【作者】 廖碧海；

【导师】 王元汉；

【作者基本信息】 华中科技大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 本文采用层次分析法、模糊数学方法、可靠度理论和方法、风险分析与决策方法、有限元分析方法，建立了既有拱桥评估与加固的理论体系。利用这些评估方法对拱桥进行安全性和可加固性评估，结果表明，采用本文提出的加固方法加固拱桥，拱桥的“可加固性高”。根据这一结论，提出了既有拱桥加固方案标准化的思路，并提出了标准化方案的具体措施、施工工序。全文主要工作如下：(1)对拱桥的受力行为进行了深入的研究。研究了拱桥之所以承载潜力较大的根本原因；从影响拱桥承载潜力的三大因素：联合作用、主拱圈、拱轴线型入手，研究了病害对拱桥承载能力的影响。(2)提出了合理挖掘拱桥潜力的既有拱桥安全性评估方法。在拱桥受力行为研究的基础上，采用层次分析法及模糊数学，提出了合理挖掘拱桥承载潜力的既有拱桥安全性评估的思路及方法，并以实腹式圬工拱桥为对象，建立了系统的拱桥安全性评估指标体系。(3)对可靠性理论在既有拱桥评估中的运用进行了研究。提出可靠性评估在拱桥中运用的基本假设，建立了拱桥加固前后可靠性评估的思路、步骤。引入时变可靠度概念，考虑汽车荷载、抗力随时间变化的条件下，对加固后的拱桥进行了寿命预测研究。(4)提出了基于可靠度的风险分析和决策方法。搜集了部分拱桥坍塌的案例，通过对案例的统计分析，研究了既有拱桥坍塌的主要原因。研究了拱桥加固前、加固后、拆除新建三种方案的总的期望损失模型。提出了拱桥风险消除率的概念并使之公式化，研究了基于拱桥“风险消除率”的决策准则。提出了基于风险的可加固性评估的思路和方法。(5)对拱桥的加固方法进行了深入的研究。对空腹式拱桥，提出了系列加固新方法，并用数值分析对新方法进行了优化研究。对实腹式拱桥，通过数值分析对比研究，优选出了从拱腹采用钢筋混凝土条带外包加固的方法。配合上述加固方法，提出了等应力法，解决了缺乏资料的情况下，拱桥的加固参数如拱背加固厚度的确定等难题。(6)得出了拱桥评估和加固的研究结论。采用本文提出的评估方法和思路，对课题组近年来完成的大量拱桥加固案例进行分析，结果表明，上述案例均“可加固性高”。由此可以推断，绝大多数拱桥利用本文提出的加固方法，其可加固性是高的。(7)提出了拱桥加固方案标准化的思路。根据本文评估与加固的研究成果，对拱桥加固标准化的方案、构造、措施、施工工序等进行了总结。更多还原

【Abstract】 Using analytic hierarchy process, fuzzy mathematics, reliability theory and risk theory, FEM as tools, a theoretical system has been established to evaluate the arch bridge before and after the reinforcement. And a number of arch bridges have been evaluated using this theoretical system. The evaluation results show that arch bridges possess high reinforcement feasibility, using the reinforcement methods provided in this study. Accordingly, the standardized methods are proposed to reinforce arch bridges. The main works are as follows:Firstly, a thorough research of the mechanics behaviors of the arch bridges has been done. And the factors for the arch bridges with high bearing capacity potential are studied. Three main factors that affect the bearing capacity of the arch bridges are studied. These include the combined effect, main arch ring and the shape of main arch ring. Then the effect of defects of the arch bridges on the bearing capacity has been studied.Secondly, the evaluation methods which use the bearing capacity potential of the arch bridges are put forward. Based on the mechanics behaviors, the analytic hierarchy process and fuzzy mathematics are used as tools. The idea of evaluating the arch bridges using arch bridges’ bearing capacity potential is proposed and the detailed methods are given. A safety evaluation system for the full-web masonry arch bridges is established.Thirdly, the reliability theory is applied in practice in evaluation of the arch bridges is applied in practice. Based on some basic assumptions, the procedure to evaluate the reliability of the arch bridges before and after the reinforcement is proposed. Then the time-dependent reliability is considered so the service life prediction can be achieved to consider that the vehicle load and structural resistances vary obviously with time.Fourthly, the risk analysis based on the reliability theory and related decision theory is applied to evaluate the arch bridges. Some collapse cases of arch bridges are collected and the main factors leading to the arch bridge accidents are studied based on the statistical analysis of the collapse cases. Three models of the expected losses have been proposed. The first one is that before reinforcement of the bridge and the second one is that after the reinforcement of the bridge. The third one is that the bridge is dismantled and rebuilt. The risk eliminating criterion is defined and formulated. Then the decision making rules based on the risk eliminating criteria are given.Fifthly, the further study is carried out for the reinforcement methods. Specifically, a series of new methods are put forward to reinforce the open spandrel arch bridges and an optimization has beeb proposed using numerical analysis. For the full-web arch bridges several methods are obtained. Then a comparison has been made for the numerical results of different reinforcement methods. Based on the comparison, the optimal method to reinforce the full-web arch bridge is wrapping reinforced concrete strips on the arch soffit. When there is no data about the arch bridge which needs reinforcement, a method called equal stress method is proposed. The problem of how to determine the reinforcement parameters such as the thickness of reinforced concrete and the reinforcement ratio has been solved.Sixthly, the research results of the evaluation and reinforcement of the arch bridges are given. Using the proposed methods, some reinforcement cases carried out in our practice are analysed and the results show that all of the cases possess high reinforcement feasibility. So it can be said that most existing arch bridges can possess high reinforcement feasibility using the proposed reinforcement methods.Finally, a new idea for the arch bridges reinforcement by the standardized methods has been proposed. Based on the research results, the details of the standardized methods, including the subject, construction, measures, procedures and key steps are summerized.更多还原