Three three-span bridges with various levels of deterioration were tested before, during, and after repair to understand the behaviour during repair, the possibilities for permanent moment redistribution to bottom reinforcement as a result of the repair, and the effectiveness of the repair method. The stiffness was found to be smaller while the specimens were being repaired, particularly when the deteriorated shoulders had to be cut. If the shoulder was originally ineffective because of excessive damage, the response was not changed after its removal. For the specimen with the most damage, the stiffness during variable depth removal became appreciably smaller than the prerepair value. The maximum postrepair deflection of this bridge was only 2 percent less than that of its prerepair counterpart, that is, the repair method did not enhance structural performance. The postrepair stiffnesses of the other bridges were 11 and 40 percent larger than the prerepair values, but for all three bridges the largest deflection was only 1/3,100 of the span length. While under repair a larger portion of the moment was resisted by the bottom reinforcement, but it was still less than the available moment capacities. After repair the top bars contributed more toward resisting the loads. However the repair method did not always restore the contribution of the top bars for the bridge with the most extensive damage. The ratings of the repaired bridges were increased because of (a) reduced dead loads from removal of the existing asphalt overlay, (b) increased capacity, and (c) the larger strength factors that could be used. (Author/publisher)
Samenvatting