Studies On Bond Behavior Of FRP-Concrete Interface

It is critical for strengthening technologies in bond development of FRP-concrete interface and debonding.Firstly,based on the experimental results,this paper presents a proposed bilinear bond model for simulating bond development of interface.By using 3DFE((dimension finite element)computational model,this paper compares differences between the proposed bilinear bond model with other models in simulating bond development of FRP-concrete interface,and analyzes the influence of the width of FRP strip,axial stiffness and bond lengths on load-displacement curves.Secondly,this paper presents a 2DFE model on basis of simplification of the original 3DFE model.Thirdly,this paper comprehensively expounds the debonding process and puts forward an overall closing equation of load-displacement by using the predicted results of 2DFE model.Comparing the collected experimental data,the results of bonding model and closing equation presented by this paper are more precise and stable,as well as gives a reference for secure and economic application of FRP-concrete reinforced technologies.This paper mainly concludes some content as follows:(1)According to the test results,this article presents a proposed bond model.In order to verify the accuracy of that model,the author puts forward a 3DFE model again and demonstrates the feasibility of 3DFE model.The corresponding results prove the accuracy and feasibility of the bond model in 3DFE model.Then,the paper also demonstrates the reasonable range of element size,which is below 30 mm but not too small.In addition,comparing the simulation results of the width of FRP strip,axial stiffness and bond lengths with that of test,this paper proves that the proposed bond model can precisely predict the load-displacement curves,and that results further demonstrate the accuracy of bond model and feasibility of the FE computational model.(2)This paper reasonably simplify 3DFE model and then gives a 2DFE model.We obtain feasibility of the 2DFE model by analyzing the element Shell63 and the test data.Comparing the analytical results of element size,we obtain that the reasonable range of element size between 0.1-10 mm.Furthermore,the analyses of the curve shape of bond model and the width of FRP strip further verify the accuracy and feasibility of 2DFE.(3)This paper presents a proposed debonding bearing capacity model on basis of proposed bondmodel.Moreover,according to the prediction of 2DFE model,this article detailedly describes the whole debonding process of FRP strip,and puts forward closing equation of load-displacement in all stages.Based on these obtained results,this paper also analyzes the influence of the width,bonding length,thickness and elasticity modulus of FRP strips on closing equation,as well as proves that the proposed equation results are generally agree well with results of the test and numerical prediction of FE.All corresponding results demonstrate that the prediction of closing equation in the bonding development of FRP-concrete is reliable and accurate.