本文關(guān)鍵詞： 龍卷風(fēng) 高層建筑 風(fēng)荷載 沖擊效應(yīng) 數(shù)值模擬　出處：《中國(guó)科學(xué)技術(shù)大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：龍卷風(fēng)具有較強(qiáng)的破壞力,是抗風(fēng)減災(zāi)工程重要的防范對(duì)象之一。近年來(lái),隨著地球環(huán)境的惡化,龍卷風(fēng)襲擊大型城市的災(zāi)害時(shí)有發(fā)生,針對(duì)城市中高層建筑的龍卷風(fēng)災(zāi)害研究開(kāi)始受到重視。已有的研究多集中于實(shí)驗(yàn)尺度模型和準(zhǔn)靜態(tài)荷載,而對(duì)龍卷風(fēng)動(dòng)態(tài)沖擊全尺寸高層的研究還比較少,特別是現(xiàn)行建筑設(shè)計(jì)規(guī)范仍沒(méi)有針對(duì)龍卷風(fēng)給出結(jié)構(gòu)設(shè)計(jì)及安全方面的具體要求和方法,迫切需要從理論模擬及實(shí)驗(yàn)等多方面開(kāi)展研究。本文首先建立了動(dòng)態(tài)運(yùn)動(dòng)龍卷風(fēng)的數(shù)值風(fēng)場(chǎng)模型,應(yīng)用大渦模擬(LES)方法開(kāi)展了龍卷風(fēng)動(dòng)態(tài)沖擊高層建筑的非定常過(guò)程模擬,對(duì)其漩渦演化及對(duì)高層建筑的沖擊風(fēng)荷載特性開(kāi)展了初步研究,并與實(shí)驗(yàn)室尺度下的荷載特征進(jìn)行了比較研究,進(jìn)一步搞清了龍卷風(fēng)沖擊不同尺度和形狀的高層建筑流場(chǎng)差異和荷載產(chǎn)生機(jī)理,主要獲得如下結(jié)論：1)在模擬龍卷風(fēng)動(dòng)態(tài)運(yùn)動(dòng)的數(shù)值風(fēng)場(chǎng)模型中,簡(jiǎn)單采用動(dòng)態(tài)速度邊界條件較難保持龍卷風(fēng)在運(yùn)動(dòng)過(guò)程中的形態(tài)和強(qiáng)度不變,采用預(yù)設(shè)旋轉(zhuǎn)強(qiáng)度和速度保持恒定的數(shù)值驅(qū)動(dòng)區(qū)是一種較簡(jiǎn)便且高效的計(jì)算方法。2)實(shí)驗(yàn)室尺度下的數(shù)值模擬結(jié)果表明：龍卷風(fēng)動(dòng)態(tài)沖擊高層建筑,其荷載響應(yīng)特性與建筑尺度有關(guān)。建筑尺度較小時(shí),沖擊荷載呈雙峰特征,沖擊效應(yīng)和時(shí)變效應(yīng)相對(duì)較小。相反,沖擊荷載呈多峰特征,時(shí)變性強(qiáng),沖擊效應(yīng)明顯。同時(shí),龍卷風(fēng)在沖擊較大尺度建筑時(shí),主渦會(huì)發(fā)生破裂,形成多個(gè)漩渦。多漩渦之間以及與建筑尾渦相互作用和耦合將導(dǎo)致更大的沖擊荷載。這種力學(xué)現(xiàn)象在國(guó)內(nèi)外龍卷風(fēng)研究中尚未發(fā)現(xiàn)類(lèi)似報(bào)道。3)全尺寸龍卷風(fēng)沖擊高層建筑的載荷響應(yīng)特性與實(shí)驗(yàn)室模擬尺度下的載荷響應(yīng)特性存在相似特性與尺度效應(yīng)。其相似性體現(xiàn)在：當(dāng)龍卷風(fēng)尺度與建筑尺度比相似時(shí),其荷載變化規(guī)律和特征存在一定相似性。不過(guò)其具體載荷系數(shù)及峰值響應(yīng)位置卻存在較大差異,這反應(yīng)了龍卷風(fēng)的尺度效應(yīng)。4)全尺寸模擬結(jié)果表明：當(dāng)建筑模型的高度相同,尺度相近時(shí),建筑的外形跟載荷響應(yīng)的大小有一定的關(guān)系。綜合不同建筑的龍卷風(fēng)載荷載荷響應(yīng)特性上看,矩形建筑的龍卷風(fēng)載荷響應(yīng)系數(shù)相對(duì)較大,且與龍卷風(fēng)襲擊攻角有關(guān)。
[Abstract]:Tornadoes have strong destructive power, which is one of the important protection objects of wind disaster mitigation engineering. In recent years, with the deterioration of the earth environment, tornadoes frequently hit large cities. The research on tornado disasters of high-rise buildings in cities has been paid more attention. Most of the existing researches focus on the experimental scale model and quasi-static load, but the research on tornado dynamic impact on the full scale high-rise is relatively rare. In particular, the current building design code still does not give the specific requirements and methods of structural design and safety for tornadoes. There is an urgent need for theoretical simulation and experimental research. Firstly, the numerical wind field model of dynamic moving tornadoes is established in this paper. The unsteady process of tornado dynamic impact on high-rise buildings is simulated by means of large eddy simulation (les) method. The vortex evolution and impact wind load characteristics of high-rise buildings are studied preliminarily. Compared with the load characteristics of laboratory scale, the flow field difference and load generation mechanism of high-rise building with different scale and shape of tornado impact are further understood. The main conclusions are as follows: 1) in the numerical wind field model of simulating tornado dynamic motion, it is difficult to maintain the shape and intensity of tornado in the course of motion by simply adopting dynamic velocity boundary condition. Numerical driving region with preset rotation strength and constant velocity is a simple and efficient calculation method. 2) numerical simulation results at laboratory scale show that tornadoes impact on high-rise buildings dynamically. The load response characteristics are related to the building scale. When the building scale is small, the impact load is bimodal, while the impact effect and time-varying effect are relatively small. On the contrary, the impact load is multi-peak and time-varying. The impact effect is obvious. At the same time, when tornadoes impact large scale buildings, the main vortex will break down. The formation of multiple whirlpools. The interaction and coupling between multiple whirlpools and building trailing vortices will lead to larger impact loads. This mechanical phenomenon has not been reported in tornadoes at home and abroad. The load response characteristics of full-scale tornado impact high-rise buildings are similar to those of laboratory simulation scale. When the scale of a tornado is similar to that of a building. The law and characteristics of load variation are similar, but the load coefficient and peak response location are different. This reflects the scale effect of tornadoes. 4) the full-scale simulation results show that when the height of the building model is the same and the scale is similar. The shape of the building has a certain relationship with the size of the load response. Considering the tornado load response characteristics of different buildings, the tornado load response coefficient of rectangular buildings is relatively large. And with tornadoes attack angle of attack related.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TU973.213

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 甘文舉;何益斌;;Rankine渦平移模型下低層房屋龍卷風(fēng)荷載的分析[J];四川建筑科學(xué)研究;2009年01期

2 宋拓;湯卓;王兆勇;呂令毅;;基于譜隨機(jī)有限元法的龍卷風(fēng)作用下核電常規(guī)島可靠度分析[J];工程力學(xué);2014年11期

3 鄭峰;謝海華;;我國(guó)近30年龍卷風(fēng)研究進(jìn)展[J];氣象科技;2010年03期

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