Copula-based joint probabilistic model of earthquakes and rain for the failure assessment of masonry-adobe structures

Abstract

Earthquakes are the most harmful natural hazard to engineering structures. During a rain event, the increased moisture content in the adobe walls of masonry-adobe composite structures may lead to short-term degradation in wall capacity. Neglecting this degradation will result in large errors in the risk assessment of structures subjected to an earthquake that occurs after a heavy rain. In this paper, marginal probability distribution models of the earthquake intensity and rain intensity were separately established based on a large amount of measured data for areas with frequent high-intensity rainfall events. A copula-based joint probabilistic model of earthquake intensity and rain intensity was proposed and subjected to a goodness-of-fit test to obtain the multihazard joint return period and annual exceedance probability. Additionally, a failure risk assessment method for masonry-adobe composite structures was proposed based on the multihazard joint probabilistic model and structural vulnerability analysis. The proposed method was used for the risk assessment of a single-story masonry-adobe composite structure. The results showed that the seismic failure probability of the structure was 142% higher when the rain-based degradation of the adobe wall was considered than when this degradation was neglected. Therefore, the accuracy of failure probability calculations for masonry-adobe composite structures can be improved by using the multihazard joint distribution.