The Structural Property Research Of Concrete Flexural Members Reinforced With Fiber Reinforced Polymer Bars

Concrete structure reinforced with fiber reinforced polymer(FRP) bars is a new structural system. Compared with traditional steel, FRP bar has its own superiority, like high tensile strength, low elastic modulus and the characteristics of line flexibility before being damaged. Therefore, instead of using steel bars, concrete structure reinforced with FRP bars can cause a greater deflection and crack width, and also results in changes such as bending strength. The thesis is devoted to study on mechanism, failure mode, mechanical models and ultimate bearing capacity of the concrete beam reinforced FRP bars, on the basis of experimental research; it combined theoretical analysis with finite element simulation. The paper mainly accomplished such work as follows:(1) The thesis summarized the basic functions of concrete structure reinforced with FRP bars, mainly including the composition and the characteristics of FRP bar, as well as the functions of collaborative work with concrete etc. Because ductility model of concrete structure reinforced FRP bars differs from the traditional concrete structure reinforced steel bars, the thesis analyses the relationship between ductility of concrete structure reinforced FRP bars and concrete strength, form of FRP bar as well as reinforcement ratio etc, gives the project definition of ductility of concrete structure reinforced FRP bars, establishes the calculation method of ductility, and verifies the accuracy of the calculation method by experimental data.(2) The thesis studies the concrete structure reinforced with FRP bars by the separate models and William-Warnke five-parameter failure criterion. The bond stress-slip relationship between FRP bars and concrete is advanced. It is studied that the nonlinear finite element model was simulated to analyze FRP reinforced concrete member. Nonlinear finite element analysis was employed to simulate the whole process of changing internal force and deformation, the appearance and development of cracks, and to describe the failure mode and the ultimate strength capacity level. In addition, it also provides some evidences for setting up a simple calculation model of concrete member reinforced with FRP bars.(3) On the basis of experiment and finite element analysis of the normal section bearing capacity of concrete flexural member reinforced with FRP bars, the thesis gives calculation model of concrete flexural member reinforced with FRP bars at different stages and the plane-section assumption. Using the limit equilibrium theory, the thesis establishes the calculation methods of FRP reinforced concrete flexural member which takes FRP bar's influence into consideration. Meanwhile, this method is simple and has a clear physical concept. The accuracy of the calculation method is proved to be true.(4) On the basis of experiment and finite element analysis of the anti-shear bearing capacity of FRP bars reinforced concrete flexural member without web reinforcement. Using of rod-arch balance theory, the thesis establishes the calculation methods of the anti-shear bearing capacity of FRP reinforced concrete flexural member which takes influence of FRP bar, shear span ratio and the rate of hoop FRP bars into consideration. Meanwhile, this method is simple and has a clear physical concept. The accuracy of the calculation method is proved to be true.(5) Through experiment and finite element analysis of crack width and deformation of concrete flexural member reinforced with FRP bars, the thesis thinks the calculation of the crack width and deformation may also use related in the current Chinese code for design concrete structure reinforced with steel bars, but coefficients of the formula must be amended. The thesis establishes the calculation methods of the crack width and deformation of FRP reinforced concrete flexural member by equivalent substitution of material strength, bonding characteristics and the surface characteristics, and there are a large number of experimental data to verify the accuracy of the calculation method.