Evaluation of Bridge Damage Data from the Loma Prieta and Northridge, California Earthquakes

The overall objective of this task was to correlate observed bridge damage resulting from the 1989 Loma Prieta and 1994 Northridge earthquake to the local ground motions, bridge structural characteristics, and repair costs and time. Damage states reported after the earthquakes were investigated and new damage state definitions for concrete bridges were proposed. Bridges were grouped by their structural characteristics and correlation studies were performed to obtain ground motion-damage relationships and ground motion-repair cost ratio relationships. Logistic regression analysis was used to obtain empirical fragility curves. Currently available fragility curves and damage probability matrices were compared to observed damage data and the empirical relationships developed in this study.