【作者】 李盛；

【导师】 袁海庆；

【作者基本信息】 武汉理工大学 ， 结构工程， 2006， 硕士

【摘要】 转体桥由于设计和施工相对简单,受力明确,因而易于掌握、易于推广。与钢结构劲性骨架和钢管混凝土轻型化转体施工方案相比,混凝土开口薄壁箱转体方案具有成本低、工种相对简单、转体操作方便的优点,更容易在山区得到推广应用。目前,在拱桥轻型化转体施工中,混凝土开口薄壁箱拱的整体稳定性和局部稳定性问题,直接涉及到设计理论与方法,涉及到施工工艺和施工控制技术方面,至今尚未有系统的研究,这就影响了这一技术的推广应用。 本文回顾了结构稳定性研究的现状,并结合实际项目指出了目前研究中存在的若干问题。接着,从大跨度桥梁的稳定理论中,引出了基本的稳定理论,及求解稳定理论的若干数值方法,列举了经典的圆弧拱面内、面外稳定问题的求解方法,及按挠度理论的基本方程建立任意拱轴线方程的推导过程。分析了半跨拱结构在脱离支架后转动合龙前及在二期浇注混凝土过程中整个半跨结构的稳定性能。 以湖北省交通厅鄂交科教[2004]343号项目为依托,本文以湖北省恩施州平地坝转体拱桥这一目前建成的跨径最大的采用开口薄壁箱技术的转体拱桥为实际工程背景,运用有限元软件ANSYS通过合理而又必要的简化,对实际结构建立了三维有限元模型,提出了此类桥型的建模处理方法。通过有限元数值模拟,对半跨拱结构脱离支架后的结构线形进行分析预测。对脱离支架后所处裸拱施工阶段的拱肋—拉索体系进行了稳定性分析,由于此施工阶段无外加荷载工况,本文定义失稳时的重力倍数为结构的稳定安全系数。通过特征值分析,并考虑扣索张拉力大小,张拉均匀性,施工时混凝土的浇注误差,加厚部分截面,钢筋笼等影响因素,给出了不同状态下半跨拱肋结构所具有的稳定安全系数及相应的失稳模态。利用合龙后结构对称性,采用半拱模型模拟了二期浇注过程中的稳定性能变化。 通过以上工作本文归纳出了此类型桥的失稳特点及应注意的问题,对今后我国西部山区同类型桥的设计施工有一定的理论价值和实用意义。更多还原

【Abstract】 In addition to the simple design and construction, owing to explicit mechanics states, it’s easy to master and develop turning bridges. Comparing with other construction project, such as steel framework, CFST, etc, open thin-walled boxes reduce quite a lot of expense, simplify the construction categories, and have some advantages in view of the turning manipulating. So it’s easier to be adopted than others in a mountainous area. At present, in the construction process of light-weight turning, the global stability and local stability problems have some effects on the design theory and method, construction art and construction controlling technology, which have not been researched systematically and have impeded the development of this technology.Firstly, the thesis reviews the history of structure stabilization, in the same time, relates to the real project, points out some problems exist in actual research. Secondly, from the stability theory of long-span bridges, the thesis elicits the basic stability theory and some numerical solution methods about it, enumerates classical buckling of circular arches and deduces the process of discretionary arch axes through the displacement theory. Considering two construction conditions that when breaking away from brackets and when in the second concrete casting stage, the thesis analyzes stability states of half-span arch structure.Relying on the science and technology project from Hubei province transportation bureau [2004]343, according to some reasonable and necessary simplifications, the thesis builds the 3D finite element model of Ping di-ba turning arch bridge which is the largest span turning bridge constructed by the open thin-walled boxes technology at present in Enshi state in Hubei province and submits a model building method for these types of bridges by the finite element software ANSYS. The thesis anticipates structural displacements’ change by finite element numerical simulation. Because there are no exterior loads that acting on structures in the stage before the ribs breaking away from brackets, the thesis defines the multiple of structure while the arch ribs lose stability as the stability safety factor. Considering the magnitude of cable force, uniformity of tension, errors from casting concrete, adding the thickness of local sections and the effect of reinforcing steel cage, the thesis provides various stability safety factors of half-span arch which correspond to different conditions. Owing to the structure’s symmetry, by using the half-span arch model, the thesis simulates the stability states when the whole bridge under the 2nd casing concrete stage.According to the above research work, the thesis concludes some instable characters and some problems which should be pay more attention to. Considering the theory value and practicability, the research results will be helpful for the western mountainous areas in China.更多还原