Effect of Number of Contribued Modes on Accuracy of Multi-Modal Pushover Seismic Analaysis of Irregular Frames

One of well-established static procedures for seismic evaluation and design of building structures in the equivalent nonlinear static procedures is Modal Pushover Analysis developed by Chopra and Goel (2002). For evaluation of effect of number of contributed modes on the accuracy of MPA procedure, 22 vertically irregular 5-story steel moment resisting frames are considered that each irregular frame is designed to represent low and high values of response reduction factor (R). Many nonlinear time histories and static pushover analyses are performed and the results of nonlinear static analyses are compared with the results for nonlinear dynamic analyses to evaluate the accuracy and conservatism of MPA for predicting target displacement, base shear, and story drifts.

Keywords:

Equivalent nonlinear static analysis , Irregular frame , Modal pushover analysis , Seismic modeling , Steel moment resisting frame