ASNZS1170.2 2002 Structural Design Actions - Wind Actions Supplement

APPENDICES

CA DEFINITIONS	41
CB NOTATION	42
CC ADDITIONAL PRESSURE COEFFICIENTS FOR ENCLOSED BUILDINGS	44
CD FREESTANDING WALLS, HOARDINGS AND CANOPIES	46
CE AERODYNAMIC SHAPE FACTORS FOR EXPOSED STRUCTURAL MEMBERS, FRAMES AND LATTICE TOWERS	49
CF FLAGS AND CIRCULAR SHAPES	53
CG ACCELERATIONS FOR WIND SENSITIVE STRUCTURES	54

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AS/NZS 1170.2 Supp 1:2002

This Joint Australian/New Zealand Standard was prepared by Joint Technical Committee BD-006, General Design Requirements and Loading on Structures. It was approved on behalf of the Council of Standards Australia on 29 March 2002 and on behalf of the Council of Standards New Zealand on 28 March 2002. It was published on 4 June 2002.

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The following are represented on Committee BD-006:

Association of Consulting Engineers Australia

Australian Building Codes Board

Australian Institute of Steel Construction

Building Research Association of New Zealand

Cement and Concrete Association of Australia

CSIRO Building, Construction and Engineering

Cyclone Testing Station—James Cook University

Electricity Supply Association of Australia

Housing Industry Association

Institution of Engineers Australia

Institution of Professional Engineers New Zealand

Master Builders Australia

New Zealand Heavy Engineering Research Association

Steel Reinforcement Institute of Australia

University of Canterbury New Zealand

University of Melbourne

University of Newcastle

Additional interests participating in the preparation of this Standard:

Bureau of Meteorology

Curtin University of Technology

Monash University

National Institute of Water and Atmospheric Research, NZ

University of Queensland

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Keeping Standards up-to-date

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Detailed information about joint Australian/New Zealand Standards can be found by visiting the Standards Australia web site at www.standards.com.au or Standards New Zealand web site at www.standards.co.nz and looking up the relevant Standard in the on-line catalogue.

Alternatively, both organizations publish an annual printed Catalogue with full details of all current Standards. For more frequent listings or notification of revisions, amendments and withdrawals, Standards Australia and Standards New Zealand offer a number of update options. For information about these services, users should contact their respective national Standards organization.

We also welcome suggestions for improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Please address your comments to the Chief Executive of either Standards Australia International or Standards New Zealand at the address shown on the back cover.

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AS/NZS 1170.2 Supplement 1:2002

Structural design actions—Wind actions—Commentary (Supplement to AS/NZS 1170.2:2002)

Originated in Australia as part of AS 1170.2—1989.
Originated in New Zealand as part of NZS 4203:1976.
Previous New Zealand edition NZS 4203:1992.
AS 1170.2—1989 and NZS 4203:1992 jointly revised, amalgamated and redesignated in part as AS/NZS 1170.2 Supplement 1:2002.

COPYRIGHT

© Standards Australia/Standards New Zealand

All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher.

Jointly published by Standards Australia International Ltd, GPO Box 5420, Sydney, NSW 2001 and Standards New Zealand, Private Bag 2439, Wellington 6020

ISBN 0 7337 4474 5

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PREFACE

This Commentary was prepared by the Joint Standards Australia/Standards New Zealand Committee BD-006, General Design Requirements and Loading on Structures, as a Supplement to AS/NZS 1170.2, Structural design actions, Part 2: Wind actions. This Commentary supersedes, in part, AS 1170.2—1989, Minimum design loads on structures, Part 2: Wind loads and, in part, NZS 4203:1992, Code of practice for general structural design and design loadings for buildings (Vol. 2).

The Commentary provides background material and guidance to the requirements of the Standard.

The clause numbers of this Commentary are prefixed by the letter ‘C’ to distinguish them from references to the Standard clauses to which they directly relate. Where a Commentary to a certain Clause is non-existent, it is because no explanation of the Clause is necessary.

Appendix CA includes a list of additional definitions used in this Commentary, and Appendix CB includes a list of additional symbols used in this Commentary.

Notwithstanding the general copyright provisions applicable to all Australian Standards as detailed in the Standard, the Standard contains intellectual material provided by other parties and permission to reproduce that material may be conditional on an appropriate royalty payment to Standards Australia, or the other party, or both.

ACKNOWLEDGEMENT

Standards Australia wishes to acknowledge and thank the following members who have contributed significantly to this Commentary:

• John Holmes
• Bill Melbourne
• Chris Letchford
• Andrew King
• Steve Reid

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CONTENTS

	Page
SECTION C1 SCOPE AND APPLICATION
C1.1 SCOPE	5
C1.2 APPLICATION	5
C1.3 REFERENCED DOCUMENTS	5
C1.4 DETERMINATION OF WIND ACTIONS	5
C1.5 UNITS	7
C1.6 DEFINITIONS	7
C1.7 NOTATION	7
SECTION C2 CALCULATION OF WIND ACTIONS
C2.1 GENERAL	8
C2.2 SITE WIND SPEED	8
C2.3 DESIGN WIND SPEED	8
C2.4 DESIGN WIND PRESSURE AND DISTRIBUTED FORCES	11
C2.5 WIND ACTIONS	12
SECTION C3 REGIONAL WIND SPEEDS
C3.1 GENERAL	14
C3.2 REGIONAL WIND SPEEDS (VR)	14
C3.3 WIND DIRECTION MULTIPLIER (Md)	14
C3.4 FACTORS FOR REGIONS C AND D (FC, FD)	15
SECTION C4 SITE EXPOSURE MULTIPLIERS
C4.1 GENERAL	16
C4.2 TERRAIN/HEIGHT MULTIPLIER (Mz,cat)	16
C4.3 SHIELDING MULTIPLIER (Ms)	24
C4.4 TOPOGRAPHIC MULTIPLIER (Mt)	25
SECTION C5 AERODYNAMIC SHAPE FACTOR
C5.1 GENERAL	28
C5.2 EVALUATION OF AERODYNAMIC SHAPE FACTOR	28
C5.3 INTERNAL PRESSURE FOR ENCLOSED RECTANGULAR BUILDINGS	28
C5.4 EXTERNAL PRESSURES FOR ENCLOSED RECTANGULAR BUILDINGS	29
C5.5 FRICTIONAL DRAG FORCES FOR ENCLOSED BUILDINGS	30
SECTION C6 DYNAMIC RESPONSE FACTOR
C6.1 EVALUATION OF DYNAMIC RESPONSE FACTOR	32
C6.2 ALONG-WIND RESPONSE FOR TALL BUILDINGS AND TOWERS	34
C6.3 CROSSWIND RESPONSE	35
C6.4 COMBINATION OF ALONG-WIND AND CROSSWIND RESPONSE	38

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APPENDICES

CA DEFINITIONS	41
CB NOTATION	42
CC ADDITIONAL PRESSURE COEFFICIENTS FOR ENCLOSED BUILDINGS	44
CD FREESTANDING WALLS, HOARDINGS AND CANOPIES	46
CE AERODYNAMIC SHAPE FACTORS FOR EXPOSED STRUCTURAL MEMBERS, FRAMES AND LATTICE TOWERS	49
CF FLAGS AND CIRCULAR SHAPES	53
CG ACCELERATIONS FOR WIND SENSITIVE STRUCTURES	54

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