【摘要】：中承式鋼管混凝土拱橋的剛度較大、結(jié)構(gòu)輕盈,在車輛荷載的作用下橋梁動力響應明顯,尤其對于大跨度的鐵路拱橋,一些高強度材料的使用使得橋跨結(jié)構(gòu)的一些構(gòu)件較為纖細,荷載作用下的局部振動的不斷累積導致局部構(gòu)件的損傷,因此車輛通過時引起的局部振動問題不容忽視。本文以某主跨202m中承式鋼管混凝土拱橋為工程背景,建立精細的全橋空間有限元動力分析模型,采用車-線-橋耦合振動分析理論對車輛荷載作用下的吊桿的動力響應進行分析,研究了吊桿局部的動力行為。論文首先簡要介紹了鐵路拱橋主要的結(jié)構(gòu)形式以及在國內(nèi)外的發(fā)展狀況,接著闡述了吊桿局部振動的計算理論及計算方法,根據(jù)該中承式拱橋的工程背景及具體的結(jié)構(gòu)設計參數(shù),詳細敘述了全橋空間有限元動力分析模型的建立。根據(jù)所建立的動力分析模型,對吊桿在運營狀態(tài)下的動軸力響應、動彎矩響應進行分析。研究發(fā)現(xiàn)在車輛運行條件下吊桿的長度越小其對車輛活載的敏感性越強；隨著行車速度的增大,短吊桿的活載應力幅逐漸增大,跨中長吊桿應力幅略有增加,但總體變化不大。柔性吊桿也具有一定的抗彎剛度,吊桿內(nèi)的次彎矩引起截面應力分布不均勻,明顯增大活載應力幅；從吊桿的內(nèi)力響應情況看來,車輛的加載頻率對吊桿動軸力的影響較小,對次彎矩的影響較大。動力系數(shù)是用來描述車輛荷載對橋梁的動力作用,通過對吊桿在車輛活載作用下的動力效應分析發(fā)現(xiàn),吊桿局部的動力系數(shù)明顯高于按主梁動撓度計算的結(jié)構(gòu)整體的動力系數(shù),吊桿的動力系數(shù)存在明顯的局部性。采用車-線-橋耦合振動分析理論對車輛荷載作用下的吊桿的動力響應進行分析,可以得到吊桿運營時的較為真實的動力行為,其計算結(jié)果不僅可以為吊桿的疲勞設計提供參考,也可以在成橋運營時規(guī)范車輛的運行,減小橋梁的損傷。
[Abstract]:The concrete-filled steel tube arch bridge has large stiffness and light structure, and the dynamic response of the bridge is obvious under the action of vehicle load, especially for the long-span railway arch bridge. The use of some high-strength materials makes some members of the bridge span structure thinner. The continuous accumulation of local vibration under load results in the damage of local members. Therefore, the local vibration caused by vehicle passing can not be ignored. In this paper, based on the engineering background of a 202m concrete-filled steel tube arch bridge with main span, a fine spatial finite element dynamic analysis model of the whole bridge is established. The dynamic response of the hanger under vehicle load is analyzed by using the coupled vibration analysis theory of vehicle-line-bridge, and the local dynamic behavior of the hanger is studied. In this paper, the main structural forms of railway arch bridge and its development at home and abroad are briefly introduced, and then the calculation theory and method of local vibration of hanger are described. According to the engineering background and concrete structural design parameters of the middle-through arch bridge, the establishment of the spatial finite element dynamic analysis model of the whole bridge is described in detail. According to the established dynamic analysis model, the dynamic axial force response and dynamic bending moment response of the hanger under operating conditions are analyzed. It is found that the smaller the length of the hanger is, the stronger the sensitivity to the live load of the vehicle is, and with the increase of the driving speed, the live stress amplitude of the short hanger increases gradually, and the stress amplitude of the mid-long span hanger increases slightly, but the overall variation is little. The flexible hanger also has a certain bending stiffness, the secondary bending moment in the hanger results in uneven distribution of the cross-section stress, and obviously increases the stress amplitude of the live load. It can be seen from the internal force response of the hanger that the loading frequency of the vehicle has little effect on the dynamic axial force of the hanger and a greater influence on the secondary bending moment. The dynamic coefficient is used to describe the dynamic effect of the vehicle load on the bridge. Through the analysis of the dynamic effect of the hanger under the live load of the vehicle, it is found that the local dynamic coefficient of the hanger is obviously higher than the overall dynamic coefficient of the structure calculated according to the dynamic deflection of the main beam. The dynamic coefficient of the hanger has obvious locality. By using the coupled vibration analysis theory of vehicle-line-bridge, the dynamic response of the hanger under vehicle load can be analyzed, and the real dynamic behavior of the hanger can be obtained. The calculated results can not only provide a reference for the fatigue design of the hanger, but also regulate the operation of the vehicle when the bridge is completed and reduce the damage of the bridge.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441.3;U448.22

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