VERIFICATION OF DISPLACEMENT-BASED PUSHOVER THROUGH INCREMENTAL DYNAMIC ANALYSIS (IDA)RESULTS

In recent years, nonlinear static analysis has received a great deal of research attention within the earthquake engineering community. For this reason, many codes and guidelines recommend the use of nonlinear static methodology to evaluate structural behavior under seismic action.During a pushover analysis, a frame structure is subjected to gravitational loads and horizontal loads applied at each storey, with the latter being incremented up to failure. Incremental Dynamic Analysis (IDA) is a parametric method where a structure is subjected to a series of nonlinear time-history analyses of increasing intensity, with the objective of attaining an accurate indication of the nonlinear dynamic response of a structure under earthquake action. The present study aims at validating pushover methodologies for steel moment frame structures through comparison with incremental dynamic analysis. A large number of design spectrum compatible time-histories have been used to perform IDA. The steel moment frame structures are design based on Iranian steel code, whereas design spectra are chosen through Iranian earthquake code (2800 standard). Simulated accelerograms have been preferred over natural time-histories. In this way a homogeneous and as large as required sampling of time-histories could be readily generated and employed. A large number of nonlinear time-histories have been done to perform incremental dynamic analysis, and a statistical verification of pushover methods for frame structures has been carried out. The ability of pushover methods to reproducethe result of nonlinear dynamic analysis has been assessed by comparing capacity curves with IDA results.