Ultimate Load Of Lattice Shell With Random Imperfection

The stability behavior is the most important respect of the design of the thin spherical lattice shell (especial for single-layer spherical lattice shell).The ultimate load of the lattice shell can beanalyzed by whole load-displacement buckling curve.The nonlinear analysis of lattice is usually divided into the geometry non-linearity and the material non-linearity. Because the ultimate load is controlled by geometry non-linear for majority single-layer spherical lattice shell .Therefore, this paper only considered the geometrical non-linearity of lattice shell.Because of the influence of construction level, the lattice shell inevitable existes initial installment imperfection, and this shall lead to the reducing of ultimate load, Therefore the study of the ultimate load of lattice shell with the initial imperfection have significant in practical engineering..This paper has studied the ultimate load of the spatial hexagon dome structure firstly. The concrete work main includes following several aspects: (1) Using finite element analysis software ANSYS, introducting stochastic imperfection, Using Monte-Carlo mathematics thought extracts value and the mean-square deviation of ultimate load of the hexagon dome structure with stochastic imperfection . (2) Using the finite element analysis software ANSYS, with consistent mode imperfection method carrying on the flaw analysis to hexagon dome structure, extracting the ultimate load, comparing the result of the consistent mode imperfection method with that of the proposed method, some significant conclusions are obtained..The paper has studied a kind of compound spherical lattice shell which is made of single-layer in center and double-layer around. It models and resolves the compound spherical lattice shell by ANSYS. The concrete work mainly launches in following several aspects: (1) The unstable state and the stability of the compound spherical lattice shell have been fully researched from initial to final stage; (2) The basis actual installment special details introduction initial imperfection, obtaining the response surface function of ultimate load of lattice shell with Random imperfection.(3) Through comparing results of consistent mode imperfection method with that of the proposed method, some significant conclusions which are helpful for practical engineering design are obtained.This research discovered: The lattice shell with random imperfection conforms to the project reality, simulating the random imperfection with the Monte-Carlo mathematics thought, has the massive degree of freedom spatial structure, the computation load is huge. But the response surface function one kind feasible, the simple and direct method, This research has some reference value for real design and building of shell.