A multi-mode displacement-based pushover (MDP) procedure for seismic assessment of buildings

Abstract

A new enhanced multi-modal pushover procedure based on the structural dynamic theory with a straightforward and easy-to-use algorithm is developed in this study for estimating the structural demands. The proposed method, which is called the multi-mode displacement-based pushover (MDP) procedure, consists of multiple single-run non-adaptive pushover analyses conducted using a range of enhanced displacement-based lateral load patterns proposed herein. These lateral load distributions are constructed by numerically adding and subtracting the modal displacement vectors modified using modification factors that are a function of the effective modal participating mass ratio (αn). The final seismic demands in the proposed procedure are computed by enveloping the results obtained by several single-run pushover analyses. The MDP procedure has the ability to account for the higher mode effects into responses, sign reversal in the modal load vectors due to the contribution of higher modes as well as the non-concurrency of the maximum modal responses. Less computational effort and time cost, compared to the adaptive methodologies, is another advantage of the proposed procedure. The accuracy and efficiency of the MDP procedure in estimating the structural demands are validated by applying it on three steel special moment frames (SMFs) with different heights. The results demonstrate that the proposed procedure is successful in predicting the critical seismic demands with acceptable accuracy.