Experimental Study And Numerical Simulation Of Prestressed Concrete Beams Strengthened With CFRP Sheets

In recent years,concrete beams reinforced with carbon fiber reinforced polymer(CFRP)sheets have been widely used both at home and abroad.In this paper,the Partially Prestressed Concrete(PPC)beams reinforced with CFRP sheets were the research object.The static test and fatigue test of the test beams obtained from the PPC beams in the reconstruction and extension of Beijing-Hong Kong-Macau Expressway project by scaling were conducted to study the effect of reinforcement on the flexural and fatigue properties.At the same time,the finite element model was established by ABAQUS to simulate the flexural properties of PPC beams reinforced with CFRP sheets based on the experiment.The finite element simulation results were compared with the experimental results to verify the accuracy and reliability of the finite element model.Finally,the finite element model was used to analyze the influence of five factors on the reinforcement effect,such as the elastic modulus of CFRP cloth,Poisson's ratio,concrete,the layers of CFRP sheets and steel percentage by adjusting the relevant parameters in the model.The fatigue life of two test beams were analyzed by FE-SAFE software based on finite element analysis.Experimental and simulation results show that:(1)The ultimate bearing capacity of the test beam increases significantly with the reinforcement by the CFRP sheets,and the increase of the ultimate bearing capacity increases with the increase of the reinforcement layer,but it does not change linearly.Within a certain limit,the larger the modulus of elasticity and the Poisson's ratio of CFRP fabric are,the greater the ultimate bearing capacity is and it also does not change linearly.At the same time,Poisson's ratio has little effect on beam deflection.(2)After the reinforcement by the CFRP sheets the cracks in the test beam show the phenomenon of "narrow","dense" and "more".The concrete is restrained by the CFRP cloth to make the cracks even and reduce the width and degree of the cracks.(3)The smaller the average reinforcement ratio of test beam is,the greater the ultimate bearing capacity will be increased after reinforcement.However,the ductility of the beam decreases with the increase of the normal steel reinforcement ratio.(4)Tensile properties of CFRP sheets can't be fully exerted when the concrete strength is low.Increasing the grade of concrete strength,the ultimate bearing capacity of reinforced test beam increases significantly.However,increasing the concrete strength level will result in a ductile decline of the test beam.(5)After the reinforcement by the CFRP sheets,test beam fatigue performance significantly increased.At the same time,the simulation results of fatigue life of two test beams with FE-SAFE are consistent with the experimental results,and the fatigue life simulation method can be applied to engineering practice.