Theoretical And Experimental Research On Multi-planar Joints With Strengthened Casing

Steel structure building has becoming more and more popular in our nation as thequick growth of Chinese economy and rapid increase of steel output. Steel tubular jointsare applied in steel structure more and more widely for its advantages of lightness,beauty and lower steel consumption. Large size steel buildings are designedincreasingly, especially in recent years, using large span and novel modeling steeltubular joints whose shapes and mechanical behaviours are complex, which is not givenspecific design method in China’s current national codes. As a result, it has importantsignificance in further studying static behaviour of such complicated multi-planar jointsand developing feasible approach to guiding engineering practice.Comprehensive experimental research and finite element (FE) method are studiedon the complex stressed multi-planar joints with strengthened casing of roof steelstructure in this paper, in the engineering background of Airport Terminal3A of secondstage expansion project in the Xi’an Xianyang International Airport. Research contentsare listed as follows:(1) Experimental research. Three full-scale joint specimens are tested in this paper.It can understand mechanical behaviour of the connection directly and verifyspecimens’ safety and reliability from experimental data. Experimental results show thatthe bearing capacity of each connection is1.78times more than the shuttle-shapecolumn’s design load fd=2526kN. Only partial zones of specimen enter into plasticstage when the testing load reaches3031kN, and the other most regions are still elastic.(2) Numerical analysis. It’s necessary to analyze this multi-planer joint with strengthened casing using FE software for its complicated stress in mutually intersectingzones. FE analysis is executed on such joints by finite element analysis softwareANSYS10.0, using shell181element of three-dimension and four-node and alsoconsidered material and geometric nonlinearity, which then get joint’s equivalent stressdistribution under testing load and its development and distribution of plastic strain. Theaccuracy of FE analytical results and feasibility of calculating method are verified bycomparing the analytical results with testing data, which also provides reliablenumerical model for subsequent parameter analysis.(3) Parameter analysis. There are many factors affecting multi-planer joint’sultimate load for its sophisticated detailing and uneven stress. As a result, parameteranalysis is carried out based on the numerical models mentioned above, selecting fourimportant parameters which effect such connections’ mechanical behaviours, includingthe thickness and length of the strengthened casing and the thickness and length of thecross stiffeners, designated as t1, l1, t2and l2respectively. Then obtained influencedegree of each parameter on the bearing capacity of the joints, which will provideimportant reference to the fabrication and erection of such connection in future practicalengineering.