The Research On Interfacial Stress And Rigidity In Sheet Partially Debonded Reinforced Concrete Beams

Fiber Reinforced Plastics (FRP) have received increasing interest in the strengthening and repair problem in civil engineering, with higher strength to weight ratio, good resistance to corrosion and fatigue and stability in temperature .The sheet called in this paper include CFRP, GFRP, AFRP, in order to compare the behavior of the interface in sheet and steel plate partially debonded beams, the steel plate is also analyzed, they are unified called sheet. In present, the assumption is that the bond is very perfect between sheet and beam, and the thickness of adhesive is even in research. In fact ,the thickness of adhesive is not perfect even and continuous with limitations of site and technology in construction .The present theory and failure mode about interfacial stress can not perfectly show the behaviors of partially debonded beams .There are differences in mechanical behaviors among concrete and sheet and adhesion , therefore ,the behaviors of the interface become very complex. It is very important to study the behaviors of partially debonded beam. In this paper, the mechanical behaviors of the interface are studied by use of theoretical and finite element analysis in partially debonded beams.After the beam is partially debonded with sheet, there is stress concentration at the end of sheet. This is the major reason of failure. This paper theoretically analyzes the stress concentration at the area of sheet end, calculates the values of the stress with the software of ANSYS and gets the distributing curves of the stress at this area. The effects of some parameters were discussed. These parameters include unbonded length, the thickness, elastics modulus and layers of sheet, the thickness and elastics modulus of adhesion. And the interfacial stress is compared between steel plate and FRP sheet in partially debonded beam.The formula of interfacial stresses is established considering the nonlinear behavior of concrete beam, and the rigidity and ductility of partially debonded beams are analyzed in this paper.