Testing the acceleration spectra given by China and USA seismic codes based on energy supply in near-fault region

摘要

For near-fault ground motion, there should be a remarkable impulsive energy supply. Therefore, it is essential to check the validity of actual seismic design codes with energy balance concept. Based on the relationship between the spectrum velocity and the input energy equivalent velocity with 5% damping ratio, the input energy spectra compatible with main China and USA seismic codes were derived, and the accuracy and applicability were veri-fied by using near-fault records. The recommended energy input design spectrum (EIDS) applicable to the distance of 0-15 km from fault was introduced to check the validity of modem seismic codes. Comparison tests show that the GB50011-2001 Code of China can just match the energy effect of near-fault ground motion to a certain extent only under seldom occurred earthquake with fortification intensity of 9 degree for site soil of IU and IV, indicating that the impact of near-fault effect has not been embodied in the current code acceleration spectrum. In order to make the design spectrum be applicable to near-fault region, it is necessary to adjust the spectrum platform pa-rameters. On the contrary, for distinct fault distance and site soil, the UBC97 Code of USA can match well with the energy supply of near-fault ground motion except for the site soil of hard rock (SA). Accordingly, correctness of the formula derivation in this paper is certified.