Stability Design Of Truss

Truss is a kind of lattice structure which consists of straight members connected at joints, while its horizontal length is much larger than the vertical length; Pipe Truss is a kind of Truss which its structural elements are all pile. As growing steel production in China, Steel-pipe Structure has also made a major breakthrough. Pipe Truss Structure, a kind of Steel-pipe Structure, is appreciated by the people according to its unique advantages. Pipe truss structure is developed from Space Truss Structure, which has unique advantages and practicality, compared with the latter, while it's more economical.Triangular Space Steel-pipe Structure (Truss Beam) contains triangular sections formed by the three chord members. In practice, it's divided into two categories; one is called Inverted Triangular Space Truss which is composed of two upper chords and one lower chord, the other is called Equilateral Triangle Space Truss which is composed of one upper chord and two lower chords. It's a kind of Space Truss with all bars are pipe. For the solid-web Beams, there are theoretical formulas to calculate flexural torsional buckling. According to mechanical characteristics of Space Truss (when the aspect ratio is greater than 1.5, it becomes a unidirectional mechanical system), Since the span of Triangular Space Steel-pipe Truss Structure is long, it belongs to a unidirectional mechanical structure, with large stiffness in its own plane. Due to increased width of upper chords, compared with plane frame, the out-of-plane stiffness and stability of truss are improved in some procedures, while the bending and twisting performance are also improved. The This research content of this paper is that the triangular cross section placed upside or down hew to improve lateral bending and torsion stability.According to this problem, we used Simple Space Triangular Steel-pipe Truss Beam respectively by inverted triangular cross-section and triangular cross-section for the study, and carried out the following aspects of their research:Firstly, starting from the introduction of the history of Space Truss Beam, it mainly introduced the evolution, mechanical system and the latest developments at home or abroad of space truss beam and presented the details of this paper.Secondly, the types of stability of steel structures and analysis methods are introduced. This paper involves the analysis of theories and methods related to adoption, for this simplified assumptions made, the calculation derived from the theory above.Thirdly, the finite element software ANSYS 11.0 is used for eigenvalue buckling analysis with various cross-section sizes; buckling mode and buckling load of the Space Steel-pile Truss are obtained. Based on the results of finite element analysis, starting from changes in section size, Influence factors and change trends for the overall stability of Space Steel-pile Truss are deduced.Finally, based on the obtained data, critical formula for elastic stability of solid-web simple Beams was simplified and fitted; simplified calculation formula for engineering application was obtained.