Experiment Study On Mechanical Behaviors Of Joints Within Assembly Steel Staggered Truss Structures Under Vertical Load

Steel staggered truss system is a new concept in structural steel frame originated from steel frame structures for high-rise buildings. It has been applied abroad widely in recent years. But it used rarely in our country due to the lagging of research on it especially for the join form. This paper puts forward several kinds of joints form and has done the experimental research. It is for the purpose of designing and developing one kind of reasonable feasible node form and providing the reference for the project practice.Based on the similar theory and relevant codes, 1:2 scaled models of four kinds of joints form of staggered truss structures was designed firstly in this paper by using the structural analysis software SAP2000. The details of global structure and the loading scheme were designed, together with the arrangement of displacement measurement and strain gauge.We observed experimental phenomena and do the data processing after the test of two specimen with hinge joint has been done under the vertical load, and the nonlinear finite element analysis is done to the four specimens using software ABAQUS at the same time, the results of finite element analysis coincide to the results of the experiments,then we can know the bearing capacity, ductility, stiffness, performance of plastic deformation, and failure mechanism of the structure. Finally through different parameter node model misalignment finite element analysis, parametric analyses were conducted on the connections to investigate the influences of compression ratio and the concrete strength in the steel tube. The results showed that: for the specimens with hinged joint, joint design in same strength will improve the bearing capacity andstiffness but reduce the ductility, for the specimens with semi-rigid connection, what method is used to design the node has little effect to the mechanical behavior. When actual load is used to design the node, specimen with semi-rigid joint is better than the specimen with hinged on the bearing capacity and stiffness, but lower in terms of the ductility. When node is designed in equal strength for connection, node form has little effect to the mechanical behavior. The bearing capacity of specimens augments with the decrease of axial pressure and the increase of the concrete strength but both them are not main influence factors.