_ASCE SEI 7-2005 Seismic Design Provisions, Overview

2007 ASCE/SEI Structures Congress Long Beach

Seismic Design Provisions of ASCE/SEI 7-2005 James R. Harris, S.E. Principal, JR Harris & Co. Chair of the ASCE 7 Main Committee (2000-2005) & Robert E. Bachman, S.E. Consulting Structural Engineer  Chair of the ASCE 7 Seismic Task Committee (2000-2005)

Overview • Part I – Bob Bachman - Background on Code Change Development - Reorganization of ASCE 7-05 and where things are found compared to ASCE 7-02 and the 1997 UBC

• Part II – Jim Harris - Basic Seismic Design Criteria for Buildings (Chapters 11-12) • Part III – Bob Bachman - Nonstruct Nonstructural ural Compo Components nents,, Materia Materiall Standards Standards,, Nonbuildi Nonbuilding ng Structures Structures (Chapters (Chapters 13 – 15) - Briefl Briefly y disc discuss uss Chapte Chapters rs 16-2 16-22, 2, Appe Appendi ndices ces 11A & B - 2006 2006 IBC IBC Modif Modifica icatio tions ns to to ASCE ASCE 7-05 7-05 Seis Seismic mic Provis Provision ionss

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OVERVIEW

• Background on Seismic Code Development • Revised Organization for ASCE 7 – 2005

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Way back in 1994 …………

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Seismic Codes and Source Documents SEAOC

NEHRP ASCE 7

Standard Building Code

BOCA National Building Code

Uniform Building Code

International Building Code 2007 Structures Congress

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NEHRP Provisions ATC 3.06

Tentative Recommended Provisions for  Seismic Regulation of Buildings

1997 EDITION

1997 EDITION

NEHRP RECOMMENDED PROVISIONS FOR SEISMIC REGULATIONS FOR NEW BUILDINGS  AND OTHER STRUCTURES

NEHRP RECOMMENDED PROVISIONS FOR SEISMIC REGULATIONS FOR NEW BUILDINGS  AND OTHER STRUCTURES

PART 1 - PROVISIONS

• • • • • •

PART 2 - COMMENTARY

First published by BSSC in 1985 Was updated on 3-year cycle (1988, 91, 94, 97 ,00, 03) –  However now on 5 - 6 year cycle 1992 - Adopted by BOCA, SBCCI 1993 – Adopted by ASCE 7 for Seismic 1995 - IBC resolves to adopt as basis for IBC 2008 – Adopts ASCE-7-05 as Reference Basis 2007 Structures Congress

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NEHRP & The Building Code National  Design Specification

Load  & Resistance Factor  Design

 ACI 

Recommended 1997 EDITION Lateral Force NEHRP RECOMMENDED PROVISIONS FORRequirements SEISMIC REGULATIONS FOR NEW BUILDINGS  AND OTHE R STRUCTURES and Commentary

1997 

U NIFORM BUILDING CODE VOLUME 2

PART 1 - PROVISIONS

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Building Codes Changed– Started in 2003  ASCE-7 Minimum Design Loads for Buildings and Other  Structures

National  Design Specification

Load  & Resistance Factor  Design

 ACI 

NFPA 5000 Building Code

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1997 UBC Development & Convergence • • •

•

SEAOC notified in mid-1994 that the 1997 UBC would be the last edition of the UBC. Replaced starting in 2000 IBC with Seismic Requirements based on the 1997 NEHRP Provisions and Adopted Available Codes (UBC, SBC, NBC). SEAOC recognized it likely could not overturn decision and adopted a 2 prong strategy - Nominated strong candidates to 1997 NEHRP PUC with concept of modifying the NEHRP to make closer to the anticipated 1997 UBC - Made extensive revisions to 1997 UBC that brought them much closer to the anticipated 1997 NEHRP Provisions and also added new concepts Strategy was called “Convergence” – to ease the transition for those using the UBC for seismic design after the IBC was adopted

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ICC , NFPA & The Governator • • • • • • •

In 1998 – 1999 time frame, the International Code Council (ICC) and  National Fire Protection Association (NFPA) had a falling out  primarily dealing with plastic pipe. NFPA decides to develop a competing building code called NFPA 5000 which is favored by labor unions. NFPA 5000 references ASCE 7-02 for engineering design requirements Calif. Gov. Gray Davis stacks Cal. Building Standards Commission and they adopt NFPA 5000 as next California Building Code (CBC) SEAOC decides to support removal of seismic requirements from 2003 IBC and instead references ASCE 7-02 Gray Davis impeached and replaced by the Governator who replaces the Building Standards Commission (BSC) appointees. New BSC adopts the 2006 IBC and in essence ASC7-05 for next CBC

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ASCE 7 • Developed by ASCE-SEI using ANSI standard consensus  process • Publication Date Varies (1993, 1995, 1998, 2002, 2005) • Latest Version ASCE 7-05 Including Supplement 1 includes references to latest material standards • Errata – go to www.seinstitute.org & click on publications & then click on errata & finally click on ASCE 7-05 (current errata included in seminar handouts) Participants:  – ASCE/SEI Standards Committee  – Task Groups (Wind, Seismic, etc)  – Public 2007 Structures Congress

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Vision of the Future • Code “evolution” should slow somewhat  Next Edition of ASCE 7 in 2010/2011  – standards are more difficult to change than codes –  ASCE 7-10/11 will be adopted by 2012 IBC  – less rapid fire adoption of major changes

• Design guidelines (SEAOC, etc) with informal consensus approval available for elective use on  projects • However, IBC Code Supplements will still occur every 18 months, with new full editions every 3 years. 2007 Structures Congress

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Overview • Background on Seismic Code Development • Revised Organization for ASCE 7 – 2005

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ASCE 7-05 Reorganization • Goals of Seismic Section Reorganization 1. To improve clarity and use 2. Reduce depth of section numbering from 6 max typical to 4 max typical (I.e. Sec. 9.5.2.5.2.2 is now Sec. 12.5.3) 3. Simplify table and figure numbering (I.e. Table 9.5.2.5.1 is now Table 12.6-1) 4. Create logical sequence of provisions aimed at the structural engineering community 5. Improve headings and clarify ambiguous provisions 2007 Structures Congress

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ASCE 7-05 Reorganization • Goals accomplished by: 1. Changing major subjects to Chapters rather than Sections (similar to the IBC and UBC) 2. Replacing Section 9 with Chapters 11-23 3. Incorporating the material appendices into the the Chapters 4. Put the Chapters into a logical sequence 5. Rewrote ambiguous headings to reflect their content 6. Examined and rewrote sections to eliminate ambiguity 7. Provided Cross Reference Table C-11-1…02 to 05 8. Used code like format and printing style 9. And also adopted 2003 NEHRP Provision Changes 2007 Structures Congress

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Comparison of Contents ASCE 7-2002 Sections

ASCE 7-2005 Chapters

1.

General

1. General

2.

Combinations of Loads

2. Combinations of Loads

3.

Dead Loads

4.

Live Loads

3. Dead Loads, Soil … and Hydrostatic

5.

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4. Live Loads 5. Flood Loads Seismic Provisions of ASCE/SEI 7-05

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Comparison, continued ASCE 7-2002 Sections

ASCE 7-2005 Chapters

6. Wind Loads 7. Snow Loads 8. Rain Loads 9. Earthquake Loads 10. Ice Loads A. Supplemental (QA) B. Serviceability

6. Wind Loads 7. Snow Loads 8. Rain Loads 9. (not used) 10. Ice Loads 11. - 23. Seismic A & B. QA & Existing

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Seismic Contents ASCE 7-2002

ASCE 7-2005

9.1 General Provisions

11. Seismic Design Criteria

9.2 Definitions/Symbols 9.3 (not used) 9.4 Ground Motion 9.5 Structural Design Criteria, Analysis, and Procedures 2007 Structures Congress

12. Seismic Design Requirements for Building Structures 13. Seismic Design Requirements for  Nonstructural Comp. Seismic Provisions of ASCE/SEI 7-05

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Seismic Contents, continued ASCE 7-2002

ASCE 7-2005

9.6 Arch, Mech, Elect Comp and Systems 9.7 Foundations 9.8 Steel 9.9 Structural Concrete 9.10 Composite Struct. 9.11 Masonry

14. Material Specific 15. Nonbuilding Structures 16. Response Hist Anal 17. Seismic Isolation 18. Damping Systems 19. Soil-Struct. Interact.

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Seismic Contents, continued ASCE 7-2002

ASCE 7-2005

9.12 Wood

20. Site Classification 21. Site-Specific Ground Motions 22. Maps 23. Reference Docs 11A. Quality Assurance 11B. Existing Buildings

9.13 Seismic Isolation 9.14 Nonbuilding Structures A9. Quality Assurance

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Seismic Contents Comparison 1997 UBC and ASCE 7-05 1997 UBC

ASCE 7-2005

1626 – 1628 General, Definitions, Glossary 1629.1 – 1629.4 Criteria Selection 1629.5 – 1629.10, 1630, 1631.1- 4, 1633 Building Seismic Design Requirements (Simplified Design not in 1997 UBC)

11. Basic Seismic Design Criteria 11. Basic Seismic Design Criteria 12. Seismic Design Requirements for Bldgs. (no simplified analysis)

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12.14 Simplified Building Design

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Seismic Contents Comparison 1997 UBC and ASCE 7-05 1997 UBC

ASCE 7-2005

1631.6 Time History Analysis

16. Response History Analysis

1632 Nonstructural Components

13. Nonstructural Components

1634 Nonbuilding Structures

15. Nonbuilding Structures

1636 Site Categorization

20. Site Categorization

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Seismic Contents Comparison 1997 UBC and ASCE 7-05 1997 UBC

ASCE 7-2005

Figure 16-2 Seismic & Near Source Maps

22. Contour maps and website

Chapter 17 Tests and Inspection

Appendix 11A* QA

Chapter 18 Foundations

Section 12.13 Fndns

Chapter 19-24 Materials

14. Materials*

Chapter 34 – Existing Bldgs

Append. 11B* Existing Bldg

Chapter 35 References

23. References

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Seismic Contents Comparison 1997 UBC and ASCE 7-05 1997 UBC Appendix – Chapter 16 Seismic isolation

ASCE 7-2005

 Not in 1997 UBC

18. Systems with Supplemental Damping

 Not in 1997 UBC

19. Soil Structure Interaction

 Not in 1997 UBC

21. Site Specific Seismic Hazard Requirements.

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Summary Regarding Reorganization • California engineers have already been transitioning to the NEHRP Requirements and ASCE 7-05 when using the 1997 UBC • California engineers actually fortunate that they did not have to use 2003 IBC and ASCE 7-02. The reformat is much better for common usage • While terminology is different, the actual design requirements are reasonably similar except for the Central Valley – This did not happen by accident. 2007 Structures Congress

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