Design-oriented approximate bound of inelastic responses of a structure under seismic loading

Abstract

The purpose of this paper is to propose an approximate upper bound of inelastic responses of a structure under a set of spectrum-compatible earthquakes. The acceleration response spectrum is assumed to be a nonincreasing function of period for a constant damping factor and to be a nonincreasing function of damping factor for a constant period. Most of the previously proposed design acceleration response spectra appear to satisfy these assumptions except in a narrow range of quite small period. The feature of the present study is that the upper bound (design-oriented upper bound) of story ductility factors can be drawn only when combined with a design method for uniform ductility which is recognized in general to be desirable for avoiding damage concentration. Inelastic time-history response analyses are performed in order to investigate the accuracy of the upper bounds and to examine the validity of an equivalent linearization technique employed in this paper.