| Reinforced concrete structure is one of the most common structural forms.However.the safety.practicability and durability of reinforced concrete structures are seriously affected by the corrosion of steel bars.In recent years,fiber reinforced composite(FRP)bars have become a substitute for traditional steel bars due to their excellent properties of high corrosion resistance and light weight and high strength.FRP is an anisotropic material.which leads to transverse shear failure of FRP tendons.It is shown intuitively that the tensile strength of FRP tendons decreases greatly when the tensile stress and shear stress act together.However.there is still a lack of research on the tension-shear composite forces of FRP tendons at home and abroad.Beam-to-column joints.as the transmission hub of frame structures.have complex forces.and shear failure of their core area may lead to serious consequences of structural collapse.Therefore.it has important engineering application value to carry out the research of FRP tendon tension-shear composite stress.In this paper.the shear problem of beam-column joints which must be solved in the development of full FRP reinforced concrete frame structures is studied.and the composite effect of FRP reinforcement and shear in different working conditions is the focus of the study.The three-dimensional refined model of FRP reinforced concrete beam-column joints is established by using finite element simulation analysis method.and the material nonlinearity is considered for simulation analysis.Based on 24 T-shaped exterior node models with different parameter combinations.the main research contents and conclusions are as follows:1.The comparative analysis of the failure modes and ultimate bearing capacity of the joint specimens shows that the results of finite element analysis are consistent with the experimental results.which verifies the validity of the finite element method.2.The crack development process,load-displacement curve and stress nephogram of FRP reinforced concrete beam-column joint model are analyzed.and the shear failure process of FRP reinforced concrete beam-column joint combination is clarified.3.Parametric analysis of stirrup ratio in core area,beam end shear span ratio,stirrup spacing in core area,stirrup ratio in beam longitudinal reinforcement ratio,stirrup ratio in beam plastic hinge area and fiber types of FRP reinforcement shows that stirrup ratio in core area,stirrup spacing in beam end,stirrup ratio in beam longitudinal reinforcement ratio and fiber types of FRP reinforcement have significant effects on the mechanical properties of FRP reinforced concrete beam-column joints.4.The tension-shear composite stress analysis of stirrups in the core zone of joints,reinforcements in the plastic hinge zone of beams and FRP bars at the end of beams shows that there may be a significant tension-shear composite stress state of FRP bars in the joint zone,which needs special attention in engineering practice. |
