Condition assessment of multispan masonry arch bridges

Abstract

This paper presents a reliability-based condition assessment procedure of multispan masonry arch bridges. Considering axle load as assessment criterion, safety margins (limit state functions) are introduced for each arch of the bridge. The introduced safety margins consist of two variables: provisional axle load (PAL) which is estimated using MEXE methods and actual axle load (AAL) which is estimated using weigh-in-motion measurements of the bridge. Both variables are assumed to follow log normal distribution. Then, failure probabilities of each arch which were estimated from statistical parameters of variables are combined to get the failure probability of the bridge using reliability bounds. The reliability index of the bridge is estimated from the failure probability. Bridge condition is predicted by comparing the reliability index with its acceptable reliability index. Further, when the statistical parameters behave as interval numbers, corresponding reliability index changes are discussed. The introduced assessment procedure is illustrated by a four span brick masonry arch bridge in Sri Lanka.