Numerical Analysis On Bearing Capacity And Hysteric Behavior Of The Strengthen Rhs Tube K-Joint

HSS (Hollow Steel section) structure has good appearance and permeability. Because the shear center and geometry center of the section are located in the same point, the structure has good performance of torsion and flexure. All the advantages are good to the member stability and economic benefits. In recent years, this structure form is generally applied to the large span structure such as airport, stadium and railway station. As joint is the critical connection part of structure, the research for its static and hysteretic performance has important realistic significance.With better stiffness, span capacity and bearing capacity, RHS (rectangular hollow section) truss, as a type of HSS structure, has always been used in overloading and long span structures. Outer sleeve as a strengthening method is often used in RHS truss. Based on static test results, this paper applies numerical analysis to study the bearing capacity and hysteretic behavior of K-type joints especially the outer sleeve ones by changing parameters and gets comprehensive results which can be used as references in actual projects.Firstly the numerical method is verified through comparison with static test results. Secondly with 112 joints, this paper compares static behavior of outer sleeve joints with the one of non-strengthen and inner stiffen joints, and proves that outer sleeve ones have higher bearing capacity and better manufacture mechanics. Studying the influence of changing designed parameters(τ,β) to bearing capacity and failure modes of outer sleeve joints, the paper proposes geometric parameters(a, D) scope of outer sleeve joints and their applied conditions. Thirdly based on available static results, select typical joints subjected to axially cyclic loads, study the hysteretic behavior, get skeleton curves and ductility coefficient which are the main indexes reflecting RHS joints seismic behaviors. Through comparison, the results prove that the outer sleeve joints have good hysteretic behavior and the proposed geometric parameters of outer sleeve are also available in strengthen joints subjected to cyclic loads. Finally by fitting the envelope of the hysteretic curve and using dimensionless method, the paper proposes bi-linear restoring force model.