T-section RC beams shear-strengthened with anchored CFRP U-strips

This paper presents the experimental results of a total of 11 full-scale T-section beams which can be divided into two series of specimens with and without steel stirrups. Each series of the beams consisted of one control beam without any strengthening and one beam strengthened with CFRP U-strips only which was used for comparison purpose, with the rest specimens being strengthened with CFRP U-strips anchored with different types of anchoring devices. The discrete FRP U-strips instead of continuous FRP sheets were used in this study, allowing a better observation on the failure process/failure mode of the strengthened beams. A newly patented anchor was used and shown to have excellent performance in improving the shear strengthening effect of FRP. Both fiber anchors and mechanical anchors (including the new anchor) were studied and their performance was compared in terms of failure mode, shear enhancement effect, load-displacement response, and the strain levels in FRP U-strips. A salient feature of the present study is that all the strengthened beams were fully instrumented to measure the strains development in the CFRP U-strips, allowing an accurately quantitative assessment on the shear interaction among different components (i.e. concrete, steel stirrups and FRP) of the shear-strengthened RC beams.