Experimental Research On Hysteretic Behavior Of T-Type SHS Joint Under Axial Loading

Steel tubular structures have been widely used in the world because of pleasing appearance, light weight, easy fabrication and rapid installation. Especially in recent years, with the gradual increase of steel output and the developing of steel tubular's processing technic, steel tubular has been widely used in our country. Many researches have been made to study the static behavior of tubular joints, and research production has been much mature, but there is little of study to research behavior of joints under cyclic axial loading. Especially in our country there is no experimental investigation into hysteretic behavior of SHS (Square Hollow Section) joints under cyclic axial loading, and there is much earthquake in our country. Based on above discussion an experimental investigation into the hysteretic behavior of T-type SHS joints under cyclic axial loading was conducted. Twelve T-type joints with two types of restraints were tested under cyclic quasi-static axial loading in order to get their hysteretic behavior. The detailed analysis for experiment process and its result were conducted. Experiment was simulated and its results were compared by ANSYS program.The main contents in the paper are listed as follows:(1) The ANSYS model of T-type SHS joint was constructed, the main parameters affecting hysteretic behavior of joints were analyzed and laboratory's existing condition was considered in order to fix geometry parameters of test specimens. Then static load-carrying capacities of these joints were analyzed to prepare for detailed designing specimens using ANSYS.(2) Specimens were designed and fabricated, and then twelve T-type joints with two types of restraints were tested under axial cyclic quasi-static loading acting on the brace end to get their hysteretic behavior. The experimental method was introduced in detail, and experimental phenomenon was also described and summarized.(3) Based on test results, the results of twelve T-type joints with two types of restrictions under cyclic axial loading were analyzed, including failure mechanism, hysteretic curve, skeleton curve, deformation capacity, load-carrying capacity, energy dissipation, stiffness decay and so on. The results show that T- type SHS joint has good ductility and aseismic capacity. Whenβis small, there is little affection of different restraints, but whenβis very large, bending deformation of chord affects the joint's hysteretic behavior.(4) Experiment was simulated, two methods considering the affection of weld were given, and the results of FEA (Finite Element Analysis) and test were compared. It is proved that it is feasible to analyze the working behavior of joint under axial cyclic quasi-static loading before the appearance of crack using ANSYS program.