Finite Element Analysis Of Multi-bar Cross Box Column Joints

At present,scholars at home and abroad have done a great deal of research on multi-bar cross-box column joints by numerical simulation,model test,numerical simulation and model test,and have achieved a lot of results.However,all the above studies are independent of the whole structure and do not consider the influence of the whole structure on the joint,which is not in accordance with the actual situation.In this paper,a multi-story dormitory building with steel frame center support structure is taken as a case study.The project is located in Tianjin City,and the seismic fortification intensity is 8 degrees.The main vertical bearing member of the dormitory building is a box column.The primary and secondary beam of the frame is joist steel,and the central support is box section.The finite element analysis software Midas is used to establish the structural whole analysis model of the local nodes,and the static analysis of the model is carried out.The interaction between the joint performance and the whole structure is considered separately.According to the above results,the design and production of steel structural members are further designed and processed.The main contents of this paper are as follows:(1)According to the construction drawing provided by the construction unit,the numerical analysis model of the whole structure is established by using the finite element analysis software Midas-gen,and the constitutive model and boundary conditions of the corresponding material are set up in the model.The static analysis of the whole structure is carried out after the parameter setting is confirmed.(2)The box column frame joints with inclined brace are intercepted from the whole structure model,and the internal forces and stresses of each member are recorded.Then,the finite-element analysis software Midas-fea is used to establish the fine model of the node,and the most unfavorable internal force of each member composed of the node is applied to the end of the corresponding member of the node by static analysis of the whole structure.The constraint conditions of each unit end of the node are set,and the static analysis of the individual node model is carried out,and the analysis results are recorded.(3)The refined model of nodes established by software Midas-fea is reimported into the whole structure model established by software Midas-gen software.The finite element nodes in the end of the rod in the refined model are rigidly connected with theend nodes of the beam element at the corresponding position in the whole model by the rigid connection command,and the structural integral analysis model of the local joint refinement is obtained after eliminating the repeated nodes.The whole structure is analyzed and the analysis results of the nodes are recorded.The static analysis results of the single node model and the local node refinement model are compared.The static stress of the local node refinement model is obviously smaller than that of the local node refinement model.It is proved that the whole structure does have an obvious effect on the joint refinement.Therefore,for checking the bearing capacity of joints and guiding the design of steel members,it is more appropriate to adopt the method of structural whole analysis with local joint refinement.(4)According to the static analysis results of the structural whole analysis model with fine local joints,the design of this kind of frame joints with multi-bar crossing in the whole building is deepened,and it is determined whether it is necessary to add horizontal partitions or take other measures to strengthen them.It provides technical support for the processing of this complex node.The research results of this paper have a positive guiding significance for the further design and processing of multi-bar cross-box column joints,and also provide a reference for further study on the overall design of steel box-shaped column-center braced frame.