Adaptive Pushover Analysis

Nonlinear static methods are simplified procedures in which the problem of evaluating themaximum expected response of a MDOF system for a specified level of earthquake motionis replaced by response evaluation of its equivalent SDOF system. The common features ofthese procedures are the use of pushover analysis to characterize the structural system. In pushover analysis both the force distribution and the target displacement are based on the assumptions that the response is controlled by the fundamental mode and that the mode shape remains unchanged after the structure yields. Therefore, the invariant forcedistributions does not account for the change of load patterns caused by the plastic hingeformation and changes in the stiffness of different structural elements. That could have some effects in the outcome of the method depending on different structural parameters. This paper introduces an adaptive pushover analysis method to improve the accuracy of the currently used pushover analysis in predicting the seismic-induced dynamic demands of the structures. Comparison of the common pushover analyses, adaptive pushover analyses and time-history analyses performed for a number of multiple-bay, short and high-rise steel structures, demonstrates the efficiency of the proposed method.