Theoretical And Experimental Research On The Stability Of The Sheet-Space Structure With Imperfections

The sheet-space structure is a new kind of light weigh and high strength structure system. The stability analysis and nonlinear analysis become important in the research and the design of the sheet-space structure. Moreover, since the sheet-space structure belongs to the imperfection sensitive structure, the stability analysis and nonlinear analysis of the structure with random imperfections are very complex, difficult and unsolved yet in designing. In this paper, the effect of imperfections on the stability of the sheet-space structure is investigated on theory and experiment. The primary content of the study includes:(1) According to the author's comprehension, some of the concepts and principle of the stability are induced and elaborated. On the basis of summarizing the basic characteristic of each kind of stability problem, a new stability classification opinion is put forward, which includes bifurcation point buckling, limiting point buckling, snap-through buckling and nonlinear bifurcation buckling. The initial imperfections criteria are put to use in the nonlinear finite element analysis, and the initial minute imperfect method is put forward to research nonlinear bifurcation buckling. The basic though and the step of the method are referred to and the merit and shortcomings are analyzed. Some theoretical and experimental examples are used to prove that the initial minute imperfect method is feasible and right.(2) The duel nonlinear stability analyses of the sheet-space structure with geometric nonlinearities and material nonlinearities are made. Some theoretical and experimental examples are put to use to study the effect of some factors, including geometric nonlinearities, material nonlinearities, the sheet and the distance of the sheet from the axis etc. This work makes us have more overall understanding to the stability behavior of the sheet-space structure.(3)The conventional analysis methods of imperfections and stability of the structures are reviewed. The theoretical and numerical analysis on the advantages and disadvantages of these methods is carried out. Advanced stochastic imperfections method is put forward,which does not require a large amount of manual computation and by which the reliability of design critical load and critical load with consistent mode imperfections method can be evaluated. Some examples of the different structure form are researched, which mainly include a few common sheet-space structures. The results of perfect model, consistent mode imperfections method and advanced stochastic imperfections method are compared, and some conclusions that are useful for engineering design and study of space-sheet structure are obtained. Consistent mode imperfections method and advanced stochastic imperfections method are adopted to study the stability of abnormal steel roof construction of Nantong sports and exhibition center. The design critical load is achieved and the reliability of design critical load and critical load with consistent mode imperfections method are evaluated.(4) In the interest of an overall understanding to the stability behavior, breakage configuration and the effects of imperfections of the sheet-space structure, a few models are studied and the destructive loading tests are conducted. In the whole loading process, the whole load-displacement curves and load-strain curves are obtained. The accuracy and reliability of the theoretic analysis and advanced stochastic imperfections method are verified by the comparison of theoretic computation and experiment results.(5) The concept of imperfection sensitive region is put forward. Just as its name implies, the imperfection sensitive region is the region in which the structure is sensitive to a certain kind of imperfection. The study of imperfection sensitive region has many important theoretical and practical values. Three examples are researched, and their imperfection sensitive regions are achieved. The results and conclusions are of important value to the design and construction of this kind of structures.