A modified approach of energy balance concept based multimode pushover analysis to estimate seismic demands for buildings

摘要

The procedure of energy balance concept based multimode pushover analysis incorporates concepts in capacity spectrum method and retains computational attractiveness with invariant force distribution, which includes the contributions of higher significant modes, and estimates the seismic demands of buildings quite accurately. Developed in this paper is a modified energy balance concept based method in which the response contributions of higher vibration modes are computed by assuming the building to be linearly elastic, thus reducing the computational effort. The modal energy capacity and demand diagrams of the buildings are constructed, and the dynamic target point is the intersection of the corresponding two diagrams. Moreover, the proposed procedure's accuracy is evaluated for buildings subjected to a variety of ground motion ensembles, including near-fault ground motions with fling-step and forward directivity pulses, and in the process of investigation some specific observations of near-fault ground motions are obtained. The statistical predictions of seismic demands of building under selected ground motions compared with the estimates of nonlinear response history analysis (NL-RHA) demonstrate that the proposed procedure is an attractive alternative for practical application.