Application of Endurance Time Method in Nonlinear Seismic Analysis of Steel Frames

Abstract In Endurance Time (ET) method gradually intensifying acceleration functions are created in a manner that the linear and nonlinear response spectra of them, while being proportional to average of real earthquakes spectra, intensifies in a uniform manner with time. These functions are used as input functions for nonlinear time history analysis of structures and performance of structures is assessed based on the maximum time duration that they can meet the specified performance objectives. In this paper, application of the ET method in nonlinear seismic analysis of structures has been investigated. Numerical procedures and optimization techniques that are used for the production of acceleration functions are described. A set of three acceleration functions have been applied to various steel moment frames and the results of analysis are compared to the results of IDA analyses. ET results of different frames approved that this method can be a good instrument to estimate IDA results with reasonably good accuracy using a few number of time history analyses. It is proved that this method can be used in nonlinear analysis of structures as a powerful tool but more research in this area is required before ET method can be recommended for practical applications.