Seismic Performance Evaluation for Steel Moment Frames

Abstract

A performance prediction and evaluation procedure based on nonlinear dynamics and reliability theory is presented. It features full integration over the three key stochastic models: ground motion hazard curve, nonlinear dynamic displacement demand, and displacement capacity. Further, both epistemic and aleatory uncertainties are evaluated and carried through the analysis. A suite of uncertainty analyses are input to the procedure such as period, live load, material properties, damping, analysis procedure, and orientation of the structure. Two limit states are defined instead of the traditional single state. The procedure provides a simple method for estimating the confidence level for satisfying the performance level for a given hazard. The confidence level of a post- and a pre-Northridge nine-story building for a given hazard level is calculated using the procedure described in the paper. New steel moment frame buildings are expected to perform much better during major earthquakes than existing buildings designed and built with older technologies.