Study On Mechanical Behavior Of Steel Tube Beam-Steel Beam Joints Strengthened With Reinforcement FRP

The joint among the reinforced FRP and concrete filled steel tubular column(CFST)and steel beam is a new type of joint connection between girder steel tube concrete column and steel beam.The joint connection is characterized in that the steel beam has no connection with the steel pipe and use the core concrete interior and Longitudinal steel bars welded by steel beams as a beam column force transmission mechanism.On the one hand,the maximum reduce the reciprocating load due to steel flanges on the steel tube pull,pressure caused by the core concrete lateral restraint decreased defects.On the other hand,vertical reinforcement is used as a compensation for the steel pipe opening to ensure the continuity of column stress in the node domain and to achieve the shear mechanism for the joint connection.At the same time,the FRP is used to restrict the column near the node domain and enhance the local strength of node connection.Therefore,compared with the traditional CFST-steel beam joints,the mechanical properties of FRP CFST-steel beam joints are better.In this paper,the finite element analysis software ABAQUS is used to simulate the CFRP-strengthened CFST-steel beam joints and to study the mechanical properties of the FRP-reinforced joints.The detailed contents are as follows:(1)New ABAQUS is based on the existing beam tube concrete column-steel beam joint test to establish model and study on the unit type,material constitutive model,boundary conditions,loading system and contact relationship.According to the compare test between the finite element calculation results and the literature test results to verify the rationality of the model.Based on this,the mechanical properties of the joint were studied by changing the connection between the steel beam and the concrete filled steel tubular column.The results show that the connection between the web and the concrete filled steel tubular column is an important factor affecting the mechanical properties of the joint.(2)Joining FRP to study on the enhancement effect of FRP constraint on the CFST near the node domain.When the amount of steel is reduced,FRP is added to restrain the requirement of flexural rigidity The finite element model is established by reducing the wall thickness of the steel tube,and review the mechanical properties influence of FRP constraint on the CFST and steel beam joint frame.The results show that the flexural rigidity of the CFST and steel beam joint frame is improved after the FRP constraint.(3)Change the way of connection to study on the force transmission mechanism of reinforced CFST and steel beam joint connection.By removing the full penetration weld of the steel pipe and the steel beam flange,the longitudinal bars arranged in the core concrete are used to realize the connection between beams and columns.Compared with the traditional joint to study on the change of the transmission mechanism between beams and columns.(4)The finite element model with different parameters is established to analysis parametric.The influences of the volume content of reinforcement,the length of steel reinforcement,the ratio of diameter to thickness,the penetration form of steel beam,the length of flange penetration and the number of reinforcement are considered.The results show that the volume content of steel,the length of the reinforcement and the length of the flange have great influence on the performance of the joints.