STUDY ON VERTICAL SEISMIC DESIGN SPECTRA OF NEAR FAULT AREA BASED ON CHINESE CODE

Due to the lack of vertical seismic design spectra for the structural design in near-fault regions, the near-fault vertical seismic design spectra are studied, which took the near-fault vertical ground motions as the research object and the format is compatible to the code for the building seismic design in China. The vertical components of 198 near-fault pulse-like ground motions are used to develop the near-fault response spectra. Results given by the comparison of the near-fault response spectra and code-specific near-fault design spectra in China show that the effects of near-fault vertical ground motion are not fully considered in Chinese seismic design code. What the amplitudes of the code-specific near-fault design spectra are smaller than that of the response one in some periods leads to difficulties in the safety of structures in near-fault regions. According to the results, a reasonable near-fault vertical seismic design spectrum, based on the code-specific seismic design spectra in China, is proposed with a spectral amplitude amplification coefficient of 1.5, restricted characteristic periods to no less than 0.40 s for frequent earthquake and 0.45 s for rare earthquake and a decreased attenuation coefficient. The proposed seismic design spectra are useful for the design of structures in near-fault regions.