Experimental Study On Shear Behaviors For Beams Strengthened With Externally Bonded CFRP Sheets

For shear degradation of RC beams due to various reasons, such as error of design, change of function, erosion of environment and so on, timely strengthening should be adopted. In the recent years, FRP is used in civil engineering extensively. Many advantages of CFRP make it getting good effects in shear strengthening of RC beams. But the researches about it are not sufficient, partly because of the complicacy of such shear failure.Based on the experiment of sixteen simply supported beams strengthened in shear with CFRP sheets, the failure process is observed, meanwhile the failure modes, the influence factors of shear strength and the strain distribution feature of CFRP intersected by the oblique section are studied. The results indicate that CFRP can evidently increase the shear bearing capacity of these specimens that fail mainly by CFRP rupture of CFRP debonding in the end. But the ultimate strength of CFRP cannot be reached and the strain distribution is not symmetrical. So the failure mechanism and the working model are discussed. Considering the non-uniformity of strains in CFRP and the angle of critical shear crack synthetically, the formulas related with shear-span ratio are proposed. And then, the calculation methods of the shear bearing capacity for the strengthened beams are established. Compared with the experimental values, the results calculated by the simplified formula give good agreement.At the same time, the FEM program, ANSYS, is used to give nonlinear numerical solution about the full test process of the strengthened beams. Through the simulative analysis, the conclusions of experimental and theoretical studies are proved, and some new ideas for further research are also enlightened.