【摘要】：近年來,隨著我國交通網(wǎng)絡(luò)的不斷完善,相繼出現(xiàn)了很多在建和擬建的深水橋梁。在地震作用下,深水橋梁下部結(jié)構(gòu)的運動會引起其周圍水體產(chǎn)生輻射波浪運動,且由于結(jié)構(gòu)和水體之間的相對運動,在橋梁的下部結(jié)構(gòu)上將作用有動水壓力,該動水壓力對結(jié)構(gòu)自身的動力特性和動力響應(yīng)有很大影響。因此充分認(rèn)識動水壓力對斜拉橋結(jié)構(gòu)地震動力響應(yīng)的影響,對于深水橋梁的抗震設(shè)計及安全評估具有重要的意義。本文的研究內(nèi)容和結(jié)論主要有下述幾個方面:1、利用Morison方程法,以附加質(zhì)量考慮動水對橋墩和樁基礎(chǔ)的影響,采用有限元軟件Midas建立了東沙特大橋的有限元數(shù)值分析模型,分別就有無動水作用的情形進(jìn)行動力特性分析,結(jié)果表明動水作用使得斜拉橋的自振頻率減小。2、對東沙特大橋有無動水作用兩種情形進(jìn)行了縱向+豎向和橫向+豎向兩種工況下的反應(yīng)譜分析和時程分析,結(jié)果表明動水對斜拉橋結(jié)構(gòu)各關(guān)鍵點位置的位移和關(guān)鍵截面的內(nèi)力有很大影響。3、利用大質(zhì)量法對東沙特大橋有無動水作用兩種情形進(jìn)行了行波效應(yīng)分析,探討研究了非一致激勵對斜拉橋結(jié)構(gòu)動力響應(yīng)的影響規(guī)律,并與一致激勵時的計算結(jié)果進(jìn)行對比。結(jié)果表明考慮行波效應(yīng)后結(jié)構(gòu)的動力響應(yīng)減小,且響應(yīng)結(jié)果都隨著波速的增加而逐漸趨于一致激勵的結(jié)果;行波效應(yīng)作用下隨著地震波視波速的不同水體對斜拉橋的地震響應(yīng)的影響也是不同的,且一致激勵和行波激勵時水體對斜拉橋的地震響應(yīng)的影響有所差異。4、通過在東沙特大橋上安裝粘滯阻尼器,研究了粘滯阻尼器的阻尼系數(shù)C和速度指數(shù)α的變化對斜拉橋結(jié)構(gòu)動力響應(yīng)的影響規(guī)律。研究發(fā)現(xiàn)選取適當(dāng)?shù)淖枘崞鲄?shù)取值,可以顯著地減小斜拉橋主塔的塔底彎矩以及各關(guān)鍵點位置的位移;綜合考慮主塔塔底彎矩、各關(guān)鍵點位置的縱橋向位移以及動水壓力的影響,建議將阻尼器的阻尼系數(shù)設(shè)置為14000k N·s/m,速度指數(shù)設(shè)置為0.35。
[Abstract]:In recent years, with the continuous improvement of China's transportation network, there have been many deep-water bridges under construction and proposed. Under earthquake action, the motion of the substructure of deep water bridge will cause the radiation wave motion in the surrounding water body, and because of the relative motion between the structure and the water body, there will be dynamic water pressure on the substructure of the bridge. The hydrodynamic pressure has great influence on the dynamic characteristics and dynamic response of the structure itself. Therefore, it is of great significance for seismic design and safety assessment of deep water bridges to fully understand the influence of dynamic water pressure on the seismic dynamic response of cable-stayed bridges. The main contents and conclusions of this paper are as follows: 1. By using Morison equation method and considering the effect of dynamic water on pier and pile foundation with additional mass, the finite element numerical analysis model of Dongsha super large bridge is established by using the finite element software Midas. The dynamic characteristics of the case with or without the action of dynamic water are analyzed, The results show that the natural vibration frequency of the cable-stayed bridge is reduced by hydrodynamic action. The response spectrum and time history analysis of the longitudinal vertical and horizontal vertical conditions are carried out for the Dongsha super bridge with or without dynamic water action. The results show that the dynamic water has a great influence on the displacement of the key points and the internal force of the key section of the cable-stayed bridge. The traveling wave effect of Dongsha super large bridge is analyzed by using the large mass method. The influence of non-uniform excitation on the dynamic response of cable-stayed bridge is studied and compared with the calculated results under uniform excitation. The results show that the dynamic response of the structure decreases when the traveling wave effect is taken into account, and the response results tend to be consistent with the increase of the wave velocity. The seismic response of cable-stayed bridges is affected by the different water bodies with the apparent wave velocities of seismic waves under the action of traveling wave. The effect of water body on seismic response of cable-stayed bridge is different from that of traveling wave excitation. The viscous dampers are installed on Dongsha Bridge. The influence of damping coefficient C and velocity exponent 偽 of viscous dampers on the dynamic response of cable-stayed bridges is studied. It is found that selecting appropriate damper parameters can significantly reduce the bottom bending moment of the main tower of cable-stayed bridge and the displacement of the key points, and consider the bending moment of the main tower bottom synthetically. It is suggested that the damping coefficient of the damper should be set to 14000k N / s / m and the velocity exponent 0.35 for the influence of the displacement of the longitudinal bridge and the dynamic pressure of the bridge at the key points.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U448.27;U442.55

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