Field monitoring of a bridge using digital image correlation

Abstract

In order to provide quantitative data to supplement visual inspections and numerical modelling as part of the overall bridge assessment process, inexpensive sensor technologies that provide useful and accurate data are required. Digital image correlation (DIC) is a measurement technique that can be used to provide displacement, crack width and strain data from the same set of digital images. This paper outlines a field application using DIC to measure static displacements at varying load levels and dynamic displacements at varying vehicle speeds of a reinforced concrete bridge. The DIC displacement measurements provided by two different camera systems are shown to be in good agreement with the results from a conventional displacement transducer for both the static and the dynamic tests. The results of the static tests with varying load levels are then used to illustrate how the bridge response can be evaluated by examining the load deflection behaviour, which remained in the linear elastic range throughout the loading. The dynamic displacement data were then compared to the static response to determine what, if any, difference in response there was to dynamic loading and thus if the use of impact factors should be considered when assessing this bridge.