Post-earthquake effects on the seismic performance of concrete gravity dams

Abstract

Seismic damage assessment of concrete gravity dams is a challenging task due to the difficulty in establishing the damage states in relation to target performance levels. Post-seismic loading and uplift in cracking is generally not considered in this complex assessment and the effects are not clear. A quantitative damage estimation approach considering post-earthquake effects is proposed in this work to investigate this issue. A novel procedure to include post-earthquake effects on the monolith cracking was proposed in which demands from the aftershocks and uplift are assessed on the cracked state after the main event. Damage state was quantified in terms of the extent of crack propagation on the dam monolith. Categorising performance as such, the effects of post-earthquake factors were investigated on three representative systems in two steps. First, over 2000 nonlinear time history analyses were conducted to obtain damage states for the main shaking event. Then, the change in these states due to the effect of post-earthquake factors, including water pressure penetrating the cracks and aftershocks, were quantified. The results, as well as the methodology proposed, can serve organisations managing dam stock risk in re-assessment of seismic analysis results considering post-earthquake effects.