Charged with reducing the complexity of existing seismic safety codes, the Simplified Seismic Design Procedures Project Management Committee (PMC) met in San Francisco on January 11 to review a detailed plan of action for 2011. The project was initiated in response to concerns expressed by engineers and building officials that the complexity of current code provisions is reducing the efficiency and reliability of seismic design, particularly for simple and small buildings. Based on its work during 2010, the PMC recommended three initiatives be pursued to develop simplified seismic provisions:
1. Refine and further simplify Minimum Design Loads for Buildings and Other Structures, Standard ASCE/SEI 7-10 Section 12.14,
2. Develop stand-alone seismic design provisions for Seismic Design Category B buildings, and
3. Develop stand-alone seismic design provisions for buildings with rigid walls and flexible diaphragms.
Separate working groups are addressing each topic. Groups for Initiatives 1 and 2 have already begun work. Given limited resources, the group responsible for Initiative 3 will focus its efforts on discussing design requirements for the subject buildings with Canadian researchers and refining a plan for the overall effort.
PMC members include William T. Holmes, Rutherford & Chekene, San Francisco; James R. Harris, PhD, PE, J. R. Harris & Company, Denver; John D. Hooper, Magnusson Klemencic Associates, Seattle; Dominic J. Kelly, Simpson Gumpertz & Heger, Waltham, Massachusetts; and Barry Welliver, BHW Engineers, Draper, Utah.
Development of Simplified Seismic Design Procedures: A Framework Report, provides detailed documentation of the work that was competed on this project in 2010. The report describes the PMC’s examination of past efforts intended to simplify seismic design provisions, the results of its efforts to obtain input from engineers around the United States, and its recommendations of initiatives for further development. See the report.
Many code development groups and organizations have previously sought ways to alleviate these concerns through the development of design guides, flow charts and simplified provisions for certain small buildings. However, it is widely recognized that efficient seismic design is often a complex process, particularly for non-standard buildings, and that the basic seismic design provisions need to be complete – and possibly complex – to cover all buildings. Some of the previous attempts at simplification of seismic design for specific building types have not been pursued because of the need to prove the equivalency of the proposed provisions to the full code. Now, a methodology to show equivalency to code-mandated seismic performance is available (FEMA P-695) and can be used to develop more innovative provisions for narrow ranges of building types or levels of seismicity.
