Investigation On Performance Of Steel Frame Bracing System Considering The Semi-rigid Space Joints

With the vigorous promotion of steel,more and more building structures adopt steel structures,and steel frame-support structure system,as a common structural building form,has good lateral resistance.Although many buildings use braces to improve the lateral resistance of structures,there is still no specification to specify how to arrange braces in steel frame structures,especially for space steel frames that need to consider spatial effects,and there is no specification to guide the arrangement of braces.At the same time,in the traditional steel structure design,for the convenience of calculation,it is customary to simplify the beam-column connection to completely rigid connection or completely hinged connection.The calculated results are quite different from the actual situation.In fact,the rigidity of steel beam-column joints is between completely rigid connection and hinged connection,which belongs to semi-rigid connection,and its performance is between completely rigid connection and fully hinged connection.Therefore,in order to make the design of the steel frame-support structure system closer to the actual project and provide effective suggestions for the actual project,this paper,based on the previous experimental results,establishes the finite element model of the space steel frame structure by using ANSYS software,and conducts more in-depth research on the steel frame-support structure system with semi-rigid space joints.The main work of this paper is as follows:(1)ANSYS software is used to establish a three-dimensional solid model of beam-column components and a finite element model using spring element COMBIN14 to simulate the connection performance of beam-column joints,and the validity of using spring element COMBIN14 to simulate semi-rigid performance is verified through the experimental results in the literature.(2)According to the basic parameters of the steel frame under test and the effective modeling method of spatial beam-column joints,the finite element model of spatial steel frame-support structure is established by ANSYS software.The results of steel frame model of rigid space joint,steel frame model of semi-rigid space joint andtest model are compared and analyzed.The research results show that the semi-rigid spatial joint steel frame model is established by using spring element COMBIN14 to simulate the spatial joint performance and conforms to the rule of test results,which proves that the modeling method of spatial joint performance using spring element COMBIN14 to simulate the model in spatial steel frame model is feasible.The simulation results of the semi-rigid space node steel frame model using spring element COMBIN14 to simulate the performance of space nodes are closer to the experimental results,which proves that the semi-rigid performance can be well simulated using spring element COMBIN14.When the strong and weak axes of the space steel frame are both provided with supports,when the supports are arranged obliquely downwards along the weak axis and obliquely downwards along the strong axis,the results of the semi-rigid space node steel frame model and the test model are the closest.Therefore,in actual engineering,the strong and weak axis supports should be arranged obliquely.(3)The semi-rigid high-rise steel frame model is established by using ANSYS software.Through the combination of strong and weak axis direction support arrangement combination scheme,wind load and vertical load are applied at the same time,the influence law of support type and arrangement form on the spatial effect of semi-rigid high-rise steel frame is analyzed.The research results show that the modeling method of spatial joint performance using spring element COMBIN14 simulation model in high-rise spatial steel frame model is feasible by using spring element COMBIN14 simulation model to establish semi-rigid spatial joint steel frame model and comparing the top layer displacement and interlayer displacement angle under various support arrangements.When the arrangement of the support in the weak axis direction remains unchanged,the lateral stiffness of the support along the middle span in the strong axis direction increases the most against the weak axis direction.When the same type of support arrangement is selected in the strong axis direction and different types are selected,the anti-lateral stiffness in the weak axis direction has the most obvious improvement effect in cross support,followed by single-layer single diagonal support and the smallest cross-layer single diagonal support.When the arrangement forms of supports are the same,single-layer single-diagonal support is more economical than cross support.