【摘要】：過去，大跨度懸索橋的抗風(fēng)研究主要集中在結(jié)構(gòu)的動(dòng)力失穩(wěn)及抖振響應(yīng)問題上。而對(duì)其在風(fēng)荷載作用下，由于主纜剛度退化而引起的靜力扭轉(zhuǎn)發(fā)散現(xiàn)象卻未給予同等的重視。近年來(lái)風(fēng)洞試驗(yàn)和研究表明，，隨著橋梁的長(zhǎng)細(xì)化，大跨度橋梁很可能發(fā)生靜風(fēng)失穩(wěn)現(xiàn)象。因此，有必要對(duì)大跨度懸索橋的靜風(fēng)失穩(wěn)機(jī)理進(jìn)行全面的研究。 本文在已有研究文獻(xiàn)的基礎(chǔ)上基于諧波合成法的原理，采用三次均勻樣條插值方法實(shí)現(xiàn)了大跨度橋梁隨機(jī)脈動(dòng)風(fēng)速的快速模擬。采用動(dòng)力有限元方法求解了紊流場(chǎng)中大跨度懸索橋的靜風(fēng)穩(wěn)定問題。進(jìn)一步完善了大跨度懸索橋結(jié)構(gòu)的剛度退化及扭轉(zhuǎn)發(fā)散機(jī)制。研究了主纜豎向變形和側(cè)向變形對(duì)主纜系統(tǒng)扭轉(zhuǎn)剛度的影響。最后，對(duì)大跨度懸索橋的風(fēng)致響應(yīng)進(jìn)行了參數(shù)分析。論文的主要工作如下： （1）介紹了大跨度橋梁靜風(fēng)穩(wěn)定問題的基本概念，綜述了大跨度橋梁靜風(fēng)穩(wěn)定問題的分析理論及其求解思路。 （2）采用諧波合成法并通過三次均勻樣條插值方法實(shí)現(xiàn)了大跨度橋梁隨機(jī)脈動(dòng)風(fēng)速的快速模擬。 （3）分別采用荷載增量與內(nèi)外雙重迭代相結(jié)合的方法(靜力有限元法)和動(dòng)力有限元法求解了均勻流場(chǎng)中大跨度懸索橋的靜風(fēng)失穩(wěn)臨界風(fēng)速，結(jié)果表明：兩種方法得出的結(jié)果是一致的。 （4）基于梁-索廣義模型，推導(dǎo)了主纜系統(tǒng)的廣義扭轉(zhuǎn)剛度表達(dá)式，并建立系統(tǒng)的廣義運(yùn)動(dòng)方程，定義了合理的扭轉(zhuǎn)失穩(wěn)臨界風(fēng)速，并評(píng)估了主纜豎向變形和側(cè)向變形對(duì)主纜系統(tǒng)剛度退化及橋梁靜風(fēng)穩(wěn)定性的影響。 （5）采用靜力有限元法計(jì)算了在均勻流場(chǎng)中西堠門大橋的扭轉(zhuǎn)發(fā)散臨界風(fēng)速和臨界豎向位移，隨后采用動(dòng)力有限元方法計(jì)算了該橋在紊流場(chǎng)中的扭轉(zhuǎn)發(fā)散臨界風(fēng)速和臨界豎向位移，并運(yùn)用第五章推導(dǎo)的理論知識(shí)來(lái)解釋這些計(jì)算成果。 （6）對(duì)大跨度懸索橋的靜風(fēng)穩(wěn)定性進(jìn)行了參數(shù)分析，主要針對(duì)初始風(fēng)攻角、主纜風(fēng)荷載、紊流強(qiáng)度、紊流的空間相關(guān)性、材料非線性等因素進(jìn)行探究并評(píng)價(jià)了這些因素對(duì)橋梁風(fēng)致響應(yīng)及其靜風(fēng)穩(wěn)定性能的影響。
[Abstract]:In the past, the wind resistance of long-span suspension bridges was mainly focused on the dynamic instability and buffeting response of the structures. However, the phenomenon of static torsional divergence caused by the degradation of the stiffness of the main cable under wind load is not given equal attention. Wind tunnel tests and studies in recent years show that the static wind instability of long-span bridges is likely to occur along with the long refinement of bridges. Therefore, it is necessary to study the mechanism of static wind instability of long span suspension bridge. In this paper, based on the principle of harmonic synthesis, the fast simulation of random pulsating wind speed of long-span bridges is realized by using cubic uniform spline interpolation method based on the previous literatures. The static wind stability of long span suspension bridge in turbulent flow is solved by using dynamic finite element method. The mechanism of stiffness degradation and torsional divergence of long span suspension bridge is further improved. The effects of vertical and lateral deformation of main cable on torsional stiffness of main cable system are studied. Finally, the wind-induced response of long-span suspension bridge is analyzed. The main work of this paper is as follows: (1) the basic concept of static wind stability of long-span bridges is introduced, and the analysis theory of static wind stability of long-span bridges and its solution are summarized. (2) using harmonic synthesis method and cubic uniform spline interpolation method, the fast simulation of random pulsating wind speed of long-span bridges is realized. (3) the static wind buckling critical wind speed of long-span suspension bridge in uniform flow field is solved by the combination of load increment and internal and external double iteration (static finite element method) and dynamic finite element method (DFEM), respectively. The results show that the results obtained by the two methods are consistent. (4) based on the beam-cable generalized model, the generalized torsional stiffness expression of the main cable system is derived, the generalized motion equation of the system is established, and the reasonable critical wind speed of torsional instability is defined. The effects of vertical and lateral deformation of main cable on stiffness degradation of main cable system and static wind stability of bridge are evaluated. (5) the critical wind speed and the critical vertical displacement of the torsional divergence in the uniform flow field are calculated by using the static finite element method. Then the critical torsional divergence wind speed and critical vertical displacement of the bridge in turbulent flow field are calculated by using the dynamic finite element method, and these results are explained by using the theoretical knowledge derived in Chapter 5. (6) the static wind stability of the long-span suspension bridge is analyzed, which is mainly aimed at the initial wind attack angle, the wind load of the main cable, the turbulence intensity and the spatial correlation of turbulence. The influence of these factors on the wind-induced response and static wind stability of bridges was investigated and evaluated.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U441;U448.25

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