EFFECT OF GRAVITY LOADING ON INELASTIC SEISMIC DEMAND OF STRUCTURES

Abstract

Performance based seismic design requires precise assessments of inelastic seismic demand. Often, the studies to assess such demands are made without due cognizance to the impact of axial load caused by gravity. In this paper, the effect of gravity-induced axial force on load resisting members on such demand quantities is examined. To encompass the behavior of steel as well concrete structures with various types of degrading features, four different hysteresis models are used in the study. The results show that the effect of axial force on inelastic seismic demand become more significant for systems with short periods having degrading hysteresis behavior. Neglecting the effect of axial force may lead to an underestimation of yield capacity resulting in an overestimation of demand implying a safer design.