STAGGERED TRUSS FRAMING SYSTEM IN AREAS OF MODERATE-HIGH SEISMIC HAZARD

摘要

Changes in the National Earthquake Hazards Reduction Program (NEHRP) seismic regulations for new buildings have forced practicing structural engineers throughout the United States to consider seismic hazard in the design of many new building structures. In areas of moderate to high seismic hazard, the structural engineer is required to design framing systems that retain structural stability after seismic force resisting elements have yielded (or in some cases failed) while providing some level of energy dissipation. The staggered truss system is unlike all others used in areas of moderate and high seismic hazard; the seismic force resisting system is integral with and reliant upon the robust performance of a highly stressed gravity force resisting system. Gravity force resisting systems are expected to behave elastically for all applied loads while seismic force resisting systems are expected to yield under certain levels of applied seismic force. Currently, there are no building code provisions, seismic regulations or design manuals developed for the use of the staggered truss framing system in areas of moderate to high seismic hazard. For those engineers considering the use of this system in these seismically active areas, little information is available regarding seismic behavior. Intended for the practicing engineer, this paper provides a description and history of the system, a literature review of existing documentation, examines the system seismic behavior, provides insight into challenges associated with the design of the system and identifies some areas critical to consider when using the system in seismically active regions.