Reliability of Nonlinear Static Methods for the Seismic Prediction of Steel Frame Buildings

Abstract

This paper summarizes the results of current research, sponsored by the SAC Steel Project, on the reliability of nonlinear static methods for predicting the seismic performance of steel moment frame buildings. As part of previous SAC studies, three steel moment frame buildings (3, 9, and 20-story), located in Los Angeles, were designed using Pre-Northridge earthquake connection details. Two DRAIN-2D models (M1 and M2) were created for each building. Model M1 is a centerline-to-centerline model, while model M2 explicitly accounts for the strength and stiffness of the panel zone and represents the more accurate model. Nonlinear dynamic time history analyses were performed for each building model using a total of 60 earthquake ground motions with seismic hazard levels having a 2%, 10%, and 50% probability of exceedance in 50 years. In the current study, nonlinear static “pushover” analyses of the buildings were performed with the same models and ground motions used in the nonlinear time history analyses. The Coefficient Method, Capacity Spectrum Method, Equivalent System Method were used to calculate building performance response quantities. The maximum roof displacement and maximum interstory drift response for models M1 and M2 were compared with the model M2 results from the nonlinear dynamic time history analyses.