Effect of gravity load on seismic response of steel-framed structures

Abstract

The effect of gravity load on inelastic seismic response of steel framed structures is investigated in this study. For this purpose, a new plastic hinge model is developed to represent inelastic behavior of beams in a structure considering the gravity load effects. From seismic analysis on an idealized frame structure using the layer model, it has been found that the hysteresis curve for the inelastic moment-rotation relationship is shifted toward the positive moment direction due to the gravity load moments, The properties of the plastic hinge model are derived from the results of the inelastic analysis on the one-story structure using the layer model. Then inelastic analyses on various multi-story steel frames are performed using the proposed plastic hinge model. The results indicate that seismic responses such as ductility demand, damage index and interstory drift may be underestimated, particularly on the lower stories of structures, if the gravity load moments are not considered in the analysis. (C) 1997 Elsevier Science Ltd.