Study On The Static Performance Of Space DKT Type Steel Square Hollow Section Gapped Intersecting Joints Under Axial Force

Steel tube intersecting joints are widely used in engineering practice.In order to meet various functional requirements of buildings,various new types of joints have emerged,such as the spatial DKT square steel tube gap intersecting join.This joint is a spatial square steel tube joint formed by two plane KT shapes combined together.In practical engineering,for the need of construction and other aspects,a large number of spatial joints appear,and the research on the mechanical properties of spatial DKT square steel tube joint is not perfect.Therefore,it is necessary to study the static performance of the spatial DKT square steel tube gap intersecting joints.Therefore,the work conducted in this paper includes the following aspects:（1）The current research status and research results of the coherent steel tube intersecting joints are reviewed,and the paper verifies the accuracy of the modeling method.The results show that the model of the square steel tube gap intersecting joints in the paper.（2）Appropriate boundary conditions,loading methods,main tube and branch tube lengths were selected,and then appropriate ultimate bearing capacity criteria were adopted to establish finite element calculation models of spatial DKT square steel tubular gap intersection joints.Finite element analyses of spatial DKT square steel tubular gap intersection joints were conducted.（3）The influence of load scheme on the spatial DKT-shaped square steel tube gap intersecting joints was studied.The load scheme include The loading scheme includes the size and direction of the load applied by the branch tube.In finite element parameter analysis,the changes in the size of the applied load on the branch tube were reflected by changes in the axial force ratio of the branch tube.The corresponding ultimate bearing capacity of the joint was calculated for different axial force ratios of the branch tube,and the stress distribution and deformation during joint failure were observed,Thus,the influence of different axial force ratios of branch tubes on the ultimate bearing capacity of joints was summarized.Two different axial force directions of branch tubes were also applied to the joints,and the stress distribution and deformation during joint failure were observed.The changes in joint bearing capacity under the two loading directions were compared to obtain the impact of load direction changes on joint bearing capacity.These provide a reference for selecting appropriate axial force ratios of branch tubes and applying load directions to branch tubes for finite element parameter analysis in the following text.（4）The finite element method is used to analyze the breaking mode of the the joint,and analyze the stress process of the joint.The influence of the single parameters on the ultimate bearing capacity of the spatial DKT-shaped square steel tube gap intersecting joint.The geometric parameters analyzed in this paper are:the ratio of the side length of K-shaped web members to that of the main tubeβ₁,the ratio of the side length of T-branch to that of the main tubeβ₂,width-to-thickness ratio of the main tubeγ,the ratio of the wall thickness of K-shaped branch tube to that of the main tubeτ₁,the ratio of the wall thickness of T-branch to that of the main tubeτ₂,the in-plane angle between the K-shaped branch tube and the main tubeθ（acute angle）.The influence of geometric parameters on the ultimate bearing capacity of spatial DKT-shaped square steel tube gap intersecting joints was studied through parameter analyses.These research results can provide suggestions for the design of spatial DKT-shaped square steel tube gap intersecting joints in engineering practice.（5）The equation for the ultimate bearing capacity of spatial DKT shaped square steel tube gap intersecting joints was deduced.Based on the equation for the ultimate bearing capacity of planar K shaped square steel tube gap intersecting joints,the coefficientψ_DKTwas introduced into it,and then a equation for calculating the ultimate bearing capacity of spatial DKT-shaped square steel tube gap intersecting joints was deduced through multiple linear regression.At the same time,the results of the finite element data and the expression operation results are compared to test the accuracy of the bearing capacity calculation formula.