大跨径钢管混凝土拱桥桁架拱肋耐久性评估研究

发布时间：2018-12-14 06:18

【摘要】：由于环境和时间因素的影响，钢管混凝土拱桥出现钢管锈蚀、混凝土脱空等耐久性病害从而导致钢管混凝土结构的耐久性发生退化，结构承载力随之下降，最终导致桥梁的使用受到限制甚至发生桥梁坍塌等，而钢管混凝土拱桥桁架拱肋作为主要的承重结构和传力结构，弦杆和腹杆等杆件众多结构复杂，其状态直接决定着拱桥的使用寿命，因此对其耐久性病害损伤的状况评定是十分必要的。本文运用传统的模糊层次法对桁架拱肋进行了详细的递阶分层，划分钢管、混凝土、其它损伤项目层，通过模糊层次评估法得到钢管、混凝土等不同项目层和拱肋目标对象的评估结果，利用变权原理和模糊贴近度处理等评估技巧使得评估更加准确。避免了现有的拱肋的耐久性评估病害划分和评估比较粗糙的缺陷。本文针对桁架拱肋的复杂结构特点运用可靠度理论结合模糊评估方法，建立了桁架拱肋的基于可靠度的模糊层次评估模型。该方法的主要内容与结论如下： ①将桁架拱肋这一复杂结构将实桥和有限元模型结合进行单元划分，将桁架拱肋拆解成各单元构件，这样可以使评估细化到拱肋的细小部位，避免了过去对于桁架拱肋只能进行整体的病害评估的缺点。 ②结合设计荷载作用下的MIDAS/Civil的分析内力结果，引入能量法中应变能的计算方法，计算桁架拱肋各部位（单元构件）的权重，得到拱肋的内力和权重的数值分布规律。该权重计算方法结合了荷载作用和构件自身材料特性，避免了传统权重计算方法的主观性、片面性与粗糙赋值的缺陷。 ③根据构件的损伤情况和单元（实桥拱肋的各部位）内力求解单元构件的可靠度，由单元权重和构件可靠度运用简捷的体系可靠度计算公式计算桁架拱肋的体系可靠度，建立钢管混凝土拱桥的构件和体系可靠性评估分级标准，根据分级标准对桁架拱肋各单元构件（拱肋部位）和整个拱肋分别进行耐久性病害下的可靠性评估。并在构件损伤的可靠性评估结果的基础上结合所有桁架拱肋的耐久性病害进行桁架拱肋整体的模糊层次评估。 ④评估实例表明基于结构可靠度的耐久性评估方法与传统模糊层次评估方法结果相近，符合桥梁实际耐久性状态。但前者可以得到桁架拱肋这一复杂结构的内力和权重分布规律，单元构件可靠度和拱肋整体可靠度评估结果，，以及所有病害下的拱肋模糊评估结果，评估结论全面且评估过程中考虑荷载和病害影响下的拱肋自身抗力衰减，对后期拱肋的养护、维修指导意义更大。
[Abstract]:Due to the influence of environment and time, the durability of concrete-filled steel tube (CFST) arch bridge is damaged by corrosion of steel tube and concrete void, which leads to the degradation of the durability of CFST structure and the decrease of the bearing capacity of CFST structure. Finally, the use of the bridge is restricted or even the bridge collapses. As the main load-bearing structure and force transfer structure, the truss arch rib of concrete-filled steel tubular arch bridge is complex, such as chord and web bar. The service life of arch bridge is directly determined by its state, so it is necessary to evaluate the condition of durability damage. In this paper, the traditional fuzzy hierarchy method is used to stratify the truss arch rib in detail, dividing the steel tube, concrete and other damage item layers, and obtaining the steel pipe by the fuzzy hierarchy evaluation method. The evaluation results of different project layers and arch ribbed objects, such as concrete, are more accurate by using variable weight principle and fuzzy closeness processing techniques. The existing arch-ribbed durability assessment of disease classification and evaluation of rough defects. In this paper, according to the complex structural characteristics of truss arch rib, the reliability theory and fuzzy evaluation method are used to establish the reliability based fuzzy hierarchy evaluation model of truss arch rib. The main contents and conclusions of this method are as follows: (1) the truss arch rib is divided into elements by combining the real bridge with the finite element model, and the arch rib of the truss is disassembled into each element member. In this way, the evaluation can be refined to the small part of the arch rib, avoiding the shortcoming that the arch rib of truss can only be evaluated as a whole in the past. (2) combined with the analysis of internal force of MIDAS/Civil under design load, the calculation method of strain energy in energy method is introduced to calculate the weight of each part of truss arch rib (element member), and the numerical distribution law of internal force and weight of arch rib is obtained. The weight calculation method combines the load action and the material characteristics of the member itself, and avoids the disadvantages of subjectivity, one-sidedness and rough assignment of the traditional weight calculation method. (3) according to the damage condition of the member and the internal force of the element (every part of the arch rib of the real bridge), the reliability of the element member is solved, and the system reliability of the truss arch rib is calculated by using the simple formula of the system reliability by using the weight of the element and the reliability of the member. The reliability evaluation criteria of concrete filled steel tube (CFST) arch bridge were established. According to the classification criteria, the reliability of each element of truss arch rib (arch rib) and the whole arch rib were evaluated under the durability disease respectively. Based on the results of reliability assessment of member damage, the fuzzy hierarchy assessment of the whole truss arch rib is carried out based on the durability disease of all truss arch ribs. (4) the evaluation example shows that the durability evaluation method based on structural reliability is similar to the traditional fuzzy hierarchy process and accords with the actual durability state of the bridge. However, the former can obtain the distribution law of internal force and weight of the complex structure of truss arch rib, the evaluation results of the reliability of element member and the whole reliability of arch rib, as well as the fuzzy evaluation result of arch rib under all diseases. The comprehensive evaluation conclusion and the resistance attenuation of arch rib under the influence of load and disease in the evaluation process are of great significance to the maintenance and maintenance of the arch rib in the later stage.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.22;U441

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