DEFINITION OF SUITABLE BILINEAR PUSHOVER CURVESIN NONLINEAR STATIC ANALYSES

摘要

Reliability of results obtained through nonlinear static analyses is strongly dependent on the assessment ofthe performance point, usually computed by means of the capacity spectrum method. The use of constantductility spectra as demand spectra, in place of reduced spectra for assigned equivalent viscous damping,can provide better results and a larger stability in the evaluation method of the performance point. In thiscase, the capacity curve of the SDOF equivalent system has to be transformed in a bilinear curve forcomputing the available ductility. Such a conversion can be performed according to several criteria thatsignificantly influence results. In this paper, results of analyses carried out in order to assess thedependence of the performance point value on parameters controlling the bilinear relationship and onconversion procedure are shown. Reliability and accuracy of procedures proposed by ATC 40, Eurocode 8and italian seismic code PCM 3274 as well as of procedures based on the use of constant ductility spectrais assessed by comparing results with the ones from nonlinear dynamic analyses.