本文選題：大跨度懸索橋　切入點(diǎn)：動(dòng)力特性　出處：《內(nèi)蒙古科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著纜索結(jié)構(gòu)橋梁的跨度不斷增大，其剛度和阻尼不斷下降，對風(fēng)荷載更加敏感。在很多情況下，，此類型橋梁的抗風(fēng)問題成為橋梁設(shè)計(jì)時(shí)要考慮的首要問題。本文以矮寨大橋?yàn)楣こ瘫尘�，研究施加抗風(fēng)纜對橋梁靜力失穩(wěn)臨界風(fēng)速、跨中節(jié)點(diǎn)位移隨風(fēng)速的變化過程和在自然風(fēng)作用下抖振響應(yīng)有何變化，為相似橋梁的抗風(fēng)設(shè)計(jì)提供參考。 首先，本文建立了矮寨大橋原橋有限元模型和施加抗風(fēng)纜后的有限元模型，通過改變抗風(fēng)纜拉桿與橋面的角度、拉桿長度、抗風(fēng)纜和拉桿的橫截面積、抗風(fēng)纜和拉桿的初應(yīng)變，研究這四種抗風(fēng)纜參數(shù)對橋梁動(dòng)力特性的影響規(guī)律，主要通過比較橋梁關(guān)鍵頻率來確定抗風(fēng)纜的最優(yōu)參數(shù)。計(jì)算結(jié)果表明：抗風(fēng)纜的施加使橋梁的各階頻率增大，表明剛度增大。抗風(fēng)纜拉桿與橋面的角度為90度的效果最好，拉桿長度對橋梁的動(dòng)力特性影響不明顯，抗風(fēng)纜和拉桿的橫截面積越大,橋梁的頻率增大越顯著，抗風(fēng)纜和拉桿的初應(yīng)變增大，橋梁頻率顯著增大。 其次，本文用線性方法計(jì)算了施加抗風(fēng)纜前后橋梁的失穩(wěn)臨界風(fēng)速，用三維非線性方法計(jì)算了施加抗風(fēng)纜前后橋梁跨中節(jié)點(diǎn)的位移和主纜跨中的軸力隨風(fēng)速的變化，得出橋梁在施加抗風(fēng)纜后橫向傾側(cè)失穩(wěn)風(fēng)速和靜力扭轉(zhuǎn)失穩(wěn)風(fēng)速分別提高10.1%和8.9%，跨中位移顯著減小。通過主纜跨中軸力變化發(fā)現(xiàn)：施加抗風(fēng)纜前橋梁失穩(wěn)風(fēng)速在120m/s左右,而施加抗風(fēng)纜后橋梁的主纜跨中軸力變化很穩(wěn)定，直到風(fēng)速180m/s時(shí)軸力還沒出現(xiàn)突變的分布，表明施加抗風(fēng)纜后結(jié)構(gòu)剛度和穩(wěn)定性都有所增強(qiáng)。 最后，根據(jù)隨機(jī)振動(dòng)理論，基于線性濾波法用MATLAB軟件模擬了橋梁跨中節(jié)點(diǎn)處的水平脈動(dòng)風(fēng)和豎向脈動(dòng)風(fēng)時(shí)程曲線，并根據(jù)達(dá)文波特力學(xué)模型把隨機(jī)風(fēng)轉(zhuǎn)化為隨機(jī)抖振力。計(jì)算結(jié)構(gòu)時(shí)程響應(yīng)表明：施加抗風(fēng)纜后橋梁的振幅減小，抗風(fēng)效果明顯。 通過計(jì)算靜力失穩(wěn)臨界風(fēng)速、跨中節(jié)點(diǎn)隨風(fēng)速變化和隨機(jī)抖振響應(yīng)表明：施加抗風(fēng)纜后靜力失穩(wěn)臨界風(fēng)速有所提高，抗風(fēng)纜對橋梁的豎向平均振幅有稍稍增大，對橋梁橫向和扭轉(zhuǎn)角的振幅有很強(qiáng)的抑制作用，而且橫向和扭轉(zhuǎn)角的振幅更加平穩(wěn)，表明抗風(fēng)纜起到了良好的抗風(fēng)效果。
[Abstract]:As the span of cable-structure bridges increases, their stiffness and damping decrease, and they are more sensitive to wind load. In many cases, The wind-resistant problem of this type of bridge becomes the most important problem to be considered in the design of the bridge. In this paper, the critical wind speed of static instability caused by wind resistant cables on the bridge is studied, taking the Aizhai Bridge as the engineering background. The variation of node displacement with wind speed and buffeting response under natural wind will provide reference for wind-resistant design of similar bridges. First of all, the finite element model of the original bridge and the wind resistant cable is established in this paper. By changing the angle between the wind resistant cable and the bridge deck, the length of the pull rod, the cross-sectional area of the wind resistant cable and the tie rod, The influence of the four kinds of wind-resistant cable parameters on the dynamic characteristics of the bridge is studied by the initial strain of the wind-resistant cable and the pull rod. The optimum parameters of wind-resistant cable are determined by comparing the key frequencies of the bridge. The calculation results show that the application of the wind-resistant cable increases the frequency of each order of the bridge, indicating that the stiffness is increased, and the angle between the wind-resistant cable rod and the bridge deck is 90 degrees. The more the cross-sectional area of wind cables and strands is, the more significant the frequency of bridges is, and the initial strain of wind cables and strands increases, and the frequency of bridges increases significantly. Secondly, the linear method is used to calculate the instability critical wind speed of the bridge before and after the application of the wind resistant cable, and the displacement of the mid-span node of the bridge and the axial force of the main cable span with the wind speed are calculated by the three-dimensional nonlinear method before and after the application of the anti-wind cable. The results show that the lateral wind speed and static torsional wind speed of the bridge are increased by 10.1% and 8.9 respectively after the application of the wind resistant cable, and the mid-span displacement is significantly reduced. It is found that the unsteady wind speed of the bridge is about 120m / s before the application of the wind resistant cable through the variation of the mid-span axial force of the main cable. The axial force of the main cable is stable until the wind speed is 180m / s, which indicates that the stiffness and stability of the structure are enhanced after the application of the wind-resistant cable. Finally, according to the random vibration theory, the horizontal and vertical pulsating wind history curves at the middle node of the bridge are simulated with MATLAB software based on the linear filtering method. According to the Davenport mechanics model, the random wind is transformed into the random buffeting force, and the time-history response of the structure shows that the amplitude of the bridge decreases with the application of the wind-resistant cable, and the wind-resistant effect is obvious. By calculating the critical wind speed of static instability, the variation of span node with the wind speed and the random buffeting response show that the critical wind speed of static instability increases after applying the wind resistant cable, and the vertical mean amplitude of the bridge is slightly increased by the wind resistant cable. The amplitude of the transverse and torsional angle of the bridge is strongly inhibited, and the amplitude of the transverse and torsional angle is more stable, which indicates that the wind-resistant cable has a good wind-resistant effect.
【學(xué)位授予單位】：內(nèi)蒙古科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U441.3

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