Mechenical Performance Analysis Of Space KX-Joints In Steel Tube Truss

Engineering practices at home and abroad in recent years have shown that: multi-planarcircular steel tubular KX-joints are one of the common joints besides KK-joints and KT-jointsin tubular structures. However, it is still a question about the design of the KX-joints in thedesign code for the steel structure(GB50017-2003), and it is unhelpful for the safety andeconomy of engineering design. As well, the static load capacity and the seismic behavior ofthe KX-joints are taken into consideration, which is carried out by ANSYS program in thispaper. The main research content in this article are as follows:(1) The eβ_xperimental results in published papers are demonstrated with analysis ofnonlinear finite element. Through comparative analysis of eβ_xperimental results and the resultsof nonlinear finite element, the appropriate model of KX-joints is established. It also carriesout the size effect of joints which demonstrates the universality of the analyzed results in thispaper.(2) It discusses that under the influence of space effect which include the load effect andgeometric effect, the force behavior of KX-joints changes with different geometricparameters β_x、 τ_x、 and φ_i. Through that, it is concluded that the aβ_xial force ratio of thebranchnX Kaffects significantly to the ultimate strength of the KX-joints comparing with therelevant planar K-joints. We concluded that it can be conservatively designed as the K-jointsin certain aβ_xial force ratios.(3) According to the failure mode of specific joints, the failure types of KX-joints arefurther to research. Also based on classification, the representative are selected, and thehistory of stress and plasticity spread of KX-joints are respectively described during thewhole loading process.(4) Under the static loading, the interact relation of the ultimate strength of the KX-jointsis studied owing to the load effect and geometric effect. It can be conclude that it isindependent for the influence of the ultimate capacity to thenX K, which is not changed withgeometric parameters, when the failure types are consistent.(5) According to the specific geometric parameter, the seismic behavior of the KX-jointsis analyzed under the influence of space effect. The energy dissipation capacity and ductilityof the joints is evaluated by the hysteretic curves. The results showed that the seismicbehavior of KX-joints is worse than that of the planar K-joints, and the energy dissipationcapacity and ductility are worse and worse with the︱nX K︱increasing.(6) The skeleton curves of KX-joints are depicted by means of the analyzed hystereticcurves. So it is concluded that the variation tendency of the skeleton cures of joints is on basicagreement with the change of thenX K. It also compares the ultimate capacity of the X branchwhen it is under the pressure or tension. (7) According to differentnX K, it is concluded that the KX-joints will be on differentfailure modes when it is under the reciprocating seismic action.