Current Practice and Future Trends for Seismic Design for Buildings in New England

Although it has not always been the case, requirements for design of buildings to resist earthquake effects are currently mostly uniform throughout New England. At this time, virtually all jurisdictions in New England have based their design requirements on a model building code that adopts ASCE/SEI 7 for most seismic design requirements. Not only are the current design requirements similar throughout New England, practicing engineers approach design similarly. For example, structural engineers generally design buildings with seismic-force-resisting systems that are commonly used. These systems are generally lower ductility systems, and systems intended to provide high ductility are rarely designed and constructed. Although design approaches similar to current approaches will likely continue, more interest in higher ductility systems is likely as new ductile systems that are less difficult to construct and more cost efficient are introduced. Also, there should be continued interest in requirements for masonry construction and how to address unreinforced masonry existing buildings. Initiatives are currently underway that will impact seismic design provisions in the future. Several of these initiatives, if incorporated into ASCE/SEI 7, will affect seismic design requirements and structural design practice in New England. The initiatives likely to affect design for earthquake effects in New England include creation of design provisions that are applicable only to seismic design category (SDC) B buildings, revisions to the Simplified Seismic Design Procedure in ASCE/SEI 7, improved estimations of diaphragm force levels and ductility, a design approach applicable to buildings dominated by the response of a roof diaphragm, strength design for foundations, revised soil site factors, revised seismicity maps, and revisions to seismic design category criteria. These initiatives are described herein.