| The multi-tower suspension bridge with new structure form which can achieve long spans and whose dvantage is obvious in similar bridge is the preferred in the cross-sea bridge project. But for now, the instances of long-span and mutil-tower suspension bridge are few in the domestic and international area, only Taizhou Yangtze River Bridge built and the building Maanshan Yangtze River Bridge and Wuhan Parrot Island Yangtze River Bridge in China. This is shown that the analysis and research of mutil-tower suspension bridge is just started, and the mechanical properties of the new structural system are not well grasp that many technical problems are to be solved. So the problems are only solved sufficiently, multi-tower suspension bridge will be better applied in practice. Therefore, the mechanical properties of in the bridge state of tow-tower and multi-tower suspension bridge are analyzed in this article, and the static and dynamic properties of two-tower and multi-tower suspension bridge are compared and analyzed. Besides, the mew structural system of three-tower suspension bridge is conducted a preliminary study. The main contents are as follows:1. First the developing historical background and the studying significance are introduced for the large-span and mutil-tower suspension bridge and the development process of the world’s suspension bridges are elaborated.Then the the instances of mutil-tower suspension bridges which have been built and the proposed programs in the design process are cited in the domestic and international area currentely. Morever the problem research of large-span multi-tower suspension bridge is focused on analyzing by the the scholars.2. The development of suspension bridge theory on the elasticity theory, deflection theory and finite displacement theory is introduced respectively, and the finite displacement theory is mainly expounded. Then relevant factors, the solution and convergence criter of the nonlinear finite element problem are analyzed. Morever the study methods of dynamic analysis theory, the vibration characteristics theory and the vibration equations of suspension bridge are conducted relevant elaboration.3. The initial equilibrium theory of suspension bridge is introduced and the differences of displacement of main cables and internal force of main cables and suspender cables in the bridge state are comparatively analyzed between two-tower and mutil-tower suspension bridge. In addition, the difference of mechanical properties between two-tower and mutil-tower suspension bridge are also analyzed under the action of vehicle load and wind load and the vibration frequency characteristics were compared in the mutil-tower suspension bridge. Through the above analysis, the purpose is to obtain different static and dynamic characteristics between two-tower suspension bridge and mutil-tower suspension bridge system and the effect of mutil-tower suspension bridge on the mechanical properties.4. The innovative structural system of three-tower suspension bridge is analyzed appropriately through taking three-tower suspension bridge as an engineering example in this article. The key design parameters of constraint form between tower and beam at the middle tower, the stiffness of middle tower, span ratio of main cable are mainly analyzed to obtain the effect on the static and dynamic properties of three-tower suspension bridge structure. And then, the Abaqus model is used to compare with the Midas civil model for the mechanical properties in order to verify the reliability of the results in the Midas civil model. Morever, the key indicators are controlled by parameters proposed through the effect generated for the calculation and analysis of various parameters in the previous paper in order to analyze the key indicators to obtain appropriate architecture of three-tower suspension bridge in the case of different design parameters. |
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