Pushover analysis of mdof systems: Explanation, demonstration and performance study

Abstract

Pushover analysis is used as an alternative to nonlinear dynamic analysis for estimation of inelastic seismic demands required for performance based design. It is rapidly gaining popularity in design offices because its application requires only simpler nonlinear static analysis instead of rigorous nonlinear dynamic analysis. To establish the domain of the applicability of various Pushover procedures for multidegree of freedom (MDOF) systems their performances are investigated for fundamental periods varying from 0.1s to 3.0s. The performance is expressed by the ratio of ductility demands obtained by.the Pushover procedures to the actual values obtained by the nonlinear dynamic analysis. Contribution of higher modes in MDOF systems in Pushover is also studied through few representative cases. Derivations of the theoretical formulations used in Pushover analysis are demonstrated to highlight the assumptions involved. A limited study on comparison of the performances for single degree of freedom (SDOF) and MDOF system is also included.