Consideration of the near‐fault effect on seismic design code for sites near the Chelungpu fault

Abstract

Abstract In this paper, based on the concept of UBC97, the modification of the design response spectrum in the current Taiwan seismic design code for sites near the Chelungpu Fault is proposed by defining the so‐called near‐source factors to increase the seismic capacity of buildings against near‐fault ground motions. The near‐source factors can be defined for different structural period ranges by the near‐fault attenuation functions for PGA and spectral acceleration demands at 0.3 and 1. 0 second periods, respectively. These attenuation functions are determined from the data recorded at sites near the Chelungpu Fault during the Chi‐Chi (Taiwan) Earthquake on September 21, 1999. Furthermore, the normalized inelastic near‐fault design base shear coefficients can be defined by the normalized near‐fault design response spectrum as well as the reduction factor for a specified ductility ratio and structural period as defined by the seismic design code. Finally, based on the near‐fault ground motion data recorded during the Chi‐Chi (Taiwan) Earthquake, the demand of the normalized inelastic base shear coefficients can be determined numerically by the EPP model. It can be used to verify the capacity of buildings defined by the modified seismic design code to resist the threat of near‐fault ground motions.