Analysis On The Out-plane Stability Of Cantilever Tube-truss Structure

In recent years, the tube-truss structure is applied more and more in large public buildings, e.g. the terminal, the railway station, and the sports stadium etc., and the cantilever tube-truss structure is mainly applied in the sports stadium. Stability is a key factor which could affect the carrying capacity of steel structure, however, there is no provision about the out-plane stability of tube-truss structure, so it is meaningful that the out-plane stability of tube-truss structure is studied in this paper.Firstly, the tube-truss structure is simplified to a model of thin-walled closed cantilever, then the differential equations are established by the energy law, and the approximate analytical solution of out-plane stability ultimate load is obtained. Compared to out-plane stability ultimate load and strength ultimate load, this paper obtain the condition that the cantilever tube-truss structure couldn't lose the out-plane stability. Secondly, the impact of geometric parameters on the out-plane stability of tube-truss structure is analyzed by the finite element method, and then, it is compared with the conclusions of analytical solution. Finally, the dynamic stability of cantilever tube-truss structure under earthquake is also analyzed by the element method.The study indicates the following conclusions: the top chords and bottom chords have little impact on the out-plane stability of tube-truss structure, although with the increase of belly bar's section area, the out-plane stability of tube-truss structure increase; when the internode length equals to the section height, the out-plane stability of cantilever tube-truss structure would be best; for each h/l, there is a critical aspect ratio b/h, when h / l 1/10, the critical aspect ratio b / h < 1/ 2.5, when 1/ 20 < h / l< 1/10, the critical aspect ratio b / h < 1/ 2, and h / l< 1/ 20 is inappropriate; within the range commonly used in engineering, the elevation has little impact on the out-plane stability of cantilever tube-truss structure.