Inelastic Earthquake Response of Steel Structures

Abstract

Results from experiments in which small three story steel frame structures were subjected to simulated earthquake motions by means of a shaking table are described. The structures, weighing 132 lb (60 kg), and consisting of 1/2 in. × 1/4 in. (13 mm × 6 mm) rectangular columns and rigid beams, were designed to reproduce the overall seismic behavior of shear‐type buildings. The motions caused large inelastic deformations in the first‐story columns. The results of the experiments were used to evaluate the accuracy of a computer program by comparing computed time histories and hysteresis loops with those obtained experimentally. It is concluded that the computer program, DRAIN‐2D, can reproduce the general features in the response of these three story structures to earthquake motions even if there are large excursions into the inelastic range of behavior. However, in order to reproduce the response precisely, the simple bilinear moment‐rotation relationship used to specify nonlinear behavior would have to be modified to account for cyclic strain hardening.