Building structures are typically designed using the assumption that the floor systems serve as a rigid diaphragm between the vertical elements of the lateral force-resisting system (lateral system). However, perimeter lateral-system structures with long floor spans possess diaphragms that behave quite flexibly. Difficulty can exist in predicting diaphragm force demand in these structures. Thus, current design may provide insufficient strength to maintain elastic diaphragm response. Inelastic diaphragm response exacerbates the effects of diaphragm flexibility. Such response may lead to poor seismic performance, including nonductile diaphragm failure or structural instability due to high drift demands in the gravity system. An analytical study was performed to determine the effect of diaphragm flexibility and strength on the seismic performance of perimeter lateral-system structures with highly flexible diaphragms. Nonlinear transient analyses were performed using ground motions suites corresponding to multiple levels of hazard for high seismic zones. Design recommendations for flexible diaphragms are presented.
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology