Theoretical Research And Nonlinear Finite Element Simulation Analysis Of Rectangular Concrete Columns Strengthened With CFRP Sheets Under Secondary Load

Having long been strictly blocked by foreign technology and products, the localizationrate of CFRP material development is relatively low, and as a result, domestic CFRP productsof high performance haven‘t been developed until to the year of2011. The restrictedtechnology of concrete structure strengthened with CFRP material has emerged in recentdozens of years, which is not yet mature and still has room for further development. CFRPreinforcement is characterized by high strength and high efficiency, simple constructionprocedures, wide adaptability, and good corrosion resistance and durability as well as wideruse range. Presently, there are mainly following problems existing in CFRP-reinforcedconcrete columns:①the research of CFRP-reinforced concrete columns focuses on circularcross-section columns, however, which mainly exist in practical projects are rectangular (orsquare) cross-section columns.②zero-unloading of reinforcement component is verydifficult in practical projects, and the reinforcement structure confronted with initial stressduring reinforcement, consequently, CFRP reinforcement is under secondary load, whoseeffect on reinforcement should be considered.③the research of CFRP-reinforced concretestructures is mainly centered on enhancing the flexural bearing capacity of components suchas beams and plates, on which a relatively mature theoretical system has been developed.However, the research of columns mainly focuses on the bearing capacity of plain concretecolumns, thus, it is extremely necessary to conduct the research of the bearing capacity ofCFRP-reinforced RC rectangular columns.The research is carried out with the focus on above-mentioned problems, with maincontents as follows:1）Make further research of existing mechanical models of rectangular concrete columnsstrengthened with CFRP sheets and conduct theoretical analysis of entire stress process ofsuch models, deduce the theoretical model of compressive strength, theoretical model ofultimate compression strain and theoretical model of stress-strain constitutive relationship ofrectangular concrete columns strengthened with CFRP sheets under secondary load inaccordance with the principle of superposition and strength substitution principle.2）Infer the computational model for bearing capacity of RC rectangular concretecolumns strengthened with CFRP sheets under secondary load based on various deducedmechanical models of rectangular concrete columns strengthened with CFRP sheets under secondary load in this paper and in accordance with existing test data and formulas.3）Analyze effects of various factors on mechanical properties such as lateral restraintstress, compressive strength and ultimate compression strain, and deduce a series of importantconclusions.4）Use finite element numerical analysis software ANSYS10.0, SOLID65unit andSHELL41unit to simulate concrete and sheets, make dynamic simulation of the entire stressprocess of rectangular concrete columns strengthened with CFRP sheets, and conductnonlinear analysis via post processors POST1and POST26to verify whether theoreticalderivation and computation is correct.