發(fā)布時(shí)間：2018-09-17 16:08

【摘要】：隨著我國(guó)交通事業(yè)的不斷發(fā)展，大跨徑預(yù)應(yīng)力混凝土連續(xù)箱梁橋憑借其施工方法靈活、剛度大、跨度大、結(jié)構(gòu)受力性能好等優(yōu)點(diǎn)在工程界得到了廣泛應(yīng)用。但是調(diào)查研究發(fā)現(xiàn)，有相當(dāng)數(shù)量的這種橋梁在運(yùn)營(yíng)過(guò)程中，箱梁截面出現(xiàn)了部位各異、程度各異的裂縫。裂縫的存在將會(huì)使橋梁結(jié)構(gòu)的安全性與耐久性受到影響，因此，必須進(jìn)行相應(yīng)的加固維修。然而，橋梁數(shù)目眾多，不可能逐一進(jìn)行加固修補(bǔ)，因此，就需要科學(xué)的判斷開裂結(jié)構(gòu)的實(shí)際狀態(tài)，以區(qū)分輕重緩急，為制定合適的維修、改造方案提供依據(jù)�，F(xiàn)如今，對(duì)大跨徑預(yù)應(yīng)力箱梁橋開裂后狀況的研究還很少，如何對(duì)開裂結(jié)構(gòu)的實(shí)際工作狀態(tài)進(jìn)行準(zhǔn)確的判斷一直未能解決。 本文以黃延高速洛河大橋?yàn)橐劳�，從箱梁產(chǎn)生的主要病害裂縫（跨中正彎矩區(qū)段底板橫向裂縫）入手，對(duì)開裂前后結(jié)構(gòu)進(jìn)行靜力、動(dòng)力分析，得到不同開裂狀態(tài)下結(jié)構(gòu)的剛度、承載能力及動(dòng)力性能（頻率）的變化規(guī)律。 首先，本文對(duì)箱梁裂縫的產(chǎn)生原理、形成因素及裂縫分類進(jìn)行了理論分析，發(fā)現(xiàn)裂縫的產(chǎn)生具有不可避免性，，裂縫的研究具有實(shí)際意義。之后，本文依據(jù)統(tǒng)計(jì)學(xué)原理建立了底板橫向裂縫的特征統(tǒng)計(jì)參數(shù)，旨在將實(shí)際存在的裂縫轉(zhuǎn)化為統(tǒng)計(jì)意義下的平均裂縫，通過(guò)在梁段上創(chuàng)造既有裂縫的方法進(jìn)行模擬研究。其次，論文還對(duì)有限元分析所需的單元、本構(gòu)關(guān)系、裂縫模型、混凝土破壞準(zhǔn)則等進(jìn)行了系統(tǒng)研究，為模型的建立及求解計(jì)算提供理論依據(jù)。最后，論文根據(jù)實(shí)橋設(shè)計(jì)資料建立開裂前后結(jié)構(gòu)的空間實(shí)體模型，分析了縱向預(yù)應(yīng)力損失、裂縫失效寬度、裂縫開裂高度、裂縫條數(shù)等不同裂縫參數(shù)改變時(shí)，結(jié)構(gòu)的應(yīng)力、撓度、頻率的變化規(guī)律，獲得不同開裂狀態(tài)下結(jié)構(gòu)的剛度、承載能力及頻率的折減系數(shù)。 分析結(jié)果表明：（1）縱向預(yù)應(yīng)力損失對(duì)結(jié)構(gòu)墩頂處的撓度影響不大，對(duì)結(jié)構(gòu)跨中處的撓度影響較大；（2）縱向預(yù)應(yīng)力損失對(duì)結(jié)構(gòu)墩頂處和跨中處的壓應(yīng)力均有較大影響；（3）底板橫向裂縫的單元失效寬度對(duì)結(jié)構(gòu)影響不大；（4）裂縫高度對(duì)結(jié)構(gòu)有一定影響，但開裂高度不大時(shí)影響微小，且開裂到一定高度后又會(huì)逐漸趨于穩(wěn)定；（5）裂縫條數(shù)對(duì)結(jié)構(gòu)影響較大。
[Abstract]:With the continuous development of transportation in our country, long-span prestressed concrete continuous box girder bridge has been widely used in engineering field by virtue of its flexible construction method, large stiffness, large span and good mechanical performance. But the investigation found that a considerable number of such bridges in the operation process, box girder cross-section of different parts, varying degrees of cracks. The existence of cracks will affect the safety and durability of bridge structure. However, there are so many bridges that it is impossible to reinforce and repair them one by one. Therefore, it is necessary to scientifically judge the actual state of the cracked structure in order to distinguish the priority and order of priority, and to provide the basis for the formulation of appropriate maintenance and renovation schemes. Nowadays, there are few researches on the post-cracking condition of long-span prestressed box girder bridge, how to accurately judge the actual working state of the cracked structure has not been solved. Based on the Luohe Bridge of Huangyan High Speed, this paper starts with the main damage cracks (transverse cracks in the bottom slab of the section of mid-bending moment), analyzes the structure before and after cracking, and obtains the stiffness of the structure under different cracking conditions. The variation of bearing capacity and dynamic performance (frequency). Firstly, this paper makes a theoretical analysis of the generation principle, formation factors and classification of cracks in box girder. It is found that the occurrence of cracks is inevitable and the study of cracks is of practical significance. Then, based on the statistical principle, this paper establishes the characteristic statistical parameters of the transverse cracks in the bottom plate, aiming at transforming the actual existing cracks into the average cracks in the statistical sense, and simulating the method of creating the existing cracks on the beam section. Secondly, the element, constitutive relation, crack model and concrete failure criterion needed for finite element analysis are systematically studied in this paper, which provides the theoretical basis for the establishment of the model and the calculation of its solution. Finally, according to the design data of the real bridge, the spatial solid model of the structure before and after cracking is established, and the stress of the structure is analyzed when the longitudinal prestress loss, crack failure width, crack height, crack bar number and other crack parameters change. The stiffness, bearing capacity and frequency reduction coefficient of the structure under different cracking conditions are obtained by the variation of deflection and frequency. The results show that: (1) the longitudinal prestress loss has little effect on the deflection at the top of the pier, but has a great effect on the deflection at the middle of the span, (2) the loss of longitudinal prestress has a great effect on the compressive stress at the top of the pier and at the middle of the span. (3) the failure width of the transverse crack of the bottom plate has little effect on the structure, (4) the crack height has a certain influence on the structure, but the crack height has little effect on the structure, and the crack will gradually become stable after cracking to a certain height. (5) the number of cracks has great influence on the structure.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U448.213;U441

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