Effects of hanging wall and forward directivity in the 1999
Chi-Chi earthquake on inelastic displacement response of structures
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Li Shuang (Àî ˬ)1 and Xie Lili (лÀñÁ¢)1,2
1. School of Civil Engineering, Harbin Institute of Technology, Harbin
150090, China
2. Institute of Engineering Mechanics, China Earthquake Administration, Harbin
150080, China
Abstract:The
characteristics of the inelastic response of structures affected by hanging wall
and forward directivity in the 1999 Chi-Chi earthquake are investigated.
Inelastic displacement ratios (IDRs) for ground motions impacted by these
near-field effects are evaluated and comprehensively compared to far-field
ground motions. In addition, the inelastic displacement responses to hanging
wall and footwall ground motions are compared. It is concluded that the
inelastic displacement response is significantly affected in the short period
range by hanging wall and in the long period range by footwall. Although high
peak ground acceleration was observed at hanging wall stations, the IDRs for
structures on hanging wall sites are only larger than footwall sites in the very
long period range. Forward directivity effects result in larger IDRs for periods
longer than about 0.5s. Adopting statistical relationships for IDRs established
using far-field ground motions may lead to either overestimation or
underestimation in the seismic evaluation of existing structures located in
near-field regions, depending on their fundamental vibration periods.
Keywords: near-field; far-field; hanging wall;
footwall; forward directivity; inelastic displacement; performance evaluation;
Chi-Chi earthquake
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