Study On The Seismic Behavior Of Different Configuration Steel Double-Channel Built-Up Chords

The staggered truss system has large bearing capacity and lateral stiffness,but the ductility is poor under the seismic load.In order to slove this problem,the special staggered truss steel frame structure was put forward,the Vierendeel panel was designed the special staggered truss that used the rotation and plastic deformation to dissipate the energy and the remaining members remained elastic under the rare earthquake action.It can be seen from the mechanical activation behavior that the rotational capacity and plastic deformation of special segment are the keypoint to energy dissipation of structural system.Based on the test results of our team,it was found that the rotational capacity of the double-channel built-up steel members of the ductile section does not reach the rotational requirements of the special segment.To slove this problem,two different configuration double-channel built-up steel members are presented in this paper to analyze the seismic performance and rotational capacity.In orde to study the seismic performance and rotational capacity of the different configuration double-channel built-up steel members,based on the test results of our team,numerical simulation and experiment was used to study the hysteretic behavior of the seismic behavior of a special segment under reversed cyclic loading,selective analysis the different parameters of cover plate and dog-bone style reducting on the double-channel steel with cover plate and dog-bone double-channel steel.The finite element analysis shows that:The current specification on the i-beam flange-cover plate connection is same applicable to the double-channel built-up steel members;The dog-bone reducting parameters c is suggested to be(0.15~0.3)b_f(b_f is the flange width of the frame beam)and the other parameters are determined according to the specifications;Increasing the length of the cover plate in a certain range can effectively increase the bearing capacity of the double-channel steel built-up steel members;The increasing of the distance from the dog-bone starting position to the nodal plate can decreased the rotational capacity and energy-dissipating capacity;With the increase of dog-bone reducting depth,the energy dissipation ability of double-channel steel built-up steel members is enhanced,and the rotational capacity of specimens is greatly improved;Compared with the ordinary double-channel steel built-up steel members,the rotational capacity of the cover plate double-channel steel built-up steel member and dog-bone double-channel steel built-up steel members is enhanced by 73%and 59%,respectively,the plastic hinge has been remote away from node;The test results show that:the double-channel built-up members strengthened by the cover plate have good overall stability,and the local buckling and fracture failure of the specimen are concentrated in the front end of the cover plate,the plastic hinge has been remote away from node;The strengthened double-channel built-up member with cover plate can greatly improve the rotating capacity of the specimen,which is 48%higher than that of the unimproved double-channel built-up member,meeting the requirement of minimum turning angle of ductility section.