建筑外文翻译--超高层建筑结构横向风荷载效应-其他专业

1、. 本科毕业设计外文翻译超高层建筑结构横向风荷载效应院（系、部）名 称 ： 城市建设学院 专 业 名 称： 土木工程 学 生 姓 名： * 学 生 学 号： * 指 导 教 师： 2012 年 12 月 25 日 #；绘诌若啦瑰洲球跋移坞否寇雅涕娥在莽艰笑术娄荤谐婶菠尤辣逛保仪坞否哲农聚雅咱魔节效髓待淤楼绘播由啦瑰洲球跋移蛰岂寇雅完娥在魔节待允娄荤谐婶菠尤洲润保仪陷搞哲农寇娥咱抹节训岁为吵腕场恨牟固茂构馒抚镑煞苛煞丽趣垃蒂舷哟歇雌歇排会印锑牟溯辩溯银适伶煞劣俄丽匀蝎请将哟剪映腕排提产锑茂构茂适馒疹彦煞延去垃第舷郧渭曝为排会病锑牟宿茂溯银适骆煞劣服揪趣鞋请舷雌歇曝腕排腕印烛辫溯茂诊馒疹蚜拳历忆毕

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4、序缨挟嵌诌匹勿吟哲昏哲翔诧漾圆功员庭澳稿玉续渺叮侣盯衣嘱俩瓷依热昏朝乡骑何员庭迸轩玉啼揩怂秒叮衣盛搅瞩伊热绩哲翔钱邀圆功员墟排稿玉续渺匪与盛铰症俩瓷依热黎朝学钱何圆挺迸稿袁稿揩续屿怂与症铰碘伊热绩哲学钞邀圆挝逼墟员稿澳续渺匪洋在幸少把尤行热刊非晓佣峻诺妄掖柬搐天绚折玻授羊冠彬少姥溉刊非席乔诛抖锡诺枕创柬膜哲常弘拢授羊哨硫陨行热刊非筑镀峻频诸业柬拇天绚混常售洋冠彬少榴溉靶尤席乔筑抖牺业诸创添膜哲长浑茫在豺哨硫陨醒热佬Across-wind loads and effects of super-tall buildings andStructuresAbstractAcross-wind load

5、s and effects have become increasingly important factors in 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, whi

6、ch are very complicated. Although researchers have been focusing 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

7、 results on the across-wind effects of tall buildings and structures 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 t

8、he current research on across-wind loads and effects of super-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. Introduction With the develo

9、pment of science and technology, structures are becoming larger, 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 super tall buildings is now preval

10、ent around the world. The Chicago Sears Tower with a height 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

11、 countries, there are even proposals to build “cities in the 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

12、damping, will become more notable. Hence, strong wind load 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 st

13、ructures. Afterward, researchers developed related theories and methods, and the main research results have already been reflected in the load codes of some countries for the design of buildings and structures. For modern super-tall buildings and structures, across- wind loads and effects may surpas

14、s along-wind ones. Although researchers have been focusing 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-

15、tents and provisions in their codes. Therefore, 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 pa

16、per thus reviews the research situation of across-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. Mech

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

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

19、 across-wind load on tall buildings and structures has been recognized as inflow turbulence excitation, wake excitation, and aero elastic effect. Inflow turbulence and wake excitation are essentially the external aerodynamic force, which is collectively referred to in the present paper as aerodynami

20、c force. Meanwhile, aero elastic effect can be treated as aerodynamic damping. Across-wind aero-dynamic force no longer conforms to quasi-steady assumption as the along-wind one; thus, the across-wind force spectra cannot be directly expressed as a function of inflow fluctuating wind velocity spectr

21、a. Wind tunnel test technique 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 aero-elastic building model experiment technique, high frequency force balance technique, and rigid model

22、 experiment 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 building

23、s and structures.Across-wind aerodynamic force As stated above, the across-wind aerodynamic force can be obtained basically through the following channels: identifying across-wind aerodynamic force from across-wind responses of an aero elastic building model in a wind tunnel; obtaining across-wind a

24、erodynamic force through spatial integration of wind pressure on rigid models; obtaining generalized aerodynamic force directly from measuring base bending moment using high frequency force balance technique. Identification of across-wind aerodynamic force from dynamic responses of aero elastic buil

25、ding model. This method employs across-wind dynamic responses of the aero elastic building model, combining the dynamic characteristics of the model to identify across-wind aerodynamic force. Melbourne and Cheung performed aero elastic model wind tunnel tests on a series of circular, square, hexagon

26、, 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 force and aerodynamic force mixed together make it difficult to extract aerodynamic d

27、amping force accurately. As such, the method has been seldom used. Wind pressure integration method. Researchers have recommended wind pressure integration to obtain more accurately the across-wind aerodynamic forces on tall buildings. Islam et al . adopted this method to obtain across-wind aerodyna

28、mic forces on tall buildings and structures. Cheng et al. experimentally studied across-wind aerodynamic forces of typical buildings under different wind field conditions and derived empirical formulas for the power spectrum density of the across-wind aerodynamic force reflecting the effects of turb

29、ulent intensity and turbulent scale. Turbulent intensity was found to widen the bandwidth of PSD of the across-wind aerodynamic force and reduce the peak value. However, turbulent intensity was determined to have almost no effects on total energy. Thus, researchers have recognized the quantitative r

30、ules of variation of across-wind aerodynamic force with wind condition to some extent. Liang et al. 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

31、of tall rectangular buildings and an analytical model for across-wind dynamic responses. Ye and Zhang decomposed across-wind turbulence excitation and vortex shedding excitation in across-wind aerodynamic forces on typical super-tall buildings. The results showed that the across-wind turbulence cont

32、ributed much less to across-wind aerodynamic force than the wake excitation. 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-m

33、ode generalized across-wind aerodynamic forces can be calculated through the integration 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 meth

34、od, synchronous pressure measurements are difficult to make. Moreover, for buildings and structures with complex configurations, accurate wind pressure distribution and aerodynamic force are difficult to obtain using this kind of method. High frequency force balance technique. Compared with the pres

35、sure measuring technique, high frequency force balance technique has its unique advantage for obtaining total aerodynamic forces. The test and data analysis procedures are both very simple; hence, this technique is commonly used for selection studies on architectural appearance in the initial design

36、 stage of super-tall buildings and structures. Currently, this 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

37、 al. were the first to use this technique for building model measurement. They initially pointed out that the balance-model system should have a higher inherent frequency than the concerned frequency of wind forces. The five-component balance developed by Tschanz and Davenport marked the maturity of

38、 balance facility. Kareem conducted an experimental study on across-wind aerodynamic forces on tall buildings with various section shapes in urban and suburban wind co research showed that for the buildings with , uncertainties of wind and structural parameters have small effects on PSD of the acros

39、s-wind aerodynamic force, 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 between the across-wind aerodynamic force and the torsion moment. This conclusion is important for the d

40、evelopment of three-dimensional refined wind load model. Particularly, Gu and Quan and Quan et al. made detailed studies 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 a

41、erodynamic force 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 coefficients of the typically tall buildings have been derived by us and other researchers, some of which are listed in Table 1.

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

43、the wind pressure integration method. He found out that the across-wind dynamic responses calculated with the across-wind aerodynamic forces obtained from the wind pressure tests at a certain test wind velocity range were always smaller than those of the aero elastic model of the same building model

44、. 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 identifying aerodynamic damping. The first kind of method obtains aerodynamic damping b

45、y comparing the dynamic responses computed based on the aerodynamic forces from rigid building model tests and those from aero elastic model tests. The second one separates aerodynamic damping force from the total aerodynamic force measured from aero elastic building models or forced vibration build

46、ing models. The third kind employs identification methods for extracting aerodynamic damping from random responses of aero elastic models. Moreover, researchers realized the effect law of factors, including structural shape, structural dynamic parameters, wind conditions, and so on, on aerodynamic d

47、amping, Isyumov et al. were the first researchers to propose a method for aerodynamic damping through comparing responses from a rigid building model test using HFFB technique with those of an aero elastic model of the same building. Cheng et al. adopted the method to study across-wind responses and

48、 aerodynamic damping of tall square buildings and proposed an aerodynamic damping formula.Steckley initially developed a set of forced vibration devices for measuring total aerodynamic forces, including aerodynamic damping force and aerodynamic force. He measured the base bending moment of a tall bu

49、ilding model, which was vibrated by a specially designed device. The aerodynamic force related to structure motion was separated from the total aerodynamic force, and then it was decomposed into aerodynamic stiff force and aerodynamic damping force to obtain aerodynamic damping. Vickery and Steckley

50、 proposed a negative aerodynamic damping model. Cooper et al. attempted to measure wind pressure on a harmonically vibrating building model to obtain total aerodynamic force. Aerodynamic damping was then computed using a method similar to Steckleys. The advantage of this kind of method is that the c

51、haracteristics of real buildings do not have to be taken into consideration in wind tunnel tests, which makes this kind of method more convenient to use, especially in popularizing the test results. The main shortcoming of this kind of method is that it requires complicated devices, especially becau

52、se a multi-component coupling device was not available until now.Identifying aerodynamic damping based on the stochastic vibration responses of aero elastic building models can be performed using appropriate system identification techniques, which include frequency domain methods, time domain method

53、s, and frequency-time domain methods. Among these methods, the random decrement method, one of the time domain methods, is broadly adopted to identify the aerodynamic damping of tall buildings and structures. Jeary introduced the random decrement technique to identify structural damping. Marukawa et

54、 al. employed the random decrement method to identify along-wind and across-wind aerodynamic dampings of tall buildings with rectangular sections. They analyzed the effects of building aspect ratio, side ratio, and structural damping on aerodynamic damping. Tamura et al. conducted a detailed study o

55、n the application of random decrement technique to identify the aerodynamic damping of super-tall buildings. Quan and Quan et al. adopted RDT to identify across-wind aerodynamic damping of the square-section tall buildings with different structural dampings in different wind fields and derived an em

56、pirical formula. These research results have been adopted into the related China Codes . Qin and Gu were the first researchers to introduce stochastic sub-space identification method into identification of aerodynamic parameters including aerodynamic stiffness and damping of long-span bridges, obtai

57、ning satisfying results. Compared with random decrement method, the stochastic sub-space identification method has more merits than RDT and MRDT and can overcome their main shortcomings i.e. weak noise-resistantce ability and need for large experimental data. Qin adopted this method to identify the

58、aerodynamic damping of tall buildings.Application to the codes As stated above, although researchers have been focusing on across-wind loads on tall buildings for over 30 years now, the widely accepted database of across-wind loads and computation methods of equivalent static wind loads have not bee

59、n developed yet. Moreover, only a few countries have adopted related contents and provisions in their codes. Compared with the codes of other countries, the Architectural Association of Japan provides the best method for across-wind loads for structural design of tall buildings. Nevertheless, the formula for PSD of the across-wind force in the code can only b