本文選題：在役拱橋 + 區(qū)間模型�。� 參考：《武漢工程大學》2014年碩士論文

【摘要】：我國在役拱橋在橋梁中所占比重大，分布地廣，近年來拱橋坍塌事故頻現(xiàn)，為了保證公路交通安全，充分發(fā)揮在役拱橋的作用，必須保證拱橋的承載能力、通行能力及良好的工作狀況。為此要對拱橋的可靠性做出評估。文中首先論述了從可靠性理論到在役結(jié)構可靠性理論的發(fā)展歷程，其特點是需要大量的數(shù)據(jù)來統(tǒng)計參數(shù)的分布形式，并且參數(shù)的小誤差會引起結(jié)果的大誤差，在這樣的情況下，人們提出了非概率可靠性理論，其所需數(shù)據(jù)量小，不需要知道參數(shù)的具體分布形式，只需要掌握參變量的界限即可，而且計算相對簡便，能有效減少計算工作量。為了克服傳統(tǒng)可靠性評估方法的不足，本文基于非概率可靠性理論提出了對在役拱橋承載能力的非概率可靠性評估方法。 非概率可靠性理論包含多種模型，其中主要有基于區(qū)間分析的非概率模型和基于橢球凸集的非概率模型，而區(qū)間分析方法更具有優(yōu)勢，所以本文選取了基于區(qū)間模型的非概率可靠性理論對拱橋進行可靠性分析。模型建立以后往往需要可利用的算法支撐，文中對結(jié)構非概率可靠性指標算法進行了總結(jié)，目前的算法各有特點，以區(qū)間分析法和優(yōu)化搜索法為主。但對于復雜的拱橋體系而言，其極限狀態(tài)方程不明確，常見方法不再適用，本文將非概率響應面法和失效點尋優(yōu)法應用于拱橋，，但通過計算發(fā)現(xiàn)非概率響應面法的計算量很大，而采用失效點尋優(yōu)法所需的有限元計算次數(shù)少，能極大的減少計算量，高效的求得非概率可靠性指標，其優(yōu)勢更加突出。 本文給出了加固前后拱橋的非概率可靠性評估流程圖，并以一雙曲拱橋為實例，通過現(xiàn)場測量數(shù)據(jù)來獲取主要參數(shù)的區(qū)間變量。利用midas有限元軟件分別建立拱橋加固前和加固后的全橋模型，對主拱圈跨中截面進行受力分析，以及對截面的抗力進行計算。通過求得加固前的非概率可靠性指標對截面進行評估，并以此為依據(jù)提出合理的加固方案，本次根據(jù)拱橋加固方法的相關研究，提出在拱圈的拱背上進行加固，分別為拱頂拱背處橋面鋪裝以最薄30cm厚的C40微膨脹混凝土與主拱圈澆筑在一起，加固長度為5m，考慮到盡量不增加橋梁恒載的前提下，在拱腳的拱背處加固10～15cm厚鋼筋混凝土。 再利用失效點尋優(yōu)法求解加固后的非概率可靠性指標，發(fā)現(xiàn)1，證明加固后效果明顯，截面安全可靠。通過本文的研究成果可以驗證將非概率可靠性理論應用于拱橋的可靠性評估是可行、有效的，同時也說明本文提出的評估 加固 評估的思路是合理的。 目前非概率可靠性理論的應用越來越廣泛，已經(jīng)滲透到各個領域，但在橋梁領域的研究還處于初步階段，后階段特別是在算法優(yōu)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.
【學位授予單位】：武漢工程大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U441;U448.22

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