Research On Anchor Of The Flexural RC Beams Strengthened With CFRP Based On The Finite Element Analysis Method

The brittle debonded failure of the flexural RC beams strengthened with CFRP has caused serious influence to project practice.Some researches indicate that the anchorage to reinforced beams can avoid debonded failure in certain extent, but the research of anchorage measures is just at the initial stage.This article has simulated the reinforced beams anchored with U-type CFRP sheet by ANSYS numerical analysis method,which is based on the existing theories and experimental studies, systematically studied the influences to load process of reinforced beams for each kind of anchorage form, proposed some anchorage measures with U-type CFRP sheet for the flexural RC beams strengthened with CFRP finally.The specific content is as follows:Firstly,this article analyses the present situation of researches about the flexural RC beams strengthened with CFRP,and proposes the necessity of anchorage research. According to the related theories of reinforced concrete and the existing research results, this article elaborates the process and forms of debonded failure as well as the elementary theories of anchorage with U-type CFRP sheet.The debonded failure of reinforced beams is caused by the local stress centralism and the concretes crack development,so we may avoid debonded failure through controlling the crack development and reducing the strain of carbon fiber.The finite element model of the flexural RC beams strengthened with CFRP is experimental verified,through finite element analysis of two RC beams and experiment result.The corresponding stress-strain of materials and element types can be choosed according to the basic principle of finite element method and each material's mechanical properties, the finite element model of reinforced beams is built by separation model. The finite element result is generally consistent with the experimental result,it could accurately reflect the load characteristic and process of beams, that provides a reliable basis for anchor analysis of reinforced beams.There are 19 reinforced beams anchored with U-type CFRP sheet,and 1 without anchor. Through the concrast between the FEA and related experiment results,we can get the anchorage measures with U-type CFRP sheet. Considered parameters include: the position, width, height and spacing of U-type CFRP sheet.This article inspects anchor influences to the resistance,crack,strain of CFRP, stress of rebar and so on.Results indicate that anchor with U-type CFRP sheet can improve the reinforced beam's resistance in certain extent,reduce the deflection,control the crack development, and reduced the strain of bottom carbon fiber and the stirrup stress, different anchor forms will produce different results. The U-type CFRP sheet is suggested to apply along the shear-cross region with same spacing,and should be applied to the position where has centralism load,and might be applied to the middle position of beam according to the need.There are some technologic requirements to the width, height and spacing of U-type CFRP sheet.