In this study, shear transferring mechanisms of an outside attached shear strengthening method for existing RC beams were examined by three-dimensional FEM analysis. The analytical parameters were cross-section shape, number of connecting anchors, embedded length of anchors and strengthening element width. The analytical results for the shear force versus drift angle relationships showed good agreements with experimental values. The analysis indicated that the arch mechanism is also formed in the strengthening element of the RC beams. Through the analysis it was verified that the effective width of the strengthening element is approximately 75mm when the maximum shear force is reached.
