The Stability Research On Pretensioned Ribs Ring Spherical Shell

For the development of spherical shell structure to super long span, the prestressed spherical reticulated mega-structure is put forward in which the cables and the pretension technique are introduced into space structure. It has a lot of advantages, such as big whole stiffness, good performance in aseismic and wind resistance, economizing steels, reducing the construction cost, sutting to grow towards long-span and super long-span, and so on. These will be widely applied to engineering practice in the futhure.The stability behaviors are the most important respect of the anslysis of the single-layer spherical lattice shell and double-layer shell with small ratio of thickness and span. The stability of the lattice shell can be analyzed by load-displacement post buckling curve. Structure's load-displacement curve can display the whole stages of the strength stiffness and stability clearly. And the initial shortage and load apply which have influence on actual lattice shell's stability can be researched through the load-displacement curve. The nonlinear problems of the lattice shell are divided into geometric nonlinearity and material nonlinearity. The material nonlinearity can be considered by the safety factor. The analysis of their stability about geometric nonlinearity is researched in this paper.The program which is developed with Visual C++ for creating the spherical reticulated mega-structure is used; and the arrangement styles of cables and geometric nonlinear stability, etc are investigated by using software ANSYS in this paper. At first; based on the analysis of arrangement styles of cables in spherical shell structure, the styles which are suitable to mechanics characteristics of spherical reticulated mega-structure can be choosed out. Then; the best arrangement styles of cables,the optimal kind of supports,and the topgallant domain of tension values in cables can be decided by comparative analysis. After that; the factors which can affect instability modality and ulitimate load bearing capacity of the structure are analyzed and summarized largely within scope of convention. The variation laws between them can also be obtained. Afterwards the influences of uneven distribution of the live load, different ratios of live load and dead load and initial shortage of structure to stability behaviors are studied. Finally; starting with example, the affection of damage in single bar to global stability of structure is inspected, and the regular pattern of unstable failure is sumed up at last.The study in this paper of such structure can provide a theoretical basis and reference on the future practical application.