本文選題：索梁錨固結(jié)構(gòu) + 鋼橋疲勞��； 參考：《北京交通大學(xué)》2017年博士論文

【摘要】：近年來(lái),為了滿足公路和鐵路共用橋位的需求,公鐵兩用斜拉橋得到了廣泛的應(yīng)用。在汽車荷載和列車荷載的共同作用下,大跨度公鐵兩用斜拉橋承受了巨大的荷載作用。作為斜拉橋中拉索和主梁的連接構(gòu)件,索梁錨固結(jié)構(gòu)具有復(fù)雜的局部焊接構(gòu)造,此外,在傳遞巨大的荷載效應(yīng)過(guò)程中,索梁錨固結(jié)構(gòu)應(yīng)力集中現(xiàn)象突出。為了解決這一問(wèn)題,在現(xiàn)有公鐵兩用斜拉橋中采用了一種連接拉索和鋼桁梁的新型索梁錨固結(jié)構(gòu)形式—復(fù)合式雙錨拉板錨箱。雙側(cè)錨拉板作為傳力豎板,上部通過(guò)焊接構(gòu)成錨箱,與拉索錨固連接,下部與主梁頂板連接。在汽車荷載和列車荷載的組合作用下,作用在索梁錨固結(jié)構(gòu)上的荷載通過(guò)連接焊縫傳遞,焊接細(xì)節(jié)的疲勞問(wèn)題十分突出。本文對(duì)復(fù)合式雙錨拉板錨箱開(kāi)展了系統(tǒng)的研究,以邊界等效的疲勞試驗(yàn)為基礎(chǔ),分別采用名義應(yīng)力、熱點(diǎn)應(yīng)力以及斷裂力學(xué)方法研究了索錨結(jié)構(gòu)的疲勞性能;結(jié)合累積損傷模型和裂紋擴(kuò)展模型中的參數(shù)特征,采用疲勞壽命分析的混合可靠度模型,對(duì)索梁錨固結(jié)構(gòu)的疲勞壽命進(jìn)行了研究。研究?jī)?nèi)容如下:(1)回顧公鐵兩用斜拉橋的建造和發(fā)展,分析了索梁錨固結(jié)構(gòu)的受力特征和結(jié)構(gòu)組成特征,結(jié)合既有鋼橋的疲勞病害情況,論述了公鐵兩用斜拉橋索梁錨固結(jié)構(gòu)中的疲勞問(wèn)題及其研究的必要性,綜述了索梁錨固結(jié)構(gòu)疲勞性能和疲勞壽命的研究現(xiàn)狀,說(shuō)明了論文研究的意義。(2)采用既有公路汽車和鐵路列車的疲勞車模型,通過(guò)數(shù)值模擬研究了斜拉橋的索梁錨固結(jié)構(gòu)的疲勞荷載及其組合方法。研究了索梁錨固結(jié)構(gòu)疲勞細(xì)節(jié)的應(yīng)力分布特征,以及各板件的幾何參數(shù)敏感性,得到了復(fù)合式雙錨拉板錨箱的基本結(jié)構(gòu)和三類疲勞敏感細(xì)節(jié),分別為錨壓板與傳力豎板連接端部軸拉細(xì)節(jié)、錨壓板與傳力豎板連接側(cè)面拉剪細(xì)節(jié),以及錨壓板承壓端部的壓剪細(xì)節(jié),并給出相應(yīng)名義應(yīng)力幅計(jì)算公式。(3)基于相似原理,考慮應(yīng)力等效和邊界等效,開(kāi)展了復(fù)合式雙錨拉板錨箱基本結(jié)構(gòu)的疲勞試驗(yàn)。初始狀態(tài)下的靜力加載測(cè)試表明:基本結(jié)構(gòu)的實(shí)測(cè)應(yīng)力分布與有限元計(jì)算值基本吻合,基本結(jié)構(gòu)與實(shí)際索梁錨固結(jié)構(gòu)中的有限元計(jì)算值具有較高的一致性,可以用于索梁錨固結(jié)構(gòu)疲勞性能研究。疲勞試驗(yàn)表明:索梁錨固結(jié)構(gòu)在軸拉細(xì)節(jié)和壓剪細(xì)節(jié)位置觀測(cè)到裂紋,軸拉細(xì)節(jié)的疲勞斷裂導(dǎo)致了索梁錨固結(jié)構(gòu)的整體失效;軸拉細(xì)節(jié)疲勞性能與錨壓板寬高比有關(guān),結(jié)合規(guī)范中相關(guān)的S-N曲線,引入與錨壓板寬高比相關(guān)的參數(shù),對(duì)軸拉細(xì)節(jié)名義應(yīng)力幅計(jì)算公式進(jìn)行修正;并給出了各細(xì)節(jié)的參考疲勞細(xì)節(jié)類別。(4)采用熱點(diǎn)應(yīng)力外推法,對(duì)索梁錨固結(jié)構(gòu)中的不同應(yīng)力狀態(tài)下的疲勞細(xì)節(jié)進(jìn)行熱點(diǎn)應(yīng)力判定,采用有限元模擬,分析了單元類型、網(wǎng)格尺寸以及外推方法對(duì)熱點(diǎn)應(yīng)力的影響。結(jié)合試驗(yàn)中軸拉細(xì)節(jié)的熱點(diǎn)應(yīng)力測(cè)試值,驗(yàn)證了有限元模擬的有效性,以及FAT90曲線在索梁錨固結(jié)構(gòu)疲勞壽命分析中的合理性。采用應(yīng)力集中系數(shù),對(duì)基本結(jié)構(gòu)中的幾何參數(shù)進(jìn)行敏感性分析,結(jié)合實(shí)橋中幾何參數(shù)的取值規(guī)律,給出軸拉細(xì)節(jié)和拉剪細(xì)節(jié)應(yīng)力集中系數(shù)的表達(dá)式。(5)采用線彈性斷裂理論研究裂紋擴(kuò)展規(guī)律,借助ANSYS與FRANC3D有限元軟件,對(duì)裂紋尖端的應(yīng)力強(qiáng)度因子和裂紋擴(kuò)展進(jìn)行模擬分析,借助文獻(xiàn)中穿透型裂紋和半橢圓表面裂紋的試驗(yàn)測(cè)試值,驗(yàn)證有限元模擬的有效性。采用最大周向應(yīng)力準(zhǔn)則對(duì)承壓板與傳力豎板連接端部裂紋進(jìn)行裂紋擴(kuò)展模擬,結(jié)合斷口形貌,研究了初始裂紋尺寸和形狀對(duì)裂紋尖端應(yīng)力強(qiáng)度因子和裂紋擴(kuò)展的影響。采用應(yīng)力強(qiáng)度因子修正系數(shù),對(duì)基本結(jié)構(gòu)中的幾何參數(shù)進(jìn)行敏感性分析,給出錨壓板與傳力豎板連接端部半橢圓裂紋的應(yīng)力強(qiáng)度因子修正系數(shù)的表達(dá)式。(6)傳統(tǒng)的鋼結(jié)構(gòu)疲勞壽命預(yù)測(cè)誤差較大,線性累積損傷模型和裂紋擴(kuò)展模型中變量具有不確定性和隨機(jī)性,基于區(qū)間-概率理論,分別推導(dǎo)了服從正態(tài)分布、對(duì)數(shù)正態(tài)分布的概率模型和區(qū)間模型的一致性關(guān)系,給出可同時(shí)考慮區(qū)間變量和隨機(jī)變量的混合可靠度理論簡(jiǎn)化分析模型和求解方法。對(duì)橋梁工字梁中的疲勞細(xì)節(jié)進(jìn)行疲勞壽命分析,驗(yàn)證本文方法的有效性和適用范圍。采用累積損傷模型和裂紋擴(kuò)展模型對(duì)索梁錨固結(jié)構(gòu)的軸拉細(xì)節(jié)進(jìn)行疲勞可靠性研究,分析索錨結(jié)構(gòu)的疲勞壽命,給出了設(shè)定合理檢修周期的建議。
[Abstract]:In recent years, in order to meet the needs of highway and railway common bridge position, the dual-purpose cable-stayed bridge has been widely used. Under the joint action of vehicle load and train load, the long-span steel and iron dual use cable-stayed bridge bears great load. As the connecting member of the cable and the main beam in the cable-stayed bridge, the cable girder anchorage structure is complex. In addition, the stress concentration of cable girder anchorage structure is prominent during the process of transferring huge load effect. In order to solve this problem, a new type of cable beam anchorage structure, a double anchor plate anchor box, is adopted in the existing dual-purpose cable-stayed bridge with cable and steel truss. The vertical plate is connected with the cable anchorage and the bottom is connected with the cable roof. Under the combined action of the vehicle load and the train load, the load on the cable beam anchorage structure is passed through the welding seam, and the fatigue problem of the welding details is very prominent. On the basis of the boundary equivalent fatigue test, the fatigue performance of cable anchor structure is studied by nominal stress, hot stress and fracture mechanics, and the fatigue life of cable beam anchorage structure is carried out by combining the cumulative damage model and the parameter characteristics of the crack propagation model and the fatigue life analysis. The research contents are as follows: (1) review the construction and development of the dual-purpose cable-stayed bridge, analyze the characteristics of the stress and structure of the cable girder anchorage structure, and combine the fatigue disease of the existing steel bridge, discuss the fatigue problem and the necessity of the study in the cable girder anchorage structure of the dual-purpose cable-stayed bridge, and summarize the consolidation of the cable girder anchorage. The research status of structure fatigue and fatigue life shows the significance of the thesis. (2) fatigue load and combination method of cable girder anchorage structure of cable-stayed bridge are studied by numerical simulation, and the stress distribution characteristics of cable girder anchorage structure are studied by numerical simulation, and the stress distribution characteristics of cable girder anchorage structure are studied. The geometric parameter sensitivity of the plate is obtained. The basic structure and three kinds of fatigue sensitive details of the composite double anchorage plate anchor box are obtained, which are the details of the end of the anchor plate and the force vertical plate, the details of the lateral tension of the anchorage plate and the force vertical plate, and the pressure shear details of the pressure end of the anchor plate, and the corresponding nominal stress amplitude is calculated. (3) based on the similarity principle and considering the stress equivalence and the boundary equivalence, the fatigue test of the basic structure of the composite double anchor plate anchorage box is carried out. The static loading test under the initial state shows that the measured stress distribution of the basic structure is basically consistent with the calculated value of the finite element, and the basic structure and the finite element calculation value of the actual cable beam anchorage structure are calculated. It has high consistency and can be used to study the fatigue performance of cable beam anchorage structure. Fatigue tests show that the cable girder anchorage structure observates cracks in the detail of axial tension and pressure shear detail, and the fatigue fracture of axial tension leads to the overall failure of the cable beam anchorage structure, and the fatigue performance of axial tension is related to the width to height ratio of the anchor plate, and is combined with the specification. The relevant S-N curve and the parameters related to the ratio of the width to height of the anchor plate are introduced, and the formulas for calculating the nominal stress amplitude of the axial tension are corrected. And the reference fatigue details of each detail are given. (4) the hot stress extrapolation method is adopted to determine the hot stress of the fatigue details under different stress states in the cable beam anchorage structure. The effect of the element type, grid size and extrapolation method on the hot stress is analyzed. The validity of the finite element simulation and the rationality of the FAT90 curve in the fatigue life analysis of the cable beam anchorage structure are verified by combining the hot stress test values of the axial tension in the test. The stress concentration coefficient is used for the basic structure. The sensitivity analysis of geometric parameters is carried out and the expression of the stress concentration coefficient of the axial tension and shear details is given. (5) the law of crack propagation is studied by the linear elastic fracture theory, and the stress intensity factor and crack propagation at the crack tip are simulated with the help of ANSYS and FRANC3D finite element software. The validity of the finite element simulation is verified by the test test values of the penetrable crack and semi elliptical surface crack in the literature. The crack propagation of the end cracks of the pressure plate and the force vertical plate is simulated by the maximum circumferential stress criterion, and the stress intensity factors of the crack tip are studied with the fracture morphology and the initial crack size and shape. The stress intensity factor correction coefficient is used to analyze the sensitivity of the geometric parameters in the basic structure. The expression of the stress intensity factor correction factor of the semi elliptical crack at the end of the anchor plate and the force vertical plate is given. (6) the fatigue life prediction error of the traditional steel structure is larger, and the linear cumulative damage model is used. The variables in the crack propagation model have uncertainty and randomness. Based on the interval probability theory, the consistency relation between the probability model and the interval model is derived, which obeys the normal distribution and the logarithmic normal distribution, and the simplified analysis model and the solution method, which can simultaneously consider the interval variable and the random variable, are given. The fatigue life analysis is carried out in the girder of the beam structure, and the validity and application range of this method are verified. The fatigue reliability of the axial tension details of the cable girder anchorage structure is studied by the cumulative damage model and the crack propagation model, and the fatigue life of the cable anchor structure is analyzed, and some suggestions for setting the reasonable maintenance period are given.

【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：U448.27
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本文編號(hào)：1839764