Abstract
In standard design codes for civil infrastructures, earthquake motion characteristics are often defined by acceleration response spectra for the convenience of design purpose. The earthquake motion time history necessary for dynamic analyses are requested to be compatible with those design response spectra. In the current design code only elastic acceleration response spectra are considered for this purpose. But in the design codes taking into account the level 2 earthquake intensity structures are designed by considering their dynamic behavior in non-elastic region, therefore if their seismic performance is checked by dynamic analysis using an earthquake motion compatible with the elastic acceleration response spectrum, it has been pointed out for long time that its non-elastic behavior cannot be properly guaranteed. Moreover non-linear response spectra with the ductility factor as a design parameter are often used for designing structures to simplify the design method in the performance-based design. Therefore in this research we develop a method to define an earthquake motion simultaneously compatible with a group of non-linear response spectra. This method can modify the selected original time history of earthquake motion as to be compatible with non-linear response spectra. For this purpose using the method that time and amplitude adjusted short period Ricker wavelets are superposed to the original time history and the equivalent linearization technique, we develop the algorithm to adjust the amplitude of each wavelet so that a recalculated nonlinear response spectra using the modified earthquake time history can converge to the group of the target nonlinear response spectra.
