Reliability-based assessment of bridges using long-term monitoring data

In this paper a method for safety and condition assessment of bridge components based on long-term monitoring data and reliability analysis is proposed with the target to provide quantitative information to bridge managers for decision making on optimizing and prioritizing bridge inspection and maintenance. In the proposed method, the probability density function (PDF) of the load effect is obtained directly from continuous strain measurement, while the PDF of the resistance is determined using the material strength and its variation coefficient prescribed in provisions or obtained by material tests, and further revised with the damage identification results. Then the safety indices of structural components are estimated using the first-order reliability method (FORM), which can be readily used to decide bridge inspection/maintenance strategy because the correspondence between the safety index and the required maintenance action has been established. This method can incorporate the identified structural damage in a probabilistic manner into the safety index evaluation. Case studies of two truss bridge structures have been provided to illustrate the proposed method.