is highly competitive. sOllle practical technologv is necessarily proprietary. BUI most practical day-to-day problems are common to the whole construction industry. These are the subjects for the Wiley Practical Construction Guides.

M. D.

MORRIS.

P.E.

v

Preface

Prestressed concrete segmental bridge construc­ tion has evolved, in the natural course of events, from the combining of the concepts of prestress­ ing, box girder design, and the cantilever method of bridge construction. It arose from a need to Qvercoml: construnion difficulties in spalIning deep valleys and river crossmgs without the use of conventional falsework, which in some instances may be impractical, economically prohibitive, or detrimental to environment and ecology. Contemporary prestressed, box girder, seg­ mental bridges began in Western Europe in the 1950s. Ulrich Finsterwalder in 1950, for a cross­ ing of the Lahn River in Balduinstein, Germany, was the first to apply cast-in-place segmental con­ struction to a bridge. In 1962 in France the first application of precast. segmental, box girder COll­ struction was made by Jean Muller to the Choisy­ Le-Roi Bridge crossing the Seine River. Since then the concept of segmental bridge construction has been improved and rdined and has spread from Europe throughout most of the world. The first application of segmental bridge con­ struction in North America was a cast-in-place segmental bridge on the Laurentian Autoroute near Ste..\dele. Qllebec. in 1964. This was fol­ lowed in 1967 by a precast segmental bridge cross­ ing the Lievre River near ~otre Dame du Laus, Quebec. In 1973 the first U.S. precast segmental bridge was ope lied to traffic in Corpus Christi. Texas, followed a year later by the cast-in-place segmental Pine Valley Bridge near San Diego, California. As of this date (1981) in the United States more than eighty segmental bridges are completed, in construction, in design, or under consideration. Prestressed concrete segmental bridges may be identified as precast or cast in place and cat­ egorized by method of construction as balanced cantilever, span-by-span, progressive placement, or incremental launching. This type of bridge has

extended the practical and competitive economic span range of concrete bridges. It is adaptable to almost any conceivable site condition. The objective of this book is to summarize in one volume the current state of the art of design and constrllction methods for all I ypc,; of segmelHal bridges as a ready reference source for ellgillcer­ ing faculties, practicing engineers, contractors, and local, state, and federal bridge engineers. Chapter I is a quick review of the historical evo­ lution to the current state of the art. It bITers the student an appreciation of the way in which seg­ mental construction of bridges developed, thc factors that influenced its development, and the various techniques used in constructing segmental bridges. Chapters 2 and 3 present case ,tudies of the pre­ dominant methodology oi constructing segmental bridges by balanced cantilever in both cast-in-place and precast concrete. Conception and design of the superstructure and piers, respectively, are dis­ cussed in Chapters 4 and 5. The other three ba­ sic methods of constructing segmental bridges­ progressive placement, span-by-span, and incre­ mental launching-are presented in Chapters 6 and i. Chapters 2 through i deal essentially with girder type bridges. However, segmental construction may also be applied to bridges of other types. Chaprer 8 discusses application of thc segmcntal concept to arch, rigid frame, and truss bridges. Chapter 9 deals with the cable-stayed type of bridge and Chapter 10 with railroad bridges. The practical aspects of fabrication, handling, and erection of segments are discussed in Chapter II. In selected a bridge type for a particular site, one of the more important parameters is economics. Economics, competitive bidding, and contractual aspects of segmental construction are discussed in Chapter 12. Most of the material presented in this book is not

vii

-

viii

Preface

original. Although acknowledgment of all the many sources is not possible, full credit is given wherever the specific source can be identified. Every effort has been made to eliminate errors; the authors will appreciate notification from the reader of any that remain. The authors are indebted to numerous publica­ tions, organizations, and individuals for their assistance and permission to reproduce photo­

.."iiliiI........... __•_ _ _ _ _ _ ---·--­

graphs, tables. and other data. Wherever possible. credit is given in the text. WALTER PODOLNY, JR. JEAN M. MULLER

Burkt, 1'h-~i1/i(J

Pans, France january 1982

Contents 1 Prestressed Concrete Bridges and Segmental Construction 1.1 1.2 1.3

1,4 1.5

1.6 1.7 1.8 1.9 1.10

1.11

1

Introduction, 1

Development of Cantilever Construction, 2

Evolution ()f Prestressed Concrete, 4

Evolution of Prestressed Concrete Bridges, 5

Long-Span Bridges with Conventional Precast Girders. R Segmental Construction, 10

Various Types of Structures, 12

Cast-in-Place and Precast Seg-mental Construction, 17

Various \Ici hods of Construction, 18 Applications of Segmental Construction in the Cnited States, 26 Applicability and Advantages of Segmental Construction, 28 References, 30

2.8 2.9 2.10 2.11 2.12 ~,

13

2.14 2.15 2.lG

3 Precast BaLanced Cantilever Girder Bridges :U 3,2

:5.3 3.-1: :~,5

2 Cast-In-Place Balanced Cantilever Girder Bridges Introduction, ~~ 1 Bendorf Bridge, German" 35 Saint Adele Bridge, Canada, 37 BOllguen Bridge in Brest and Llcroix Falgarde Bridge, France, 38 2.5 Saint Jean Bridge over the Garonne River at Bordeaux, France. 41 2.6 Siegtal and Kochertal Bridges. Germany, 43 2.7 Pine Valley Creek Bridge, U.S.A.,46

2.1 2,2 2.3 2,4

Gennevilliers Bridge, France, 52

Grand';"'fere Bridge, Canada, 55

Arnhem Bridge, Holland, 58

:-';apa River Bridge, C.S.A., 59

Koror-Babelthuap, C.S. Pacific Trust Territon', 61

Vejle \'jord Bridge, Denmark, 63

Houston Ship Channel Bridge, C.s.A.,68 Other ~otable Structures, 71

Conclusion, 81

References, 81

J.b

31

;~,7

:L8

:t9 3.1 () ;) .11

:U2 3.13 3.14 3.15 3.16

82

I III roclllU iOIl , 82

Choisy Le Roi Bridge and Other

Structures in Greater Paris,

France, 83

Pierre Benite Bridges near Lyons,

France, 89

Other Precast Segmental Bridges

in Paris, 91

Oleron Viaduct, France, 96

Chillon Viaduct, Switzerland, 99

Hartel Bridge, Holland, 103

Rio-~iteroi Bridge, Brazil, 106

Bear River Bridge, Canada, 108

J FK ;"'lell1orial Cause\\ay,

U.S.A., 109

Saint Andre de Cubzac Bridges,

France. 113

Saint Cloud Bridge, France, 114

Sallingsund Bridge,

Denmark, 122

B-3 South Viaducts, France, 124

Alpine ~Iotorway Structures,

France, 129

Bridge over the Eastern Scheidt,

Holland, 134

IX

Contents

x

3.17 3.18

4 Design of Segmental Bridges 4.1 4.2 4.3 4.4 4.5 4.6

4.7 4.8

4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19

5.4

5.6 5.7

Introduction, 225 Loads Applied to the Piers, 230 Suggestions on Aesthetics of Piers and Abutments, 232 Moment-Resisting Piers and Their Foundations, 234

........ iI' ...._ .. _._._ _ _ _ _ _

~.--~

-------­

5.8 5.9

148

Introduction, 148 Live Load Requirements, 149 Span Arrangement and Related Principle of Construction, 149 Deck Expansion, Hinges, and Continuity, 151 Type, Shape and Dimensions of the Superstructure, 159 Transverse Distribution of Loads Between Box Girders in ~1ultibox Girders, 164 Effect of Temperature Gradients in Bridge Superstructures, 170 Design of Longitudinal Members for Flexure and Tendon Profiles, 173 Ultimate Bending Capacity of Longitudinal Members, 190 Shear and Design of Cross Section. 193 Joints Between Match-Cast Segments, 199 Design of Superstructure Cross Section, 202 Special Problems in Superstructure Design, 203 DeAections of Cantilever Bridges and Camber Design, 205 Fatigue in Segmental Bridges, 210 Provisions for Future Prestressing, 212 Design Example, 212 Quantities of Materials, 219 Potential Problem Areas, 220 References, 224

5 Foundations, Piers, and Abutments 5.1 5.2 5.3

5.5

Captain Cook Bridge, Australia, 136 Other Notable Structures, 139 References, 147

6

Progressive and Span-by-Span Construction of Segmental Bridges 6.1 6.2 6.3 6.4 6.5 6.6

7

7.5 7.G 7.7 7.8 7.9 7.10

225

8.3 8.4 8.5 8.6

321

Illlrodunioll.321 Rio Carolli, Venezuela, 323 Val Resle! Viaduct, Italy, 327 Ravensbosch Valley Bridge. Holland, 329 Olifant's River Bridge, South Africa, 331 Various Bridges ill France. 333 Wabash River Bridge, U.S.A., 335 Other ~otable Bridges. 338 Design of Incrementall) Launched Bridge~. 34::1 Demolition of a Structure by Incremental La~nching, 352 References, 352

Concrete Segmental Arches, Rigid Frames, and Truss Bridges 8.1 8.2

281

Introduction, 281 Progressive Cast-i n- Place Bridges, 283 Progressive Precast Bridges, 289 Span-by-Span Cast-in-Place Bridges, 293 Span-by-Span Precast Bridges, 308 Design Aspects of Segmental Progressive Const ruction, 314 References, 319

Incrementally Launched Bridges 7.1 7.2 7.3 7.4

8

Piers with Double Elastomeric Bearings, 241 Piers with Twin Flexible Legs, 253 Flexible Piers and Their Stability During Construction, 263 Abutments. 271 Effect of Differential Settlements on Continuous Decks, 276 References, 280

Introduction, 354 Segmental Precast Bridges over the Marne River, France, 357 Caracas Viaducts, Venezuela, 363 Gladesville Bridge, Australia, 371 Arches Built in Cantilever, 374 Rigid Frame Bridges, 382

354

xi

Contents

8.7

9 Concrete Segmental Cable-Stayed Bridges 9.1

9.2 9.3 9.1

9.5 9.6 9.7 9.8 9,9

11

Truss Bridges, 392 References. 399

Technology and Construction of Segmental Bridges Il.l 11.2

400

Introuuction,400 Lake Maracaibo Bridge, Venezuela. 405 Wadi Kuf Bridge, Libya. 407 Chaco/Corrientes Bridge, Argentina, 408 \lainbrticke, GermallV, 410 Tiel Bridge. ~etherlands. 412 Pasco-Kennewick Bridge. C.S.A., 418 BrolOnne Bridge, France. 41!:l Dalluhe Canal Bridge,

11.3 11.1

11.5

11.6 11.7

:\ll~lri;l, '1~7

9.10

10

~()table

Examples of Concepls, 4:W Referellces, 439

Segmental Railway Bridges Illtl'OdllUioll 10 Panicubr :\spects of Rail\Va~ Bridges and Field of Applicatioll, 441 IO,':! La VOlllte Bridge over the Rholle Ri\'('l'. Frallct'. 4·12 10.:l \Ior:llld Bridge III L\om, Frallce,442 IO,,! Cerg\ POlltoise Bridge Ileal' ":Iris, Frallce, ·'·H 10,5 :-'!allle La Vallee and Torn Bridges for the ~e\V Express Lille lIeal' Paris, Fl'allce, 444 !(Ui Clichy Bridge Ileal' Paris, Frallce, ·l!q 10.7 Oidaill's Bridge, SOllth :\frica, '1:)2 1O.H [ncremental" Lallllched R;lil\\';!\ Bri( for the High-Speed Line, Paris to Lmlls, France, 45:~ 10.9 Segll1ental Raih,'av Brid~es ill Japall,457 to, 1() Special Oe'iign A~ peets of Segmenral Railwav Bridges, 458 10.11 Proposed Concepts for Future Segmental Railwav Bridges, 404

11.8

441

12

IO.l

l~.l

12,,~

13

Scope and Introduction. 465 Concrete and Formwork for Segmental Construction. 466 Post-tensioning Materials and Operations, 470 Segment Fabrication for Cast-In-Place Cantilever Construction, 475 Characteristics of Precast Segmellts and \Iatch-Cast Epoxy Joints. 485 \1anufacture of Precast Segments, 493 Handling and Temporan :\ssclllhh of Preca,1 Segments, 507 Placing Precast Segments, 50!} References. 517

Economics and Contractual Aspects of Segmental Construction 12.2

1:3.4 LL")

13,6

Index Index Index Index

518

Bidding Procedures, 518 Exam pies of Some Interest illg Biddillgs alld Costs, 523 j lit I CI,C ill EITlticll(\ ill Concrete Bridge~, 528 References, 535

Future Trends and Developments

1:3.1 1:),2 1:3,:~

465

536

Introductiol1,536 ~!aterials, 536 Segmental Application to Bridg;e Decks, 542 Se~l11enlal Bridge Piers and Substructures, 543 Application to Existing or :\ew Bridge I) pe~, ij·H Summary, 548 References, ;")49

of Bridges of Personal Names of Firms and Organizations of Subjects

551 555 557 559

1

Prestressed Concrete Bridges and Segmental Construction

1.1 1.2 1.3 1.4 1.5

INTRODUCTION DEVELOP!'v1ENT OF CANTILEVER CONSTRUCTION EVOLUTION OF PRESTRESSED CONCRETE EVOLUTION OF PRESTRESSED CONCRETE BRIDGES LONG-SPAN BRIDGES WITH CONVENTIONAL PRE­ CAST GIRDERS 1.6 SEGMENTAL CONSTRUCTION 1.7 VARIOUS TYPES OF STRUCTURES 1.7.1 Girder Bridges 1.7.2 TnJsses 1.7.3 Frarn(>, with Slant I.(>~, 1.7.4 Concrete Arch Bridges 1.7.5 Concrete Cable-Stayed Bridges 1.8 CAST-IN-PLACE AND PRECAST SEGMENTAL CON­ STRUCTION

1.1

Introduction

The conception, development, and worldwide ac­ ceptance of seglllental c()n~trllcti()n in till' field or prestressed concrele bridges represents one 01 the most intere~ting and illlport;lIlt achievelllents in civil engineering durillg the past thirtv \ears. Rec­ ognized toeyolJ(l 1he reach of Sce GlIltile\'cr are often two or three times those of the same camilever made of precast segments. The local effects of concentrated forces behind the anchors of prestress tendons ill a young con­ crete (two or four days old) are always a potential source of concern and difficulties, /.8.2

FIGURE 1.42.

Ihotollllt' Bridge. Frallct',

and ecolloll1iGlI ill balallced calltilevel' with a larg-e nUlllber of sta\'s 1IIlifol'lllh' di~tril)ljted ;dollg- the deck. Fig-ure IAI, I'lIe long-cst 'ipall or this type is the Brotolllle Bridge ill Fraw" with a 10;)0 It ctW 01) dear Illaill'ip,lll mer the Seille River. Figlll'(' 1.42, Single In lOllS alld olle lillc of Sla\s :IIT iOCllCd along the centl'rlllll' 01 !Ill' hl'ld;..il',

1.8

1,8,1

Cast-in-Place and Precast Segmental C()ns/ruction Cfl,W, ! CT/JUS TICS OF L1SI',/\',/JI..I1 h \\,;IS ollh 5.~) It (I.S m) for Ihe cle;n' 275 l't (S:l.S 111) sp;ln ;lIHI4.S It (1.-+7111) for the clear 21-+

fI (G5.3 111) span. ll1aking both structures very slen­ der. Figures 't.l0l alld 2.102. StitT "V" piers in both structures help reduce the flexibility of the deck. 2.15.11

TRIC/SnV RRII)(;E, FR. LVCt:

This structure spam the Rhone River with no piers in the river, which necessitates a long center span and two yerv short side spans anchored at bOlh ends against uplift. The center portion of the main span is of lightweight concrete, while the two zones over the piers where stresses are high are of con­ ventional concrete, Figures 2.103 and 2.104. 2.15.12

FIGURE 2.88.

Puente del Azufre. Spain.

ESCH-ICHTAL BRlDGE, GERMANY

This bridge is located near Stuttgart, Germam'. The superstructure consists of a large single-cell box girder with large top flange cantilevers sup­ ported by precast struts. Because of the weight in­ volved, the central box was cast in one operation; struts were installed and flanges cast subsequently, Figures 2.105 and 2.106.

..

TO WINDSOR

TO TRURO

"EST

--­ ----------------­ --' 'I EXISTING RIVER SOTTOM

Elevation

It.

I

I 1

I~

, I

11:5

Section at Midspan

Section over Piers

FIGURE 2.89.

Shubcllacadic

Brid~e,

FIGURE 2.90. Shubenacadie Bddge, support system for unbalanced cantilever moment at pier (courtesy of the Portland Cement Association),

74

de\, '" ~

14"

';::

12" Cross Section

FIGURE 2.95.

Kipapa Stream Bridge. elevatioll and cross section.

FIGURE 2.96. Kipapa Stream Bridge, construction view (courtesy of Dyckerhoff & Widmann).

5

FIGURE 2.97. Ferry Bridge, ref. 17,

Parrots dimensions,

COUPE (!)

LONGITUDINALE

0)

FIGURE 2.98.

(!J

I..f AAllLOH

:-­

~Iagnan

Viaduct, \Ol1giludill,d ;,enioll.

FIGURE 2.99.

:\[agnan ViaduC[, view of a cantilever.

FIGURE 2.100. :-"Iagnan Viaduct, aerial view of [he completed bridge.

ii

...

FIGURE 2.101.

Putcaux Bridge, aerial "iew of the completed bridge.

COUPE LONGITUDIIILE

P2

Ct

C4

P3

i

---~.--

i

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J.

-----~ --------~--

II...

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IJU.."

".

/_1 /

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2 . . . , US

...........

nu FIGURE 2.102.

78

Puteaux Bridge. longitudinal section.

PlRIII - PIll '1111

n

r

\ I

I i

203 DO 30.25

25.25

"~

(counes\, or lhe American

COf1cr('lC

InslillHc).

view of the final structure is shown in Figurcs 3.28 and 3.34. The Olcron Viaduct was thc first applicJtiolJ of the launching-gantry concept for placing segments in cantilever. Se\'craJ structures were later de­ siglled and huilt \\'ith the same construction method. \iention should be lIlade here of three special bridges: I. Blois Bridp,f min tlt(, Loir(' Hit'('r The princi­ pal dimensiolls are given in Figure 3.35. The superstructure box girders rest on the pier shafts through twin elastomeric bearings, which allow thermal expansion while prm'iding partial re­ straint for bcnding-moment transfer between deck and piers. Consequently, sa\'illgs are ohtained both in the deck and in the foundations. All segments were placed in the bridge wit h an improved ver­ sion of the launching gantry first designed for the Oleron Viad uct. High-strength steel and stays were used to provide minimum weight with a sat­ isfactory stillness during operations, Figure 3.36. High-strength bolt connections were used throughout to make the gantTv completely capable of dismantling and easily transportable to other construction sites.

2. Aramon Bridge over the Rhone River This was the next structure where the same gantry could be used, Figure 3.37. 3. Seudre Viaduct Located just a few miles south of Oleron over the Seudre River, this 3300 ft (1000 m) long viaduct was also of precast segmen­ tal construction and used the same launching gan­

Chillon Viaduct, Switzerland

99

CONTiNENT

OLERON

PIERS ON FOOTINGS

PIERS ON FOOTINGS

FIGURE 3.33.

Olcl'OlI Viaduct, program of work,

tn. The linished structure is shown in Figure 3.:HL Foundations foJ' the cellter spalls were built Illside sheet pile cofferdams in spite of verv swift tidal currents.

3.6

Twin rectangular slip-formed shafts were used for the piers. varying in height from 10 to 150 ft (3 to 45 m). Stability during construction was excel· lent and required little temporary bracing except between the slender walls to prevent elastic insta· bility.! With the exception of three piers in each

Chillon Viaduct, Switzerland

The 7251 ft (2210 111) long dual structures of the Chillon Viaduct are part of European Highwav E-2 and are located at the eastern end of Lake Geneva passing through an environmentallv sensitive area and very close to the famed Castle of Chillon, Fig­ ure 3.39. In addition, the structures have verv difficult geometrical constraints consisting of 3% grades, 6% superelevation, and tight-radius curves as low as 2500 ft (760 m). Each structure has 23 spans of 302 ft (92 m), 322 ft (98 m), or 341 ft (104 m). The variable spans allowed the viaduct to be fitted to the geology and topography, providing minimum impact on the scenic forest. The viaducts are divided bv expansion joints into five sections of an approximate length of 1500 ft (457 m),

FIGURE 3.34. bridge.

Oleron Viaduct, aerial view of finished

Precast Balanced Cantilever Girder Bridges

100

CD

ELEVATIOn - ELEVATION

9.100

9\00

PI

91,00

P?

P 3

61,50

p,

CI) (DUPE TfiAnSVERSALr CROSS SECTION

to

4~ 79

m at midspan

FIGURE 3.35.

Blois Bridge. elevation and t\'pical cross section,

\'iaduct, all piers are hinged at the top. The piers that are less than 72 ft (22 m) high are hinged at the base; taller piers are fixed at their base, being sufficiently flexible to absorb longitudinal move-

FIGURE 3.36. Blois Bridge, operating on the superstructure.

launching

ment of the superstructure. The superstructure consists of a single-cell rec­ tangular box with a cellular cantilever top flange, Figure 3.40, and with a depth varying from 18.5 ft

gantry

FIGURE 3.37.

Aramon Bridge, launching gantry.

Chillon Viaduct, Switzerland

FIGURE 3.38.

FIGURE 3.39.

Seudre Bridge, finished structure.

(5.64 m) at the longer-span piers to 7.2 ft (2.2 m) at midspan. Widths of top and bottom flange are re­ spectively 42.7 ft (13 m) and 16.4 ft (5 m). Dimen­ sions of the two typical cantilevers are noted in Figure g.41. :\laximum segmem weight was 88 tons (80 mIl. :\ cellular cantilever top Bange was used because the overall width of the top flange ex-

101

Chillon Viaduct, aerial vie\\'.

ceeded 40 ft (approx. 12 m) and the cantilever length was 13.15 ft (4 Ill). An altemative would have been to provide stiffening ribs as used in the Saint Andre de Cubzac Viaducts (Section 3.11) and the Sallingsund Bridge (Section 3.13). Segments were precast in a yard at one end of the structure with five casting machines, allowing

Over supports (a)

1300

1300

5.00

At mid-span (b)

FIGURE 3.40.

Chilion Viaduct, cross sections. (a) Over supports. (b) At midspan,

=

III

102

91

Hartel Bridge, Holland

103

Sections I, II, and V, conventional cast-in-place prestressed concrete box girders Sections III and IV, precast prestressed concrete segmental box girders Two steel bascule bridges.

FIGURE 3.42.

Chillon Viaduct, precasting yard.

an average production of 22 to 24 segments per week (see aerial view, Figure 3.42). Erection was by the conventional balanced can­ tilever method with a launching gantry designed to accommodate the bridge-deck geometry in terms of curve and variable superelevation. The overall length of the gantry was 400 ft (122 m) and the total weight 2,50 tons (230 mt). Special features of this gantry will be discussed in Chapter 11. Can­ tilever placing of precast segments is shown in Fig­ ure 3.43. This structure is truly an achievement of mod­ ern technology with emphasis upon the aesthetic and ecological aspects of design.

3.7

Hartel Bridge, Holland

The 1917 ft (584.5 m) long Hartel Bridge crosses a .canal in Rotterdam, Figllre 3.44, and consists of the following elements:

FIGURE 3.43. Chillon Viaduct, cantilever construc­ tion with launching gantry.

The original design contemplated that the total structure would be constructed as conventional cast-in-place box girders on falsework. Substitution at the contractor's request of cast-in-place seg­ mental construction by precast segmental con­ struction for sections III and IV saved the exten­ sive temporary pile foundation system necessary to avoid uneven settlement of false work because of initial soil conditions. The redesign proposed two single-cell rectangular box girders as opposed to one three-cell box girder, Figure 3.44, omitting the center portion of the bottom flange and providing thinner webs and a thicker bottom flange. In the segmental box girder design the climen­ sions of the deck slab are constant over the entire length, girder depth varies from 4.92 ft (1.5 m) to 17 ft (5.18 m), the webs have a constant thickness of 13.8 in. (0.35 m), and the bottom flange thickness varies from 10 in. (0.26 m) to 33 in. (0.85 m). Up to a depth of 9.35 ft (2.85 m) the segments have a length of 15.8 ft (4.8 m); over 9.3 ft (2.85 m) the length decreases to 12.3 ft (3.75 m). The vertical curvature of the bridge was made constant for the full length of sections III and IV by increasing the radius from 9842.,5 ft (3000 111) to J9,029 ft (,5800 m), which resulted in a repetition of eight times half the center span. This repetition justified precast segments. A long-line casting bed (see Chapter 11) was con­ structed on the centerline of the bridge box girders at ground level, Figure 3.45. Thus, a portal crane was able to transport the cast segments to the stor­ age area and also erect them in the superstructure, Figure 3.46. The end spans have three more seg­ ments than half the center span; these were sup­ ported on temporary falsework until all the pre­ stressing tendons were placed and stressed, Figure 3.46. The first segment cast was the pier segment; each of the remaining segments was then match­ cast against the precedi.ng segment. The pier seg­ ment was positioned on bearings on top of the pier, Figure 3.47, and the two adjoining segments were positioned (one after the other) and the joints glued with epoxy resin. Temporary high-tensile bars located on the top of the deck slab and in the bottom flange were stressed to prestress the three

Precast Balanced Cantilever Girder Bridges

104

._v ~

84.1

117.4

Elevation

I I r~

F

"• no

'"

I

I I

0

I

-

A

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FIGURE 3.44. Hartd Bridge. typical dimensions: c!('yatioll, cross sections of the origi­ nal design. noss sections of the redesign (coune,\" or Brice Bender, BV:\ISTS).

segments together. After the epoxy had hardened, the permanent tendons were placed and stressed. The two segments adjoining the pier segment were supported during erection on Hat jacks on the top

of the outside struts of a steel scaffolding bearing on the pier foundation. Thus, the flat jacks were used for adjustment of the segments to achieve proper geometry control. The remaining segments were

FIGURE 3.45. Hanel Bridge. method of casting segments (courtesy of Brice Bender, BVN/STS.

Hartel Bridge, Holland

FIGURE 3.48.

FIGURE 3.46. dling segments.

105

Hartel Bridge, completed structure.

Hartel Bridge, portal crane for han­

erccted in thc cOT1\'enlional balanced Glnlilever met hod. Thc cOl11pleted struclurc is shown in Fig­ ure 3.4H. Othcr slructures using prccast scgmental con­ strllction wcre suhscquentl\' designcd and built in the \iclhcrlands. Shown in Figurc 3.49 is the Ilridgc o\'cr the ljssel at Deventcr, where segments in thc 2·n It (74 111) SP;Il1S were placed with a launching gallln. The overall Icngth of the gantry was S2() ft (i:')ti 111), allowing the legs to bear on the permanent concrete piers and impose no loading on the deck during construction. Figure 3.50 .

FIGURE 3.49. Dnenler Bridge, \\'ith the launching gantry.

. . . . --f--..--._-.. ---f

.___._____._%_n__ n_______ :~~[

FIGURE 3.47. Hartel Bridge, erection sequence and detail of tempo­ ran- pier bracing (courtesy of Brice Bender, BVN/STS).

placing segments

106

Precast Balanced Cantilever Girder Bridges 156 m (520 It)

74 m

ttl

Max bridge span 74 m (247 ttl

FIGURE 3.50.

Deventer Bridge. elevation of gantry.

3.8 Rio·Niteroi Bridge, Brazil The Rio-Niteroi Bridge crosses the Guanabara Bay connecting the cities of Rio de Janeiro and Niteroi, thereby avoiding a detour of 37 miles (60 km). This structure also closes the gap in the new 2485 mile (4()OO km) highway that interconnects north and south Brazil and links the towns and cities on the eastern seaboard, Figure 3.51. Although the route taken by the bridge across the Bay seems somewhat indirect, it was selected because it avoids very deep water and is clear of the flight path from Santos Dumont Airport.

Total project length is approximately 10.5 miles (17 km). of which about 5.65 miles (9. I km) is {)\"er water. The alignment begins at the Rio side with a 3940 ft (1200 m) radius curve, then a straight sec: tioll. \\·itl1in which are located steel box girder na\'igation spans totaling 2872 ft (848 m) in length. This is followed by an island, where the viaduct is interrupted by a road section of604 ft (184 ml. and finally

f4C

FIGURE 3.82. Angers Bridge, view of the completed structure.

FIGURE 3.83. Sallingsund Bridge, view of the com­ pleted structure.

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124

Precast Balanced Cantilever Girder Bridges

su perstructure consists of precast concrete box girder segments 11.7 ft (3.57 Ill) in length, with epoxy match-cast joints, which are prestressed to­ gether. Segment depth varies from 8.2 ft (2.5 m) at midspan to 18 ft (5.5 m) at the pier. The precast superstructure segments were match-cast by the short-line method (see Chapter 11). There are altogether 453 segments varying in weight from 86 t (78 mt) to 118 t (107 mt). The typical segment shown in FigUl'e 3.85 has web cor­ rugated shear keys together with top and bottom flange keys. Hinge segments equipped with a roadway expansion joint for thermal movement of the superstructure are placed every other span near the point of contraAexure. A hinge segment with its diaphragm is shown in Figure 3.86.,seg­ ments are placed in the structure in cantilever with a cable-stayed launching gantry. Transfer from the casting area and the storage yard to the construc­ tion site and the launching gantry is achieved by a low-bed dolly pushed by a tractor, Figure 3.87. The gantry shown in Figure 3.88 should look

familiar to the reader, as it was previously used at the Saint Cloud and Angers Bridges. Each pier in the v,ater consists of the followjng, ~s shown in Figure 3.89:

FIGURE 3.85. Sallingsund Bridge. "iew of a typical segment.

FIGURE 3.87. Sallingsund Bridge, segment trans­

Twenty-four pipe piles filled with reinforced con­

crete after driving

A guiding template and a tremie concrete seal A precast substructure block and precast ICe breaker

A cast-in-place hollow box shaft with cap for re­

ceiving the superstructure

Chapter 5 gives a detailed description of the foun­

dation principles in design and construction.

3.14

-. •

B-3 South Viaducts, France

The South Viaducts or the B-3 Motorway, Figure 3.90, east of Paris, are 1.25 miles (2 km) in length

port.

"

.1'''''''' /-.

FIGURE 3.86. Sallingsund Bridge, hinge segment with diaphragm.

.•

FIGURE 3.88. Sallingsund Bridge, launching gantry.

;

8-3 South Viaducts, France

125

Figure 3.91 presents a plan of this pf(~iecl and shows a subdivision in accordance with the type of cross sections used. It includes the following main subdivisions: 1. The main viaduct VP I-A through VP I-J. 2. The main viaduct VP 2-A and VP 2-B. 3. The viaducts VI and V2, which are access ramps to the main viaduct VP 2. 4. The viaducts V3 and V4, which are access ramps to the \iational Road R:\3.

FIGURE 3.8iJ.

Sallingsund Bridge, elevation of main

piers in water. and have 860,000 sq ft (80,000 m 2 ) of bridge deck. The project is in a congested area that required the crossing of railway tracks, canals, and more than 20 roads; its diverse structural geometry contains curves, superelevation ranging from 2.5 to 6% and grades up to 5%.

FIGURE 3.90.

B-3 South Viaduct, overall view.

The original design for this project, prepared by the French authorities, was based on conventional cast-in-place construction of the superstructure in complete spans using movable formwork. The contractor proposed a more economical design based on the use of precast segmellts. The alterna­ tive design had advantages in erectioll, wherein parts were erected by a launching truss and parts by a mobile crane in conjunction with an auxiliary truss and winch. The use of precast units allowed a deeper and thus a more economical superstruc­ ture, because the space required for formwork did not have to be deducted in the clearance require­ ments over existing roads and other facilities. The superstructure has a constant depth of 6.5 ft (2 m), consisting of three different cross sections, Figure 3.91. Different width and transitions were accommodated bv varying the width of the east­ in-place median slab connecting the top Aanges of the precast segments. Only the V3 and V 4 access ramps were of conventional cast-in-place construc­ tion. The webs of the precast segments have a con­ stant thickness of 12 in. (310 mm), increased in some cases to 2'0 in. (500 mm) near a pier. Webs are stiffened by an interior rib, which also serves to an­ chor the longitudinal prestressing inside the box rather than in the web at the end of a segment. Where the webs are not thickened near a support, they are prestressed vertically by bars to accommo­ date shear forces. The top Aanges of the segments are cantilevered 10 ft (3 m). In the case of segment types 2 and 3, Figure 3.91, the top flange cantilever between box sections is 9 ft (2.75 rn). The top Aange follows the superelevation of the roadway. The thickness of the cast-in-place longitudinal slab between box girders varies from 7.9 to 13.8 in. (200 to 350 mm), depending upon its width. The total superstructure is supported on neo­ prene or sliding bearings. Expansion joints are spaced at distances up to 1970 ft (600 m) and are

Precast Balanced Cantilever Girder Bridges

126

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FIGURE 3.91.

B-3 South Viaducl, plan showing segment type location.

located in special hinge joints near a pier. Superstructure spans vary from 89.6 to 174 ft (27 to 53 m), with 90% of them being in the range of III to 125 ft (34 to 38 m). This project required 2225 precast segments, all manufactured by the short-line method (see Chapter 11), which involved the following opera­ tions: I. Subassembly of mild steel reinforcing on a template. 2. Storage of subassembly units. 3. Assembly of complete reinforcement cages in­ cluding tendon ducts. 4. Placing of the cages in the forms. 5. Concreting and curing of the segments. 6. After concreting and curing, transportation of the segment by a dolly to a position where one end would act as a bulkhead for the casting of the next segment. At the same time its position was adjusted to conform to the proper geometric configuration of the superstructure. 7. Transfer of the segment that had previously acted as the bulkhead to temporary storage for further curing.

8. Transfer of the segment, eight hours after curing, to a more permanent storage until re­ quired for erection. 9. Return of the mold bottom, after temporary storage, to the casting area for reuse. Curing of the segments was accomplished with low-pressure steam in the following 44-hour cycle: I. An initial 14-hour curing period at 35°C. 2. A two-hour temperature rise reaching 65"C. 3. A one-hour curing period at a level of 65"C. The short curing cycle can be accomplished if the following conditions are satisfied: use of a proper cement, preheating of the materials to 35"C, rigid forms, and proper supervision. Casting of a seg­ ment required nine hours, allowing two segments per day per form; the four forms used produced a total of eight segments per day. Erection of precast segments by the launching gantry shown in Figure 3.92 is schematically illus­ trated in Figure 3.93. After being rotated 90", segments V2 and V'2 were placed at the same time by means of two trolleys suspended from the bot­ tom chord of the launching girder, Figure 3.94.

B·] South Viaducts, France

FIGURE 3.92. in operation.

127

V2 and V' 2 were then attached to the previously erected segments by temporary prestressing. During the erection operation of V2 and V'2 a transport dolly delivered segment V' 3, then V3, and so on. In this manner the erection of segments could be carried out without being delayed by transportation of the segrIJents from the storage area. In addition, the tfueading and stressing of the permanent prestressing tendons were inde· pendent of the erection cycle. since the tendons were anchored in the internal ribs and could be prestressed inside the box girder. Where the span length was less than 125 ft (38 m), the pier segments were placed by the gantry in its normal working position. The pier segment po· sition was adjusted from a platform fixed to the top of the pier to avoid delaying the placement or can­ tilever segments at the preceding pier. For the few

B-3 SOllth Viaduct. launching gantry

The matching faces of the segments being erected and the previouslv erected segments, V 1 and V' 1, were coated with epoxy joint material. Segments

(a)

PI

P2

FIGURE 3.93. B-3 South Viaduct. erection sequence. (a) Placin.g the units: The two trolleys bring the units V2 and V'2 which will be placed, after rotation at 90°, against the units VI and V' 1. During this time, the lorry carries the units V'3. then V3, and so on. (b) Laullching the truss: The rear and the central are lifted abo\'e the piers PO and PI. the tmss is supported by trestles and trolleys ill 1 alld P2 and moves forward by the action of the trolley motors until the legs reach PI and P2. Thus the truss has advanced along one span length and can place the pile-unit in P3 and the cantilevers from P2.

128

Precast Balanced CantiLever Girder Bridges

_.... FIGURE 3.94. B-3 South Viaduct, placing two seg­ ments in balanced cantilever.

larger spans, the pier segment was placed after clo­ sure of the preceding completed spans and ad­ vancement of the launching gantry. The center leg was advanced out onto the last completed half­ span cantilever, but it remained in the proximity of tlte pier. Launching of the gantry to the next span was achieved b\· using the two segment transporta­ tion dollies temporarily fixed on the completed superstructure by two auxiliary steel trusses. The high degree of mechanization of the gantry to­ gether with the repetitive nature of the project al­ lowed speedy erection. A typical 130 ft (39 m) span was erected and completed in two working days. To maintain the construction schedule and minimize required erection equipment, the super­

structure segments wel'e placed simultaneously by two different methods. The launching gantry previously described placed 57% of the seg­ ments and a mobile crane in conjunction with a movable winch frame erected the remaining ones. The latter method was used where access was available for a truck-mounted crane and the seg­ ment transportation dolly. The truck-mml11ted crane could easily be used along the centerline of the structure to place segments at outboard can­ tileyer ends. However, its use became complicated in the midspan area, particularly when it was used to place the closure segments. To solve this prob­ lem, an auxiliary truss equipped with a winch was used in conjunction with the mobile crane. This truss was supported at one end over the pier where cantilever construction proceeded and at the other end over the last completed cantilever arm, which might or might not require a temporary support. pier, Figure 3.95. The segments were lifted by a trolley-mounted winch traveling along the truss. This truss was also used to stabilize the cantilevers during erection, since it was fixed to the pier and the completed ponion of the superstructure. After the pier segment was positioned by the m()bile crane, the frame was launched with the trolley in a counterweight position at the rear of the frame. \Vhen the span exceeded 65 ft (20 m), the front of the frame was held by the crane~ This structure exemplifies an innovative appli­ cation of precast balanced cantilever segmental construction to a difficult urban site and shows its adaptability to almost any site conditions.

FIGURE 3.95. B-3 South Viaduct, auxiliary truss for segment assembly (crane placing). (1) Auxiliary truss, (2) winch for segment lifting, (3) precast segment, (4) possible tempo­ rary support (as required), and (5) concrete cantilever stability device.

Alpine Motorway Structures, France

3.15

Alpine Motorway Structures, France

The new Rhone-Alps Motorway system in South East France includes 220 miles (350 km) of toll­ ways, of which 60 miles (100 km) are an optional section, between the cities of Lyons, Grenoble, Geneva, and Valence in order to improve com­ munications between Germany and Switzerland on one hand and South France and Spain on the other. The motorway is situated among the beauti­ ful western slopes of the Alpine mountain range (see the location map, Figure 3.96). The first 160 miles (250 km) include the following structures: Ten viaducts varving in length between 500 and 1300 ft (150 to 400 m) Two hundred overpass bridges Fifty underpasses Such a project afforded an exceptional occasion

to

129

optimize the structures in terms of initial invest­ ment and low maintenance costs. The underpasses had to accommodate a variable and often considerable depth of fill to reduce the constraints of the longitudinal profile in this mountainous region. The ideal answer was found in the use of reinforced concrete arch structures, which proved extremely well adapted and had a cost approximately half that of conventional girder bridges. Apart from the first section of the motorway (East of Lyons), which had to be built immediately and therefore called for conventional solutions (cast-in-place prestressed concrete slab), and ex­ cept for certain special situations (excessive skew, railroad crossing, and so on), a careful study showed that the remaining 150 overpass bridges should be of precast concrete segmental construc­ tion, which were 20% more economical than other methods and practically maintenance free. The study further showed that segmental construction

-

"

Alpine Motorway, location map.

130

Precast Balanced Cantilever Girder Bridges

should be extended to viaduct structures and that all segments for both overpasses and viaducts could be economically built in a single factory lo­ cated near the center of gravity of the motorway network. The maximum carrying distance was 110 more than 75 miles (120 km) and the average was 40 miles (60 km). Figures 3.97 and 3.98 are views of a typical viaduct and a typical overpass in the motorway network. The two-span and th ree-span overpass bridges have spans ranging from 59 to 98 ft (18 to 30 m). A variety of standardized precast cross sections were developed for this project, depending upon span and width requirements. The first structures used single and double-cell trapezoidal box sections, al­ though later on voided slab sections were pre­ ferred, as illustrated in Figure 3.99a. This solution proved aesthetically pleasing and very simple to manufacture and assemble. The viaducts had to satisfy a wide range of environmental require­ ments. It was found that span lengths could be limited at all sites to a maximum of 200 ft (60 m),

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138

Precast Balanced Cantilever Girder Bridges

structure of prestressed concrete segmental two­ cell boxes, Figures 3.115 and 3.116.17 Steel rocker bearings were llsed to support the superstructure at piers 1, 3, and 4, and large­ diameter single steel roller bearings were used at pier 2. Lubricated bronze bearings sliding on stainless steel were used at the north abutment and for the movable bearings at the suspended spans. Steel finger joints, allowing a lOin. (250 mm) maxirnum movement, were provided at each slid-

FIGURE 3.115. Capt. Cook Bridge, cross section at pier :~. from ref. J 7.

FIGURE 3.116. Capt. Cook Bridge, two-cell box gir­ der segment being erected (courtesy of G. Bcloff. Main Roads Department).

ing bearing location and rubber and steel finger joints at the remaining locations." The box girder segments have a maximum depth of 32 ft (9.75 m) and a minimum depth of 6 ft (1.83 111). Segment length is 8 ft 8 in. (2.64 m). A 16 in. (0.4 m) cast-in-place, fully reinforced joint was used between segments. Maximum segment weight is 126 tons (114 mt). A total of 364 precast segments were required in the superstructure with the two segments over the tie-wall in the south abutment being cast in place. 17 The contractor chose to locate the precasting operation on the river bank near the south abut­ ment. This casting yard consisted of a concrete mixing plant, steam-curing plant, three adjustable steel forms, segment tilting frame, and a gantry crane to transport the segments to a storage area along the river bank. Segments were designed so that the top flange and upper portion of the webs had a cOllstant thickness. The depth and lower portion accolllmodated all variations. allowing the contractor to cast in two sets of adjustable forms. Segments were cast with their longitudinal axis in a vertical position for ease of concrete placement around the prestressing ducts. Separate interior forms were constructed for each box to permit variations in the bottom flange alld web thickness and size of fillets. Aher casting and curing, seg­ ments were lifted into a tilting frame {() realign the segment into its normal position ready for han­ dling and storage.]; _A floating crane, designed and built bv the con­ tractor, was used for erection of the segmen ts. I twas essentially a rectangular pontoon with mounted A-frame lifting legs rising to 120 ft (36.6 m) with adequate clearance to service the finished deck level, while the stability was sufficient to transport the segments to the erection position, Figure 3.117. An extended reach was required to position seg­ ments on the first two spans in the shallow water near the bank. 17 Segments on each side of the pier were sup­ ported on falsework anchored to the pier shafts, Figure 3.118. From this point additional segments, as they were erected, were supported on a can­ tilever falsework from the completed portion of the structure. This falsework was fixed under the completed girder and supported from deck level, Figure 3.119. When the capacity of the pier to carry the segment unbalanced load was reached, a temporary prop support on driven piles was con­ structed before cantilever erection could continue. Segment erection then proceeded on each side until either the joint position of the suspended

Other Notable Structures

139

FIGURE 3.119. Capt. Cook Bridge, cradle support trusses and temporary support tower (courtesy of G. Beloff, Main Roads Department).

FIGURE 3.117. Cap. Cook Bridge, ~egment being transported by barge derrick to 6nal position (courtesy of G. Beloff, l\Iain Roads Department).

span was attained or the closure gap in span 3 was reached. The completed st.ructure was opened to traffic in 1971, Figure 3.120. 3.18

Other Notable Structures

In Sections 3.2 through 3.15 the historical de­ velopment of precast segmental bridges with match-cast joints has been illustrated by examples,

FIGU~E

3.118. Capt. Cook Bridge, support for seg­ ments on each side of pier (courtesy of G. Beloff, Main Roads Department).

ranging from the first structure at Choisy-le-Roi to the largest applications such as the Rio Niteroi and Saint Cloud bridges. Emphasis has been placed on North American experience as well as on the advantages of precast segmental construction for urban structures (B-3 Viaducts) or repetitive ap­ plications (Alpine Motorways). Two particularly outstanding structures, deserving special mention because of their size and characteristics where pre­ cast serrmental was used with conventional joints (not m~tch-cast) were the Oosterschelde and Cap­ tain Cook Bridges (Sections 3,16 and 3.17). Before closing this important chapter, let us briefly give due credit to several other contemporary match­ cast segmental bridges. 3./8.1

CALIX BRIDGE, FRANCE

This Itl-span superstructure has a maximum span length of 512 ft (156 m) over the maritime

FIGURE 3.120. Capt. Cook Bridge. completed structure (courtesy of G. Beloff, :vIain Roads Depart­ ment).

.

Precast Balanced Cantilever Girder Bridges

140

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FIGURE 3.121. Calix Vi,lIi

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FIGURE 4.23. Typical dimensions of some segmental cantilever bridges in Europe. Year of construction and maximum span length (ft): (aj Felsenau, Switzerland (1978), cast in place, 512; (b) Tarento, Italy (1977), cast in place, 500; (c) Kochertal, Germany (1979), cast in place, 453. 168

Transverse Distribution of Loads Between Box Girders in Multibox Girders Typical Cross Section

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FIGURE 4.24. Typical dimensions of some segmental cantilever bridges in the Americas. Year of construction and maximum span length (1'1): (a) Rio Niteroi, Brazil (1971), precast, 262; (h) Pine Valley, U.S.A. (1974), cast in place, 450: (c) Kipapa. U.S.A. (1977), cast in place, 250; (d) Kishwaukee, U.S.A., precast, 250; (e) Long Key, U.S.A., precast, 118;(/) Seven ~lile, lJ.S.A., precast, 135; (g) Columbia River, C.S.A., cast in place and precast, 600;' (h) Zilws~e,

due

flange as thin as 5 or 6 in, has been used in early bridges), it is almost irnpossible to distribute the concentrated load of I he anchor block in the slab without subsequent cracking. For a 7 or 8 in. Bange il is recommended'that no more than two anchor

1,000'

x 1/2", tendons) Typ,

FIGURE 4.39. Secondary stresses due to cun'ed prestressing tendons, nu­ merical example, Assumed longitudinal radius = 1000 ft. Weight of bottom slab 2000 psi, com­ 100 psf. Effect of compressive stresses: unloaded bridge.}, (2000 x 8 x 12)/1000 200psf; loaded bridge, 0 pressive radial Joad:f,.tIR psi. Effect of prestressing tendons: stranded tendons (twelve! in. dia strands) at 10 in. interval with a 280 kip capacity, mrresponding l-adial load: FIR = 280,000/[(10112) 1000J = 336, say 340 psL Total loads on bottom slab: (1) during construction, load = 100 psf; (2) unloaded bridge, load = 100 - 200 + 340 240 psi; (3) loaded bridge, load 100 + 340 = 440 psC moment = wet /12 = 9 (9000 x 12)/[( 12 x 64)/6] 840 psi. kips ftlft, stress in bottom slab:} MIS

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Design of Longitudinal Membr.?rs for Flexure and Tendon Profile

183

tendons may be made continuous through the expansion joint or equipped with couplers. d.

e. Partial elevation

f.

FIGURE 4.40. 1Fcstrcss,

Ellen of

misaligllIllclH 0[' continuity

blocks for (I ~ } ilL diameter strands) tendOllS be placed ill the sallle transverse sectioll ill conjullc­ tion with additional reinforcing to resist burstillg stresses. Wherever possible. the anchor blocks for cOlltinuitv telldollS should f)e placed ill the fillet between the web alld flallge where the lrallsverse sect iOll has t he largest rigidity. LIH)!'T OF PRl;;SrR/~'SS I.V STf?L'CrCR/,'S JrrJlI 11/\ (;J,'S I.\'/) fY,I'I\',shaped lifting hook, Figure 6.5~, The truss is sllpported against the barge crane and lIloved pamllel to the Ilew bridge ulltil it

Section at midspan

Long Ke\' Bridge, typical cross section of superstructure,

312

Progressive and Span-by-Span c..onstruction of Segmental Bridges

The span by span erection concept utilizes a temporary steel assembly truss in conjunction with a barge mounted crane as shown. The steel truss spanning between the piers is equipped with post-tensioning tendons along the bottom chord to facilitate adjustments for deflectiOns and lowering the truss upon completion of the span.

Iii I FIGURE 6.52.

Long Key Bridge, span-by-span erection scheme.

reaches the position for a new span, and the cycle is repealed. 6.5.2

SEVEN AlILE BRIDGE, U.S.A.

The Seven Mile Bridge, Figure 6.54, in the Florida Keys carries U.S. Highway 1 across Seven Mile Channel and Moser Channel from Knights Key west and southwest across Pigeon Key to Little Duck Key.

The existing structure consists of 209 masonry arch spans, 300 spans of steel girders resting on masonry piers, and a swing span over Moser Channel. The spans range in length from 42 ft in. (I3 m) to 47 ft 4t in. (14.4 m) for the masonry arches and from 59 ft 9 in. (18.2 m) to 80 ft (24.4 m) for the steel girders resting on masonry piers, which along with the 256 ft 10 in. (78.3 m) swing span, produce a total bridge length of 35,716 ft 3 in. (10,886 m).

Span-by-Span Precast Bridges

313

DETAIL 1 $CoiJlr'

PERSPEC TlVE

I·"/~O"

VIEw

DETAIL SuII!"

2

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ELEVATION

FIGURE 6.53. out. ­

Long Key Bridge, typical tendon lay­

'.

FIGURE 6.54.

Seven Mile Bridge, anist's rendering.

The new bridge, presently under construction, is located to the south of the existing bridge. It is a precast segmental box girder constructed by the span-by-span method with 264 spans at 135 ft (41.15 m), a west-end span of 81 ft in. (24.88 m), and an east-end span of 141 ft 9 in. (43.2 m) for a in. (l0,931 m). The total length of 35,863 ft roadway requirements are the same as for the Long Key Bridge and the cross section is almost identical, Figure 6.50. Seven Mile Bridge crosses the Intracoastal Waterwav with 65 ft (19.8 m) verti­ cal clearance, and its alignment has both vertical and horizontal curvature.

The consultants, Figg and \Iuller Engineers, I nc., used the same concepts as had been used for the Long Key Bridge. except they omitted the V-pier alternative in favor of a rectangular hollow box-pier scheme that is precast in segments and post-tensioned vertically to the foundation system. As mentioned in Section 1.9.3, the contractor elecred to alter the constru10.• "alional .\eadem\" of Sciences, \VashinglOn, D,C.

Progressive and Span-by-Span Construction of Segmental Bridges

320

:), l', FillSterwed location. .

7.8

Other Notable Structures

illg permanent pier bv two stavs or lOin. hy lOin. (~S4 IIlIll hy ~54 111m) stl'llctllral sleel tubing. Fig'­ ures 7.:14 and 7.42. The jackillg procedure during launching used t ht' two-jack S\'stelll (one \'ertical and one horizon­ Ld) and teflon pads, as described in Figure 7.2. The vCltical jack~ had a 2 in. (50 llllll) stroke and the

Allot her example of this I\Ve of constructioll is the \1iihlbachtalbnkke ahout 30 llliles (50 km) south­ west or Stuttgart, West Germany, Figure 7.44. This structure has an overall length of 1903 it (580111) with 141 It (43 111) spallS. The far-side trapezoidal box girder is shown in Figure 7.44 cOlllpleted from abutment 10 abutment: the near-side trapezoidal box girder has heen launched frolll the lefl abut­ ment and the launching nose has reached the first pier. A general view or the SI ruct ure is presented ill Figu re 7.45.

FIGURE 7042. tuhing lie.

FIGURE 7.43. bearing.

FIGURE 7041.

Wabash Ri\cr Bridge, temporary steel

bellI.

Wabash Rh'cr Bridge, structural steel

Wabash River Bridge, lateral guide

l 339

Other Notable Structures

FIGURE 7.47. \Ilihlhachtalhrticke, stressing tendoll anchorage.

FIGURE 7.44.

\llihlbachtalhrllCke, aerial \'iew.

FIGURE 7.45.

\fiihlbachtalbriicke, general \'iew.

111

pre­

!

FIGURE 7.48. \fiihlbachtalhriicke, second-stage pre­ ~tressillg ;mchorage block.

7.8.2

\liihlbachtalbrucke, segment

first-stage

.(

Some ide;1 of the size of the box girder IlW\ be obtained frol1l Figure 7.46, showing the intel·ior of' the fornnvork at the rear of the abutment. First­ stage prestressing telldon anchorage at the lOp or lhe web I1l