【作者】 李传夫；

【导师】 李术才；

【作者基本信息】 山东大学 ， 岩土工程， 2008， 硕士

【摘要】 钢管混凝土拱桥是大跨拱桥的一种比较理想的结构形式,也是我国近年来桥梁建筑发展的新技术,能较好地解决修建桥梁所需求的用料省、施工简便、承载能力大等诸多问题。但随着跨度的增加,首先遇到的技术难题就是施工问题。由于吊装节段重量的限制,吊装节段必须增多,这就给拱肋吊装施工提出了新的问题:怎样在多节段拱肋吊装施工中,使最后合龙的拱肋满足设计要求的合龙精度。由于拱桥自身的受力特点,一旦拱肋合龙,就无法再对拱肋的线形进行调整,而合龙后的拱轴线形将决定成桥后的受力状态,因此应重视拱肋吊装中拱轴线线形的优化,确保钢管混凝土拱桥建成后的轴线和设计轴线相吻合,保证拱桥受力最合理。钢管拱桥结构型式复杂,在设计计算、施工过程模拟和反分析等结构仿真计算中常常面临参数最优化的问题,运用非线性规划的方法去处理具有明显的优势。针对支井河特大桥的特殊斜拉扣挂系统,将最优化理论引入正装迭代计算中,提出迭代优化算法,应用于拱肋吊装过程的线形控制和索力优化。设置合理的优化变量、约束条件和目标函数,可建立可测控变量与控制目标之间的函数关系。应用扣索一次张拉到位、预抬高控制的思想,将索力优化分散到各个施工阶段单独进行,依靠线形偏差修正和外部嵌套的循环实现总体线形的控制。该算法用于拱桥吊装施工的模拟,考虑了扣索垂度等非线性影响后,一轮优化得到的预抬高和扣索索力即可基本满足线形控制的要求。为克服这种方法难以调整主拱肋内力和预抬高量可能偏大的缺陷,并注意到合龙前后拆除扣索的程序差异会对拱肋的线形、内力产生影响,提出修正的拆扣方案,并对几种可行方案进行了分析和优化比选,确定一个最佳的更利于施工控制的方案。另外,稳定性也成为制约钢管混凝土拱桥发展的主要因素之一。钢管混凝土使得拱肋轻质高强化的同时,也带来了拱肋刚度减小的问题,使得其稳定问题日渐突出。经验表明:在很多情况下,施工过程中的稳定性要低于成桥以后的稳定性,因此对施工过程中的整体稳定性分析要通过科学的计算予以确认和评价。这一点在支井河特大桥的长悬臂、长施工期的情况下尤为突出。本文在静力分析的基础上运用线弹性和非线性稳定理论,针对悬臂合龙阶段的特殊受力状态,对支井河特大桥的拱肋吊装施工期的稳定性进行了细致的计算分析,包括线弹性、几何非线性、材料非线性和双重非线性屈曲分析。并且还考虑了初始缺陷、风荷载以及扣索非保向力的影响,提出了一些有实际意义的结论。更多还原

【Abstract】 Concrete-Filled Steel Tubular arch bridge is one of the ideal forms for long-span arch bridge, and it’s also a newly developed bridge engineering technology of our country. It can preferably solve many problems in bridge construction, for instance: material economization, simple and convenient construction, high bearing capacity etc. But with the bridge span increasing, the first technical problem we encounter is the matter of construction. Limited by the weight of erecting section, the number of the sections has to be increased, so a new question is brought forward to erection: how to ensure arch rib satisfying the precision required by design after final closure in multi-section erecting process. Because of the bearing peculiarity of the arch bridge, in case the arch rib is completely joined, the alignment of the rib can not be adjusted here from. However, the joined alignment of arch rib shall determine the stress of the completive bridge, so alignment control during rib erecting must be attached importance to in order to ensure the final arch axis tallying with the designed axis and bearing state of the arch bridge being most reasonable.Steel arch bridge structure embodies complex types and a legion of influencing factors, and in the meantime we frequently face the problems of parameter optimization in design calculation, construction process simulation and back analysis etc. Great advantage will be gained when the method of nonlinear programming is exercised. Aiming at the special cable-stay system of Zhijinghe Bridge, optimum theory is import in advancing calculation method and iterative optimization method is introduced into alignment control and cable-force calculation of erection stage. Via reasonable design variable, constraints and optimization function set up, the relationship between measure-controllable variables of the structure and control objective is established. With appliance of the idea of once-tension and precambers control, cable force optimization is separated into parts that performed in every construction stage, and alignment differences are modified and exterior loops are performed to ensure the alignment control. Using this method in simulation of arch bridge erection, after taking nonlinear effect like droop of cable etc into account, precambers and the cable forces ascertained in the first round optimization can basically meet the demand of alignment control. In order to overcome the limitations of this method that hard to refine the internal force of the arch rib as well as possibly too large precambers, taking notice of the influence on alignment and internal force of the rib by procedure differences of cable-removing before and after the closure, modified cable-removing schemes are brought forward which are analyzed and compared with each other, and then a best scheme with easier control is determined.On the other hand, stability has also been a restriction to the development of CFST arch bridge. CFST makes the arch rib lightweight and high-strength, but at one time it decreases the stiffness of the rib, causing stability problem more and more prominent. It has been indicated by experience that, in many cases, the stability of the bridge under construction is lower than that after construction, so the overall stability analysis during construction process should be affirmed and evaluated through scientific calculation. This point is particularly important in the conditions of long cantilever and construction period of Zhijinghe Bridge. Based on the static analysis, linear and nonlinear stability theories are applied. Aiming at the special bearing state of cantilever-closure phase, detailed calculation and analysis for stability of the Zhijinghe Bridge during erecting period are carried out including linear buckling analysis, geometrical, material and double nonlinear analysis. Original disfigurement, wind loading as well as the effect of non-oriented conservative loading of the cable is considered, and some practical conclusions are advanced in the end.更多还原