Parameter Study On Shear Behavior Of FRP Reinforced Concrete Frame Beam Column Joints

Reinforced concrete structure has been the most widely used structure in the field of engineering structure.However,in the normal use of the structure,the peeling off of the concrete cover or the reduction of the internal alkalinity is easy to cause the corrosion of the reinforcement,which will seriously affect the durability and safety of the reinforced concrete structure.Fiber reinforced polymer(FRP)bars,which have excellent properties of light weight,high strength and corrosion resistance,have gradually become one of the new choices of reinforced concrete structures in the engineering field.FRP bars are anisotropic materials,which have higher tensile strength than ordinary steel bars,but their shear performance is poor.Under the combined action of shear stress and tensile stress,the tensile strength of FRP bars will be greatly reduced,resulting in shear failure of FRP bars.Therefore,it is of great significance to study the composite effect of FRP tendons.At present,the research on FRP bars is mainly focused on the concrete beam and column structure,and the research on the application of FRP bars in the joints of frame structure is still lacking.As the most complex and important component in the structure,the frame joint is easy to cause the collapse of the whole structure when it is destroyed.Therefore,it is necessary to carry out a detailed analysis and Research on the mechanical performance of FRP bars in the joint.In this paper,the finite element analysis software simulation method is selected to establish 39 joint 3D models,including 27 T-joints and 12 cross joints,according to the parameters that affect the shear performance of FRP reinforced concrete joints.The specific research contents and conclusions are as follows:1.Comparing the bearing capacity and failure mode of the FRP joint test and simulation model,the results are consistent,which verifies the effectiveness of the simulation results.2.The load displacement curve,crack development process,compressive stress contrast of concrete in the core area and the results of tensile stress and shear stress of FRP bars are analyzed in detail.The change rule of the composite stress of FRP bars in the jointmodel is mainly investigated.3.Parameters such as stirrup reinforcement ratio in the core area,longitudinal reinforcement ratio in the beam,stirrup reinforcement ratio in the beam,shear span ratio at the beam end,stirrup spacing in the core area,fiber type and joint type of FRP reinforcement that may affect the shear performance of FRP reinforced beam column joints and the tensile shear composite effect of FRP reinforcement are analyzed.The effects and rules of the parameters on the shear capacity of FRP reinforced concrete beam column joints and the tension shear composite stress of FRP bars are mainly investigated.4.The results show that changing different parameters will lead to different changing trends of the composite stress of FRP bars at different positions of the joint,which should be adjusted according to the actual needs in the engineering field.