_ASCE SEI 7-2005 Seismic Design Provisions, Overview

8/12/2019 _ASCE SEI 7-2005 Seismic Design Provisions, Overview

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2007 ASCE/SEI Structures CongressLong Beach

Seismic Design Provisionsof 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)


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2007 Structures Congress Seismic Provisions of ASCE/SEI 7-05 2

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- Nonstructural Components, Material Standards, Nonbuilding

Structures (Chapters 13 15)- Briefly discuss Chapters 16-22, Appendices 11A & B

- 2006 IBC Modifications to ASCE 7-05 Seismic Provisions


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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 SourceSeismic Codes and SourceDocumentsDocuments

SEAOC

ASCE 7

NEHRP

StandardStandard

Building CodeBuilding Code

UniformUniform


BOCA NationalBOCA National

Building CodeBuilding CodeStandardStandard


UniformUniform


BOCA NationalBOCA National


International Building CodeInternational Building Code


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NEHRP ProvisionsATC 3.06

Tentative

Recommended

Provisions forSeismic Regulation

of Buildings

1997 EDITION

NEHRP RECOMMENDED PROVISIONS

FOR SEISMIC REGULATIONSFOR NEW BUILDINGS

AND OTHER STRUCTURES

PART 1 - PROVISIONS

1997 EDITION




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


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National

Design

Specification

Load

&Resistance

Factor

Design

ACI

NEHRP & The Building Code

1997

UNIFORM

BUILDING

CODE

VOLUME 2

Recommended

Lateral Force

Requirements

and Commentary

1997 EDITION




PART 1 - PROVISIONS


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Building Codes ChangedStarted in 2003

NFPA 5000

Building Code

ASCE-7

MinimumDesign Loads

for Buildings

and Other

Structures

National

Design

Specification

ACI

Load

&

Resistance

Factor

Design


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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 ofmodifying the NEHRP to make closer to the anticipated 1997 UBC

- Made extensive revisions to 1997 UBC that brought them muchcloser to the anticipated 1997 NEHRP Provisions and also added new

concepts Strategy was called Convergence to ease the transition for thoseusing 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 outprimarily dealing with plastic pipe.

NFPA decides to develop a competing building code called NFPA5000 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 from2003 IBC and instead references ASCE 7-02

Gray Davis impeached and replaced by the Governator who replacesthe 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 consensusprocess

Publication Date Varies (1993, 1995, 1998, 2002, 2005)

Latest Version ASCE 7-05 Including Supplement 1includes 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


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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 informalconsensus approval available for elective use on

projects

However, IBC Code Supplements will still occurevery 18 months, with new full editions every 3years.


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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 thestructural engineering community

5. Improve headings and clarify ambiguous provisions


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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 thethe 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-11-102 to 058. Used code like format and printing style

9. And also adopted 2003 NEHRP Provision Changes


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Comparison of Contents

ASCE 7-2002 Sections

1. General

2. Combinations of

Loads3. Dead Loads

4. Live Loads

5. Soil and Hydrostatic

and Flood Loads

ASCE 7-2005 Chapters

1. General

2. Combinations of

Loads3. Dead Loads, Soil

and Hydrostatic

4. Live Loads

5. Flood Loads


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Seismic Contents

ASCE 7-2002

9.1 General Provisions

9.2 Definitions/Symbols

9.3 (not used)9.4 Ground Motion

9.5 Structural Design

Criteria, Analysis,and Procedures

ASCE 7-2005

11. Seismic Design

Criteria

12. Seismic DesignRequirements for

Building Structures

13. Seismic DesignRequirements for

Nonstructural Comp.


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Seismic Contents, continued

ASCE 7-2002

9.12 Wood

9.13 Seismic Isolation

9.14 NonbuildingStructures

A9. Quality Assurance

ASCE 7-2005

20. Site Classification

21. Site-Specific GroundMotions

22. Maps

23. Reference Docs

11A. Quality Assurance11B. Existing Buildings


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Seismic Contents Comparison

1997 UBC and ASCE 7-05

1997 UBC

1626 1628 General,Definitions, Glossary

1629.1 1629.4 CriteriaSelection

1629.5 1629.10, 1630,1631.1- 4, 1633 BuildingSeismic DesignRequirements

(Simplified Design notin 1997 UBC)

ASCE 7-2005

11. Basic Seismic DesignCriteria

11. Basic Seismic DesignCriteria

12. Seismic DesignRequirements for Bldgs.(no simplified analysis)

12.14 Simplified BuildingDesign


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Seismic Contents Comparison

1997 UBC and ASCE 7-05

1997 UBC

Figure 16-2 Seismic & Near

Source Maps

Chapter 17 Tests and

InspectionChapter 18 Foundations

Chapter 19-24 Materials

Chapter 34 Existing BldgsChapter 35 References

ASCE 7-2005

22. Contour maps and

website

Appendix 11A* QA

Section 12.13 Fndns

14. Materials*

Append. 11B* Existing Bldg23. References


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Seismic Contents Comparison1997 UBC and ASCE 7-05

1997 UBC

Appendix Chapter 16Seismic isolation

Not in 1997 UBC

Not in 1997 UBC

Not in 1997 UBC

ASCE 7-2005

17. Seismic Isolation

18. Systems with

Supplemental Damping

19. Soil Structure Interaction

21. Site Specific SeismicHazard Requirements.


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Summary Regarding Reorganization

California engineers have already beentransitioning to the NEHRP Requirements and

ASCE 7-05 when using the 1997 UBC

California engineers actually fortunate that theydid not have to use 2003 IBC and ASCE 7-02. The

reformat is much better for common usage

While terminology is different, the actual designrequirements are reasonably similar except for the

Central Valley This did not happen by accident.

_ASCE SEI 7-2005 Seismic Design Provisions, Overview

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