Accuracy of the N2 and overdamped spectrum method for different hysteretic models

"In this work an extensive parametric analysis was carried out to evaluate the structural dynamic behaviour varying the hysteretic behaviour of a structure. In particular, SDOF systems have been analysed with elasto-plastic and flag-shape cyclic behaviour, the latter one with three different cycles amplitude, with the aim to investigate the accuracy of the inelastic spectra given by the N2 and overdamped spectrum methods. The analyses were carried out. with a purposely developed software that uses the Newmark method to determine the non-linear response of SDOF systems. By using a set of 15 recorded earthquake ground motions which are, with their average values, spectrumconsistent, the response spectra were calculated for different ductility values. The analysis was then extended to. MDOF structures in order to validate what observed in the SDOF systems. In both cases, the analyses demonstrated. the accuracy of the N2 method, also for the hysteretic behaviour characterised by reduced energy dissipation, whereas larger approximations were detected by the overdamped spectrum method."