本文選題：穩(wěn)定 + 非線性��； 參考：《合肥工業(yè)大學(xué)》2017年碩士論文

【摘要】：拱橋的拱肋在活載作用下為壓彎構(gòu)件,其穩(wěn)定問題突出。本文以安徽淮南孔李淮河三跨連續(xù)下承式鋼箱拱橋為工程背景,采用有限元方法,建立該橋的三維整體有限元模型,進行了線彈性穩(wěn)定(分枝點失穩(wěn))和極限承載力(極值點失穩(wěn))計算和分析。鑒于鋼橋由局部板件連接而成,受壓的局部板件極易發(fā)生局部屈曲,依據(jù)薄板屈曲理論和加勁板屈曲理論,對主拱肋各截面加勁板件進行了局部彈性穩(wěn)定的理論計算。最后,根據(jù)需要詳細分析的部位,建立了孔李淮河大橋的多尺度有限元模型,進行了局部—整體相關(guān)屈曲的極限承載力計算,可供橋梁結(jié)構(gòu)分析局部構(gòu)件破壞參考。論文的主要研究工作和結(jié)論:1.建立了淮南孔李淮河大橋結(jié)構(gòu)尺度的三維有限元模型,進行了整體彈性穩(wěn)定和參數(shù)分析。結(jié)果表明,淮南孔李淮河大橋的主拱失穩(wěn)的階次靠前,是整體穩(wěn)定的重點,橋面豎向荷載對彈性穩(wěn)定結(jié)果影響比較大,橫向風(fēng)荷載影響較小。面內(nèi)穩(wěn)定性主要由拱肋面內(nèi)抗彎剛度決定,面外穩(wěn)定性主要由拱肋面外抗彎剛度決定,而拱肋扭轉(zhuǎn)剛度對面內(nèi)和面外彈性整體穩(wěn)定性的影響都較小。2.考慮結(jié)構(gòu)的幾何和材料雙重非線性,對淮南孔李淮河大橋整體極限承載力進行了計算和分析。結(jié)果表明,幾何非線性對在該拱橋的極限承載影響較小,材料非線性是該拱橋整體極限承載力的控制因素。通過分析拱肋的屈服路徑發(fā)現(xiàn),主跨L/6處的拱肋和拱頂處的拱肋截面最先失效,是該橋拱肋極限承載力的關(guān)鍵部位。在穩(wěn)定極限承載力狀態(tài)下,拱肋關(guān)鍵截面的屈服所導(dǎo)致的截面抗彎剛度的改變和大變形,引起吊桿內(nèi)力的重分布,并導(dǎo)致了拱肋關(guān)鍵截面的彎矩出現(xiàn)卸載現(xiàn)象。3.在橋梁極限承載力狀態(tài),此時作用的荷載非常大,部分局部板件會首先會發(fā)生局部屈曲,而傳統(tǒng)的桿系有限元整體模型無法考慮局部板件的屈曲。論文根據(jù)前面整體極限承載力和局部穩(wěn)定理論計算結(jié)果,確定小尺度建模的目標(biāo)部位。然后,用板殼單元建立目標(biāo)部位的局部板件尺度模型,用桿梁單元建立非目標(biāo)部位的全橋的結(jié)構(gòu)尺度模型;最后,采用位移協(xié)調(diào)方程實現(xiàn)其界面連接形成多尺度有限元模型。該建模思路可以為鋼箱拱橋局部—整體相關(guān)屈曲極限承載力的研究提供建模參考。4.依據(jù)多尺度有限元模型,對孔李淮河大橋局部—整體相關(guān)屈曲極限承載力進行了計算分析。結(jié)果表明,所建立的多尺度有限元模型,可以實現(xiàn)局部板件尺度和整體結(jié)構(gòu)尺度的協(xié)同計算,可以考慮局部板件屈曲和整體結(jié)構(gòu)屈曲的相互作用,并可以詳細揭示局部板件的失效模式。拱肋局部板件屈曲后,并不意味著拱肋立即喪失承載力,橋梁整體仍能繼續(xù)承受更大的荷載,并且不同部位的局部屈曲對整體極限承載力的影響不同。
[Abstract]:The arch rib of the arch bridge is a bending member under the action of live load, and its stability problem is prominent. In this paper, based on the engineering background of the three-span continuous through steel box arch bridge in Huainan, Anhui Province, the three-dimensional integral finite element model of the bridge is established by using the finite element method. The linear elastic stability (branch point instability) and ultimate bearing capacity (extreme point instability) are calculated and analyzed. In view of the fact that the steel bridge is connected by local plates, local buckling of compressed local plates is easy to occur. Based on the theory of thin plate buckling and stiffening plate buckling, the local elastic stability of stiffened plates with different sections of the main arch rib is calculated based on the theory of thin plate buckling and stiffening plate buckling. Finally, the multi-scale finite element model of Kongli Huaihe River Bridge is established according to the location that needs to be analyzed in detail, and the ultimate bearing capacity of the local and global buckling is calculated, which can be used as a reference for the analysis of the failure of the local members of the bridge structure. The main research work and conclusion of this paper: 1. A three dimensional finite element model for the structural scale of Huainan Konglihuai River Bridge is established, and the overall elastic stability and parameter analysis are carried out. The results show that the order of instability of the main arch of Huainan Konglihuai River Bridge is the key point of overall stability. The vertical load on the bridge deck has a great influence on the elastic stability results, while the influence of the transverse wind load is relatively small. The in-plane stability is mainly determined by the in-plane bending stiffness of the arch rib, and the out-of-plane stability is mainly determined by the out-of-plane bending stiffness of the arch rib. Considering the geometric and material nonlinearity of the structure, the overall ultimate bearing capacity of the Lihuai River Bridge is calculated and analyzed. The results show that the geometric nonlinearity has little influence on the ultimate bearing capacity of the arch bridge, and the material nonlinearity is the controlling factor of the overall ultimate bearing capacity of the arch bridge. By analyzing the yield path of the arch rib, it is found that the arch rib at the main span L / 6 and the arch rib section at the top of the arch are the first failure, which is the key part of the ultimate bearing capacity of the arch rib of the bridge. Under the condition of stable ultimate bearing capacity, the bending stiffness and deformation of arch rib caused by the yield of key section of arch rib cause the redistribution of internal force of suspender and the unloading phenomenon of moment of key section of arch rib. In the state of ultimate bearing capacity of the bridge, the load acting on the bridge is very large, part of the local plate will first occur local buckling, but the traditional finite element global model of the bar system can not consider the buckling of the local plate. According to the calculation results of global ultimate bearing capacity and local stability theory, the target location of small scale modeling is determined in this paper. Then, the local scale model of the target part is established by using the plate and shell element, the structure scale model of the whole bridge at the non-target position is established by the bar and beam element, and the multi-scale finite element model is formed by using the displacement coordination equation to realize the interface connection. The method can be used as a reference for the study of the ultimate bearing capacity of local and global buckling of steel box arch bridge. Based on the multi-scale finite element model, the ultimate bearing capacity of local-global correlation buckling of Kongli-Huaihe River Bridge is calculated and analyzed. The results show that the multi-scale finite element model can realize the cooperative calculation between the local plate size and the global structure scale, and the interaction between the local plate buckling and the global structure buckling can be considered. The failure mode of local plates can be revealed in detail. The local buckling of arch rib does not mean that the arch rib loses its bearing capacity immediately, and the whole bridge can continue to bear larger load, and the effect of local buckling on the ultimate bearing capacity of the bridge is different.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U448.22;U441

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