英文翻譯：超高層建筑結(jié)構(gòu)橫向風(fēng)荷載效應(yīng)

1、武漢科技大學(xué)本科畢業(yè)設(shè)計(jì)外文翻譯Across-wind loads and effects of super-tall buildings and structuresGU Ming & QUAN Yong SCIENCE CHINA Technological Sciences,2011,54(10):25312541超高層建筑結(jié)構(gòu)橫向風(fēng)荷載效應(yīng)顧明 全勇中國科學(xué) 技術(shù)科學(xué)，2011，54(10):25312541摘 要隨著建筑高度的不斷增加，橫

2、向風(fēng)荷載效應(yīng)已經(jīng)成為影響超高層建筑結(jié)構(gòu)設(shè)計(jì)越來越重要的因素。高層建筑結(jié)構(gòu)的橫向風(fēng)荷載效應(yīng)被認(rèn)為由空氣湍流，搖擺以及空氣流體結(jié)構(gòu)相互作用所引起的。這些都是非常復(fù)雜的。盡管30年來，研究人員一直關(guān)注這個(gè)問題，但橫向風(fēng)荷載效應(yīng)的數(shù)據(jù)庫以及等效靜力風(fēng)荷載的計(jì)算方法還沒有被開發(fā)，大多數(shù)國家在荷載規(guī)范里還沒有相關(guān)的規(guī)定。對(duì)超高層建筑結(jié)構(gòu)的橫向風(fēng)荷載效應(yīng)的研究成果主要包括橫向風(fēng)荷載的動(dòng)力以及動(dòng)力阻尼的測(cè)定，數(shù)據(jù)庫的開發(fā)和等效靜力風(fēng)荷載的理論方法的等等。在本文中，我們首先審查目前國內(nèi)外關(guān)于超高層建筑結(jié)構(gòu)風(fēng)荷載的影響的研究。然后我們?cè)陉U述我們的研究成果。最后，我們會(huì)列舉我們研究成果在超高層建筑結(jié)構(gòu)中應(yīng)用的的案例

3、。1 引言隨著科技的發(fā)展，建筑物也越來越長、高、大，越來越對(duì)強(qiáng)風(fēng)敏感。因此，風(fēng)工程研究人員面臨著更多新的挑戰(zhàn)，甚至一些未知的問題。例如，超高層建筑現(xiàn)在在全世界普遍流行。高度為443米的芝加哥希爾斯塔保持了是世界上最高建筑物26年的記錄，現(xiàn)在還有幾十個(gè)超過400米的超高層建筑被建造。828米高的迪拜塔已經(jīng)建造完成。在發(fā)達(dá)國家，甚至有人建議建造數(shù)千米的“空中城市”。隨著高度的增加，輕質(zhì)高強(qiáng)材料的使用，風(fēng)荷載效應(yīng)特別是具有低阻尼的超高層建筑橫向風(fēng)動(dòng)力響應(yīng)將變得更加顯著。因此，強(qiáng)風(fēng)荷載將成為設(shè)計(jì)安全的超高層建筑結(jié)構(gòu)中的一個(gè)重要的控制因素。達(dá)文最初引入隨機(jī)的概念和方法應(yīng)用發(fā)哦順風(fēng)向荷載效應(yīng)的建筑物和其他

4、結(jié)構(gòu)的抗風(fēng)研究。之后，研究人員完善了相關(guān)的理論和方法，并且主要的研究成果已經(jīng)反映在一些國家的結(jié)構(gòu)設(shè)計(jì)荷載規(guī)范里。對(duì)現(xiàn)代超高層建筑結(jié)構(gòu)，橫風(fēng)向風(fēng)荷載的作用可能已經(jīng)超過順風(fēng)向荷載效用。雖然研究人員已經(jīng)關(guān)注這個(gè)方向已經(jīng)30多年了，但能夠被廣泛接受的橫風(fēng)向荷載數(shù)據(jù)庫以及等效靜力荷載的計(jì)算方法還沒有形成。只有少數(shù)國家在他們的荷載規(guī)范里有相關(guān)的內(nèi)容和規(guī)定。因此，研究超高層建筑結(jié)構(gòu)橫風(fēng)向風(fēng)振和等效靜力荷載在超高層建筑設(shè)計(jì)領(lǐng)域內(nèi)具有重要的理論意義和實(shí)用價(jià)值。 2 研究現(xiàn)狀2.1 橫風(fēng)向荷載及作用機(jī)制 過去的研究主要集中在橫風(fēng)向荷載機(jī)制。郭指出橫風(fēng)向荷載的激發(fā)主要由于被公認(rèn)為空氣動(dòng)力阻尼的尾

5、流、空氣湍流以及風(fēng)荷載耦合作用。索拉里認(rèn)為橫風(fēng)向荷載主要由于尾流的原因所引起?？ɡ锬仿暦Q橫風(fēng)向的效應(yīng)主要是由分離剪切層和尾流波動(dòng)引起的橫向均勻壓力波動(dòng)所引起的。目前，高層建筑橫風(fēng)向荷載機(jī)制已被人為是流入湍流激發(fā)、尾流激發(fā)、以及氣動(dòng)彈性影響。湍流以及尾流激勵(lì)一般是外部空氣動(dòng)力，在本文章中，所涉及的統(tǒng)稱為空氣動(dòng)力。同時(shí)，氣體的彈性效應(yīng)可以被認(rèn)為是氣體動(dòng)力阻尼。橫風(fēng)向氣體動(dòng)力不再像順向風(fēng)一樣符合準(zhǔn)穩(wěn)態(tài)假設(shè)。因此，橫向風(fēng)荷載譜不能直接作為一個(gè)脈動(dòng)風(fēng)速譜。對(duì)不穩(wěn)定風(fēng)壓力來說，風(fēng)洞試驗(yàn)技術(shù)是目前研究橫向風(fēng)動(dòng)力的主要技術(shù)。風(fēng)洞試驗(yàn)技術(shù)主要包括氣體彈性模型試驗(yàn)、高頻力平衡試驗(yàn)以及對(duì)多點(diǎn)壓力測(cè)量的剛性模型實(shí)驗(yàn)技

6、術(shù)。用橫風(fēng)向外部動(dòng)力，橫風(fēng)向氣動(dòng)阻尼，橫向風(fēng)響應(yīng)和建筑結(jié)構(gòu)等效靜力風(fēng)荷載的數(shù)據(jù)可以對(duì)超高層建筑結(jié)構(gòu)進(jìn)行計(jì)算。2.2 橫風(fēng)向氣動(dòng)力 如上所述，橫風(fēng)向氣動(dòng)力基本上可以通過以下途徑獲得：從氣動(dòng)彈性模型在一個(gè)風(fēng)洞的橫風(fēng)向響應(yīng)確定橫風(fēng)向氣動(dòng)力；通過剛性模型風(fēng)壓空間一體化獲得橫向風(fēng)動(dòng)力；使用高頻測(cè)力天平技術(shù)測(cè)量基底彎矩來獲得廣義的氣動(dòng)力。 2.2.1 從氣動(dòng)彈性模型的動(dòng)態(tài)響應(yīng)確定橫風(fēng)向氣動(dòng)力這種方法采用的是氣動(dòng)彈性模型的橫風(fēng)向風(fēng)振響應(yīng)，結(jié)合動(dòng)態(tài)特性的模型識(shí)別橫風(fēng)向氣動(dòng)力。墨爾本對(duì)對(duì)一系列圓形、方形、六角形、多邊形沿高度分布進(jìn)行氣動(dòng)彈性模型風(fēng)洞試驗(yàn)。然而進(jìn)一步試驗(yàn)表明您橫風(fēng)向氣動(dòng)阻力與氣

7、動(dòng)力混合在一起，使他難以準(zhǔn)確地提取氣動(dòng)阻尼力。因此，該方法很少使用。2.2.2 風(fēng)壓積分法 研究人員建議用風(fēng)壓積分法獲取更準(zhǔn)確的高層建筑橫風(fēng)向氣動(dòng)力。伊斯蘭等人采用這種方法得到橫風(fēng)向氣動(dòng)力，陳等人研究了典型建筑結(jié)構(gòu)在不同風(fēng)場(chǎng)條件橫風(fēng)向氣動(dòng)力。影響橫風(fēng)向氣動(dòng)力的因素主要有湍流強(qiáng)度、湍流尺度。湍流強(qiáng)度被發(fā)現(xiàn)擴(kuò)大帶氣動(dòng)力和降低峰值。然而,湍流強(qiáng)度被認(rèn)為對(duì)總能量幾乎沒有影響。因此,研究人員在某種程度上已經(jīng)意識(shí)到了在風(fēng)力條件定量規(guī)則的變化橫風(fēng)氣動(dòng)力。梁等人使用這種方法檢查了建筑物上的典型矩形邊界層風(fēng)洞橫風(fēng)向氣動(dòng)力，從而提出高大的建筑物的經(jīng)驗(yàn)公式和橫風(fēng)向動(dòng)態(tài)響應(yīng)模型。結(jié)果表明, 橫風(fēng)向

8、湍流對(duì)于橫風(fēng)向氣動(dòng)力的貢獻(xiàn)比那些激勵(lì)要小的多?；诖罅康慕Y(jié)果,導(dǎo)出橫風(fēng)向湍流激勵(lì)和激發(fā)后的PSD計(jì)算公式。第一廣義的橫風(fēng)向氣動(dòng)力計(jì)算可以通過在剛性建筑模型整合壓力分布得到，這是該方法一個(gè)重要的優(yōu)越性。然而,考慮到在這類方法需要大量的大規(guī)模的結(jié)構(gòu)測(cè)壓，同步測(cè)量風(fēng)壓是很難實(shí)現(xiàn)的。此外,對(duì)于建筑和結(jié)構(gòu)復(fù)雜的配置,準(zhǔn)確的風(fēng)壓分布和空氣動(dòng)力難以使用這種方法。2.2.3 高頻測(cè)力平衡技術(shù) 與壓力測(cè)量技術(shù)相比，高頻力平衡技術(shù)對(duì)于得到總氣動(dòng)力有其獨(dú)特的優(yōu)勢(shì)，檢測(cè)和數(shù)據(jù)分析過程都很簡單。因此這項(xiàng)技術(shù)通常應(yīng)用于初期設(shè)計(jì)階段的建筑外觀的選擇。目前這項(xiàng)技術(shù)被廣泛應(yīng)用于作用在超高層建筑結(jié)構(gòu)的全風(fēng)荷載以及動(dòng)力響

9、應(yīng)計(jì)算。高頻力平衡技術(shù)自從1970年已經(jīng)逐漸發(fā)展起來。賽馬可等人是第一批把此技術(shù)應(yīng)用到模型測(cè)量的人。他們最初提出平衡模型系統(tǒng)應(yīng)有一個(gè)比風(fēng)力頻率更高的固有頻率。由常和達(dá)文發(fā)展的平衡技術(shù)標(biāo)志著平衡設(shè)備的成熟。 卡里姆進(jìn)行了一項(xiàng)實(shí)驗(yàn)研究。對(duì)于在城市和郊區(qū)具有不同截面形式的高層建筑的橫風(fēng)向氣動(dòng)力研究表明對(duì)于建筑物風(fēng)的不確定以及結(jié)構(gòu)參數(shù)對(duì)橫風(fēng)向空氣動(dòng)力的設(shè)計(jì)有很小的影響并且順風(fēng)向和橫風(fēng)向氣動(dòng)力或扭矩之間的聯(lián)系時(shí)微不足道的。但橫風(fēng)向動(dòng)力和扭矩之間的聯(lián)系是非常密切的。這個(gè)結(jié)論對(duì)于三維方向精確的風(fēng)荷載模型是很重要的。特別是石和全等人做了一系列關(guān)于矩形建筑的邊率，建筑物橫截面形狀，建筑的面率的效應(yīng)以及

10、用五元平衡的高層建筑橫風(fēng)向動(dòng)力設(shè)計(jì)的風(fēng)域條件。事實(shí)上，基于大量的風(fēng)隧道檢測(cè)結(jié)果典型高層建筑橫風(fēng)向氣動(dòng)力系數(shù)的公式已經(jīng)被我們建立了。2.3 橫風(fēng)向氣動(dòng)阻尼 1978年卡里姆對(duì)基于氣動(dòng)彈性模型技術(shù)和風(fēng)壓積分法的高層建筑橫風(fēng)向動(dòng)力響應(yīng)做了一次調(diào)查研究。他指出由在一定范圍內(nèi)風(fēng)壓力測(cè)試獲得的橫風(fēng)向氣動(dòng)力計(jì)算而得到的橫風(fēng)向風(fēng)振響應(yīng)總是比那些相同建筑模型的氣動(dòng)彈性模型要小。這個(gè)重要的研究成果使得研究人員認(rèn)識(shí)到橫風(fēng)向氣動(dòng)負(fù)阻尼的存在。 后來，研究人員對(duì)這個(gè)問題進(jìn)行了大量的研究并且找到了有效的方案來確定氣動(dòng)阻尼。第一種方法是通過比較基于來自剛性模型試驗(yàn)和氣動(dòng)彈性模型試驗(yàn)的氣動(dòng)力所得到的到哪個(gè)

11、臺(tái)響應(yīng)。第二種方法是從由氣動(dòng)彈性模型或強(qiáng)迫振動(dòng)模型所得到的總氣動(dòng)力中分離出氣動(dòng)阻力。第三種方法是從氣動(dòng)彈性模型分離氣動(dòng)阻尼的的識(shí)別方法。此外，研究人員意識(shí)到風(fēng)因素的影響規(guī)律。這些因素包括結(jié)構(gòu)形狀、結(jié)構(gòu)動(dòng)力參數(shù)、風(fēng)條件等等?？ɡ锬返热耸堑谝慌岢鐾ㄟ^比較來確定氣動(dòng)阻尼的方法。陳等人采用這種技術(shù)來研究橫風(fēng)向效應(yīng)和高層建筑結(jié)構(gòu)的動(dòng)態(tài)阻尼并提出了一個(gè)氣動(dòng)阻尼公式。 史迪克最初制造了一批測(cè)定總氣動(dòng)力、氣動(dòng)阻尼力與氣動(dòng)力的強(qiáng)迫振動(dòng)測(cè)量設(shè)備。他測(cè)量高層建筑模型基底彎矩是通過一個(gè)專門的設(shè)計(jì)裝置產(chǎn)生振動(dòng)所產(chǎn)生的有關(guān)的氣動(dòng)力從總氣動(dòng)力脫離進(jìn)而分解為氣動(dòng)應(yīng)力和氣動(dòng)阻尼力獲得氣動(dòng)阻尼?？虏噲D對(duì)諧波振動(dòng)建筑

12、模型測(cè)量風(fēng)壓獲得總氣動(dòng)力。然后用類似史迪克的方法計(jì)算空氣阻尼。這種方法的優(yōu)點(diǎn)是真實(shí)的建筑特性并非必須被考慮到。這種方法更方便更實(shí)用，特別是在推廣實(shí)驗(yàn)結(jié)果。這種方法的的主要缺點(diǎn)是它需要復(fù)雜的設(shè)備，尤其是直到現(xiàn)在多元耦合裝置是不可用的。 確定氣動(dòng)阻尼的隨機(jī)振動(dòng)響應(yīng)的氣動(dòng)彈性模型課采用適當(dāng)?shù)南到y(tǒng)識(shí)別技術(shù)，其中包括頻域法，時(shí)域的方法以及時(shí)域頻域的方法。在這些方法中隨機(jī)減量法、時(shí)域方法被廣泛采用以確定高層建筑的氣動(dòng)阻尼。杰瑞介紹隨機(jī)減量法來識(shí)別結(jié)構(gòu)阻尼。馬克采用隨機(jī)減量法確定高層建筑順橫風(fēng)向氣動(dòng)阻尼。他們分析了影響建筑長寬比、邊比、氣動(dòng)阻尼、結(jié)構(gòu)阻尼。田村等人用隨機(jī)減量技術(shù)確定超高層建筑氣動(dòng)阻

13、尼。全等人通過實(shí)驗(yàn)確定在不同的風(fēng)領(lǐng)域具有不同結(jié)構(gòu)中阻尼方形截面的橫風(fēng)向氣動(dòng)阻尼，并得出了一個(gè)經(jīng)驗(yàn)公式。這些研究成果已通過相關(guān)的中國規(guī)范。秦和谷是第一個(gè)引入隨機(jī)空間識(shí)別方法于氣動(dòng)參數(shù)的確認(rèn)的研究人員。這些氣動(dòng)參數(shù)包括大跨度橋梁氣動(dòng)剛度和阻尼。于隨機(jī)變量法相比，隨機(jī)空間識(shí)別方法具有更多的優(yōu)點(diǎn)。它能克服隨機(jī)變量法的弱噪音抵抗力和需要大量實(shí)驗(yàn)數(shù)據(jù)的缺點(diǎn)。秦采用這種方法來確定高層建筑的氣動(dòng)阻尼。2.4規(guī)范的實(shí)用性 如上所說，雖然研究者一直關(guān)注高層建筑風(fēng)荷載超過30年了，但被廣泛接受的橫風(fēng)向風(fēng)荷載數(shù)據(jù)庫和計(jì)算方法，等效靜力風(fēng)荷載尚未開發(fā)。此外，只有少數(shù)國家采用相關(guān)的規(guī)定和代碼。于其他國家相比，日

14、本建筑協(xié)會(huì)提供了計(jì)算高層建筑結(jié)構(gòu)橫風(fēng)向荷載的最好方法。然而公式的橫風(fēng)向代碼知適用于高層建筑高寬比小于六，這似乎很難滿足實(shí)際需要。而且此方法在這種方法里氣動(dòng)阻尼沒有被考慮。 在目前的中國建筑結(jié)構(gòu)荷載規(guī)范只提供了一個(gè)簡單的方法來計(jì)算渦激共振的高聳結(jié)構(gòu)，而一般不適用于高層建筑結(jié)構(gòu)抗風(fēng)設(shè)計(jì)。在題為“高層建筑鋼結(jié)構(gòu)設(shè)計(jì)詳細(xì)說明”里，我們的研究成果已經(jīng)通過。2.5 總結(jié) 隨著建筑高度不斷增加，橫風(fēng)向荷載效應(yīng)已經(jīng)成為超高層建筑結(jié)構(gòu)設(shè)計(jì)的重要因素。目前，對(duì)超高層建筑結(jié)構(gòu)橫風(fēng)向荷載的研究主要包括橫風(fēng)向風(fēng)荷載的機(jī)制，橫風(fēng)向氣動(dòng)力、氣動(dòng)阻尼和在規(guī)范中的應(yīng)用。因此我們的一些研究成果主要有典型建筑結(jié)

15、構(gòu)的橫風(fēng)向力，氣動(dòng)阻尼以及在中國規(guī)范的應(yīng)用。最后介紹了典型的案例，在這個(gè)案例中建造更高層建筑的趨勢(shì)預(yù)示著風(fēng)工程研究人員將面臨著更多更新的挑戰(zhàn)，甚至到現(xiàn)在他們都沒有意識(shí)到的問題。因此需要更多地努力去解決工程設(shè)計(jì)問題，同時(shí)進(jìn)一步發(fā)展風(fēng)工程。附件：英文原文Across-wind loads and effects of super-tall buildings and structuresGU Ming & QUAN YongAbstractAcross-wind loads and effects have become increasingly important factors in

16、the structural design of super-tall buildings and structures with increasing height. Across-wind loads and effects of tall buildings and structures are believed to be excited by inflow turbulence, wake, and inflow-structure interaction, which are very complicated. Although researchers have been focu

17、sing on the problem for over 30 years, the database of across-wind loads and effects and the computation methods of equivalent static wind loads have not yet been developed, most countries having no related rules in the load codes. Research results on the across-wind effects of tall buildings and st

18、ructures mainly involve the determination of across-wind aerodynamic forces and across-wind aerodynamic damping, development of their databases, theoretical methods of equivalent static wind loads, and so on. In this paper we first review the current research on across-wind loads and effects of supe

19、r-tall buildings and structures both at home and abroad. Then we present the results of our study. Finally, we illustrate a case study in which our research results are applied to a typical super-tall structure.1 Introduction With the development of science and technology, structures are becoming la

20、rger, longer, taller, and more sensitive to strong wind . Thus, wind engineering researchers are facing with more new challenges, even problems they are currently unaware of. For example, the construction of su-per-tall buildings is now prevalent around the world. The Chicago Sears Tower with a heig

21、ht of 443 m has kept the record of the worlds tallest building for 26 years now. Dozens of super-tall buildings with heights of over 400 m are set to be constructed. Burj Dubai Tower with a height of 828 m has just been completed. In developed countries,here are even proposals to build “cities in th

22、e air” with thousands of meters of magnitude. With the increase in height and use of light and high-strength materials, wind-induced dynamic responses, especially across-wind dynamic responses of super-tall buildings and structures with low damping, will become more notable. Hence, strong wind load

23、will become an important control factor in designing safe super-tall buildings and structures. Davenport initially introduced stochastic concepts and methods into wind-resistant study on along-wind loads and effects of buildings and other structures. Afterward, researchers developed related theories

24、 and methods 817, and the main research results have already been reflected in the load codes of somecountries for the design of buildings and structures 1823. For modern super-tall buildings and structures, across-wind loads and effects may surpass along-wind ones. Al-though researchers have been f

25、ocusing on the complex problem for over 30 years now, the widely accepted data-base of across-wind loads and computation methods of equivalent static wind loads have not been formed yet. Only a few countries have accordingly adopted the related con-tents and provisions in their codes 18, 20. Therefo

26、re, studying across-wind vibration and the equivalent static wind loads of super-tall buildings and structures is of great theoretical significance and practical value in the field of structural design of super-tall buildings and structures. The current paper thus reviews the research situation of a

27、cross-wind loads and effects of super-tall buildings and structures both at home and abroad. Then, the research results given by us are presented. Finally, a case study of across-wind loads and effects of a typical super-tall structure is illustrated.2 Research situation 2.1 Mechanism of across-wind

28、 loads and effects Previous researches focused mainly on the mechanism of across-wind load. Kwok 2426 pointed out that across-wind excitation comes from wake, inflow turbulence, and wind-structure interaction effect, which could be recog-nized as aerodynamic damping. Solari 27 attributed the across-

29、wind load to across-wind turbulence and wake exci-tations, considering wake as the main excitation. Islam et al. 28 and Kareem 13 claimed that across-wind responses are induced by lateral uniform pressure fluctuation due to separation shear layer and wake fluctuation. Currently, the mechanism of acr

30、oss-wind load on tall buildings and struc-tures has been recognized as inflow turbulence excitation, wake excitation, and aeroelastic effect. Inflow turbulence and wake excitation are essentially the external aerody-namic force, which is collectively referred to in the present paper as aerodynamic f

31、orce. Meanwhile, aeroelastic effect can be treated as aerodynamic damping. Across-wind aero-dynamic force no longer conforms to quasi-steady assump-tion as the along-wind one; thus, the across-wind force spectra cannot be directly expressed as a function of inflow fluctuating wind velocity spectra.

32、Wind tunnel test tech-nique for unsteady wind pressures or forces is presently a main tool for studying across-wind aerodynamic forces. The wind tunnel experiment technique mainly involves the aeroelastic building model experiment technique, high fre-quency force balance technique, and rigid model e

33、xperiment technique for multi-point pressure measurement. Using data of across-wind external aerodynamic force and across-wind aerodynamic damping, across-wind responses and the equivalent static wind load of buildings and structures can be computed for the structural design of super-tall buildings

34、and structures.2.2 Across-wind aerodynamic force As stated above, the across-wind aerodynamic force can be obtained basically through the following channels: (i) iden-tifying across-wind aerodynamic force from across-wind responses of an aeroelastic building model in a wind tunnel; (ii) obtaining ac

35、ross-wind aerodynamic force through spa-tial integration of wind pressure on rigid models; (iii) ob-taining generalized aerodynamic force directly from meas-uring base bending moment using high frequency force balance technique. 2.2.1 Identification of across-wind aerodynamic force from dynamic resp

36、onses of aeroelastic building model This method employs across-wind dynamic responses of the aeroelastic building model, combining the dynamic charac-teristics of the model to identify across-wind aerodynamic force. Saunders 29, Kwok 24, Kwok and Melbourne 30, Kwok 25, and Melbourne and Cheung 31 pe

37、rformed aeroelastic model wind tunnel tests on a series of circular, square, hexagon, polygon with eight angles, square with reentrant angles and fillets, and tall or cylindrical structures with sections contracting along height. However, further studies showed that across-wind aerodynamic damping f

38、orce and aerodynamic force mixed together make it diffi-cult to extract aerodynamic damping force accurately. As such, the method has been seldom used. 2.2.2 Wind pressure integration method Researchers have recommended wind pressure integration to obtain more accurately the across-wind aerodynamic

39、forces on tall buildings. Islam et al. 28, Cheng et al. 32, Nishimura and Taniike 33, Liang et al. 34, 35, Ye 36, Tang 37, Zhang 38, and Gu et al. 39 adopted this method to obtain across-wind aerodynamic forces on tall buildings and structures. Cheng et al. 32 experimentally studied across-wind aero

40、dynamic forces of typical buildings under different wind field conditions and derived empirical formulas for the power spectrum density (PSD) of the across-wind aerodynamic force reflecting the effects of tur-bulent intensity and turbulent scale. Turbulent intensity was found to widen the bandwidth

41、of PSD of the across-wind aerodynamic force and reduce the peak value. However, tur-bulent intensity was determined to have almost no effects on total energy. Thus, researchers have recognized the quantita-tive rules of variation of across-wind aerodynamic force with wind condition to some extent. L

42、iang et al. 34, 35 examined across-wind aerodynamic forces on typical rectangular buildings in a boundary layer wind tunnel using this method, thus proposing empirical formulas for PSD of across-wind aerodynamic forces of tall rectangular buildings and an ana-lytical model for across-wind dynamic re

43、sponses. Ye 36 and Zhang 38 decomposed across-wind turbulence excita-tion and vortex shedding excitation in across-wind aerody-namic forces on typical super-tall buildings. The resultsshowed that the across-wind turbulence contributed much less to across-wind aerodynamic force than the wake excita-t

44、ion. Based on a large number of results, we derived PSD formulas for the across-wind turbulence excitation and the wake excitation, and further derived a new formula for the across-wind aerodynamic force. The first- and higher-mode generalized across-wind aerodynamic forces can be calculated through

45、 the integra-tion of pressure distribution on rigid building models, which is an important advantage of this method. However, given the need for a large number of pressure taps for very large-scale structures in this kind of method, synchronous pressure measurements are difficult to make. Moreover,

46、for buildings and structures with complex configurations, ac-curate wind pressure distribution and aerodynamic force are difficult to obtain using this kind of method. 2.2.3 High frequency force balance technique Compared with the pressure measuring technique, high fre-quency force balance technique

47、 has its unique advantage for obtaining total aerodynamic forces. The test and data analy-sis procedures are both very simple; hence, this technique is commonly used for selection studies on architectural ap-pearance in the initial design stage of super-tall buildings and structures. Currently, this

48、 technique is widely used for total wind loads acting on super-tall buildings and structures, and for dynamic response computation as well. The high frequency force balance technique has been gradually developed since the 1970s. Cermak et al. 40 were the first to use this technique for building mode

49、l measurement. They initially pointed out that the bal-ance-model system should have a higher inherent frequency than the concerned frequency of wind forces. The five-component balance developed by Tschanz and Daven-port 41 marked the maturity of balance facility. Kareem conducted an experimental st

50、udy on across- wind aerodynamic forces on tall buildings with various sec-tion shapes in urban and suburban wind conditions. The research showed that for the buildings with aspect ratios of 46, uncertainties of wind and structural parameters have small effects on PSD of the across-wind aerodynamic f

51、orce, and the correlation between the along-wind aerodynamic force and the across-wind aerodynamic force or the torsion moment is negligible, but there is a strong correlation be-tween the across-wind aerodynamic force and the torsion moment. This conclusion is important for the development of three

52、-dimensional refined wind load model. Particularly, Gu and Quan 42 and Quan et al. 43 made detailed stud-ies on the effects of the side ratio of a rectangular building, cross-section shape of a building, aspect ratio of a building, and wind field condition on the PSD of the across-wind aerodynamic f

53、orce of tall buildings using a five-component balance. In fact, based on a large number of wind tunnel test results, formulas for across-wind aerodynamic force coeffi-cients of the typically tall buildings have been derived by us and other researchers, some of which are listed in Table 1. In additio

54、n, in Table 1, the formula derived by Gu and Quan 42 has already been adopted in related design codes in China.2.3 Across-wind aerodynamic damping In 1978, Kareem 44 performed an investigation on across-wind dynamic responses of tall buildings based on both of the aeroelastic model technique and the

55、 wind pres-sure integration method. He found out that the across-wind dynamic responses calculated with the across-wind aerody-namic forces obtained from the wind pressure tests at a certain test wind velocity range were always smaller than those of the aeroelastic model of the same building model.

56、This important result made researchers realize the existence of across-wind negative aerodynamic damping.Subsequently, researchers carried out numerous studies on the problem and developed effective methods for identi-fying aerodynamic damping. The first kind of method ob-tains aerodynamic damping b

57、y comparing the dynamic re-sponses computed based on the aerodynamic forces from rigid building model tests and those from aeroelastic model tests. The second one separates aerodynamic damping force from the total aerodynamic force measured from aeroelastic building models or forced vibration buildi

58、ng models. The third kind employs identification methods for extracting aerodynamic damping from random responses of aeroelastic models. Moreover, researchers realized the effect law of factors, including structural shape, structural dynamic pa-rameters, wind conditions, and so on, on aerodynamic da

59、mping, Isyumov et al. 45 were the first researchers to propose a method for aerodynamic damping through com-paring responses from a rigid building model test using HFFB technique with those of an aeroelastic model of the same building. Cheng et al. 46 adopted the method to study across-wind responses and aerodynamic damping of tall square buildings and proposed an aerodynamic damping formula.Steckley