Geometrical Imperfections on Inelastic Frame Behavior

Abstract

A methodology for the analysis of geometrically imperfect framed structures that takes into consideration geometrical and material nonlinearities is presented. The analysis is an extension of the pseudo-load method for geometrical and material nonlinear frame analysis by Lui in 1988, and Lui and Zhang in 1990. In the formulation, geometrical imperfections present in the form of initial crookedness and out-of-plumbness are accounted for by a pseudocurvature loading on the member. A parametric study of inelastic framed structures with geometrical imperfections has indicated that the effect of the out-of-plumbness of the frame is more significant than the effect of out-of-straightness of the member. A moment-magnification factor that accounts for the out-of-plumbness effect in building design is proposed.