Analysis of Out-Of-Plane Stability for Cantilever Steel Tube-Truss Structure Under Uniform Load

Stability is a key factor to the ultimate bearing capacity of steel structure. Until recently, the out-of-plane stability design method is absent for cantilever steel tube-truss structure in the current codes. In this paper, firstly the structure is simplified as a model of thin-walled cantilever beam with close section, and an approximate analytical solution of the strength bearing load and out-of-plane stability critical load are derived. Secondly based on the analytical solution, the conditions are proposed when the structure does not lose out-of-plane stability. Finally, compared with the results by the finite element analysis, it shows that web members have more effects than the upper and lower chords as well as upper chords' connection bar on the out-of-plane stability. When panel length is equal to sectional height, out-of-stability of structure is the best. The sectional height-to-cantilever length ratio and sectional width-to-height ratio are the most important factors for out-of-plane stability of this structure.