Approximate Evaluation of Deflection Amplification Factor

Abstract

In seismic design provisions, the maximum story drift occurring in major earthquakes is estimated by amplifying the drifts computed from an elastic analysis at the prescribed design seismic force level with a deflection amplification factor. A survey of several seismic design provisions indicates that the deflection amplification factor, in most of the provisions, is independent of significant factors such as ductility ratio, fundamental period, and number of stories. In this paper, a statistical evaluation of deflection amplification factor is presented in order to indicate the parameters that have an effect on this factor. Elastoplastic multidegree of freedom (MDOF) models with various dynamic characteristics are first considered. Consequently, nonlinear and corresponding linear time history analyses for 21 severe earthquake ground motions are performed in order to obtain structural response data, which are then used to derive an empirical formula for the deflection amplification factor. Finally, an app...