-
Across-wind loads and effects of super-tall buildings and Structures AbstractAcross-wind loads 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, which 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 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 the 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.6452
- 上一篇：计算机数字控制机床英文文献和中文翻译
- 下一篇：多支间歇精馏塔英文文献和翻译
Introduction
With the development 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 prevalent around the world. The Chicago Sears Tower with a height of 443 m has kept the record of the world’s 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, 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 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 structures. 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 surpass 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-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 paper 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.
Mechanism 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 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 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 aerodynamic 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 spectra. 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 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 buildings and structures.