Fragility Functions for Older Rc Beam-column Joints

A critical step in performance-based seismic design is the prediction and definition of earthquake performance using terms that are meaningful to building owners. Recently, economic impact, defined as the cost of repairing earthquake damage and the building downtime required to complete the repair work, has been adopted as a meaningful measure of building performance. To enable earthquake engineers to predict the economic impact of earthquake loading, models are required linking the engineering measures used traditionally to define building performance with damage, repair methods, economic loss and repair time. The work presented here develops these models for older reinforced concrete beam-column joints. The results of previous research are used to develop empirical relationships between damage states and traditional engineering response measures, such as inter-story drift, joint deformation and number of loading cycles. The proposed damage states are characterized by parameters such as concrete crack width, extent of concrete spalling and yielding and buckling of reinforcement. The results of previous research and practical experience by engineers and contractors are used to define a series of repair methods that can be used to restore a damaged joint to its original condition. Each damage state is associated with a specific repair technique, and probabilistic models are developed to enable prediction required repair.