Development of time-dependent fragility functions for deteriorating reinforced concrete bridge piers

摘要

This is the second article of an effort to develop a time-dependent framework for earthquake risk assessment. In this paper, a model is developed for estimating fragility functions that depend on the degree of structural deterioration. The deterioration model presented in the first paper is used to model the change in the structure over time and due to exposure to different environmental conditions. The effect of deterioration on structural demand and capacities is considered in the evaluation of the fragility functions. Three reinforced concrete columns are designed to correspond to seismic design criteria in place in 1960, 1980 and 2000. Fragility functions are developed for non-deteriorating and deteriorating columns based on their age and environmental exposure. It is shown that the time of construction, which reflects the seismic design criteria, and the environmental conditions dictate the amount of structural deterioration. Older columns in highly corrosive environments show the highest vulnerability. Thus, ignoring the degree of deterioration can lead to a significant underestimation of damage and loss.