ИСТИНА

Site response on seismic loading is analyzed. Two approaches to site profile behavior are considered: elastic (linear) and viscoelastic (equivalent linear modeling). Four typical soil profiles are taken into account; input peak values are within the range from 0.1 to 0.6g. For all the profiles, when ignoring the non-linear behavior the calculated impacts are still within the standard response spectrum used in Russian codes. When the non-linearity is taken into account the result is completely different. The standard spectrum is abundantly conservative for high frequencies, meanwhile it essentially underestimates the level of hazard at low frequencies. Therefore, the shape of standard spectra in a whole does not describe adequately seismic hazard, especially when the input signal is higher than 0.2g.