【摘要】：隨著機(jī)動車輛保有量的迅速增長，交通擁堵現(xiàn)象在各大城市頻頻出現(xiàn)。研究發(fā)現(xiàn)，，汽車擁堵在靜力荷載作用下，不會對城市橋梁造成直接的危害。但在動力荷載作用下，情況大不相同，車輛擁堵時(shí)發(fā)動機(jī)處于怠速狀態(tài)，此時(shí)發(fā)動機(jī)轉(zhuǎn)速在600~800轉(zhuǎn)/分鐘（頻率為10.0~13.3Hz）內(nèi)，此頻率處于很大部分橋梁的基頻（1.23Hz~14Hz）范圍內(nèi)�？紤]發(fā)動機(jī)怠速振動，橋梁的位移和應(yīng)力水平與靜力荷載相比有顯著的增加，當(dāng)汽車發(fā)動機(jī)怠速轉(zhuǎn)速與橋梁的某一階頻率相同或相近時(shí)，甚至可能發(fā)生車橋共振的現(xiàn)象。本文結(jié)合前人結(jié)構(gòu)動力理論研究成果，查閱城市橋梁堵車狀況相關(guān)統(tǒng)計(jì)資料，選取了一座具有代表性的城市橋梁來展開這方面研究。 本文選取了深圳市某一三跨連續(xù)梁橋作為實(shí)例，根據(jù)城市車輛組成的統(tǒng)計(jì)分析和城市橋梁的車輛通行特點(diǎn)，對城市橋梁的車輛類型、車長、軸重、軸距、車間距等參數(shù)進(jìn)行調(diào)查。選用大客車擁堵荷載作為荷載模型，研究了大客車怠速時(shí)的靜力、動力荷載，并取發(fā)動機(jī)引起的動荷載幅值為靜載的20%。由于擁堵動荷載效應(yīng)與發(fā)動機(jī)的初相位有很大關(guān)系，本文從最不利荷載角度出發(fā)，設(shè)計(jì)了同相位或反相位的7種較為不利的堵車工況。 利用ANSYS有限元模型，對橋梁實(shí)例進(jìn)行仿真分析，獲取橋梁的自振特性，并計(jì)算出橋梁在7種工況下的振幅-頻率關(guān)系，以及3種最不利堵車工況下的橋梁瞬態(tài)響應(yīng)。從而發(fā)現(xiàn)該橋梁雙向堵車作用效應(yīng)較單向堵車不利，豎彎振動比扭轉(zhuǎn)振動的動載響應(yīng)系數(shù)更大。最后通過修改該橋的約束條件，對簡支梁橋及連續(xù)剛構(gòu)橋的堵車共振效應(yīng)進(jìn)一步研究得出，同一堵車共振條件下，簡支梁橋的振動效應(yīng)最�。贿B續(xù)剛構(gòu)橋豎彎振動響應(yīng)比連續(xù)梁橋大，而扭轉(zhuǎn)振動響應(yīng)比連續(xù)梁橋小�？芍獙τ谛】鐝匠鞘袠蛄海x擇簡支梁結(jié)構(gòu)形式更有利于減少堵車共振引起的橋梁結(jié)構(gòu)破壞。
[Abstract]:With the rapid growth of vehicle ownership, traffic congestion occurs frequently in major cities. It is found that vehicle congestion under static load will not cause direct harm to urban bridges. However, under the dynamic load, the situation is very different, the engine is in idle state when the vehicle is congested, and the engine speed is in the range of 600,800 rpm (frequency is 10.0~13.3Hz), which is within the 1.23Hz~14Hz range of most bridges. Considering the engine idling vibration, the displacement and stress level of the bridge are significantly increased compared with the static load. When the idling speed of the automobile engine is the same or close to the bridge's first order frequency, even the bridge resonance may occur. In this paper, based on the previous research results of structural dynamic theory, we select a representative urban bridge to carry out this study by referring to the relevant statistical data of the traffic jam situation of urban bridges. Based on the statistical analysis of urban vehicle composition and the traffic characteristics of urban bridges, this paper selects a one-three-span continuous girder bridge in Shenzhen as an example to study the vehicle types, vehicle length, axle load, wheelbase of urban bridges The distance between vehicles and other parameters were investigated. In this paper, the static and dynamic loads of bus at idle speed are studied by using bus congestion load as load model, and the dynamic load amplitude caused by engine is taken as 20 parts of static load. Due to the fact that the congested dynamic load effect is closely related to the initial phase of the engine, this paper designs seven unfavorable traffic jam conditions in the same phase or inverse phase from the point of view of the most unfavorable load. The ANSYS finite element model is used to simulate and analyze the bridge examples to obtain the natural vibration characteristics of the bridge. The amplitude-frequency relationship of the bridge under 7 working conditions and the transient response of the bridge under the three most unfavorable traffic jam conditions are calculated. It is found that the effect of two-way traffic jam of the bridge is more adverse than that of one-way traffic jam, and the dynamic load response coefficient of vertical bending vibration is greater than that of torsional vibration. Finally, by modifying the constraint conditions of the bridge, the resonance effect of traffic jam of simply supported beam bridge and continuous rigid frame bridge is further studied. It is concluded that the vibration effect of simply supported beam bridge is the least under the same condition of traffic jam resonance. The vertical bending vibration response of continuous rigid frame bridge is larger than that of continuous beam bridge, while the torsional vibration response is smaller than that of continuous beam bridge. For small span urban bridges, simply supported beam structure is more favorable to reduce the bridge structure damage caused by traffic jam resonance.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U491.265;U441.3

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