Research On Overall Stability Behaviors And Design Method Of Steel Pipe Truss Structure

Being developed from grid structure, steel pipe truss structure is a structuaral form that can make full use of material properties, and meet the requirements of good archtectural performance and economic benefits perfectly.This paper established structural modals with the software ansys8.1, used consistent imperfection mode method to consider the influence of initial geometricl imperfection on the behaviors of structre, and trached the full load-displacement path of structre with arc-length method, through which the load-bearing performance and failure models of several kinds of steel pipe truss structure that are often employed in practice such as truss beam, truss arch, and latticed frame were made clear. On the basis of the research work above mentioned, orthogonal experiment analysis method was employed to conduct multi-parameter and multi-level analysis, through which important factors that have great effects on the in-plane or out-plane global stability of above mentioned structures were gained. One factor analysis with the different parameters were also conducted, and some useful suggestions were drawn. Part of the outcomes were list as follow:(1)Three parameters, W/H,H/L and Constraint form, have significant effect on the out-of-plane stability of truss beam; But as for trussed arch, only the parameter, W/H, has significant effect on its in and out-of-plane stability; W/H,H/L and Bar cross-section have significant effect on the out-of-plane stability of latticed frame.(2) Because of its large section rigidity (in plane, out plane and torsional) the falilure model of truss beam is Flexural-torsional divergence buckling model and have stable post buckling load-bearing capacity(3) Initial geometrical imperfection has significant effect on in-plane buckling path of trussed arch under full and half-span evenly distributed loads, but has little effect on the structure under mid-span concentrated load.(4) The out of plane load-bearing capacity of Truss increases according the increase of the value of "W/H", and has larger increasing rate when W/H is between 1/40 and 1/25. The optimal f/L rate of truss arch is about 0.2.(5) Parameter analysis results show that restriction condition of the middle node is essential to improve the out-of-plane bearing capacity of latticed frame, the most effecive support number is 3, more than the number, extral support bars have little effect.Based on a large number of caculated data, discrimination formulas to judge the necessity of overall stability analysis of truss beam are obtained, which can be used conveniently by engineering designers.This paper also analyzed the load bearing performace of cable arch.The influence of different cable arrangement pattens on the behavios of cable arch were examined, and some useful suggestions for improving structural bearing capacity and controlling structural deformation were given.