Evaluation of lateral load pattern in pushover analysis

Abstract

The objective of this study is to evaluate the performance of the frame structures for various load patterns and a variety of natural periods by performing pushover and nonlinear dynamic time history analyses. 3, 5, 7, 9 and 13-story moment steel frame structures are used in the analyses and the load distributions for pushover analyses are chosen as triangular, IBC (k=2) and rectangular. These frames have five different natural periods. Even though the nonlinear dynamic time history analysis is the best way to compute seismic demands, FEMA-356 and ATC-40 proposes tthe use of nonlinear static procedure or pushover analysis. The five frame structures have been analyzed using the nonlinear program SAP2000. This paper is also intended to compare the results of pushover and nonlinear dynamic time history analyses. To evaluate the results from the pushover analyses for three load patterns and also five natural periods, nonlinear dynamic time history analyses are performed. Earthquake ground motions recorded at 3 stations during various earthquakes are used in the analyses. The ground motion records used in this study include TABAS, NAGHAN and ELCENTRO. Pushover and nonlinear time history analyses results are compared to choose the best load distribution for a specific natural period for this type of frame structure.