Australian/NewZealandStandardTM
Structuraldesignactions
Part 2:Wind actions
AS/NZS 1170.2:2021
This Standard was published on 30 July 2021.
The following are represented on Committee BD-006:Australasian Wind Engineering Society Australian Buillding Codes BoardBureau of Steel Manufacturers of Australia Australian Steel InstituteCement Concrete & Aggregates Australia -CementConcrete Masonry Association of Australia Engineers AustrallaForest and Wood Products Australia Housing Industry AssociationInsurance Council of Australia James Cook UniversityNew Zealand Heavy Engineering Research Association Property Council of AustrallaSwinbune University of Technology Steel Reinforcement Institute of AustralliaThink Brick Australia University of MelbourneUniversity of Newcastle University of Canterbury New Zealand
This Joint Australian/New Zealand Standard# was prepared by Joint Technical CommitteeBD006 General Design Requirements and Loading on Structures. It was approved on pez man auq pue ontuoeesnyspepues o oun a jo ieStandards Approval Board on 2 June 2021.
This Standard was ssued in draft form for ment as DR AS/NZS 1170.2:2020.
Australian/NewZealandStandardTM
Structuraldesignactions
Part2:Windactions
PreviousAustralian edition AS1170.2-1989. Originated in New Zealand as part of NZS 1900:1964.Previous NewZealand edition NZS 4203:1992.AS 1170.21989andNZS 4203:1992 Secondedition 2011. jointly revised amalgamatedand redesignated in part as AS/NZS 1170.2:2002.Third edition 2021.
Preface
006 General Design Requirements and Loading on Structures to supersede AS/NZS 1170.2:2011.
The objective of this Standard is to provide wind actions for use in the design of structures subjectto wind action. It provides a detailed procedure for the determination of wind actions on structures varying from those less sensitive to wind action to those for which dynamic response are to be takeninto consideration.
The objectives of this revision are to remove ambiguities and to incorporate recent research andexperiences from recent severe wind events in Australia and New Zealand.
This Standard is Part 2 of the Structural design actions series which prises the following parts:
AS/NZS 1170.0 Structural design actions Part 0: General principles
AS/NZS 1170.1 Structural design actions Part 1: Permanent imposed and other actions
AS/NZS 1170.2 Structural design actions Part 2: Wind actions
AS/NZS 1170.3 Structural design actions Part 3: Snow and ice actions
AS 1170.4 Structural design actions Part 4: Earthquake actions in Australia
NZS 1170.5 Structural design actions Part 5: Earthquake actions - New Zealand
The wind speeds provided are based on analysis of existing data. The major changes in this editionare as follows:
(a) Definitions and notation have been moved to Clauses 14 and 15 respectively and new definitions and notation added. Appendices C to G have been re-labelled as Appendices A to E.(b) Structures covered by and excluded from this Standard have been clarified in Clause 1.1.(c) The aerodynamic shape factor is now denoted as Cshp (in previous editions it was Cig).(d) A climate change multiplier (Mc) has been included (Equation 2.2 and Clause 3.4) witha current value of 1.05 for cyclonic regions. The uncertainty factors Fc and Fo for cyclonicregions have been removed.() roof height for buildings with two or more roofs has been clarified.Windborne debris test speeds when the impacted surface is not vertical or horizontal havebeen provided (Clause 2.5.8).(g) New regional boundaries for Australia and New Zealand have been defined with new RegionsA0 B1 B2 NZ1 NZ2 NZ3 and NZ4 [Eigures 3.1(A) and 3.1(B)].(b) Interpolation between boundaries according to distance from the coastline is allowed in[Table 3.1(B)].() Wind direction multipliers (Ma) have been revised for all regions in Australia and New Zealand. The wind direction multiplier (Ma) has been set to 1.0 for circular or polygonalchimneys tanks and poles.Terrain Category 1.5 has been removed. Terrain Category 1 has been re-defined to include allover-water surfaces. The description of Terrain Category 2.5 has been revised (Clause 4.2).
(k) Terrain-height multipliers (M at) and turbulence intensities for Terrain Category 1 have been reduced toreflect observed values of gust factors and turbulence intensities forover-water winds.① Terrain-height multipliers for Region Ao have been revised to reflect measured wind gustprofiles measured in convective downdrafts.(m) The shielding multiplier (Ms) has been set to 1.0 for buildings greater than 25 m in height and for buildings on steep slopes.() The topographic multiplier (M) has been reduced in Region A0.(0) New lee effect multipliers and zones have been defined for New Zealand.(p) A new clause Clause 5.3.4) has been added for an open area/volume factor. This allows someus pue suo gea aue supq jo anssad qea sead u uonpaopening areas.(q) Values of area reduction factor (Ka) have been included for windward and leeward walls (Clause 5.4.2).The reference area a for local pressure factors has been changed for roofs of large low-risebuildings. A new local pressure case (RCz) has been introduced for the windward end of high-Further clarification of the applicability of Section 6 has been given in Clause 6.1. Highly pitched gable roofs (Clause 5.4.4).(s) dynamically wind-sensitive structures are excluded.New methods are provided for the dynamic response factor for the along-wind response ofpoles or masts with headframes and for long span horizontal structures.(u) The equations for the crosswind force spectrum coefficient (Cs) for tall buildings withrectangular cross-sections have been revised (Clause 6.3.2.3). A new more accurate method for the crosswind response of chimneys poles and masts of circular cross-section has beenintroduced (Clause 6.3.3).() A new method for the bination of along-wind and crosswind base moments has been introduced (Clause 6.4.1).(w) Some altermate values of external pressure coeffcient (Cp.e) for saw-tooth roofed buildingshave been included (Clause A.2).(x) The external pressure coefficients for curved roofs have been revised (Table A.3).() New net pressure coefcients (Gp n) have been provided for conical canopies (Clause B.3.3) and for arrays of inclined ground-mounted solar panels.(2) suosas tensuesau jo asuodsa pusassous Supseau suqurem pue sguejd jepnsnpu New Notes havebeen addedinAppendixCfordetermination of windloads onplex porous(ee) New informative Clauses have been added to AppendixE for rotational velocities (Clause E4).peak torsional accelerations (Clause E.5) and bined peak accelerations (Clause E.6).
The design wind actions prescribed in this Standard are the minimum for the general cases described.The Joint Committee has considered exhaustive research and testing information from Australian New Zealand and overseas sources in the preparation of this Standard.
The terms “normative and “informative” are used in Standards to define the application of theappendices to which they apply. A *normative” appendix is an integral part of a Standard whereas an “informative” appendix is only for information and guidance.
Notes to the text contain information and guidance and are not considered to be an integral part of the Standard.
