Advances in Wind Engineering

C. Kramer, H.J. Gerhardt

• Publisher: North Holland
• Year: 2012
• Print ISBN: 9780444871565
• eBook ISBN: 9780444599766
• Topic: Tecnologia e ingegneria
• Subtopic: Meccanica dei fluidi

Held under the auspices of the International Association for Wind Engineering, 226 delegates from twenty-three countries took part in the conference. This three volume work contains about 90 papers published in full length, together with summaries and discussions on other interesting and valuable papers presented at the conference.

Part 1

Session 1

Wind characteristics and description

INTRODUCTION TO WIND CHARACTERISTICS AND DESCRIPTION

CHAIRMAN

J. Wieringa

Koninklijk Nederlands Meteorologisch Institut

De Bilt, Netherlands

CO–CHAIRMAN

H. Ruscheweyh

Institut für Stahlbau

Aachen Technical University

Aachen, Germany

GENERAL REPORTER

A.J. Bowen

Mechanical Engineering Department

University of Canterbury

Christchurch, New Zealand

REVIEW OF PAPERS FOR SESSION 1 : WIND CHARACTERISTICS AND DESCRIPTION

A.J. BOWEN, Mechanical Engineering Department, University of Canterbury, Christchurch New Zealand

Publisher Summary

This chapter presents the results of a pilot study of wind velocity data gathered over 25 years at four stations in Southern Brazil. It discusses the development of data gathering and processing procedures to be used in the subsequent analysis of records from about 80 other stations throughout Brazil. The specific issues investigated are influence of storm type, influence of wind direction, and the feasibility of a scheme for regional predictions. Thunderstorms are identified by the short duration of the intense wind activity and from visual observations. The steady decrease in the annual maximum wind speeds measured throughout Japan at the weather stations may be attributed to the steady increase in ground roughness due to long-term building development rather than because of an overall decrease in the number of severe typhoons afflicting that country. Although the meteorological variation cannot be denied, the effect of ground roughness variation with time is of the same order of magnitude. The chapter describes the techniques for modelling the plume and measuring the temperature field.

It is my pleasure to introduce the first Conference Session on Wind Characteristics and Description and to present a brief review of seven submitted papers which are unable to be presented in full at this Conference.

While browsing over the proceedings of the previous four Conferences on Wind Engineering together with the present list of papers, it became apparent that the general goals of most engineering-related investigations into wind structure have not changed significantly over those sixteen years. However the growing demand for less conservative and therefore more economic structural designs has produced a strong need for improved accuracy in the prediction of wind loadings. There is therefore an urgent need for a significant improvement in the accuracy of the basic wind speed data and in the understanding of atmospheric turbulence which is available to the practising engineer. Progress in gathering more accurate models for the wind characteristics under any significant climatic event must keep pace with the outstanding improvements evident in our understanding of the distribution of pressure coefficients around a particular building shape and in the dynamic loading prediction techniques. The overall design is only as accurate as the accuracy of each of its parts, including the information used to define the design wind characteristics.

Developments in our understanding of wind characteristics for engineering purposes have been aptly categorised by Professor Hans Panofsky at the 1975 Wind Engineering Conference at Heathrow, London and these categories are still relevant today. The papers submitted to this Conference Session may also be grouped into the same categories for the purpose of this discussion.

LONG-PERIOD WIND STATISTICS

The formulation of more accurate methods of analysis and the accumulation of more accurate extreme wind speed statistics for the codified prediction of Basic Wind Speeds are still necessary. There is lately an increased interest in the extreme wind statistics of short term or local violent storms not normally identifiable in mean wind data. For example, in the occurrence of thunderstorms and their seasonal and directional dependence. Before processing, the wind speed data must be fully corrected for terrain and roughness effects and indeed, some of today’s papers address these aspects.

The first paper in this category by Riera and Nanni (1) reports the results of a pilot study of wind velocity data gathered over 25 years at four stations in Southern Brazil. The main objective was the development of data gathering and processing procedures to be used in the subsequent analysis of records from about 80 other stations throughout Brazil.

The specific issues investigated were;

a) influence of storm type (storms generated by mature pressure, systems as distinct from local intense thunderstorms),

b) influence of wind direction,

c) the feasibility of a scheme for regional predictions.

Thunderstorms were identified by the short duration of the intense wind activity and from visual observations. Winds over 13 knots were classified as an extreme wind event. The maximum 2-3 second average gust velocity was recorded for each event and corrected to standard site conditions.

The authors concluded that;

a) There was statistical evidence justifying the independent processing of major storm and local thunderstorm events.

b) For individual sectors of direction and storm type, the extreme type I (Gumbel) probability distribution presented the best fit.

c) For combined wind events, the data departed significantly from the type I distribution.

d) Regression techniques described in the paper appeared to adequately account for the influence of geographical location and wind orientation.

The second paper by Tamura and Suda (2) shows that the steady decrease in the ann...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• INTERNATIONAL ASSOCIATION FOR WIND ENGINEERING
• THE CONFERENCE
• PROGRAM SUMMARY
• ACKNOWLEDGMENTS
• Part 1
• Author Index Parts 1, 2 and 3