【作者】 赵冬兵；

【导师】 范立础；

【作者基本信息】 同济大学 ， 桥梁与隧道工程， 2005， 博士

【摘要】 钢筋锈蚀是影响钢筋混凝土桥梁耐久性的重要因素，随着锈蚀过程的持续，结构可靠度降低、失效概率增大。在桥梁的设计基准期(生命周期)内，如何合理地选择维修方案，就有着相当重要的现实意义。本文的研究包括了腐蚀介质在混凝土中的传播、钢筋锈蚀速度、时变可靠度分析、维修需求预测模型等，通过吴淞江桥的工程实际，对设计基准期内的不同维修方案进行了比较，预测了结构在设计基准期内的维修需求。混凝土碳化、氯离子渗透、钢筋锈蚀是结构生命周期内可靠度评估的重要基础，本文在已有研究成果的基础上，对混凝土碳化和氯离子渗透进行有限元分析，用数值分析的方法预测钢筋锈蚀开始时间。通过现有模型的比较分析，提出一般大气条件下钢筋锈蚀速度的建议模型和新的桥梁维修需求预测模型。在通过试验对计算假定进行验证的基础上，分析了结构响应的敏感度，计算了其在设计基准期内的时变可靠度和失效概率。最后，对进一步工作的方向进行了简要的讨论。本文的主要研究工作和创新成果有：(1)在已有研究成果和数学模型的基础上，提出了混凝土碳化有限元数值模拟方法，并通过文献中的试验资料进行了验证。探讨了碳化区内物质含量的分布规律，并利用分析成果对结构长期碳化过程中的影响因素和计算参数的合理取值进行了研究；(2)通过氯离子渗透模型的有限元分析，对开裂混凝土裂缝深度对氯离子渗透速度的影响进行了研究。得出了在裂缝深度较大时，氯离子渗透的研究必须建立2维模型的结论；(3)通过现有钢筋锈蚀模型的比较，提出了一般大气环境下钢筋脱钝后锈蚀速度的建议计算公式；(4)提出考虑关键截面约束条件的有限元计算方法，并通过文献中的试验资料进行验证。以钢筋锈蚀时间为研究变量，对结构的时变可靠度和失效概率进行计算。(5)在已有模型的基础上，通过比较分析，提出综合考虑目标可靠度和维修成本效益分析的维修需求预测模型；(6)以吴淞江桥为工程实例，进行了模型的综合应用和维修方案比较，证明了本文提出方法的适用性和有效性。更多还原

【Abstract】 The rebar corrosion is the important factor that has an effect on the durability of reinforced concrete bridge. With the development of corrosion, the reliability of bridge structures will be reduced and the fail probability will be increased. How to choose repair plan reasonably in the lifetime of bridges will be critical. The thesis includes the transportation process of corrosive substances in the concrete, rebar corrosion model, structural time-varied reliability analysis and repair demand forecast model. At last, all above mentioned models are used in the Wusongjiang Bridge, and as a result, the different repair plans are analyzed and compared.Concrete carbonation, chloride ion permeation and rebar corrosion are the bases of the structural reliability assessment in the lifetime of bridges. Based on existing research achievements, the finite element method is used in the numerical simulation of carbonation process and chloride ion permeation in the concrete, and then the initial time of rebar corrosion in the concrete can be predicted by numerical method. By the comparison of existing models, the rebar corrosion model under normal atmosphere and new repair demand forecast model are proposed. The computational assumptions are verified by test results of Buckhouse beam, and then the sensitivity of structural response, time-varied structure reliability and failure probability are computed. In the finality, the problems in further studies are briefly discussed. The major contributions of the work presented in this thesis are listed as follows:(1) Based on existing rsearch works and mathematical models, the finite element numerical simulation method of concrete carbonation is first proposed, and the predictions of this method are shown to be in close agreement with available test results. Next, the variation principles of substances contents in carbonated zone of concrete are discussed and the results are used in the study of parameters in the long term carbonation process of existing structure.(2) The influence of crack depth on the velocity of chloride ion permeation in concrete is studied by finite element analysis, and the conclusion that the chloride permeation model in cracked concrete should be two-dimensional is given.(3) By the comparison of existing rebar corrosion models, the rebar corrosion model under normal atmosphere is suggested.(4) The finite element method based on constraint in critical section is proposed, and the computation results are shown to be in good agreement with test results. In addition, regarding rebar corrosion as studying parameter, the time-varied structure reliability and failure probability are discussed.(5) Based on existing models, the new repair demand forecast model including target reliability index and cost-benefit analysis is proposed.(6) At last, all above mentioned models are used in the Wusongjiang Bridge, and as a result, the different repair plans are analyzed and compared, which proves the effectiveness and validation of methods proposed in this thesis.更多还原