Shear Repair Methods for Conventionally Reinforced Concrete Girders and Bent Caps

摘要

Thirteen large-scale girders and two bent caps that replicated as close as possible bridge components from the 1950s were cast and loaded to cause initial cracking similar to that observed in the field. The girders were repaired with epoxy crack injection, internal steel bars, external steel bars, surface bonded CFRP, and near-surface mount CFRP. The bent caps were repaired with surface-bonded CFRP and post-tensioning. The beams were loaded to failure while sensors recorded how the beams deformed. In addition, two bridges, one with surface-bonded CFRP strengthening and one with internal steel strengthening, were instrumented before and after strengthening to assess changes in behavior. The test results were used in conjunction with previous research to compare the repair methods based on ten attributes such as shear capacity improvement, aesthetics, durability, and installation requirements. Surface bonded CFRP, external stirrups, and internal stirrups were all effective in increasing shear capacity of girders. Epoxy injection had minimal impact on capacity, and there were not enough data to make a conclusion for near-surface mounted CFRP. Considering surface bonded CFRP, external bars, and internal bars, no method was clearly superior, but internal stirrups did offer many advantages across the attributes considered. The surface bonded CFRP and post-tensioning repairs for the bent caps did not provide as much capacity improvement as expected. However, there was only one bent cap specimen for each of the two repair methods tested; therefore, the results from these tests are considered a basis for further investigation.