Nondestructive and Destructive Testing of a Three Span Skewed R. C. Slab Bridge

A three span, skewed, reinforced concrete slab bridge was field tested to destruction by the authors. Before the actual destructive test, nondestructive tests were performed to determine the condition of the bridge. The tests were a truck load test and modal analysis. The truck load test consisted of mounting about 30 instruments under the bridge and monitoring deflection under truck loads. The recorded deflections were compared with analytical FEM predictions. It was possible to determine that there was damage to the shoulders of the bridge, even though this damage was, at the time, hidden by a layer as asphalt. The modal analysis consisted of dividing the bridge deck into a fine grid. Accelerometers were placed at some of the grid points and the grid points were then struck with an impact hammer. Using the recorded accelerometer data, it was possible to determine the vibrational mode shapes of the bridge. These shapes could then be compared with those obtained from theoretical models to find damage to the shoulders of the bridge.