Research On Mechanical Behavior Of Steel Reinforced Concrete Column-Composite Joint In Frame Structures

The rigid concrete column composite beam frame structure has the characteristics of high bearing capacity,large stiffness,good ductility,rapid construction and high comprehensive economic benefits.It is widely used in practical engineering.Joints are important parts of beam and column members.The joints are complicated in structure and cumbersome in structure,usually inconvenient for construction.The reasonable node structure can make the transfer force more clear at the node,and ensure that the structure satisfies the design intention of "strong column,weak beam and stronger node".The combined node refers to the joint beam and column member using the nodes of different materials,to study the mechanical properties of the combined nodes,and to put forward the structural forms which meet the requirements of mechanical properties,construction simplicity and economy,which have important engineering practical value in practical engineering.In this paper,the structural forms and destruction forms of common composite joints are analyzed and studied,and the composite joints of the stiffened concrete columns and composite beams are selected in this paper.1.Based on the experimental data of the existing literature,the finite element model of the node is established by using the ABAQUS finite element software,and the nonlinear finite element analysis under the action of Liang Duan's reciprocating load is carried out.The finite element method is in agreement with the experimental results.The loading position of the joint is improved,and the beam end load is changed to the column end loading.The simulation results reflect the mechanical properties of the actual node more accurately.The results show that there is no obvious buckling and plastic hinge at the root of the test node,and the shear failure of the core area is a typical "weak node" failure.2.Considering the effect of the concrete slab on the test node,the joint model of H type steel composite beam and unequal limb H steel composite beam considering the participation of the concrete slab is established.The nonlinear finite element analysis of the joint under the reciprocating load of the column end is analyzed.It is found that the concrete slab is involved in the work and the equal limb H Steel Group is considered.The bearing capacity and the ductility of the joint have been improved,but the "weak node" failure mode of the joint has not been changed;the upper limb of the H type steel is weakened,and the joint of the unequal limb H steel composite beam is used in the loading process to form the plastic hinge in Liang Duan,and the failure of the beam is preceded to the node,which embodies the seismic design of the "weak component".Thought.3.According to the general structural measures of steel structure joints,the reinforced joints of beam end and horizontal stiffeners applied in the core area of the beam end are established,and the column stiffening joints are applied to the core area of the column joints.The finite element analysis is carried out.The results show that the beam end reinforced joints are in the loading path,and the beam is in the stiffened plate variable section position.When the failure mechanism of plastic hinge is obvious,the node is the "strong node" failure mode,the ultimate bearing capacity of the node is improved remarkably,the hysteresis performance and the ductility are better.The column reinforced joints have no obvious effect on the bearing capacity of the joints,but the restraint effect on the core area reduces the yield of the stirrup in the core area to a certain extent.4.Based on the reinforcement and column reinforcement of the joint beams of unequal limb steel composite beams,the influence of the thickness of the stiffeners on the beam end and the different forms of the horizontal stiffeners and the thickness of the plate on the mechanical properties of the joints is studied in this paper.The study shows that when the thickness of the beam end is 1~1.4 times of the thickness of the flange plate of the steel beam,the node has a good hysteresis and bearing capacity,and the horizontal stiffener is added in the core area of the node.When the thickness of the stiffener rib is the same,the hysteresis performance of the ring stiffener is obviously better than the ladder stiffener node,and the Trapezoid Stiffened Rib node.It is also a little better than the triangular stiffener.When the stiffener rib is 0.8 times the thickness of the flange plate of the steel beam,the hysteresis performance of the joint is relatively poor.When the stiffener rib plate is 1~1.6 times of the thickness of the steel beam flange plate,the hysteresis performance is relatively good,and there is no obvious change.The common parameters such as axial compression ratio,concrete strength and layout of longitudinal reinforcement are also analyzed.