| The long-span beam string structure (BSS) is a self-equilibrium system which using bar connecting bending resistance member and tension member and applied pre-stress on tension member. BSS was applied increasingly at home and abroad because it can make full advantage of two rigid-flexible materials' performance; it is clear in load carrying capacity and its system is simple. In order to get a better application of BSS, this paper used geometric nonlinear finite element to build analysis model. The form finding of the long-span BSS and the mechanical performance of single-direction and dual-direction BSS were studied systemically. The main contents of this paper are as follow:At first, based on discussing the introduce method of the pre-stress in cable, a new efficient method named equivalent decreasing temperature method was used in the paper. The paper used equivalent decreasing temperature method to solve the form finding of BSS. It can get the initial geometry in geometry zero state and the stress distribution in initial equilibrium state to construct BSS.Secondly, the effects of the number of bars, sag-span ratio, rise span ratio and pre-stress of the string on the mechanics performance and displacement of single-direction BSS were studied systemically in detail in this paper. There are also many disagreements with the influence of rise-span ratio, sag-span ratio and the pre-stress of string on the bending of single-direction BSS, which were reviewed more comprehensive with numerical and theoretic analysis in this paper.Finally, the whole mechanics performance of dual-direction BSS were researched systemically in the paper. In comparison with single-direction BSS, some limitations such as the non-uniform distribution of stiffness and insufficient use of the lower cable-bar structure were presented. The effects of the load, sag-span ratio, rise span ratio and pre-stress of the string on the mechanics performance and displacement of dual-direction BSS were studied systemically. |
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