Damaging potential of low-magnitude near-field earthquakes on low-rise shear walls

Abstract

The purpose of this study is to show that small earthquakes close to the site cause less damage in reinforced concrete structure than what is implied by their peak or spectral acceleration, used often as indicators of the destructive potential of earthquake shaking. For this purpose, an important step is to set up a simplified model of a representative reinforced concrete structure, capable of reproducing the global damage. A non-linear single degree of freedom model of a low-rise shear wall, proposed in a previous paper, has been adopted [Eng Struct 25 (2003) 1]. In this paper, the validity of the simplified approach is confirmed by comparing numerical damage predictions engendered by 501 strong motion records with those provided by a finite element approach using local models. Thanks to the drastic reduction of the computation time, the interdependency between the seismic acceleration parameters proposed in the literature and the damage is explored. A spectral intensity, taking into account the degradation of the fundamental frequency, is proposed. The spectral intensity turns out to be much more independent of the distance and magnitude of the causative earthquakes than the PGA and the spectral acceleration at the initial frequency corresponding to the undamaged state.