Research On Seismic Behavior Of Strengthening Joints By Enlarging Column Section And Bonding CFRP

The node is an important part in the structure of framework and it plays role of transmitting and distributing the internal force to ensure the effect of structural integrity.The node of the frame is also the weakest and the most vulnerable part in earthquake cases.It may cause situation that the bearing capacity,ductility,stiffness and seismic performance of the structure do not meet the requirements of structural safety when the node with improper design,reasonable construction method such as less feed or leakage stirrup of the node or the actual earthquake fortification intensity is higher than that in the region of structure and at this time the seismic performance of the structure can be improved by the reinforcement of node.This paper studies a new type of reinforced method of joints,namely strengthening joints by enlarging column section and bonding CFRP,chooses axial compression ratio,increasing thickness of the concrete and carbon fiber layer as parameters,uses ABAQUS software to analyze the seismic performance of cross node according to the finite element theory and compares the influence of enlarging column section,bonding CFRP and composite method of joints for seismic performance.This article compares the results based on failure mechanism and morphology of the specimens,ultimate bearing capacity,ductility,stiffness and energy dissipation and draws the following conclusion:(1)The composite reinforcement method can effectively improve the destruction form of the node,shear failure of core area is transformed into the beam bending damage and greatly improve the node's bearing capacity,ductility,stiffness and energy dissipation capacity.(2)Effect of composite reinforcement method in improving the bearing capacity,ductility,stiffness,energy dissipation is good than the method of enlarging column section and bonding CFRP,overcome the shortcomings of the method of enlarging column section in slightly increasing the ductility and the method of bonding CFRP in improving the shear bearing capacity slightly,stiffness and energy dissipation capability.(3)With the increasing of the thickness of the column section,the shear bearing capacity,stiffness,energy dissipation capacity of the node are improved,and the ductility of the node first increases then decreases.The ductility of node is best when the thickness of column section increased to 60mm.(4)With the increase of carbon fiber layer,the stiffness and energy dissipation capacity of node increase slightly,but the effect is not obvious.Pasting carbon fiber can stability improve the ductility of the node and improve the bearing capacity of the node indirectly.(5)With the increasing of axial compression ratio,the bearing capacity and energy dissipation ability will decline when more than this range.In this paper,bearing capacity and energy dissipation of the specimens with the axial compression ratio of 0.5 is the best.The ductility of the node decrease with the increasing of axial compression ratio.