Effectiveness of cyclic pushover analysis in the prediction of seismic response of steel MRFs

Nonlinear static methods of analysis were developed to provide a level of accuracy of the seismic response of structures comparable with that of nonlinear dynamic analysis, but with a lower computational burden. Scientific literature offers a variety of nonlinear static methods of analysis, and some of them have also been recommended for the seismic assessment of structures by the American and European seismic codes. Although these methods of analysis are generally deemed accurate for the assessment of plane frames where the contribution of a single mode of vibration is significant, they are applied with a monotonically increasing lateral load and thus neglect the cumulative damage that occurs in the structural members due to repeated loading cycles. Because of this, they tend to overestimate the strength and stiffness, and generally underestimate the prediction of the displacement demand. To overcome this drawback, this paper investigates the possibility of conducting a Cyclic Pushover Analysis (CPA) to assess the seismic response of structures. To investigate the effectiveness of the CPA, a steel moment resisting frame has been assumed as case study building. The seismic demand of this frame has been determined by CPA and the cyclic response of the case study has been compared to that obtained by nonlinear dynamic analysis. Two sets of accelerograms are adopted to consider accelerograms that are characterised by similar response spectrum but different significant durations.