Seismic Performance of Low-Rise Steel Perimeter Frames

The seismic response arising from strong ground motions of steel frames constructed with moment-resisting connections causes significant inelastic deformations in the members and connections. The inelastic behavior is dependent upon several design parameters, such as proportioning and selection of members, magnitude of design base shear, and configuration of lateral force-resisting system. The influence of these parameters was investigated by performing inelastic time-history analyses of six variations of a structural frame for a typical five-story building. The direct design procedure adopted in the 1988 edition of the Uniform Building Code was used in the seismic design of the steel frames that were providing all of the lateral stability. The computed inelastic behavior for each frame design is compared with the expected behavior as envisioned by the code. The results reveal the calculated story drifts are larger than the acceptable limits for the structural frames investigated in this study when subjected to the design earthquake. Design implications with regard to the provisions of the direct design procedure are suggested to improve the structural performance of low-rise steel frames subjected to strong ground motions.