Movable bridges are unique structures due to the complex interaction of the structural, mechanical and electrical systems. These mechanisms provideversatility to movable bridges; however, their intricate interrelation combined with the harsh environmental effects also produces some inherent drawbacks. Movable bridges are reported as experiencing significantly higher maintenance costs than regular fixed bridges, due to their special operational demands, structural designs and interaction of different systems. In this paper, a novel system for Structural Health Monitoring (SHM) of a movable bridge, with emphasis on load rating, is designed and implemented in the State of Florida. Video images are analyzed by means of computer vision techniques to detect and track vehicles crossing the bridge. Traditional sensor data is correlated with computer images to extract Unit Influence Lines (UIL) which are used as index for rating assessment. Based on UILs, moments on critical sections for the rating truck HL-93 are predictedand load rating is calculated continuously with neither need for load tests nor bridge closures to the traffic.
Abstract