Study On Mechanical Performance Of RC Beams Combination Strengthened With CFRP And Steel Plate Under Secondary Load

At present, the need for strenthening and retrofitting the existing or damagedreinforced concrete structures is one of the main problems that the practicalengineering face. The researches on the technique of strenthening concrete structureshave been concentrated on the application of single material in domestic and overseas.The carbon fiber-wrapping and steel-bonding are the typical ways of them. In fact,both of them have their own advantages and disadvantages. The combinationstrenthening technique will be more effective than the single material reinforcementtechnique. Based on the previous researches, the finite element numerical simulationof reinforced concrete beam combination strenghened by bonded steel plate and CFRPwas carried out using the finite element sofware ANSYS. The ductility and stiffnessof combination strenghened concrete beam was also involved. The followings are themain research work in the thesis:(1) In the thesis, firstly, by sorting out the data and materials on the topic indomestic and overseas, it introduces and analyzes the research and development levelof the combination strenthening with bonded CFRP and steel plate.(2) The finite element theory is applied to the nonlinear analysis of thereinforced concrete structure, the cell model, object model are established and thefinite element analytical methods are also determined.(3) Mainly focused on the factors that affect strenthening effect, the thesisstudied the flexural properties of the combination strenghened members from theaspects of characteristic load, deflection and strain by analyzing the numericalsimulation results systematically. The corresponding proposals for design andapplication are also put forward in the thesis according to the results derived from theanalysis.(4) Safety, applicability and durability are the symbols of a reliable structure.When the ultimate load capacity of members meet requirements, the ductility andstiffness are the important factors that characterize the flexural performance under theservicability limit state. Therefore, the calculation method of the member’s ductilityis put forward when the effect of secondary load is considered based on themechanical performance of the combination strenghened reinforced concrete beamand the analysis of ductility is carried out with the method. At the same time, based onthe deformation feature of the combination strenghened concrete beam, the calculation formula of the flexural stiffness under the secondary load is proposedpreliminarily and the calculation value can match the experiment data well. They allcan be the theoretical guide for the combination strenthening applicating in thepractical engineering.