Journal of Wind Engineering and Industrial Aerodynamics
Wind loads on low buildings: in the wake of Alan Davenport's contributions
Introduction
Alan Garnett Davenport, a Doyen of Wind Engineering, is more well known for his extraordinary achievements in the development of wind engineering, as far as the statistical description of wind loading or the design of major structures such as the twin towers of the World Trade Center in New York are concerned. However, as one of Davenport's graduate students in the 1970s, I had the direct opportunity to appreciate his thoughtful insight and his many contributions in the evaluation of wind loads on low buildings, particularly in the development of wind code and design standard provisions.
State-of-the-art papers on wind loads on low buildings have been written by Holmes [1], Stathopoulos [2], Krishna [3] and others. This paper will refer to the evolution of research and thinking in the formulation of wind loading provisions under the influence of Alan Davenport. Although these provisions have found their way in the North American wind standards and codes of practice, to which this paper particularly refers, they have also influenced and continue to play a significant role in the development of other national and international standards. The level of confidence in the new provisions becomes higher but the complexity of the specifications also increases. Typical key results are presented and outstanding issues requiring more research are also discussed. These include but are not limited to the effects of upstream roughness and its variation for different azimuths on the evaluation of wind loads on low buildings; the wind loads on buildings with geometries different from those examined in previous studies, particularly the evaluation of appropriate loading for the design of primary structural systems and other indirectly loaded surfaces; the total wind load acting on architectural features such as parapets and the like.
The paper will also address some of the most recent developments, in the wake of Alan Davenport's contributions. The effect of new technologies on the evaluation of wind loads on low buildings will be discussed. Particular emphasis will be placed on innovative computational techniques, means of artificial intelligence as well as numerical simulation and their current and potential influence on the generation and application of knowledge in this area.
Section snippets
Evaluation of wind pressures on low buildings
Historical reviews about the evaluation of wind loads on low buildings have been provided by Stathopoulos [4] and Surry [5]. Although wind pressures on buildings reported prior to the postulation of Jensen's “Model Law for Phenomena in Natural Wind” [46], may not be representative, some of the early ideas hold well up to date. As early as 1884, Sir Benjamin Baker, following wind load measurement experiments on boards of various sizes, stated that the mean wind pressure on a large area must be
Additional wind load considerations for low buildings
The UWO study under the direction of Alan Davenport in the 1970s has found that the effect of roof slope and building height are significant but the dependence of load coefficients on height reduces considerably by referencing them to the velocity pressure at eaves or mid-roof height; the influence of length on the wind loads is not so significant; the effect of tributary area was recognized as a key parameter in the wind load evaluation of various roof and wall components. The dynamic
Computational evaluation of wind loads
Computational Wind Engineering (CWE) deals with the application of Computational Fluid Dynamics (CFD) methodologies, typically numerical solutions of Navier–Stokes equations using appropriate turbulence models, into wind engineering problems. Methods for turbulence treatment can be classified into three groups, i.e. Reynolds-averaged Navier–Stokes equations with a turbulence model, large eddy simulation and direct numerical simulation; these methods were reviewed by Murakami [25].
At the present
Computer simulation
Wind tunnel and field experimentation is the traditional approach for the investigation of wind-induced pressure fluctuations and time histories. However, the collection of long time histories of wind and pressure data might be time consuming and laborious, considering the inherent variability in such time histories affected by building geometry, measurement location, surroundings and other factors. This, on the other hand, can be efficiently handled by computer simulation using
Summary and conclusions
The paper has reviewed the latest developments and the progress made in the evaluation of wind loads on low buildings in the wake of Alan Davenport contributions. It refers to some of the most recent studies that have led or will lead to the updating of the North American and other national wind codes and standards. Such updates relate with the re-examination of wind-induced pressures on gable-roof low buildings with intermediate roof angles (10–30°), the introduction of pressure coefficient
Acknowledgments
The author thanks heartily Alan G. Davenport for all the help, support and ongoing appreciation he has provided to his research efforts both directly and indirectly. Words are not sufficient to express this gratitude and indebtedness for all the things learned from his association with Alan. It may only be possible to try to radiate this experience and appreciation to his graduate students and co-workers. One of them, Mr. Girma T. Bitsuamlak, needs particular mentioning for the assistance he
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