Reliability Importance as a Measure of Bridge Element Condition Index for Deteriorating Bridges

Abstract

As a concerted effort to improve the outcomes of bridge asset management, state highway agencies and Departments of Transportation (DOT) often improve their modes of bridge performance assessment using advanced deterioration models, optimized cost models, and other multi-objective preservation analysis in bridge monitoring processes. This paper attempts to utilize reliability importance index of a bridge component as a performance measure of the criticality of each element or subsystem to the entire bridge system. This paper investigates three major concepts regarding the importance of bridge elements: (i) the contribution of individual bridge elements to the overall reliability of the bridge system, (ii) the effect of critical elements on bridge deterioration, and (iii) the rank of the importance of elements and the potential economic consequence of their failure for optimal resource allocation. Computational methodologies are applied to legacy inspection data for bridges monitored over 20 years to evaluate the probability of failure of certain bridge elements. Based on the reliability importance criterion, the superstructure and substructure elements were considered to be critical to the survival of bridges. Bridge management and miscellaneous elements (such as expansion joints, railings, and sign structures), though important, did not generally contribute to the overall deterioration of the bridge.