Seismic assessment of steel moment frames using simplified nonlinear models

Abstract

This chapter discusses the effectiveness of simplified nonlinear models for seismic assessment of steel moment frames using single and multi-mode nonlinear static methods. It is demonstrated that the nonlinear static procedure (NSP) has much value in understanding important behavior characteristics that are not being explored in a nonlinear response history analysis (NRHA) in which engineers usually focus on a “blind” demand/capacity assessment rather than interpretation and visualization of the steel frame behavior. It is also shown that NSP procedures have many limitations for quantitative assessment of steel moment frame demands even for low-rise frames. The conclusion is that both NSP and NRHA have intrinsic value and that it is advisable to employ a combination of both to understand seismic performance of steel moment frames and to quantify important engineering demand parameters for these lateral resisting structural systems.