Experimental Study And Finite Element Analysis Of Hysteretic Behaviour Of Square Hollow Section(SHS) Brace-H-shaped Chord T-joints

H-shaped steel is widely used as chord bar in joint design because of its good flexural performance,material saving and easy to design and choose.Hybrid joints composed of steel tubes with various cross-sections can resist external loads together.The connection of square steel pipe and H-shaped steel effectively avoids the problem that the intersection surface is a curved surface,which greatly reduces the difficulty of component fabrication and installation,so it is widely used in engineering.On the other hand,seismic fortification has become one of the important links in the design of building structures.Hysteretic performance,as an important index to measure the energy dissipation capacity of structures,has important research significance.In this paper,the hysteretic behavior of H-shaped steel chord-square-branch T-joints is tested and analyzed by finite element method,and the virtual beam element method is introduced to simplify the model,so as to evaluate the seismic performance of H-shaped steel chord-square-branch T-joint from the structural level,and to provide a powerful tool for future engineering applications.The main contents and conclusions of the study are as follows:Firstly,three H-shaped steel chord members with the same size and different crosssection width of Square branch pipe were designed and tested under hysteretic load.The test results show that with the increase of the width of the square branch,the hysteretic performance of the joints increases,and the energy dissipation capacity and ductility of the joints increase.Secondly,the finite element modeling method is used to simulate the actual failure of the joint.The finite element modeling software is ABAQUS.In ABAQUS,the joint model of the specimen is constructed by using the extended finite element analysis method.The finite element results are compared with the experimental data,which proves the correctness of the established finite element model.Finally,aiming at the problem of huge number of elements and low computational efficiency in building solid element models at structural level,virtual beam element modeling method is introduced to simulate the strength,stiffness,ductility and energy dissipation capacity of T-joints.Then,the virtual beam element model is applied to the engineering example at the structural level,and the elastic-plastic time history analysis is used to investigate the effect of the relative displacement of the top under the action of seismic wave on the width of Square branch pipe.The analysis results show that the overall stiffness of the joint is strengthened and the peak horizontal displacement of the vertex decreases gradually with the increase of the width of the Square branch of the model.