The Large Span Cross-section Down The Overall Stability Of The Triangular Space Truss

Through the research on the domestic project of large span space truss with inverted triangle section, we find it's difficult for structure engineering designers to use the current design standard of steel structure to analyze the integral stability of this kind of structure, because there is no relative calculation formula and design rules in the current design standard. So we take advantage of the linear and nonlinear finite element methods to analyze the integral stability of the roof system composed by space truss with uniform section and inverted triangle section. At the same time, we analyze the effect of the width-height ratio of space truss, the horizontal tied bar and the horizontal brace in its upper chord on the integral stability of space truss roof system.First, four kinds of stability analysis methods are introduced briefly and concisely. They are linear analysis which only considers elasticity, nonlinear analysis which considers both initial geometrical imperfection and geometric nonlinearity, nonlinear analysis which considers both geometric and material nonlinearities, and nonlinear analysis which considers initial geometrical imperfection, geometric and material nonlinearities. In this paper, we make use of the finite element software ANSYS8.0 to realize these four kinds of stability analysis. And it provides APDL languages of four kinds of stability analysis with this software for steel structure engineering designers and researchers' reference.Secondly, combined with the actual engineering design, eight calculation models of space truss are established, a size of parameters including design parameter, section size and geometric parameter are provided and operation steps about solution procedure of stability capacity are listed simply in this article.Finally, compared with the results of nonlinear analysis, We have a comprehensive understanding to the effect of the width-height ratio, horizontal tied bar in upper chord, the horizontal brace in upper chord and longitudinal edge trass process on the stability of the space truss roof system, then offer some sciential suggests on the readjust of design.