本文關(guān)鍵詞： 動(dòng)水壓力 地震響應(yīng) 流固耦合 附加質(zhì)量比 Morison方程 斜拉橋　出處：《西南交通大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：如今伴隨著我國(guó)高速發(fā)展的經(jīng)濟(jì),我國(guó)的交通運(yùn)輸行業(yè)也在蓬勃發(fā)展,橋梁作為交通運(yùn)輸鏈中不可或缺的一部分也在快速的發(fā)展。在受到地震環(huán)境的影響下,位于深水中的橋墩會(huì)在地震的激勵(lì)下隨之振動(dòng),進(jìn)而帶動(dòng)圍繞在墩身附近的水體振動(dòng),而水體的振動(dòng)又會(huì)對(duì)橋墩的動(dòng)力特性造成一定的影響,也就是橋墩與水體之間的耦合振動(dòng)。目前已有的文獻(xiàn)以及相關(guān)資料當(dāng)中,研究地震作用下的動(dòng)水壓力的方法不多,對(duì)大型深水橋梁的研究也較少,只有部分文獻(xiàn)對(duì)位于深水環(huán)境中的橋墩在受到地震激勵(lì)時(shí)的動(dòng)力響應(yīng)做過研究。因此本文以深水環(huán)境下的橋墩,以及橋墩入水深度較大的大型斜拉橋?yàn)檠芯繉?duì)象對(duì)其地震響應(yīng)做了如下研究:討論流體聲單元法、附加質(zhì)量比法、Morison方程附加質(zhì)量三種方法在橋墩受地震激勵(lì)下動(dòng)水壓力的計(jì)算效率,并對(duì)比了不同方法下不同截面尺寸的正方形截面以及圓形截面橋墩的一階頻率及一階頻率降低率,同時(shí)分析了墩頂位置處的位移以及墩柱結(jié)構(gòu)底部的反力及彎矩受動(dòng)水壓力作用時(shí)的影響。對(duì)比發(fā)現(xiàn),隨著截面尺寸的增大橋墩自振頻率逐漸增大,一階頻率降低率逐漸減小,且減小幅度也在逐漸縮小;在動(dòng)水壓力存在的條件下,墩頂位移及墩底反力、彎矩均受其影響有所增大,增大幅度隨著橋墩截面尺寸的增大而逐漸減小,墩柱結(jié)構(gòu)底部反力所受動(dòng)水壓力作用時(shí)發(fā)生的改變較其彎矩而言較大。Morison方程計(jì)算出的結(jié)果較為保守,隨著截面尺寸的增大,附加質(zhì)量比法與流體聲單元?jiǎng)t較為實(shí)用。以此為開端,本文以奉節(jié)長(zhǎng)江大橋作為工程實(shí)例,采用上述三種方法,使用大型通用有限元軟件ANSYS建立了斜拉橋的梁?jiǎn)卧Ｐ秃蛯?shí)體單元模型,以沿縱橋向的地震波對(duì)橋梁結(jié)構(gòu)在深水以及無水條件下進(jìn)行時(shí)程分析。通過計(jì)算發(fā)現(xiàn),深水條件下水對(duì)大型橋梁的固有頻率影響不大。水體對(duì)地震作用下的橋梁動(dòng)力響應(yīng)影響較大,塔頂以及主梁兩端的縱向位移均有增大,塔底的剪力以及彎矩也有大幅的增大,并且剪力的增幅大于彎矩,同時(shí)墩身的剪力及彎矩隨墩高的變化而變化,相較無水條件下的極值也有所增大。三種方法相較而言,附加質(zhì)量比法計(jì)算出的動(dòng)力響應(yīng)結(jié)果最小與流體聲單元法較為接近,Morison最大偏于安全,流體聲單元法所得結(jié)果適中。
[Abstract]:Nowadays, with the rapid development of China's economy, the transportation industry in China is booming, and bridges, as an indispensable part of the transportation chain, are also developing rapidly. Under the influence of the earthquake environment, The pier in deep water will vibrate under the excitation of earthquake, which will lead to the vibration of the water around the pier, and the vibration of the water will have a certain impact on the dynamic characteristics of the pier. That is, the coupling vibration between piers and water bodies. Among the existing documents and related data, there are few methods to study the dynamic water pressure under earthquake, and less research on large deep water bridges. Only part of the literature has studied the dynamic response of piers in deep water environment when subjected to earthquake excitation. The seismic response of large cable-stayed bridge with high depth of piers entering water is studied as follows: the fluid acoustic element method is discussed. Additional mass ratio method and Morison equation three methods for calculating dynamic water pressure of pier under earthquake excitation are presented. The first-order frequency and first-order frequency reduction rate of square section and circular section pier under different methods are compared. At the same time, the effects of the displacement at the top of the pier and the reaction force and bending moment at the bottom of the pier structure under the action of dynamic water pressure are analyzed. It is found that with the increase of the cross section size, the natural vibration frequency of the pier increases gradually, and the reduction rate of the first order frequency decreases gradually. Under the condition of dynamic water pressure, the displacement of pier top and the reaction force and bending moment of pier bottom are affected by it, and the increasing range decreases gradually with the increase of the section size of pier. The change of the reaction force at the bottom of the pier column under the action of dynamic water pressure is larger than that of the bending moment. The results calculated by Morison equation are more conservative, and with the increase of the section size, The additional mass ratio method and the fluid acoustic unit are more practical. In this paper, the Fengjie Yangtze River Bridge is taken as an engineering example and the above three methods are used. The beam element model and solid element model of cable-stayed bridge are established by using the large-scale general finite element software ANSYS. The seismic waves along the longitudinal bridge are used to carry out the time-history analysis of the bridge structure in deep water and under the condition of anhydrous. The deep water has little effect on the natural frequency of large bridges. The water body has a great influence on the dynamic response of bridges under earthquake. The longitudinal displacement of the tower top and the two ends of the main beam is increased, and the shear force and bending moment of the tower bottom are also greatly increased. And the increase of shear force is greater than that of bending moment, and the shear force and bending moment of pier body vary with the height of pier, and the extreme value of pier body is also increased compared with the maximum value under the condition of anhydrous condition. The minimum dynamic response obtained by the additional mass ratio method is close to that of the fluid acoustic element method, and the maximum deviation of the fluid acoustic element method is relatively safe. The results obtained by the fluid acoustic element method are moderate.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U442.55;U448.27

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