Design spectra including effect of rupture directivity in near-fault region
Xu Longjun (ÐìÁú¾ü)1,2,
Adrian Rodriguez-Marek3
and Xie Lili (лÀñÁ¢)2
1. College of
Engineering, Ocean University of China, Qingdao 266100, China
2. School of Civil Engineering, Harbin Institute of Technology, Harbin 150090,
China
3. Department of Civil and Environmental Engineering, Washington State
University, Pullman, WA 99164-2910, USA
Abstract: In order to
propose a seismic design spectrum that includes the effect of rupture
directivity in the near-fault region, this study investigates the application of
equivalent pulses to the parameter attenuation relationships developed for
near-fault, forward-directivity motions. Near-fault ground motions are
represented by equivalent pulses with different waveforms defined by a small
number of parameters (peak acceleration, A, and velocity V; and pulse period,
Tv). Dimensionless ratios between these parameters (e.g., ATv /V, VTv /D) and
response spectral shapes and amplitudes are examined for different pulses to
gain insight on their dependence on basic pulse waveforms. Ratios of ATv /V, VTv
/D, and the ratio of pulse period to the period for peak spectral velocity
(Tv-p) are utilized to quantify the difference between rock and soil sites for
near-fault forward-directivity ground motions. The ATv /V ratio of recorded
near-fault motions is substantially larger for rock sites than that for soil
sites, while Tv-p /Tv ratios are smaller at rock sites than at soil sites.
Furthermore, using simple pulses and available predictive relationships for the
pulse parameters, a preliminary model for the design acceleration response
spectra for the near-fault region that includes the dependence on magnitude,
rupture distance, and local site conditions are developed.
Keywords:
near-fault ground motion; pulse; attenuation relation;
velocity pulse period; design spectrum
