Research On The Earthquake Spectra For Site Class Ⅲ

Since the performance based seismic design is becoming the trend of the earthquake engineering, this paper tends to research the response spectra including acceleration, velocity, displacement spectra, the energy spectra and the performance objective based spectra in performance based seismic design. The contents and conclusions are shown as follows:(1) The method of the ground motion data processing and grouping are recommended in this paper, the theory of the earthquake spectra, the proceedings of the earthquake spectra and the influencing factors are introduced. Besides, the earthquake ground motion data used in this paper are grouped according to the design earthquake group in Chinese code.□The elastic and inelastic spectra of the 342 ground motions are calculated based on the time history analysis. The empirical probability distributions of the spectral value of acceleration, velocity and displacement spectra for each period are derived according to the goodness-of-fit test. The simplified equations for acceleration, velocity and displacement spectra are given, the equations are simply and can be easily used in engineering design. The research can provides the foundation for the performance based seismic design.□Based on the energy response of the SDOF systems calculated using 342 ground motions, the energy spectra with different damping ratio (ξ=2%, 5%, 10%, 20%) and different ductility demand(μ=1,2,4,6,8) are derived. The influencing of the ductility demand, the damping ratio and design earthquake group to the energy spectra are analyzed.□Based on the determined performance objectives of the structures, the performance spectra of different performance levels are derived by making the response of the SDOF systems reach to the performance objectives under earthquake ground motions.