Comparison the structural nonlinear response under traditional ida and the conditional spectrum-based selected earthquakes

Selecting sufficient number of appropriate ground motions compatible with regional tectonic condition is a major step in Incremental Dynamic Analysis method (IDA). This article is intended to compare and assess the nonlinear structural response of the selected four frames (two steel moment-resisting frames and two RC Special Moment Frames) through performing IDA method by use of the traditional and Conditional Spectrum methods. First, the CMS and CS approaches are briefly explained and discussed. The selected frames are dynamically nonlinearly analyzed using the traditional IDA and CS methods at four hazard levels (50%, 10%, 2%, and 1%). The plots of results obtained from the two approaches, in the form of mean curves, are compared and assessed. It is concluded that the CS method ends up with more reasonable results except in case where the frame poses structural instability as the result of using CS method. The necessity of performing more research work in this area is highlighted.