【作者】 潘韬；

【导师】 杨德灿；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2006， 硕士

【摘要】 悬索桥是由主缆、主塔、加劲梁、吊索等构成的组合体系,因其主缆受拉力,材料利用效率高,已成为特大跨度桥梁的首选桥型。随着跨度的增大,加劲梁的刚度在全桥刚度中所占比例很小,桥梁的刚度主要来自于具有相当大恒载初张力的承重缆索,在受力本质上大跨度悬索桥应是一种柔索结构体系,分析必须计入构件初应力及结构变位的影响,即必须采用几何非线性分析。 主缆是结构体系中的主要承重构件,悬索桥主缆的成桥线形是进行结构设计、计算和指导施工的关键控制因素,建立符合实际情况的主缆成桥线形计算方法十分必要。本文采用迭代算法对悬索桥的主缆成桥线形进行分析,具体思路是:将成桥状态结构的几何参数(主缆的设计垂度、吊索位置、鞍座中心位置、桥面设计线形等)作为控制目标,假设一个施工理想初态,采用前进分析的迭代算法,反复修正施工理想初态使得计算所得成桥状态的有关参数与控制目标相比,误差满足精度要求,从而得到符合设计要求的悬索桥主缆成桥线形。 本文基于有限位移理论,利用通用有限元程序建立悬索桥全桥模型并进行分析,计算过程中计及了大位移引起的悬索桥几何非线性的因素,实现了悬索桥施工过程模拟计算的通用有限元程序方法。 通过理论分析和实例的计算表明:1)在悬索桥主缆成桥线形分析过程中,须考虑主塔鞍座的偏位以及二期恒载由主缆和加劲梁共同承担的实际情况;2)在第一次假设施工理想初态时,以成桥状态已知的主缆跨中垂度建立施工理想初态模型,同时在迭代计算的过程中,建立合理的修正公式,才能使收敛的速度快:3)在成桥状态时主缆的线形既不是抛物线,也不是悬链线,而是介于抛物线与悬链线之间,更接近于悬链线的索多边形。更多还原

【Abstract】 Suspension bridge is a composite system made up of cable, tower, stiff girder and suspender. Because the main cable is tensioned, the material is utilized efficiently. It has become the first choice for the long-span bridges. Along with the length increment, stiff girder accounts for a small proportion of rigidity in the whole bridge. The rigidity of the whole bridge mainly originates from the supporting cable with large initial tension caused by the dead load. The long-span suspension bridge is a flexile cable system. So the analysis must take the influence of component’s initial stress and structure’s deflection into account. Namely, the geometric non-linearity analysis must be adopted.The cable is the main supporting component in the system. Its shape in the bridge’s completion state is the key controlling factor of structure design, calculation and guiding construction. It is necessary to establish the cable shape’s computation method complying with the actually situation. This paper adopted the iteration algorithm to analyze the cable shape in the bridge’s completion state. The thought is that taking geometric parameter (cable design sag, rope site, saddle center site, the deck design shape, etc) in the bridge’s completion state as control target, supposing a construction ideal initial state, the calculation proceeds through iteration algorithm in advancing analysis. Then the constructions ideal initial state is amended repetitively to meet the demands that the error between the control target and the related parameter through calculation in the bridge’s completion state satisfies the precision requirement. Then cable shape in the bridge’s completion state complying with the design request is obtained.This paper, based on the finite displacement theory, utilized the general FEM program to establish the whole bridge model and analyzed the model. The geometric non-linearity factors of suspension bridge caused by large displacement were considered in the calculation. The general finite element method simulating the construction process of suspension bridge was realized.According to theory analysis and example computation, the following conclusions are obtained.1. During the analysis on the cable shape in the suspension bridge’s completion state, the pre-displacement of saddle and the case that the cable and stiff girder commonly bear the second-stage dead load should be considered.2. When supposing the construction ideal initial state in the first time, if the initial state model is established according the cable’s span central sag in the bridge’s completion state, and the reasonable correction formulation is created in the iteration process, the result can converges fast.3. The cable shape in the bridge’s completion state is not parabolic, nor catenary. It is between parabola and catenary. Actually it is funicular polygon closer to the catenary.更多还原