Analysis Of Resisting Flexural Strength Of RC Beams Strengthened With Steel Plates And Prestressed CFRP Sheets

After a long period of operation of concrete girder bridge,concrete cracking and other damage will occur,resulting in lower structural bearing capacity and dangerous situation of buildings.The reinforcement of the bridge can restore and even enhance the bending shear performance of the reinforced concrete old bridge to ensure the function.At present,the technology of two reinforced concrete structures,such as pasting the steel plate or CFRP,have developed rapidly and matured in engineering application.In order to combine the two materials effectively,this paper proposes a new approach of steel plate-CFRP composite reinforcement: the steel plates are anchored at the bottom of the reinforced concrete beam,and carbon fiber reinforced polymer(CFRP)sheets are pasted on the steel plates after having been prestressed.The combination of steel plate and CFRP sheet greatly enhances paste effect,the application of prestress has made it a way of active force.This article discusses the paste steel plate and paste CFRP,and the combination of the two reinforcement method in the research status at home and abroad,introduces the operation steps of steel plate-CFRP composite reinforcement as well as two main types of prestressed concrete,then discusses the stress situation of Unreinforced beam(contrast beam),pasting steel plate reinforced beam,pasting CFRP reinforcement beam and steel plate-CFRP composite reinforcement theoretically,based on the study of bending performance of composite reinforcement beam,the calculation formula for normal section flexural capacity of the composite reinforcement method is established systematically,and the results got by the calculation formula were coMPared with the test results in relevant literature.The results show that theoretical value is close to test value of relevant literature,the failure modes of beams in the test are consistent with predicted failure modes.CoMPared with the prestressed CFRP sheet reinforcement,the values of ultimate moment of RC beams strengthened with prestressed CFRP sheets and steel plates increase 37.4%-57.1%,the values of yield moment increase 60.4%-95.7%;CoMPared with the steel plate reinforcement,the values of ultimate moment increase 25.4%-39.7%.It shows that steel plate-CFRP combination reinforcement technology improves flexural behavior of RC beams effectively.Then,the model is built using finite element analysis software according to the constitutive relations of various materials,the model is separate model,and the paper introduces the unit type used by various materials,the analysis results show that analysis results are in good agreement with those obtained with the test phenomena,the calculated formula of flexural capacity is reasonable and reliable.Finally the failure modes of RC beams strengthened with prestressed CFRP sheets and steel plates are analyzed.based on references and other related test,the composite reinforcement beam section flexural failure mode can be divided into three types: the over-reinforced damage,the proper-reinforced damage and delaminating damage.