基于时变可靠理论的既有钢筋混凝土梁桥剩余寿命评估

发布时间：2018-02-28 10:55

本文关键词： 可靠性评估结构耐久性时变可靠度剩余使用寿命可靠指标　出处：《兰州交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着自然条件的不断变化、经济发展带来的交通流量及荷载等级的不断增大，桥梁结构正面临着前所未有的考验。在众多因素共同作用下，随着时间的推移，钢筋混凝土桥梁结构将会出现不同程度的损伤，这些损伤通常包括材料、构件和结构三个方面。各种损伤的不断累积势必会造成桥梁性能劣化、承载能力和耐久性下降的结果，最终影响其正常使用并造成安全隐患。如何科学合理地评估既有钢筋混凝土桥梁的可靠性，并对其剩余使用寿命进行预测，已成为目前国内外桥梁学术界研究的重点问题之一。通过开展对既有钢筋混凝土桥梁结构可靠性评估及使用寿命预测的研究，一方面可以指导桥梁的设计、施工和安全运营；另一方面有助于尽早发现既有桥梁的潜在危机，，及时做出维修加固或拆除重建的决策。本文以时变可靠度理论为依据，结合已有的材料耐久性的研究成果，从可靠性和使用寿命入手对既有钢筋混凝土简支梁桥进行了研究分析，主要进行了以下几方面的内容：首先，就已有的对既有桥梁可靠性评估方法及研究现状进行了总结和特点评述，奠定了本文研究的理论基础。桥梁在实际运营时，其抗力受很多不定因素的影响，并且它是一个随时间衰减且不可恢复的过程，所以应该将抗力视为一个随机过程进行处理。由此可知，桥梁结构的可靠性评估应是一个时变问题。本文借鉴了以前学者对抗力影响因素的研究成果，根据工程案例的实际背景建立了抗力计算模型、荷载概率时变模型及抗力衰减时变模型。考虑抗力随时间衰减问题，本文从混凝土碳化、钢筋锈蚀、材料强度变化等方面入手，分析了其对抗力的影响。在进行可靠指标的计算时，我们首先需要将抗力随机过程转换为随机变量的形式，并需要通过迭代进行求解，因此本文利用MATLAB程序以辅助求解。最后，通过工程实例，利用时变可靠指标计算程序求出由8片T梁组成的20m长的钢筋混凝土简支梁桥对应的时变可靠指标，然后与目标可靠指标进行比较求出了该桥的剩余使用寿命。
[Abstract]:With the continuous change of natural conditions and the increasing traffic flow and load grade brought by economic development, the bridge structure is facing an unprecedented test. The damage of reinforced concrete bridge structure usually includes three aspects: material, member and structure. The continuous accumulation of various damage will inevitably result in the deterioration of bridge performance, the decrease of bearing capacity and durability. How to scientifically and reasonably evaluate the reliability of existing reinforced concrete bridges and predict their remaining service life has become one of the key issues in the academic research of bridges at home and abroad. Through the research on reliability evaluation and service life prediction of existing reinforced concrete bridge structure, on the one hand, it can guide the design, construction and safe operation of the bridge; on the other hand, it can help to discover the potential crisis of the existing bridge as soon as possible. Make timely decision to repair, reinforce or dismantle and rebuild. Based on the theory of time-varying reliability and combined with the research results of material durability, this paper studies and analyzes the existing reinforced concrete simply supported beam bridge from the reliability and service life. The main contents are as follows:. Firstly, the existing reliability assessment methods and research status of existing bridges are summarized and reviewed, which lays the theoretical foundation of this paper. When the bridge is in operation, its resistance is affected by many uncertain factors, and it is a process of decay and irrecoverability over time, so the resistance should be treated as a random process. The reliability evaluation of bridge structure should be a time-varying problem. This paper draws lessons from the previous research results of the influence factors of the resistance force, and establishes the resistance calculation model according to the actual background of the engineering case. The load probability time-varying model and the resistance attenuation time-varying model. Considering the problem of resistance attenuation with time, this paper analyzes the influence of resistance force on concrete carbonization, steel bar corrosion, material strength change and so on. We first need to convert the resistance stochastic process to the form of random variable and to solve it by iteration. So we use MATLAB program to help solve the problem. Finally, through an engineering example, the time-varying reliability index corresponding to a 20m long reinforced concrete simply supported beam bridge composed of 8 T-beams is calculated by using the time-varying reliability index calculation program. Then compared with the target reliability index, the remaining service life of the bridge is obtained.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U445.7

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