Comparison of Nonlinear Response Spectra of Elastoplastic Systems Resulting from Two Excitation Interpolation Methods

In this paper, the non-linear response spectra of elastoplastic systems with constant ductility for three accelerograms which were obtained by linear interpolation method of excitation and also by using cubic spline function are compared with each other. Non-linear response spectra were calculated for ductility of 1, 1.5, 2, 4 and 8. For a more detailed analysis, the time interval between the accelerogram points was divided into 2, 5, 10, 20, 50 and 100 equal parts, respectively, and new accelerograms were produced once using linear interpolation and once using spline interpolation, and the non-linear response spectra of these two types of accelerograms were compared. The results of the work indicated that the maximum and minimum values had significant values. In addition, in most cases, the maximum value of the difference was greater than the absolute value of the corresponding minimum difference. Also, in most periods, the spectral values did not differ much, but in small periods, which are related to stiff structures, the amount of difference was significant.