Description
This research explores complementary shear strengthening and anchorage effects of CFRP U-wraps on reinforced concrete beams strengthened in flexure using externally bonded CFRP sheets. Through experimental testing of large-scale beams, the research aims to enhance the understanding of how the dual strengthening and anchorage functions of U-wraps interact and contribute to the overall structural performance of flexurally-strengthened beams. The specimens were divided into three groups based on existing steel shear reinforcement ratio; each was strengthened with different configurations of U-wraps and fiber anchors. This paper reports the results of twelve beams tested to date. The test matrix is designed in a way that evaluates the conditions under which shear-controlled beams transition to flexure-controlled failure modes, allowing for the evaluation of the dual contribution (i.e., shear strengthening and anchorage) of U-wraps. Based on the initial results, U-wraps increased shear strength by 76% in shear-deficient beams while, at the same time, increasing the strain utilization of flexural CFRP sheets in flexure-controlled specimens by up to 118% over the ACI 440.2-prescribed debonding strain. The addition of U-wraps also shifted the failure mode of flexural CFRP sheet from intermediate crack (IC) debonding to U-wrap rupture or U-wrap debonding.
