Variability and Accuracy of Target Displacement from Nonlinear Static Procedures

This paper compares the target displacement estimate from four current nonlinear static procedures—FEMA-356 CM, ASCE­ 41 CM, ATC-40 CSM, and FEMA-440 CSM—with the value derived from recorded motions of five strongly shaken reinforced concrete buildings.This comparison provides useful insight into two important questions: (1) how much does the target displacement vary among the four nonlinear static procedures? and (2) can the engineering profession “accurately” predict the response of a real building during an earthquake event using currently available modeling techniques and pushover analysis procedures? It is shown that these procedures may lead to significantly different estimates of the target displacement, particularly for short-period buildings responding in the nonlinear range. Furthermore, various nonlinear static procedures applied to nonlinear models developed using generally accepted engineering practice provide either significant over estimation or under estimation of the target roof displacement when compared to the value derived from recorded motions.