عنوان مقاله [English]
Nonlinear time history analysis is the most accurate method for seismic response analysis of structures, and performing it for designing and evaluating purposes is inevitable in some cases. The most important issue in nonlinear time history analysis is the scaling method of ground motion records in order to have an accurate estimation of structural responses. In this paper, a new method for scaling of ground motion records is proposed, in which the nonlinear behavior of structures is considered. In the proposed method named SNSP (Scaling based on Nonlinear Structural Properties), the scaling factor of each record is determined in a way that the peak displacement of the equivalent single degree of freedom (SDOF) system subjected to the scaled record matches the target displacement. The target displacement is determined by averaging the values of the peak displacement of the equivalent SDOF system subjected to a large number of unscaled ground motion records. The characteristic parameters
of the equivalent SDOF system are determined based on the modal pushover analysis, in which the load pattern is derived from the modal story shear profile of the structure. Thus, in the equivalent SDOF system, the effect of higher modes and the interaction between them in the inelastic phase are considered. Furthermore, the characteristics of the selected ground motion records are also considered using their response spectra in the proposed scaling procedure. The accuracy and efficiency of the proposed method were verified through four 4-, 8-, 14- and 20-story buildings under 21 near-fault records and was compared with the scaling method of the Iranian code of practice for the seismic resistant design of buildings, Standard No. 2800. Results show that the structural responses obtained from the proposed scaling method are close to the average responses considering site-specific records and the dispersion of responses is low.