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William T. HolmesRutherford
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1. William T. Holmes
Rutherford & Chekene
1 FEMA Task Order to BSSCThe Simplified Seismic Design Project William T. Holmes
Structural Engineer
Rutherford & Chekene
San Francisco, CA
2. William T. Holmes
Rutherford & Chekene
2 Team FEMA Project Officer: Mike Tong
Project Management Committee
Bill Holmes, Chair
Jim Harris
John Hooper
Dominic Kelly
Barry Welliver
Project Review Committee-to be named
Development Working Groups-to be named
3. William T. Holmes
Rutherford & Chekene
3 Background Ongoing concern that the ratcheting development process of building code seismic regulations has resulted in complexities that may be counter-productive for providing performance objectives
Of some buildings
Designed by some engineers
Convention Construction rules and Simplified design base shear are examples of efforts from development of the UBC
4. William T. Holmes
Rutherford & Chekene
4 BSSC Efforts 1998-2000: Simplified Procedures Task Group
SPTG under TS 2 in 2000 Update
Developed three options
1. Clarify/simplify by editing, possibly for sub-groups of the entire building universe
2. Procedure with limited use simpler (but more conservative) than general code, but that can be shown to produce equal or safer structures that the full code
3. Procedure completely different than general code (perhaps capacity design), but that could be shownor judgedto be equivalent.
5. William T. Holmes
Rutherford & Chekene
5 Results from SDPG SPTG favored approach 3 (new procedures) but PUC discouraged its development due to concerns of equivalency.
SDPG developed provisions for rigid wall, flexible diaphragm buildings combining approach 1 and 2. Resulting Provisions achieved very little simplification and saw little, if any, of the light of day.
SDPG developed draft provisions for low-rise bearing wall and building frame systems that had simplified calculations (fewer) due to conservative base shear.
6. William T. Holmes
Rutherford & Chekene
6 2003 Provisions Update Simplified Design development effort from a stand-alone committee: Simplified Design Task Group
Simplify design for low rise by encouraging good buildings
Many limitations starting with 3 stories or less and Bearing Wall or Braced Frame Systems.
Limited irregularities
Limited layout of lateral force resisting system
Primarily simplified calculations, but not simplified concepts or reduced detailing requirements.
Appeared as appendix to Chapter 4, in 2003 Provisions
Was carried into ASCE 7-05
7. William T. Holmes
Rutherford & Chekene
7 Genesis of Current Project ASCE 7 Simplified Method not extensively used
FEMA continued to get complaints
Mike Tong solicited comments from a large number of stakeholders around the country and became convinced that additional effort was justified, especially considering
Advantages may result even if limited to moderate and low seismicity.
Advantages may result even if limited to a narrowly defined building typeif extensively built
FEMA P695 (ATC 63) is now available to demonstrate buildings designed by a procedure entirely different than the normal code are equivalent
8. William T. Holmes
Rutherford & Chekene
8 Summary Work PlanPhase 1 PMC performs initial investigation
Tasks and Report Organization
Summary of past efforts
Examples from other countries
Regional needs and potential building types
Development of Approach
Simplified/prescriptive/capacity design for specific building types
Confirmation lf acceptance with P695 Methods valid
Methods to incorporate into ASCE 7 or other reference location
Challenges/Restrictions of approach
Recommendations for one or more building types
Detailed Work Plan for Phase II
Meeting with Review panel of 12 or more members
Revise report considering input from review panel
9. William T. Holmes
Rutherford & Chekene
9 Summary Work PlanPhase 2 FEMA/BSSC/PMC selects and hires Project Working Groups (PWGs) to develop procedures and run concurrent P695 type analysistwo such groups currently anticipated
PWG = practitioner/code writer + academic and student for analysis
PMC closely oversees development work
Results are reviewed by Review Panel and refined.
Results presented to PUC for review and possible action.
10. William T. Holmes
Rutherford & Chekene
10 Schedule Year 1
35% of development by PWGs by Sept 29, 2010.
Year 2
Balance of development subcontracts
Review Panel
Summary Report and Recommendation
Report to PUC