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CONTENTS
Volume 1, Number 4, December 1998
 

Abstract
This paper formulates a probabilistic model which is able to represent the maximum instantaneous wind velocity. Unlike the classical methods, where the randomness is circumscribed within the mean maximum component, this model relies also on the randomness of the maximum value of the turbulent fluctuation. The application of the FOSM method furnishes the first and second statistical moments in closed form. The comparison between the results herein obtained and those supplied by classical methods points out the central role of the turbulence intensity. Its importance is exalted when extending the analysis from the wind velocity to the wind pressure.

Key Words
FOSM(First-Order Second-Moments); maximum distribution; probability theory; turbulence intensity; velocity gust factor; wind actions; wind velocity.

Address
DISEG, Department of Structural and Geotechnical Engineering, University of Genova, via Montallegro, 1, 16145 Genova, Italy

Abstract
Full-scale measurements have been made to determine the increase in wind speed over two exposed embankments, one of 23degree slope and 4.7m in height, the other of 24 degree slope and 7.3m in height. Measurements were made at heights of 5, 10 and 15m above the upper edge of each embankment and at the same heights approximately 100m upwind in the lower-level approach fetch. Despite the modest sizes of the embankments, the maximum recorded increase in mean wind speed was 28% and the minimum was 13%; these increase relate to increases in wind loads on structures erected at the top of the embankments of 64% and 28% respectively. The associated increases in gust speeds are estimated at 33% and 18%, which imply increases in gust loading of 77% and 39% respectively. These experimental results are compared with predictions obtained from a computational fluid dynamics (CFD) analysis, using three high Reynolds number eddy-viscosity models and estimates from the UK wind loading code, BS 6399: Part 2. The CFD results are generally in agreement with the experimental data, although near-ground effects on the embankment crest are poorly reproduced.

Key Words
embankment; escarpment; topography; wind speed-up factor; wind loading; computational fluid dynamics; design codes and standards.

Address
Environment Group, Silsoe Research Institute, Wrest Park, Silsoe, Bedfordshire MK45 4HS, U.K.rnFlint & Neill Partnership, 21 Dartmouth Street, London SW1H 9BP, U.K.

Abstract
In this paper the appraisal of a folding dome structure under the influence of wind loading is discussed. The foldable structure considered from an assembly of interconnected elements, together with a flexible membrane, all of which are initially store in a compact form and on deployment expand, like an umbrella, into a dome structure. Loading on the dome was obtained from a wind tunnel analysis of the pressure distribution over the roof of a 1:10 scale model of the structure. The critical loading obtained from the wind tunnel investigation was used, together with individual member and material tests, to form a series of numerical non-linear finite element models which were, in turn, used to investigate the forces within the structure. The numerical analysis was used to determine the critical wind loading that the structure can sustain, as well as providing a method by which to investigate the failure modes of the structure. In order to enhance the load carrying capacity of the dome it was found that both the strength and stiffeness of the structural nodes needed to be enhanced and in addition, changes were necessary to substantially increase the stiffeness of the individual member and caps.

Key Words
folding dome; wind loading; structural analysis; structural collapse.

Address
Department of Civil Engineering, University of Surrey, Guilfod, Surrey GU2 5XH, U.K.rnDepartment of Engineering, Sahand University of Technology, Tabriz, Iran

Abstract
A numerical and experimental study was performed for the wind flow field in one area, comprising a group of several pavilions separated by passageways, of the EXPO

Key Words
pedestrian comfort; wind around buildings; interference; numerical simulation; k-e RNG model.

Address
Mechanical Engineering Department, University of Coimbra, Polo II, 3030 Coimbra, PortugalrnMechanical Engineering Department, University of New Brunswick, P.O. Box 4400, Fredericton, NB, E3B 5A3, Canada

Abstract
In wind tunnel experiments , the blockage effect is a very important factor which affects the test results significantly. A. number of investigations into this problem, especially on the blockage correction of drag coefficient, have been carried out in the past. However, only a limited number of works have been reported on the wind tunnel blockage effect on wind-induced vibration although it is considered to be fairly important. This paper discusses the aerodynamic characteristics of the square model and square model with corner cut based on a series of the wind tunnel tests with various blockage ratios and angles of attack. From the test results, the aerodynamic behavior of square models with up to 10% blockage ratio are almost the same and square models with up to 10% blockage ratio can be tested as a group which behaves similarly.

Key Words
blockage effect; wind-induced vibration; wind tunnel experiment.

Address
Department of Civil Engineering, KAIST, Yusong, Taejon 305-701, Korea


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