An approach for estimating the response of steel moment resisting frames to pulse-like ground motions

Given the limitations of equivalent pulses in investigating the effects of pulse-like ground motions, the present study is mainly aimed at providing an approach to capture the maximum response characteristics of steel moment resisting frames using the simulated pulses. Accordingly, the behavior of three moment resisting frames of 3, 9, and 20-story buildings from the SAC project prior to the Northridge earthquake in the Seattle are investigated under pulse-like ground motions. Twenty-six pulse-like records from Imperial Valley and Northridge earthquakes in 1979 and 1994 are selected from the Next Generation Attenuation (NGA) Project database. The pulse-like records are developed in selected seismic regions by combining of high frequency content of records and artificial pulses. The inter-story drift, critical story, and base shear are evaluated as structural demand parameters using over 54000 nonlinear time history analyses. Then response contours are provided to determine the critical story, the largest normalized base shear, and estimate the structural damage. The results indicate the contribution of high frequency content to the response. The response contours are often conservative or offer acceptable estimates of the largest maximum inter-story drift and the largest normalized base shear.