【摘要】：隨著橋梁技術(shù)的發(fā)展創(chuàng)新,橋梁在結(jié)構(gòu)形式上也越來越多樣化,在橋梁設(shè)計中如何兼顧安全性和經(jīng)濟性成為設(shè)計的重點。Loukouni橋是剛果(布)國家1號公路中的一座典型上承式鋼箱拱橋,為了使用最少的成本設(shè)計出結(jié)構(gòu)最優(yōu),安全性能良好的大橋,提高其使用年限,并為以后類似拱橋的設(shè)計研究提供技術(shù)支持,對Loukouni橋的靜力優(yōu)化分析和疲勞性能研究是具有重要意義的。本文的主要研究內(nèi)容包括:(1)使用ANSYS軟件建立了Loukouni橋的全橋有限元模型,分別對拱橋的拱軸系數(shù)、拱肋截面尺寸以及拱肋與立柱連接節(jié)點形式進行了優(yōu)化。結(jié)果表明:拱軸系數(shù)為1.543時是最合理的;Loukouni橋的拱肋截面具有一定的優(yōu)化空間,且在四個截面關(guān)鍵參數(shù)中,截面應(yīng)力值對截面高度h的變化最為敏感;推薦使用立柱兩端全部剛接的節(jié)點連接形式。(2)選取了拱肋和橫撐處構(gòu)造細節(jié),參考不同國家的疲勞車輛荷載模型,通過影響面最不利加載方式計算出了構(gòu)造細節(jié)處的疲勞應(yīng)力幅,結(jié)果表明:這兩處構(gòu)造細節(jié)是安全的,歐洲規(guī)范下的疲勞驗算最為保守,在設(shè)計時推薦使用歐洲規(guī)范,以保障橋梁疲勞設(shè)計的安全性。(3)針對選取的2個構(gòu)造細節(jié)進行了疲勞試驗研究,每種類型的構(gòu)造細節(jié)得到了21個有效數(shù)據(jù)點,對其進行了名義應(yīng)力-壽命曲線擬合,并與各國規(guī)范中的曲線進行了比較,發(fā)現(xiàn)擬合出的直線與中歐2種規(guī)范給出的直線擬合度較高,說明試驗結(jié)果能夠很好地反應(yīng)構(gòu)造細節(jié)的疲勞性能,并且可將擬合出的疲勞曲線應(yīng)用于以后類似工程的相關(guān)構(gòu)造細節(jié)中。(4)用ANSYS軟件建立了2個構(gòu)造細節(jié)的精細化有限元模型,使用國際焊接學會中給出的線性外推路徑法得到拱肋處疲勞細節(jié)的應(yīng)力集中系數(shù)。并對該處細節(jié)進行了熱點應(yīng)力-壽命曲線擬合,與各國規(guī)范相應(yīng)曲線進行了比較,結(jié)果表明目前規(guī)范給出的熱點應(yīng)力-壽命曲線的安全性是有待考證的。對2處構(gòu)造細節(jié)進行了疲勞壽命評估和疲勞使用年限預(yù)測,建議在Loukouni橋的構(gòu)造細節(jié)達到疲勞使用年限前對其進行安全檢測以防止危險事故的發(fā)生。本課題研究可為以后橋梁的靜力和疲勞性能研究提供技術(shù)支持,并有利于對各國規(guī)范的深入認識和挖掘,為今后相關(guān)規(guī)范的學習、修正和制定提供一些參考。
[Abstract]:With the development and innovation of bridge technology, the structure of bridge is becoming more and more diversified. How to balance safety and economy in bridge design. Loukouni Bridge is a typical steel box arch bridge in Congo (Brazzaville) No. 1 highway. In order to use the least cost, the structure of Loukouni Bridge is the best. The bridge with good safety performance can improve its service life and provide technical support for the design and research of similar arch bridges in the future. It is of great significance for the static optimization analysis and fatigue performance study of Loukouni bridges. The main contents of this paper are as follows: (1) the finite element model of the full bridge of Loukouni bridge is established by using ANSYS software, and the arch axis coefficient, the section size of arch rib and the connection form of arch rib and column are optimized respectively. The results show that the arch rib section of Loukouni bridge has some optimized space when the arch axis coefficient is 1.543, and the stress value of the section is the most sensitive to the change of the section height h among the four key parameters of the section. It is recommended to use all rigid connections at both ends of column. (2) the structure details of arch rib and transverse brace are selected, and the fatigue vehicle load models of different countries are referred to. The fatigue stress amplitude at the structural details is calculated by the most unfavorable loading method of the influence surface. The results show that the two structural details are safe and the fatigue checking calculation under the European Code is the most conservative, and the European Code is recommended in the design. In order to ensure the safety of bridge fatigue design. (3) fatigue test was carried out for two selected structural details. 21 valid data points were obtained for each type of structural details, and the nominal stress-life curve fitting was carried out. Compared with the curves in the codes of various countries, it is found that the fitted straight line is higher than that of the two kinds of codes in Central Europe, which shows that the test results can well reflect the fatigue performance of the structural details. And the fitted fatigue curve can be applied to the related structural details of similar projects. (4) two fine finite element models of structural details are established by using ANSYS software. The stress concentration factors of the fatigue details of arch ribs are obtained by using the linear extrapolation path method given in the International Welding Institute. The details of the hot spot stress-life curve are fitted and compared with the corresponding curves in various countries. The results show that the safety of the hot-spot stress-life curve given by the current code needs to be verified by textual research. The fatigue life evaluation and fatigue life prediction of two structural details are carried out. It is suggested that the Loukouni bridge should be inspected safely before it reaches its fatigue life in order to prevent the occurrence of dangerous accidents. This research can provide technical support for the study of the static and fatigue performance of bridges in the future, and also be helpful to the further understanding and excavation of the national norms, and provide some references for the study, revision and formulation of the relevant codes in the future.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441

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