在役拱桥非概率可靠性研究与应用

发布时间：2018-05-31 22:40

本文选题：在役拱桥 + 区间模型　；参考：《武汉工程大学》2014年硕士论文

【摘要】：我国在役拱桥在桥梁中所占比重大，分布地广，近年来拱桥坍塌事故频现，为了保证公路交通安全，充分发挥在役拱桥的作用，必须保证拱桥的承载能力、通行能力及良好的工作状况。为此要对拱桥的可靠性做出评估。文中首先论述了从可靠性理论到在役结构可靠性理论的发展历程，其特点是需要大量的数据来统计参数的分布形式，并且参数的小误差会引起结果的大误差，在这样的情况下，人们提出了非概率可靠性理论，其所需数据量小，不需要知道参数的具体分布形式，只需要掌握参变量的界限即可，而且计算相对简便，能有效减少计算工作量。为了克服传统可靠性评估方法的不足，本文基于非概率可靠性理论提出了对在役拱桥承载能力的非概率可靠性评估方法。非概率可靠性理论包含多种模型，其中主要有基于区间分析的非概率模型和基于椭球凸集的非概率模型，而区间分析方法更具有优势，所以本文选取了基于区间模型的非概率可靠性理论对拱桥进行可靠性分析。模型建立以后往往需要可利用的算法支撑，文中对结构非概率可靠性指标算法进行了总结，目前的算法各有特点，以区间分析法和优化搜索法为主。但对于复杂的拱桥体系而言，其极限状态方程不明确，常见方法不再适用，本文将非概率响应面法和失效点寻优法应用于拱桥，，但通过计算发现非概率响应面法的计算量很大，而采用失效点寻优法所需的有限元计算次数少，能极大的减少计算量，高效的求得非概率可靠性指标，其优势更加突出。本文给出了加固前后拱桥的非概率可靠性评估流程图，并以一双曲拱桥为实例，通过现场测量数据来获取主要参数的区间变量。利用midas有限元软件分别建立拱桥加固前和加固后的全桥模型，对主拱圈跨中截面进行受力分析，以及对截面的抗力进行计算。通过求得加固前的非概率可靠性指标对截面进行评估，并以此为依据提出合理的加固方案，本次根据拱桥加固方法的相关研究，提出在拱圈的拱背上进行加固，分别为拱顶拱背处桥面铺装以最薄30cm厚的C40微膨胀混凝土与主拱圈浇筑在一起，加固长度为5m，考虑到尽量不增加桥梁恒载的前提下，在拱脚的拱背处加固10～15cm厚钢筋混凝土。再利用失效点寻优法求解加固后的非概率可靠性指标，发现1，证明加固后效果明显，截面安全可靠。通过本文的研究成果可以验证将非概率可靠性理论应用于拱桥的可靠性评估是可行、有效的，同时也说明本文提出的评估加固评估的思路是合理的。目前非概率可靠性理论的应用越来越广泛，已经渗透到各个领域，但在桥梁领域的研究还处于初步阶段，后阶段特别是在算法优化方面需要更大的突破。
[Abstract]:In order to ensure the safety of highway traffic and give full play to the function of in-service arch bridge, the bearing capacity of arch bridge must be guaranteed in order to ensure the safety of highway traffic and give full play to the function of in-service arch bridge. Capacity and good working condition. Therefore, the reliability of the arch bridge should be evaluated. In this paper, the development process from reliability theory to in-service structure reliability theory is first discussed, which is characterized by the need for a large amount of data to calculate the distribution of parameters, and the small error in the parameters will lead to large errors in the results. The theory of non-probabilistic reliability is proposed, which requires a small amount of data, does not need to know the specific distribution form of parameters, but only needs to master the bounds of parameter variables, and the calculation is relatively simple, which can effectively reduce the calculation workload. In order to overcome the shortcomings of traditional reliability assessment methods, a non-probabilistic reliability evaluation method for in-service arch bridges is proposed based on the theory of non-probabilistic reliability. The theory of non-probabilistic reliability includes many models, including non-probabilistic model based on interval analysis and non-probabilistic model based on ellipsoidal convex set. Therefore, this paper selects the non-probabilistic reliability theory based on interval model to analyze the reliability of arch bridge. After the establishment of the model, the available algorithms are often needed. In this paper, the non-probabilistic reliability index algorithms of structures are summarized. The current algorithms have their own characteristics, mainly using interval analysis method and optimization search method. However, for complex arch bridge systems, the limit state equation is not clear and the common methods are no longer applicable. In this paper, non-probabilistic response surface method and failure point optimization method are applied to arch bridge, but it is found that the calculation of non-probabilistic response surface method is very heavy. But the failure point optimization method needs less times of finite element calculation, can greatly reduce the amount of calculation, and efficiently obtain the non-probabilistic reliability index, its advantages are more prominent. This paper presents the flow chart of non-probabilistic reliability evaluation of arch bridges before and after reinforcement. Taking a hyperbolic arch bridge as an example, the interval variables of main parameters are obtained by field measurement data. The midas finite element software is used to establish the model of the arch bridge before and after reinforcement respectively. The stress analysis of the middle section of the main arch ring span and the calculation of the resistance of the section are carried out. The section is evaluated by obtaining the non-probabilistic reliability index before reinforcement, and a reasonable reinforcement scheme is put forward based on it. According to the relevant research of the reinforcement method of the arch bridge, the reinforcement on the arch back of the arch ring is put forward in this paper. The bridge deck at the back of the arch is respectively paved with the thinnest 30cm thick C40 micro-expansion concrete and the main arch ring is poured together, and the reinforcement length is 5 m. Considering the premise of not increasing the dead load of the bridge as far as possible, the 10~15cm thick reinforced concrete is strengthened at the back of the arch foot. Then the failure point optimization method is used to solve the non-probabilistic reliability index after reinforcement. The results show that the effect of reinforcement is obvious and the section is safe and reliable. The application of the non-probabilistic reliability theory to the reliability assessment of arch bridges is feasible and effective, and it also shows that the idea of evaluation and reinforcement evaluation proposed in this paper is reasonable. At present, the application of non-probabilistic reliability theory is more and more extensive, which has penetrated into various fields, but the research in the field of bridge is still in the initial stage, especially in the later stage, especially in the optimization of algorithm.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.22

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