Assessment of a bascule lift bridge using digital image correlation

Abstract

The LaSalle Causeway lift bridge is a 100 year old highway bridge that is integral to the transportation network of Kingston, Ontario, Canada. Rehabilitation of the bridge was planned to address corrosion of the bottom chord and a gap identified at the support of the lifting end. To determine the effectiveness of this rehabilitation, the displacements of the bridge were monitored before and after the rehabilitation, during a static load test, and under regular traffic loading. Since the bridge crosses the Cataraqui River, there are no stationary reference points near midspan from which to measure displacement using conventional sensors. For this reason, digital image correlation was selected as an appropriate monitoring technology. Displacements at the midspan and supports of the bridge were recorded and used to assess the performance of the bridge. The results of this research indicate that the bridge complies with displacement limits and that the rehabilitation of the bridge was successful in rehabilitating the support conditions of the bridge.