Research On Failure Mechanism Of FRP Shear Strengthening

The method of superimposing the contribution of FRP shear strengthening and the Shear capacity of non-reinforced beam to calculate the bearing capacity of FRP shear reinforcement has been used in most study about FRP shear reinforcement for concrete beams.Therefore,the research mainly concentrated in the FRP shear contribution.According to test results,if the construction quality of paste is reliable enough,FRP-concrete interface behavior depends mainly on spin-off of the concrete interface.This is the difficulty of application of the FRP reinforced concrete technology.In this paper,a systematic study has beng made about the mechanism of FRP-reinforced concrete.And also the corresponding numerical model and the Calculation method have been presented based on a fully understanding of the failure mechanism.This paper can be summarized as the following 4 parts:1) By the analysis of FRP-concrete interface behavior in the case of micro-element,the mechanical situation at all stages of the process have been researched when the load-displacement changes;2) On the assumption of the constitutive relations of FRP-concrete in the unloading situations,the FRP-concrete interface behavior in the process of unloading has been obtained after deriving;3) The calculated model of shear debonding for analysis has been establishment. Shear debonding problem has been researched,using FRP-concrete interface relations in the infinitesimal situation which is obtained in this paper.4) Supposed that the distribution of shear inclined cracks is diamond,bonding on both side of concrete beams,by numerical analysis calculation on the entire process of shear debonding failure,the curve of the relations between FRP shear contribution and the crack width as well as the normal stress in the FRP along the inclined crack and the distribution of shear stress on the FRP in various cross-section has been obtained.This study of FRP-reinforced concrete shear behavior in the whole process of debonding has come to a clear result and pushed the research of the FRP-reinforced concrete shear behavior forward.In this paper,the research methods also provide a number of ideas for other studies about FRP,and it would contribute to the basic theory research work of FRP-concrete in future.