Study On Seismic Performance Of Steel-timber Composite Beam-column Exterior Joints

Steel-timber structure is a new type of composite structure.In general steel structures,steel plates are relatively thin,which are prone to local buckling or overall instability under the action of earthquake.After adding timber to form composite members,timber has the role of lateral support for steel plates,which can prevent steel plates from bending too early,thus improving the stability of steel structure and giving full play to the strength advantage of steel.At present,researchers have studied the static performance of steel timber composite beams with structural adhesive and bolt connection,the bending mechanical performance of steel timber composite beams with various cross-sections and the mechanical performance of H-shaped steel timber composite columns under eccentric pressure.The test results show that the steel timber composite members connected by structural adhesive and bolt have good overall mechanical properties,and the steel timber composite members have high bearing capacity.But at present,the research of steel-timber composite structure is mostly focused on the mechanical properties of composite beam and single component of composite column,and the research of steel-timber composite joint is very few,so it is necessary to discuss and test the connection mode of steel-timber composite beam column joint.In this paper,three Steel-timber composite beam column exterior joints are designed and made.The three joints are connected by welding end plates and bolts,and the steel-timber composite beam in each joint is the same.The three exterior joints are:beam column exterior joint(JT joint)composed of glued timber rectangular section column,beam column exterior joint(JS joint)composed of H-shaped steel section column,and beam column exterior joint(JSTC joint)composed of H-shaped steel glued timber rectangular section column.In order to study the influence of the cross-section form of the column on the seismic performance of the steel timber composite beam column exterior joints,the quasi-static test of the three composite beam column exterior joints was carried out with the cross-section form of the column as the basic variable.During the quasi-static test,the failure characteristics of different joints were observed,and the load,displacement and strain data of the joint core area were collected.Through the processing of the test data,the Load-Displacement hysteretic curve and skeleton curve of the beam column exterior joint are obtained,and the mechanical performance indexes such as energy dissipation coefficient,ductility coefficient,ultimate bearing capacity,stiffness and shear deformation of the core area of the joint are calculated.The cracking load of the beam column exterior joint and the relative corner deformation of the connection between beams and columns are calculated theoretically.Finally,the quasi-static tests of two beam column joints are simulated by ABAQUS software,and the results are compared with the test results.The results show that:in the JT joint composed of glued timber column,the timber in the bolt gasket area of the timber column is first crushed,the bolt is pulled out,the welded end plate is bent and warped,and then the weld crack at the welded end plate leads to the ultimate failure of the joint.The joint failure of JS and JSTC is mainly caused by the weld cracking at the welding end plate.In the whole process of pseudo static test,there is no obvious stress cracking in the steel timber composite beam and steel timber composite column.Among the three steel timber composite joints,JT joint has the worst energy dissipation capacity,the largest relative corner deformation between beams and columns,and the smallest ultimate bearing capacity and stiffness when the joint is damaged;JS and JSTC joints have better energy dissipation capacity and ductility,higher ultimate bearing capacity and stiffness,and JS joint has the most full hysteretic loop and the strongest energy dissipation capacity.Through the shear deformation comparison of the core area of each joint,it can be seen that the shear deformation of the core area of the beam column joint can be effectively reduced by filling glued timber on both exteriors of the H-shaped steel column web.Most of the relative angular deformation between beams and columns of JS and JSTC joints is caused by the weld cracking at the welded end plate.The finite element simulation results of JS and JSTC nodes are in good agreement with the test results.