Experimental Study On Seismic Behavior Of The New Full-Bolt Connections For Steel Frames

China is an earthquake-prone country,because of its good seismic performance and light weight,short construction period,quick investment recovery,less environmental pollution and other advantages of more and more widespread public concern,the steel frame acts as the structural bearing member of the steel structure and plays an important role in it.The beam-column connection is an important part of the steel frame,which plays an important role in the whole structure.In addition,the different connection forms have a great influence on the seismic performance of the structure,and the connection form has a direct bearing on the bearing capacity and seismic performance of the structure.Therefore,for the square steel pipe and the combination of H-shaped steel beam connection,the square steel pipe is closed,which can not simply connect the current use of all-welded connection due to uneven quality of welding resulting in node connection bearing.The force and the anti-seismic performance are reduced and so on.The new type of full-bolt connection method of the steel square column and the H-shaped steel beam is put forward.The nut is no longer needed for the bolts,the thread is directly tapped on the connecting steel plate,and the beam-column connection is carried out in one step.In this paper,the internal connections between the nodes under the combination of the columns and the end plates are obtained by analyzing the bearing capacity,the seismic performance and the failure mode of the nodes,which are connected by the proposed new node connection.And finally obtained the optimal combination of column and end plates.The main contents and conclusions are as follows:(1)Based on the combination of experimental and theoretical derivation,the flexural changes of the corresponding points of the elastic thin plate under the concentrated force are studied by using the knowledge of elastic mechanics,and the experimental results are obtained.Approximate formulas of the corresponding point deflection of the pipe wall and plates welding plate,through which and substitute into the size parameters can be concluded that the bolts' tension values with the corresponding relation of bolt point deflection value.(2)In order to study the seismic behavior of new full-bolted joint of square steel column and welding combination H-beam,the seismic behavior under different column-wall thickness,end-plate thickness,material type and so on,and find out the corresponding failure mode,six sets of cross-shaped composite joints with 200 mm×200 mm cross-sectional dimension are designed.The test data and failure phenomena of hysteresis curve and skeleton curve corresponding to the corresponding nodes are obtained by low-cycle repeated loading test.According to the test data and failure phenomena,and the optimum combination of column wall and end plate thickness is obtained.The results show that the square steel pipe column-H steel composite node in the section size of 200 mm×200 mm is in a reasonable thickness of the column and end plates.When the thickness of the wall is the same,the thickness of the end plate is relatively thinner,the ultimate bearing capacity is higher,and the ductility is better.When the thickness of the column and the end plate is 20 mm×16 mm,the seismic performance of the joint is the best under the cross-sectional dimensions of this side of the steel pipe column.(3)In order to study the similarities and the similarities of the failure modes of the new joints under different cross-sectional dimensions and the changes of their seismic performance,five sets of square steel tubular beam-column connections with 300 mm×300 mm cross section are added,and compared with those of 200 mm×200 mm square steel tubular beam-column connections.The results show that the combination of a wall thickness of 20 mm and an end plate thickness of 16 mm have advantages in hysteresis performance with the end wall of the square steel pipe with the cross section size of 200 mm×200 mm.The results show that the combination of a wall thickness of 20 mm and an end plate thickness of 16 mm have advantages in hysteresis performance with the end wall of the square steel pipe with the cross section size of 200 mm×200 mm.With the corresponding increasing in the cross-sectional size,the thickness of the corresponding combination of the optimal column wall ends is gradually increasing slightly.When the thickness of the column and the end plate combination is 16 mm and 20 mm,the larger the cross-sectional size,the stronger the energy consumption.And when the thickness of the column wall is too large,the cross-sectional size is larger,but the energy consumption capacity is declining.