#SAIGLOBAL LICENCE for ASINZS 1170.2 - Structural design actions Licensee: Or Manh Tran Date: 2022-11-14 03:32:13 This matorial is electronically reproduced by SAl Global under license from Standards Ausiralla who retain fall copyright in the document No part of the printed publication, nor any part of this electronic flo, may be reproduced or transmitted in any form, including transmittal by e-mail by File Transfer Protocol (FTP), or by being made part ofa network-accessibie system, without the prior ‘written permission ofthe Publisner of SAV Global. 'SAI Global makes no guarantees of warranties as to the correctness of the document or as tothe results arising from the purchase and use of the document and is not responsible for problems in the delivery of the document. Any dificuties or ‘Queries should be addressed to SAI Global below. In USA and Canada Contact ‘SAI GLOBAL, 20 Carlson Court, Etobicoke, ON MSW 7K6, Canada +1 416 401 8730. 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Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material ASINZS 1170.2:2021 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 19 July 2021 and by the New Zealand ‘Standards Approval Board on 2 June 2021. This Standard was published on 30 July 2024. ‘The following are represented on Committee BD-006: Australasian Wind Engineering Society Australian Building Codes Board ‘Australian Steel Institute Bureau of Steel Manufacturers of Australia Cement Concrete & Aggregates Australia — Cement Concrete Masonry Association of Australia Engineers Australia Forest and Wood Products Australia Housing Industry Association Insurance Council of Australia James Cook University New Zealand Heavy Engineering Research Association Property Council of Australia Steel Reinforcement Institute of Australia ‘Swinburne University of Technology University of Melbourne Think Brick Australia University of Canterbury New Zealand University of Newcastle ‘This Standard was issued in draft form for comment as DR AS/NZS 1170,2:2020, Keeping Standards up-to-date Ensure you have the latest versions of our publications and keep up-to-date about Amendments, Rulings, Withdrawals, and new projects by visiting: www.standards.ora.au ISBN 978 1 76113 448 7ribution, storage or use on a network is prohibited, 14-14 n, >wed by: [manh.tran@jacobs.com] @ 202 p (Australia) Pty Ltd.Further reproduc Printed / icensed to SAI Global"Jacobs Grou AS/NZS 1170.2:2021 Australian/New Zealand Standard™ Structural design actions Part 2: Wind actions Originated in New Zealand as part of NZS 1900:1964. Previous Australian edition AS 1170,2—1989, Previous New Zealand edition NZS 4203:1992.AS 1170.2—1989 and NZS 4203:1992 jointly revised, amalgamatedand redesignated in part as AS/NZS 1170.2:2002, ‘Second edition 2011 ‘Third edition 202, © Standards Australia Limited/the Crown in right of New Zealand, administered by the New Zealand Standards Executive 2021, All ights 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 ofthe publisher, unless otherwise permitted under the Copyright Act 1968 (Cth) or the Copyright Met 1994 (New Zealand).|, storage or use on a network is prohibited, 1-11-14 p (Australia) Pty Ltd. Further reproduction, distribution, iewed by: [manh.tran@jacobs.com] @ 202 Printed / vi icensed to SAI GlobalJacobs Grou AS/NZS 1170.2:2021 it Preface This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee, BD- 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 subject to 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 taken into consideration, The objectives of this revision are to remove ambiguities, and to incorporate recent research and experiences from recent severe wind events in Australia and New Zealand. This Standard is Part 2 of the Structural design actions series, which comprises 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 edition are as follows: @ Definitions and notation have been moved to Clauses 1.4 and 1.5 respectively and new definitions and notation added. Appendices C to G have been re-labelled as Appendices A to E. Standard have been clarified in Clause 1. (6) Structures covered by and excluded from tl © ‘The aerodynamic shape factor is now denoted as Csnp (In previous editions it was Cig) (@ A climate change multiplier (M.) has been included (Equation 2.2 and Clause 34), with a current value of 1.05 for cyclonic regions. The uncertainty factors Fc and Fp for cyclonic regions have been removed. © ‘The ground level datum for buildings on sloping or excavated sites has been clarified. Average roof height for buildings with two or more roofs has been clarified. (9) Windborne debris test speeds when the impacted surface is not vertical or horizontal have been provided (Clause 2.5.8). (8) ___ New regional boundaries for Australia and New Zealand have been defined with new Regions AO, B1, B2, NZ1, NZ2, NZ3, and NZ4 [Figures 3.1(A) and 3.1(B)]. (h) Interpolation between boundaries, according to distance from the coastline, is allowed in Regions C and D [able 3.1(A)]. Regional wind speeds for New Zealand have been revised 0 Wind direction multipliers (Ma) have been revised for all regions in Australia and New Zealand. The wind direction multiplier (Mg) has been set to 1.0 for circular or polygonal chimneys, tanks and poles. @ ‘Terrain Category 1.5 has been removed. Terrain Category 1 has been re-defined to include all over-water surfaces. The description of Terrain Category 2.5 has been revised (Clause 4.2). (© Standards Australia Limited/Standards New Zealand 2021Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 8 & 2 5 z 2 s 5 g 8 ® 3 & s Ss = 2 so § 3 8 S & 5 s 5 g 3 g. £ 3g < s. 8 oO 3 8 s 3 g 2 oO z 6 2 2 3 Copyrighted material 3) QO (m) @ © ® @ © ) 0 w@ a) (w) @ o) @ faa) m7 AS/NZS 1170.2:2021 ‘Terrain-height multipliers (M,.ca)), and turbulence intensities, for Terrain Category 1 have been reduced to reflect observed values of gust factors and turbulence intensities for over-water winds. Terrain-height multipliers for Region AO have been revised to reflect measured wind gust profiles measured in convective downdrafts. ‘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 (Mj has been reduced in Region AO. New lee effect multipliers and zones have been defined for New Zealand. Anew clause (Clause 5.3.4) has been added for an open area/volume factor. This allows some reduction in peak internal pressure for buildings with large internal volumes, and small ‘opening areas. 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-rise buildings. A new local pressure case (RC2) has been introduced for the windward end of high- pitched gable roofs (Clause 5.4.4). Further clarification of the applicability of Section 6 has been given in Clause 6.1. Highly dynamically wind-sensitive structures are excluded. New methods are provided for the dynamic response factor for the along-wind response of poles or masts with headframes, and for long span horizontal structures. ‘The equations for the crosswind force spectrum coefficient (Cis) for tall buildings with rectangular 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 been introduced (Clause 6.3.3). A new method for the combination of along-wind and crosswind base moments has been introduced (Clause 6.4.1). Some alternate values of external pressure coefficient (Cp,¢) for saw-tooth roofed buildings have been included (Clause A.2). The external pressure coefficients for curved roofs have been revised (Table.A.3). New net pressure coefficients (Cp.x) have been provided for conical canopies (Clause B.3,3), and for arrays of inclined ground-mounted solar panels. New Notes have been added in Appendix C for determination of wind loads on complex, porous industrial plants, and warnings regarding crosswind response of rectangular sections. New informative Clauses have been added to Appendix for rotational velocities (Clause E.4), peak torsional accelerations (Clause E.5) and combined 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 the appendices 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. © Standards Australia Limited/Standards New Zealand 2021Pty Ltd.Further reproduction, distribution, storage or use on a network is prohibited. Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global"Jacobs Group (Austr AS/NZS 1170.2:2021 iv Contents Preface. Section 1 Ld 12 13 14 15 16 Section 4 4d 42 43 44 Section 5 51 52 53 54 Scope and general. Scope... Application... - Normative references Seen oo Terms and definitions ..ceonenmm oo oon Notation ~ Determination of wind actions inn... cn Units. inet Calculation of wind actions... seme en a - vn Site wind speed... Design wind speed... Design wind pressure and distributed fOrC€8.— nomen 241 Design wind pressures... onsen 24.2 Design frictional drag force per u Wind actions... oon a co 25.2 Directions... en oe 25.3 Forces on surfaces or structural elements 2mm 2.5.4 Forces and moments on complete structures... ~ 2.5.5 Number of stress exceedances produced by wind loading... 2.5.6 Performance of cladding elements sensitive to low-cycle fatigue. 2.5.7 _Deflections of dynamically wind-sensitive structures. _ 2.5.8 Impact loading from windborne debPS vernon Regional wind speeds. -ennn-wnnnennnennennenni ee nnn Regional wind speeds (Vi) wocwenrnern — Wind direction multiplier (Ma) oo Climate change multiplier (Me). Site exposure multipliers ..---vo0-ronwinnnnnnnennnn General nen ne - a Terrain/height multiplier (Mzcat). conn 4.2.1 Terrain category definitions. eccrine 42.2 Determination of terrain /height multiplier (Mzaq) 4.2.3 Averaging of terrain categories and terrain-height multipliers. Shielding multiplier (M,).. a 43.1 General. a 43.2 Buildings providing shielding... 4.3.3 Shielding parameter (s) ‘Topographic multiplier (Mi) -1on--mmnnnnnnnnnnnennnnsnnne 44.1 General estnnsnnninnn 442 Hill-shape multiplier (My). ssn 44.3. Lee multiplier (Mjee) mnwnsner-wnnennnennnnnnnnnnnnnn Aerodynamic shape f8CtOr -.-cew-nonnennnnnnsnntninnenn ae enn Evaluation of aerodynamic shape factor... . Internal pressure for enclosed rectangular buildings. nono 5.3.1 Internal pressure ceennnnnnn con 5.3.2 Openings. _ oon 5.3.3 Internal walls and ceilings... — 5.34 Open area/volume faCtOt, Kyoonc em External pressures for enclosed rectangular buildings.......Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAl Global'Jacobs Group (Australia) Pty Ltd.Further reproduction, distribution, storage or use on a network is prohibited. vy AS/NZS 1170.2:2021 External pressure coefficients (Cp_) mean - Area reduction factor (Ka) for roofs and walls... : Action combination factor (Kg).-onr-n1nonn Local pressure factor (Ky) for cladding... a "4.5 Permeable cladding reduction factor (Kp) for roofs and side walls... 56 5.5 Frictional drag forces for enclosed buildings... os conn 56 Section 6 Dynamic response factor. cone cosnntncnnnennnininnnneinin SB 641 Introduction em ~ - 58 6.2 Structures for Which Cyn = 1.0 --onnommnnennnn ~ cone 5B 6.3. Other structures... onan — conn 5B 64 Along-wind response. enn 59 6.4.1 Dynamic response factor (Caya) for tall buildings and free-standing towers ~...59 642 Dynamic response factor for towers, poles and masts with head frames (Coy) mn eoemr none onc 7 61 64.3 Dynamic response factor for horizontal slender structures (Cayq) vn-wrnona-62 65 Crosswind response. : nena vn 62 a — monestnmincnnnincrnmnnnns 2 655.2 Crosswind response of tall enclosed buildings and towers of rectangular {CFOSS-S€CLIOM ee nonnnenne ~ 63 6.5.3 Crosswind response of cantilevered chimneys, masts and poles of circular cross-section. nnn 6.6 Combination of along-wind and crosswind response on... - 6.6.1 Combination of base MOMENtS .:mninienseennnnnnnnnnnevenenne 6.6.2 Combination of load effects... Appendix A (normative) Additional pressure coefficients for enclosed buildings. 70 Appendix B (normative) Freestanding walls, hoardings, canopies and solar panels,-...-.0e-0=.77 Appendix C (normative) Aerodynamic shape factors for exposed structural members, frames and lattice towers ..-.-.onv-s0nn-nnonenn on pence Appendix D (normative) Flags and circular shapes ..-.-.-----ewwnnn ns (1) Appendix E (informative) Acceterations and rotational velocities for wind-sensitive SUEUCEUFES onan nnnnnnnnninninnnnininnsinninnnnnnnnrnnnnenees 108 Bibliography... 112NOTES PL-LL-120z © [woo'sqooe{uesy yuu] :kq pmo / peu “Peutaiyoid s} omMou e Uo esn 40 aBev0Is ‘uoANgUIsip ‘Uolonpasdey JeYyUN.F PY] Ald (elfensMy) dnois sqoseryeqo|O IWS 0} PosuEd! feUOTEUI payyBUkdoPrinted / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 x 2 2 g 5 2 3 2 © 5 5 g 5 ° 2 g 5 § 3 & 3 3 8 5 £ 2 5 a zg sg = 3 = $. 2 6 a 3 8 8 3 g 3 o a 6 2 2 8 1 AS/NZS 11702:2021 Australian/New Zealand Standard Structural design actions Part 2: Wind actions Section 1 Scope and general 1.1. Scope This Standard sets out procedures for determining wind speeds and resulting wind actions to be used. in the structural design of structures subjected to wind actions other than those caused by tornadoes. The Standard covers structures within the following criteria: @ Buildings and towers less than or equal to 200 m (b) Structures with unsupported roof spans of less than 100 m. © Offshore structures within 30 km from the nearest coastline. (@ _—_ Other structures apart from: offshore structures more than 30 km from the nearest coastline, bridges, windfarm structures and power transmission and distribution structures, including supporting towers and poles. NOTE 1 This Standard is a stand-alone document for structures within the above criteria, It may be used, in general, for all structures but other information may be necessary. NOTE 2 If a tall building has a natural frequency less than 1 Hz, Section 6 requires dynamic analysis to be carried out, For other structures, such as lighting poles, dynamic analysis may be required even ifthe first-mode Frequency exceeds 1 Hz (see limits in Clause 6.1). NOTE 3. For structures excluded by (a) and (b), specialist techniques, including wind-tunnel testing, are required. Further advice, which may include wind-tunnel testing, also should be sought for roofs with unusual geometries or support systems, or the roofs of podiums at the base of tall buildings. NOTE4 Forstructures excluded by (d), wind loads are specified by other Australian or New Zealand Standards (bridges and power transmission and distribution structures), or by international standards (structures more than 30 km offshore, and windfarm structures). These may draw on this Standard for some aspects of wind load determination. NOTES Structures on any island territory of Australia and New Zealand, and offshore structures within 30 km ofthe shoreline of any of those territories, are covered by this Standard, NOTE6 Inthisdocument, the words this Standard” indicates AS/NZS 1170.2, whichis Part2 ofthe AS/NZS 1170 series (see Preface). 1.2 Application This Standard shall be read in conjunction with AS/NZS 1170.0. This Standard may be used as a means for demonstrating conformance with the requirements of Part B1 of the National Construction Code (Australia). NOTE Use of methods or information not given in this Standard should be justified by a special study (refer to AS/NZS 1170.0, Appendix A} © Standards Australia Limited Standards New Zealand 2021, Storage or use on a network is prohibited, ) Pty Ltd. Further reproduction, distribution, Copyrighted material licensed to SAI Global"Jacobs Group (Australia| Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 AS/NZS 1170.2:2021 2 1.3 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this Standard. NOTE Documents referenced for informative purposes are listed in the Bibliography. AS 4040.3, Methods of testing sheet roof and wall cladding, Method 3: Resistance to wind pressures for cyclone regions AS/NZS 1170.0, Structural design actions, Part 0: General principles Australian Building Codes Board, National Construction Code (NCC) 1.4 Terms and definitions For the purposes of this document, the following terms and definitions apply. 144 aerodynamic shape factor factor to account for the effects of the geometry of the structure on surface pressure due to wind 1.4.2 aspect ratio ratio of the average roof height of a building to the smallest horizontal dimension, or the ratio of the largest dimension of a structural member to its crosswind breadth 14.3 average recurrence interval average interval (R) between exceedances of a given wind speed, usually measured in years Note 1 to entry: For values of R greater than 5 years, this is equal to the reciprocal of the annual probability. of exceedance 144 awning roof-like structure, usually of limited extent, projecting from a wall ofa building 14.5 canopy roof adjacent to or attached toa building, generally not enclosed by walls 14.6 cladding material that forms the external surface over the framing of a building or structure 147 design wind speed wind speed for use in design, adjusted for average recurrence interval, wind direction, geographic position, surrounding environment and height 148 discharge coefficient for a ventilator, a non-dimensional quantity relating the rate of airflow through the ventilator to the pressure drop across it Note 1 to entry: Values for particular ventilators can be obtained from tests carried out by manufacturers or suppliers. (© Standards Australia Limited/Standards New Zealand 2021Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 2 8 5 2 6 5 5 S ® 2 8 s 3 3 3 5 3 8 a 2 2 = 5 a zg > a s. = 3 s 2 s 2 6 a 8 8 3 8 3 o =z 6 2 3 AS/NZS 1170.2:2021 149 downdraft vertical air motion originating in a thunderstorm, resulting in severe horizontal winds at ground level Note 1 to entry: Strong winds of this type are the dominant extreme wind event in inland Australia (Region AO) and may also occur in some coastal regions. 1.4.10 drag force acting in the direction of the wind stream. Note 1 to entry: See also lift (4.4.31), 1441 dynamic response factor factor to account for the effects of fluctuating forces and resonant response on wind-sensitive structures 1.4.12 eccentricity distance from the centroid of a surface, to the point of application of the resultant force derived from the net wind pressure 1.4.13 effective surface wall, roof or internal surface of a building that contributes significantly to load effects on major structural elements 14.14 elevated building building with a clear, unwalled space underneath the first floor, level with a height from ground to underside of the first floor of one-third or more of the total height of the building 14.15 enclosed building building that has a roof and full perimeter walls (nominally sealed) from floor to roof level 1.4.16 escarpment two-dimensional, steeply sloping face between nominally level lower and upper plains, where the plains have average slopes of not greater than 5% 1.4.17 first mode shape deflected shape of a structure at its maximum amplitude under first mode natural vibration 1.4.18 first mode natural frequency frequency of free oscillation corresponding to the lowest harmonic of vibration of a structure 1.419 force coefficient coefficient that, when multiplied by the incident wind pressure and a reference area, gives the force in a specific direction 1.4.20 free roof roof (of any type) with no enclosing walls underneath Note 1 to entry: For example, a freestanding carport. © Standards Australia Limited /Standards New Zealand 2021in, storage or use on a.network is prohibited. ip (Australia) Pty Ltd.Further reproduction, dist ited / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAl Global’Jacobs Grou AS/NZS 1170.2:2021 4 14.21 freestanding walls walls that are exposed to the wind on both sides, with no roof attached Note 1 to entry: Includes fences. 1.4.22 frictional drag wind force per unit area acting in a direction parallel to the surface in question 1.4.23 gable roof Tidged roof with two sloping surfaces and vertical triangular end walls 1.4.24 hill isolated three-dimensional topographic feature standing above the surrounding plains having slopes <5 % hip roof roof with four sloping (pitched) surfaces, pyramidal in shape, and with level eaves all round Note 1 to entry: A hip roof on a rectangular plan has two triangular sloping roofs atthe short sides (hip ends) and two trapezoidal sloping roofs at the long sides. 1.4.26 hoardings freestanding (rectangular) signboards, and the like, supported clear ofthe ground 1.4.27 immediate supports supporting members to which cladding is directly fixed Note 1 to entry: Examples include battens, purlins, girts and studs. 1.4.28 lag distance horizontal distance downwind, required for the effects of a change in terrain roughness on wind speed to reach the height being investigated 1.4.29 large opening opening greater than 0.5 % of the area in the external surface of an enclosed building, which directly influences the average internal pressure 1.4.30 lattice towers three-dimensional frameworks comprising three or more linear boundary members interconnected by linear bracing members joined at common points (nodes), enclosing an open area through which the wind may pass 1.4.31 lift force acting at 90° to the wind stream Note 1 to entry: See also drag (1.4.10). © Standards Australia Limited/Standards New Zealand 2021,n, distribution, storage or use on a network is prohibited. Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 nsed to SAI Global‘Jacobs Group (Australia) Pty Ltd.Further reproduc Copyrighted material 5 AS/NZS 1170.2:2021 1.4.32 mansard roof roof with two slopes on all four sides, the lower slope steeper than the upper slope Note 1 to entry: A mansard roof with the upper slopes less than 10° may be assumed to be flat topped. 1.4.33 monoslope roof planar roof with a constant slope and without a ridge Note 1 to entry: See also skillion roof (1.4.86). 1.4.34 obstructions natural or man-made objects that generate turbulent wind flow, ranging from single trees to forests and from isolated small structures to closely spaced multi-storey buildings 1.4.35 offshore structures fixed or floating platforms, jetties, towers or poles Note 1 to entry: This Standard only applies to offshore structures within 30 km from the nearest coastline of Australian or New Zealand territory. 1.4.36 permeable surface with an aggregation of small openings, cracks, and the like, which allows air to pass through under the action of a pressure differential 1.4.37 pitched roof bi-fold, bi-planar roof (two sloping surfaces) meeting at a ridge 1.4.38 pressure air pressure referenced to ambient air pressure Note 1 to entry: In this Standard, negative values are less than ambient (suction), positive values exceed ambient. Net pressures act normal to a surface in the direction specified. 14.39 pressure coefficient ratio of the pressure acting at the point on a surface, to the free-stream dynamic pressure of the incident wind 1.4.40 rectangular building building generally made up of rectangular shapes in plan Note 1 to entry: See Section 5 for calculation of the aerodynamic shape factor for rectangular buildings. 1441 Reynolds number Re ratio of the inertial forces to the viscous forces in the airflow 1.4.42 ridge (topographic feature) two-dimensional crest or chain of hills with sloping faces on either side of the crest (© Standards Australia Limited /Standards New Zealand 2021, storage or use on a network is prohibited. production, distribution, p (Australia) Pty Ltd.Further rey Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global"Jacobs Grou AS/NZS 1170.2:2021 6 1.4.43 roughness length theoretical quantification of the turbulence-inducing nature of a particular type of terrain on airflow (wind) 1.4.44 Scruton number Se mass-damping parameter 1.4.45 shelter room space designated to provide shelter to one or more persons 14.46 skillion roof roof on a building with a single roof slope that has a high edge at one side of the building and a low edge at the opposite side Note 1 to entry: See also monoslope roof (1.4.23). 1.4.47 solidity (of cladding) ratio of the solid area to the total area of the surface 1.4.48 structural elements, major structural elements with tributary areas that are greater than 10 m2 1.449 structural elements, minor structural elements with tributary areas that are less than or equal to 10 m2 1.4.50 terrain surface roughness condition when considering the size and arrangement of obstructions to the wind 14.51 topography major land surface features, comprising hills, valleys and plains, that strongly influence wind flow patterns 14.52 tornado violently rotating column of air, that is suspended, observable as a funnel cloud attached to the cloud base of a convective cloud 1.4.53 tributary area area of building surface contributing to the force being considered 14.54 tropical cyclone non-frontal warm-cored low-pressure weather system of synoptic scale that develops over warm waters and has deep organised convection and gale force mean winds or greater extending more than half-way around near the centre and persisting for at least 6 hours (SOURCE: Reproduced by permission of Bureau of Meteorology, © 2021 Commonwealth of Australia] Note 1 to entry: Wind, rain, wave and storm surge impacts can extend hundreds of kilometres from the centre depending on the storm intensity and scale © Standards Australia Limited Standards New Zealand 2021:) Pty Ltd. Further reproduction, distribution, storage or use on a network is prohibited, Printed / viewed by: [manh.tran@jacobs.comn] @ 2021-11-14 Copyrighted material licensed to SAI Global" Jacobs Group (Austral 7 AS/NZS 1170.2:2021 Note 2 to entry: Refer to the Commonwealth of Australia Bureau of Meteorology for further information. Note 3 to entry: Winds circulate in a clockwise direction in the southern hemisphere 14.55 troughed roof bi-fold, bi-planar roof with a valley at its lowest point 14.56 turbulence intensity ratio of the standard deviation of the fluctuating component of wind speed to the mean (time averaged) wind speed 1.5 Notation Unless stated otherwise, the notation used in this Standard has the following meaning with respect to the structure, member or condition to which the Clause applies. NOTE See Clause 1,7 for units. 4 surface area ofthe element or the tributary area that transmits wind forces to the element, being— area upon which the pressure acts, which may not always be normal to the wind stream when used in conjunction with the pressure coefficient (C,); = projected area normal to the wind stream when used in conjunction with a drag force coefficient (Ca); or = areas as defined in applicable clauses (see Appendix C) when used in conjunction with a force coefficient (Cz) or (Cry) A = reference area ofancillaries on a tower a = constant for determination of the response to vortex shedding of structures circular cross section (Clause 6.3.3) Aref = reference area of flag Ans = total projected area of the tower section at height z Ae = reference area, at height (2), upon which the pressure (p,) at that height acts a = dimension used in defining the extent of application of local pressure factors = exponential decay factor B = background factor for horizontal slender structures Bs = background factor, which isa measure ofthe slowly varying background component of the fluctuating response, caused by low-frequency wind speed variations b = breadth ofa structure or element, usually normal to the wind stream; or = average diameter ofa circular section bo = diagonal breadth of UHF antennas bert = effective breadth ofa headframe © Standards Australia Limited/Standards New Zealand 20213B & as/nzs.1170.2:2021 2 $ a Sb = z 2 by = « = bon = Bo bs = 5 bsp = & 2b = S ob = bjw = Can = Cae = Cayo = Cex = (Australia) Pty Ltd.Further reproduction, distribution, p . Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 cue = Copyrighted material licensed to SAl Global’Jacobs Grou average diameter or breadth of a section of a tower member normal breadth of UHE antennas average breadth of the structure between heights 0 and h average breadth of shielding buildings, normal to the wind stream average breadth of the structure between heights s and h average breadth of the top third of the structure average breadth of the structure at the section at height (2) ratio of the average diameter of an ancillary to the average width of a structure aerodynamic excitation parameter (Clause 6.3.3.1) drag force coefficient fora structure or member in the direction ofthe wind stream value of drag force coefficient (Ca) on an isolated ancillary ona tower effective drag force coefficient for a tower section with ancillaries dynamic response factor force coefficient for a structure or member, in the direction of the x-axis force coefficient for a structure or member, in the direction of the y-axis frictional drag force coefficient crosswind force spectrum coefficient generalized for a linear mode shape external pressure coefficient for sides of bins, silos and tanks external pressure coefficient internal pressure coefficient net pressure coefficient for the leeward half of a free roof net pressure coefficient acting normal to the surface for canopies, freestanding roofs, walls and the like net pressure coefficient for the windward half of a free roof, external pressure coefficient on walls of bins, silos or tanks of unit aspect ratio (c/b= asa function of aerodynamic shape factor aerodynamic shape factor for the first frame in the upwind direction exponential decay parameter (Clause C.4.2.3) net height of a hoarding, flag, bin, silo or tank (not including roof or lid height); or height between the highest and lowest points on a hyperbolic paraboloid roof parameters for crosswind response calculation (Clause 6.3.3.1) (© Standards Australia Limited /Standards New Zealand 2021n, distribution, storage or use on a network is prohibited. wed by: [manh.tran@jacobs,com] @ 2021-11-14 Printed / 5 3 8 & 8 2 5. e 3 x = 2 = 3g < 8 8 oO 2 g 8 os g 2 oO z 3 2 3 5 dy ds Fe hott 9 AS/NZS 1170.2:2021. downwind roof slope depth or distance parallel to the wind stream to which the plan or cross-section ofa structure or shape extends (e.g, the outside diameter); or length of span of curved roof along-wind depth ofa porous wall or roof surface length of span of the first pitched roof in a multi-span building site elevation above mean sea level spectrum of turbulence in the approaching wind stream. the base of Napierian logarithms (approximately 2.71828) horizontal eccentricity of net pressure (Clause B.2.1) force on a building element, in newtons resonant component of the along-wind force (Appendix E) frictional force per unit area parallel to a surface, in newtons per square metre the design frictional-distributed force parallel to the surface, calculated in Clause 2.4.2 at heightz, in newtons per square metre peak factor for resonant response (10 min period) peak factor cross-wind response of chimneys, masts and poles peak factor for upwind velocity fluctuations height of the hill, ridge or escarpment height factor for the resonant response average roof height of structure above ground component heights of a conical canopy height from ground to the attached canopy, freestanding roof, wall or the like effective height ofa headframe height of parapet above average roof level average height of surface roughness average roof height of shielding buildings turbulence intensity, obtained from Table 6.1 by setting z equal to h turbulence intensity at height z given for various terrain categories in Table 6.1 factor for maximum tip deflection factor (Clause 5.4.2); or aerodynamic damping parameter (Clause 6. area redui 2) © Standards Australia Limited/Standards New Zealand 2021AS/NZS 1170.2:2021 Kar = n, storage or use on a network is prohibited. B K = PRT RR “8 “oon ww p (Australia) Pty Ltd.Further reproduction, distrib ited / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 = & . Me . Copyrighted material licensed to SAI Global’Jacobs Grou 10 aspect ratio correction factor for individual member forces factor for breadth/span of curved roofs (Clause A,3) combination factor combination factor for external pressures combination factor for internal pressures factor to account for the angle of inclination of the axis of members to the wind direction correction factor for interference local pressure factor mode shape correction factor for crosswind acceleration net porosity factor, used for free walls; or porous cladding reductive factor, used for cladding on buildings parapet reduction factor shielding factor for shielded frames in multiple open-framed structures open area and volume factor for internal pressures mode shape power exponent factor fora circular bin measure of integral turbulence length scale at height h horizontal distance upwind from the crest of the hill, ridge or escarpment toa level half the height below the crest length scale, in metres, to determine the vertical variation of Mp, to be taken as the greater of 0.36 Ly or 0.4 H length scale, in metres, to determine the horizontal variation of My, to be taken as 41, upwind for all types, and downwind for hills and ridges, or 10 Ly downwind for escarpments leeward wall; or life of structure length of member flag length average spacing of shielding buildings upwind segment of the roofs of circular, bins, silos and tanks climate change multiplier (see Clause 3.4}; or crosswind base overturning moment © Standards Australia Limited/Standards New Zealand 2021ited, , storage or use on a network is prohil ribution, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 ;nsed to SAI Global’Jacobs Group (Australia) Pty Ltd.Further reproduction, Copyrighted material m = na = Ne = Ts = ng = a AS/NZS 1170.2:2021 wind direction multiplier (see Clause 3.3) hill shape multiplier lee (effect) multiplier (takenas 1.0, except in New Zealand lee zones, see Clause 4.4.3) resonant component of the along-wind base moment (Appendix E) shielding multiplier topographic multiplier terrain/height multiplier average mass per unit height mass per unit area of flag average mass per unit height over the top third of the structure mass per unit height as a function of height z reduced frequency (non-dimensional) number of stress exceedances number of spans of a multi-span roof first mode natural frequency of vibration of a structure, in hertz first mode natural frequency of vibration of structure in the along-wind direction, in hertz first mode natural frequency of vibration of a structure in the crosswind direction, inhertz, number of upwind shielding buildings within a 45° sector of radius 20h and with hszh natural frequency of twisting (torsional) mode of a tall building (Appendix E) design wind pressure acting normal toa surface, in pascals Pe, Pi or pn where the sign is given by the Cp values used to evaluate Csnp NOTE: Pressures are taken as positive, indicating pressures above ambient and negative, indicating pressures below ambient. external wind pressure internal wind pressure net wind pressure design wind pressure, in pascals (normal to the surface), at height z, calculated in Clause 2.41, NOTE: The sign convention for pressures leads to forces towards the surface for positive pressures and forces away from the surface for negative pressures. average recurrence interval of the wind speed in years (Clause 3.2); or (© Standards Australia Limited/Standards New Zealand 2021AS/NZS 1170.2:2021 Re = , storage or use on a network is prohibited. z ee ernas "nwo 5 s 2 3 & S 8 z 8 5 £ z 5 = z = = & Ss. £ g < 2 ea = faes 8 = Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11 Vaese@Q = Ya = VR = Copyrighted material licensed to SAI Global"Jacobs Grou 2 furthest point from the centre of rigidity (Appendix E) crosswind roof slope distance from the initiating crestto the leeward edge ofthe shadow zone (Clause 44,3) Reynolds number rise of a curved roof; corner radius ofa structural shape; or aspect ratio of a building (Clause 5.4.4) radius ofa conical canopy size reduction factor for tall buildings and free-standing towers effective size reduction factor for towers, poles and masts with headframes size reduction factor for horizontal slender structures side wall Scruton number Strouhal number — non-dimensional vortex shedding frequency shielding parameter; height of the level at which action effects are calculated for a structure; or distance between the underside ofa solar panel and the roof surface equivalent frame spacing top roof section upwind roof slope building orthogonal design wind speeds (usually, @ = 0°, 90°, 180° and 270°), as given in Clause 2.3 NOTE: Vaes,a may be expressed asa function of height z, for some applications, e.g. windward walls of tall buildings (°25 m). building orthogonal design wind speeds as a function of height z reduced velocity (non-dimensional) regional gust wind speed, in metres per second, for annual probability of exceedance of 1/R wind speeds for a site, varying according to compass direction wind actions (refer to AS/NZS 1170.0) windward wall wind actions for serviceability limit states (determined using a regional wind speed appropriate to the annual probability of exceedance for serviceability limit states) (© Standards Australia Limited/Standards New Zealand 2021WM Xi Vana Yoax ) Pty Ltd.Further reproduction, distribution, storage or use on a network is prohibited. 20 Ca Az Printed / viewed by: {manh.tran@jacobs.com] @ 2021-11-14 be Fam Copyrighted material licensed to SAl Global’Jacobs Group (Austral 3 AS/NZS 1170.2:2021 wind actions for ultimate limit states (determined using a regional wind speed appropriate to the annual probability of exceedance specified for ultimate limit, states) width of a tower; or shortest horizontal dimension of the building width of canopy, awning carport, or similar, from the face of the buil equivalent static wind force per unit height as a function of height z distance from the windward edge of a canopy or cantilevered roof; distance from initiating crest (NZ lee zones — Clause 4.4.3); or horizontal distance upwind or downwind of the structure to the crest ofthe hill, ridge or escarpment distance downwind from the start ofanew terrain roughness to the position where the developed height of the inner layer equals z (lag distance) peak acceleration, at the top of structure in the along-wind direction peak acceleration, at the top of a structure in the crosswind direction maximum amplitude of tip deflection in crosswind vibration at the critical wind speed reference height on the structure above the average local ground level, or rotational displacement (Appendix E) aerodynamic roughness length angle of slope of a roof angle of compass wind direction, measured clockwise from North (0°), for determining site wind velocities additional drag coefficient due to an ancillary attached to one face or located inside the tower section height of the section of the structure upon which the wind pressure acts solidity ratio.of the structure (surface or open frame) which is the ratio of solid area to total area of the structure effective solidity ratio for an open frame action effect derived from the mean along-wind response action effect derived from the peak along-wind response action effect derived from the peak crosswind response combined peak scalar dynamic action effect ratio of structural damping to critical damping of a structure stress level (© Standards Australia Limited Standards New Zealand 2021n, storage or use on a network is prohibited. 1-14 Printed / viewed by: [manh.tran@jacobs.com] @ 2031 Copyrighted material licensed to SAI Global'Jacobs Group (Australia) Pty Ltd.Further reproduction, distrib AS/NZS 1170. Fatxy2) Om a ~ 12) “4 combined peak acceleration (see Appendix E) standard deviation of acceleration (Appendix E) maximum stress angle of upwind direction to the orthogonal axes of a structure, in degrees; or rotational displacement (Appendix E) rotational velocity (Appendix E) angle of deviation of the wind stream from the line joining the centre of the tower cross-section to the centre of the ancillary, in degrees angle from the wind direction to a point on the wall of a circular bin, silo or tank, in degrees angle between the wind direction and the longitudinal axis of the member, in degrees spacing ratio for parallel open frames, equal to the frame spacing (centre-to-centre) divided by the projected frame width normal to the wind direction the ratio of the circumference of any circle to its diameter (approx. 3.14159) ratio of the highest component of peak acceleration to the second highest density of air, which shall be taken as 1.2 kg/m3 NOTE: This value is based on 20°C and typical ground level atmospheric pressure and variation may be necessary for very high altitudes or cold environments. first mode shape as a function of height z, normalized to unity at = h 1.6 Determination of wind actions Values of wind actions (W) for use in design shall be established. The values shall be appropriate for the type of structure or structural element, its intended use, design working life and exposure to wind action, ‘The following wind actions, determined in accordance with this Standard (using the procedures detailed in Section 2 and the values given in the remaining Sections) are deemed to conform to the requirements of this Clause: @ Wa determined using a regional wind speed appropriate to the annual probability of exceedance (P) specified for ultimate limit states as given in AS/NZS 1170.0, or the National Construction Code (Australia). (0) W, determined using a regional wind speed appropriate to the annual probability of exceedance for the serviceability limit states (see Note 3). NOTE 1 Information on serviceability conditions and criteria can be found in AS/NZS 1170.0 (see Preface). NOTE 2 Some design processes require the determination of wind pressure (ultimate or serviceability wind pressure). Such pressures should be calculated for the wind speed associated with the annual probability of exceedance (P) appropriate to the limit state being considered. NOTE3 For guidance on Item (b), refor to AS/NZS 1170.0, @ Standards Australia Limited/Standards New Zealand 2021S & a 3 2 o 5 9 8 5 s g £ S Ss a £ ¢ 5 8 ® = 8 8 s © 5 2 5 E£ 1) Pty Ltd.Further reproduction, Printed / viewed by: ensed to SAI Global"Jacobs Group (Australia) s s 3 Ee 3 2 = = 8 8 15 AS/NZS 1170.2:2021 1.7. Units Except where specifically noted, this Standard uses the SI units of kilogram, metre, second, pascal, newton, degree and hertz (kg, m, s, Pa, N, Hz). (© Standards Australla Limited/Standards New Zealand 2021, storage or use on a.network is prohibited. ip (Australia) Pty Ltd.Further reproduction, distribution, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAl GlobalJacobs Grou AS/NZS 1170. 021 16 Section2 Calculation of wind actions 2.1 General ‘The procedure for determining wind actions (W) on structures and elements of structures or buildings shall be as follows: @ Determine site wind speeds (see Clause 2.2). (®) _Determine design wind speed from the site wind speeds (see Clause 2.3). © Determine design wind pressures and distributed forces (see Clause 2.4). (2) Calculate wind actions (see Clause 2.5). 2.2 Site wind speed The site wind speeds (Vee) defined for the 8 cardinal directions (8) at the reference height (2) above ground (see Figure 2.1) shall be calculated from Equation 2.2: Vag = YaMeMa (Meat MMe) 22 where VR = regional gust wind speed, in metres per second, for average recurrence interval of Ryears, as given in Section 3 Meo = climate change multiplier, as given in Section 3 Ma = wind directional multipliers for the 8 cardinal directions (f) as given in Section 3 Maat = terrain /height multiplier, as given in Section 4 Mo = shielding multiplier, as given in Section 4 Meo = topographic multiplier, as given in Section 4 Generally, the wind speed is determined at the average roof height (A). In some cases, this varies according to the structure. 2.3 Design wind speed The building orthogonal design wind speeds (Vjes,¢) shall be taken as the maximum cardinal direction site wind speed (Vsizg) linearly interpolated between cardinal points within a sector + 45° to the orthogonal direction being considered (see Figures 2.2 and 2.3). NOTE That is, Vies0 equals the maximum value of site wind speed (Vsig) in the range [8 = 0 + 45°] where B is the cardinal direction clockwise from true North and @is the angle tothe building orthogonal axes. In cases such as walls and hoardings and lattice towers, where an incident angle of 45° is considered, Vaes,9 shall be the maximum value of Vei,g in a sector + 22.5° from the 45° direction being considered. For ultimate limit states design, Vies@ shall not be less than 30 m/s. A conservative approach is to design the structure using the wind speed and multipliers for the worst direction, For example, for a building on an escarpment it may be easily checked whether the Ve Mc Ma (Mya Mg Md on the exposed face (towards the escarpment) is the worst case. To simplify design, this value could then be used as the design wind speed for all directions on the building, (© Standards Australia Limited/Standards New Zealand 2021Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 nsed to SAI GlobalJacobs Group (Australia) Pty Ltd.Further reproduction, Copyrighted material v7 AS/NZS 1170.2:2021 With reference to Figure 2.1, when determining the reference height on a structure, the ground level shall be taken as that of the natural ground (ie. excluding any excavations, etc, at the centroid of the footprint of the roof(s). Where there are upper and lower roof(s) on a building, the average roof height shall be taken as that of the upper roof. Average roof height — Average roof height Figure 2.1 — Reference height of structures © Standards Australia Limited/Standards New Zealand 2021AS/NZS 1170.2:2021 18 peo Cardinal directions — —~ w. B= 270" Building orthogonal axes 987? So sw f= 180° Pty Ltd.Further reproduction, distribution, storage or use on a network is prohibited. Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 s Figure 2.2 — Relationship of wind directions and building orthogonal axes ensed to SAI Global'Jacobs Group (Australi (© Standards Australia Limited Standards New Zealand 2021, Copyrighted material, storage or use on a network is prohibited. distributi 11-14 0 urther reproduction, distribution. Printed / viewed by: [manh.tran@jacobs.com] @ 202 sensed to SAI Global"Jacobs Group (Australia) Pty Ltd.Furthe \ducti 19 AS/NZS 1170.2:2021 ° 45° 90° 180° 270° N NE E 8 w N CARDINAL DIRECTION, 6 NOTE The value of Vaeso is the maximum of Vaieg in the range 6 + 45°, which, in the case shown here, is the wind speed x. Figure 2.3 — Example of Vsi.g conversion to Vaes,0 2.4 Design wind pressure and distributed forces 2.41 Design wind pressures ‘The design wind pressures (p), in pascals, shall be determined for structures and parts of structures from Equation 2.4(1): P= (0.5Pxe)[Yaeso] Sanam aac where P Pair Viws.o Csnp Cayn design wind pressure in pascals Pe, pi or pa where the sign is given by the Cp values used to evaluate Cenp NOTE: Pressures are taken as positive, indicating pressures above ambient and negative, indicating pressures below ambient. density of air, which shall be taken as 1.2 kg/m3 building orthogonal design wind speeds (usually, @ = 0°, 90°, 180° and 270°), as given in Clause 2.3 NOTE: For some applications, Vies may be a single value or may be expressed as a function of height (2), e.g, windward walls of tall buildings (+25 m). aerodynamic shape factor, as given in Section 5 dynamic response factor, as given in Section 6 (the value is 1.0 except where the structure is dynamically wind sensitive [see Section 6]) © standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited. production, distribution up (Australia) Pty Ltd.Further re Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global‘Jacobs Grou; AS/NZS 1170.2:2021 20 2.4.2 Design frictional drag force per unit area The design wind frictional drag force per unit area (f), in pascals, shall be taken for structures and parts of structures from Equation 2.4(2): F=(0-5.e)[Yaese ] Goup 24(2) 2.5 Wind actions 2.5.1 General Wind actions (WW and W, for use in AS/NZS 1170.0 shall be determined as given in Clauses 2.5.2 to 2.5.4 and deflections and accelerations of dynamically wind-sensitive structures as given in Clause 2.5.7 2.5.2. Directions Wind actions shall be derived by considering wind from no fewer than four orthogonal directions aligned to the structure. 2.5.3 Forces on surfaces or structural elements 2.5.3.1 Forces derived from wind pressure To determine wind actions, the forces (F) in newtons, on surfaces or structural elements, such as a wall or a roof, shall be the vector sum of the forces calculated from the pressures applicable to the assumed areas (A), using Equation 2,5(1): =D.) 25(0) where Ps = _ design wind pressure in pascals (normal to the surface) at height z, calculated in Clause 2.4.1. NOTE: The sign convention for pressures leads to forces towards the surface for positive pressures and forces away from the surface for negative pressures, Az = _teference area, in square metres, at height z, upon which the pressure at that height (p.) acts For enclosed buildings, internal pressures shall be taken to act simultaneously with external pressures, including the effects of local pressure factors (Ke). Generally, the most severe combinations of internal and external pressures shall be selected for design, but some reduction in the combined load may be applicable according to Clause 5.4.3. Where it is required to divide the height of a tall structure into sectors to calculate wind actions (e.g, windward walls of tall buildings [Table 5.2(A)] or for lattice towers [Clause C.4.1)), the sectors shall be ofa size to represent reasonably the variation of wind speed with height, as given in Clause 4.2.2. (© Standards Australia Limited/Standards New Zealand 2021= 2 a a 3 a é « 5 2 g 5 2 3 g 2 s 5 2 Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 nsed to SAI Global“Jacobs Group (Australia) Pty Ltd.Further reproduction, Copyrighted material a AS/NZS 1170.2:2021 2.5.3.2 Forces derived from frictional drag To determine wind actions, the forces (F), in newtons, on a building element, such as a wall or a roof, shall be the vector sumn of the forces calculated from distributed frictional drag stresses appticable to the assumed areas, using Equation 2.5(2): F= (fA) 2502) where Se = design frictional drag per unit area parallel to the surface (calculated in Clause 2.4.2) at height z, in pascals Az = _ reference area, in square metres, on which the distributed frictional drag stresses (f) act. 2.5.3.3 Forces derived from force coefficients Appendices C and D cover structures for which shape factors are given in the form of force coeff rather than pressure coefficients, In these cases, to determine wind actions, the forces (F) in newtons shall be calculated from Equation 2.5(3): 2 F =(0.50,,)[Vaeso] CyapCayne 25(3) where Ar = _ as defined in Clause C.4 for lattice towers Ix b for members and simple sections in Clause C2 Areas defined in Appendix D for flags and circular shapes 2.5.4 Forces and moments on complete structures To determine wind actions, the total resultant forces and overturning moments on complete structures shall be taken to be the summation of the effects of the external pressures on all surfaces of the building. For rectangular enclosed buildings with h > 70 m, torsion shall be applied, based on an eccentricity of 0.2b with respect to the centre of geometry of the building on the along-wind loading, NOTE. For d/b > 1.5, the torsional moments are primarily generated by crosswind forces and specialist advice should be sought. For dynamic effects, the combination of along-wind and crosswind responses shall be calculated in accordance with Section 6. 2.5.5 Number of stress exceedances produced by wind loading For structures that may be fatigue sensitive, Figure 2.4 and Equation 2.5(4) show the number of times, Ng, that a stress level, o, is exceeded under wind loading in a lifetime, L, where 1. is 20 to 100 years and is, expressed as a percentage of the expected maximum stress, dmax, in the lifetime, L. NOTE 1 To assess potential high-cycle fatigue damage in elements of a structure subjected to repeated and fluctuating stresses under wind loading, the stress count given in Figure 24 and in Equation 2.5(4) may be used, together with stress/cycles to failure relationships, (S-N curves), such as those given for various detail categories in AS 4100, The stress counts in Figure 2.4 include quasi-static stress cycles produced by wind gusting, as well as those produced by resonant vibrations. (© Standards Australia Limited Standards New Zealand 2021, storage or use on a network is prohibited. z ¢ § g 3 § 3 8 5 s 3 2 5 a 3 5 2 z g =< 2 Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11- Copyrighted material licensed to SAI Global’Jacobs Grou AS/NZS 1170.2:2021 22 NOTE2 _Asimplified design approach to steel design, that links the design for fatigue under wind loading to the ‘maximum stress associated with the ultimate load is given by Holmes and Genner (2012). This approach makes use ofthe cycle count of Figure 24 NOTE 3. The methods in this Clause are not appropriate for assessing the low-cycle fatigue performance of cladding elements in Regions Cand D, which is covered separately in Clause 2.5.6. NOTE 4 The methods of this Clause are appropriate to wind-induced fluctuating loading from buffeting by turbulence (usually acting in the along-wind direction), They are not suitable to assess fatigue damage produced by crosswind vibrations of slender structures produced by vortex shedding (see Clause 6.3.3). In those cases, Potential fatigue damage should be avoided by mitigating the vibrations by various means, such as auxiliary dampers, or aerodynamic devices such as helical strakes. 100 a 10° 107 102 to to# 1010810708 Ny igure 2.4 — Number of wind load cycles, Ng, for an effect, c/omax, during a 20 to 100 year period ‘The relationship between 0/omax and Ng is given by Equation 2.5(4),as follows ~&=0.7(log(N,))° -17-41og(Wg)+100 2504) Cmax 2.5.6 Performance of cladding elements sensitive to low-cycle fatigue In Regions C and D, cladding, its connections and immediate supporting members and their fixings shall demonstrate performance under the pressure sequences defined in AS 4040.3 and the National Construction Code (Australia), based on the ultimate limit state wind pressure on external and internal surfaces, as determined in accordance with this Standard. 2.8.7. Deflections of dynamically wind-sensitive structures Wind actions for dynamically wind-sensitive structures (as defined in Clause 6.1), which may include chimneys, masts and poles of circular cross-section, shall be calculated in accordance with Section 6. NOTE Information on peak acceleration of other wind-sensitive structures is given in Appendix E, © Standards Australia Limited/Standards New Zealand 2021,, storage or use on a network is prohibited S 2 mn, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 3 3 8 5 8 £ = é z g > é fz. £ 3 < s. 3 oO 3 3 a 3 2 oO <= Fs 2 3 3 5 23 AS/NZS 1170.2:2021 2.5.8 Impact loading from windborne debris Where windborne debris loading is required for impact resistance testing, the debris impact loading shall be— (@ —_atimber test member of 4 kg mass, of a density of at least 600 kg/m?, with a nominal cross- section of 100 mm x 50 mm impacting end on at: oO 0.4 Va, normal to wall surfaces; (i)_—_0.4- Vg sine of the roof slope, normal to roof surfaces greater than 15° pitch; and (iii) 0.1 Va, normal to roof surfaces less than, or equal to, 15° pitch; and (6) aspherical stee! ball, 8 mm in diameter (approximately 2 g mass) impacting at 0.4 Vx normal to wall surfaces, and roof surfaces greater than 35° pitch; and 0,3 Va normal to roof surfaces less than, or equal to, 35° pitch, where Va is the regional wind speed given in Clause 3.2. NOTE1 Examples ofthe use ofthis Clause would be for the evaluation of internal pressure (see Clause 5.3.2), or the demonstration of resistance to penetration of the building envelope enclosing a shelter room. NOTE 2 The two test debris items are representative of a large range of windborne debris of varying masses and sizes that can be generated in severe wind storms, NOTE3 The spherical ball missile is representative of small missiles, which could penetrate protective screens with large mesh sizes. NOTE4 These impact loadings should be applied independently in time and location. NOTES This Standard does not specify a test method or acceptance criteria. Acceptance criteria may vary according to the purpose of the test. An appropriate test method and acceptance criteria for debris tests are given in Technical Note No. 4 (see Bibliography), ‘© Standards Australia Limited /Standards New Zealand 2021istribution, storage or use on a network is prohibited, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 icensed to SAI Global"Jacobs Group (Australia) Pty Ltd.Further reproduction, AS/NZS 1170.2:2021 a Section3 Re; nal wind speeds 3.1. General This Section shall be used to calculate gust wind speeds appropriate to the region in which a structure is to be constructed, including wind direction effects. 3.2. Regional wind speeds (Vp) Regional wind speeds (Vg) for all directions based on peak gust wind data shall be as given in Table 3.1(A) or Table 3.1(B) for the regions shown in Figure 3.1(A) and Figure 3.1(B) where R (average recurrence interval) is the average time interval between exceedances of the wind speed listed. For R= S years, itis equal to the reciprocal of the annual probability of exceedance of the wind speed. ‘The calculated values of Vg have been rounded to the nearest 1 m/s. In Region C, values of Vp shall be obtained by linear interpolation between the value given for Region C (maximum) and the value given for Region B2 for the same R, according to the distance from the smoothed coastline. In Region D, values of Va shall be obtained by linear interpolation between the value given for Region D (maximum) and the value given for Region C (maximum) for the same R, according to the distance from the smoothed coastline. (© Standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited, ) Pty Ltd.Further reproduction, distribution Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 icensed to SAI Global" Jacobs Group (Australi Copyrighted material 25 AS/NZS 1170.2:2021 Table 3.1(A) — Regional wind speeds — Australia Regional wind Region speed Non-eyclonic Gydonie (mvs) _ ats) | _B1,B2 C(maximum) | _D (maximum) Ve 30 26 23 2 Vs 32 28 33 35 = Vio 34 33 39 8 Vea 37 38 5 51 Vas 7 39 a7 53 Vs0 39 44 52 60 Vioo nm | 6 Va00| 8 52 a 72 Vaso 4B 53 a 7 5 57 66 80 Vao00 46 60 70 85 ~Va000 48 8 a 30 Vasoo 48 a 7! | OL ¥s000 | 50 7 7% | 95 Vi0000 51 Co 81 99 Va (R2 5 years) MRA | _106-92R-04 122-104R-04 156-142-041 INOTE 1 The peak gust has an equivalent moving average time of approximately 0.2 s (Holmes and Ginger, 2012), INOTE2 Values for Vi have not been calculated by the formula for Vg in the Australian regions. INOTE 3 For ultimate or serviceability limit states, refer to the National Construction Code (Australia) or [AS/NZS 1170.0 for information on values of importance level and annual probability of exceedance appropriate] for the design of structures, For buildings in townships in cyclonic regions, users should consider overall risk to {a community when selecting importance levels. NOTE 4 For Regions C and D, only the maximum values for the region are tabulated. Lower values of Vg may] [apply in those regions, depending on the distance of the site from the smooth coastline. (© Standards Australia Limited Standards New Zealand 2021AS/NZS 1170.2:2021 26 Table 3.1(B) — Regional wind speeds — New Zealand , storage or use on a-network is prohibited Regional wind speed _ Region (m/s) NZ (1to2) NZ3. NZ4 vi 31 37 38 uy 35 2 2 Vio 37 44 B Va0 3 46 4 Vas, 39 | 46 45 Vso a 48 6 < Vioo 2 50 a g Yao a a 48 Et Vaso 7 44 51 49 $2 ¥500 ra 3 50 es Vi 000 | 46 54 50 §8 V2000 - 47 55 51 se Va 500 a7 55 52 | 2e Vs000 48 56 52 38 Yioo00 9 57 _ 3 53 Va 1-30R-01 71-34R-04 63-25-04 5 £8 |NoTE 1 The peak gust bas an equivalent moving average time of approximately 0.2 s (Holmes and 5 & |cinger, 2012). GS |Nove 2 For ulate or serviceability limit states, refer to AS/NZS 1170.0 for information on values of &§ importance level and annual probability of exceedance appropriate for the design of structures in New Zealand, ‘2 es 3.3 Wind direction multiplier (Ma) ‘S. Except for the following cases, the wind direction multiplier (Mg) for all regions shall be as given in © Table3.2(4) or Table 3.2(8). For the following cases, Ma shall be taken as 1.0: 2 @) structures such as chimneys, tanks and poles with circular or polygonal cross-sections; and = cladding and immediate supporting structure (as defined in Clause 5.4.4) on buildings in 3 Regions B2, Cand D. E NOTE tn regions where the prevailing wind directions vary with wind speed, wind direction multipliers have © been calculated for the higher wind gusts (Le. those associated with ultimate limit states design) (© Standards Australia Limited/Standards New Zealand 2021 Copyrighted material licensed to SAI Global’Jacobs Group (Australia)11-14 production, distribution, storage or use on a network is proh tralia) Pty Ltd.Further reproducti ustralia) distributi iewed by: [manh.tran@jacobs.com] @ 2021: Printed / vi ensed to SAI Global Jacobs Group (A\ a AS/NZS 1170.2:2021 ‘Table 3.2(A) — Wind direction multiplier (Ma) — Australia Garnal Region Ao [Region At [Region A2|Region A3] Region Ad Region As Region | Resions w 090] 090] 08s | 080085 095 | 075] 030 NE os | oss | 075 | 075 | 075 | oso | 078 | 090 E 0.85, 0.85 0.85, 0.75 075, 0.80 0.85 090 | SE 0.90 080 | 095 0.90 0.80 0.80 090 | 090 s 0.90 0.80 0.95 0.90 0.80 080 | 095 0.90 sw 095 | 095 095 0.95 0.90 0.95 0.95 0.90 Ww x00] 100~| 100 | 100 | 100 | 100 | 09s | 090 | NW | 095 | 095 | 095 | 09s | 100 [085 | 090 | 090 NOTE In Region AO non-synoptic winds are dominant. In Regions Al and A4, extra-tropical synoptic winds lare dominant. Extreme winds in Regions A2, A3, AS and B1 are caused by a mixture of synoptic (extra-tropical large-scale pressure systems, or tropical cyclones in the case of B1) and non-synoptic (thunderstorm) events. In [Regions B2, C, and D, extreme winds from tropical cyclones are dominant, ‘Table 3.2(B) — Wind direction multiplier (Ma) — New Zealand (Cardinal directions] Region NZL Region NZ2 Region NZ3 Region NZ4 N 080 095 1.00 095; NE _ 095 090 078 075 E 095 0.80 078 075 SE 095 090 o.as 075 s 030 095 0.85 sw. 1.00 1.00 095 095 w 1.00 1.00 090 1.00 nwo 095 1.00 100 1.00 [NOTE _Inall New Zealand regions, extra-tropical synoptic winds are dominant. 3.4 Climate change multiplier (M.) ‘The climate change multiplier (Mc) shall be as given in Table 3.3. Table 3.3 — Climate change multiplier (M<) Region Me Atos) TO BL 10 22 1.05 c 1.05 D 1.05 NZ (104) 10 NOTE The climate change multiplier allows for possible| changes in climate affecting extreme winds during the life of structures designed by this Standard. Values of Mc may be| Jadjusted in future amendments, depending on observed or| [predicted trends. (© Standards Australia Limited/Standards New Zealand 2021AS/NZS 1170.2:2021 2B , storage or use on a network is prohibited. é s 3 2 ise aes a Figure 3.1(A) — Wind regions — Australia Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 (© Standards Australia Limited/Standards New Zealand 2021 Copyrighted material licensed to SAI Global\Jacobs Group (Australia) Pty Ltd.Further reproduction,29 AS/NZS 1170.2:2021 REGION NZt & , storage or use on a network is prohibited. s 3 a n, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 REGION Nz3. REGION Nz ee REGION Nz4 (includes Chatham and Auckland Islands) Figure 3.1(B) — Wind regions — New Zealand 3 ¢ 5 ge 2 5 e z z, 8 g < 3. 2 oO g a 8 3 os 3 2 oO z bi £ 2 5 © Standards Australia Limited/Standards New Zealand 2021 Copyrighted material, storage or use on a network is prohibited. ty Ltd. Further reproduction, distribution, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 icensed to SAl Global’Jacobs Group (Australia) P Copyrighted materi AS/NZS 1170.2:2021 30 Section 4 Site exposure multipliers 4.1 General This Section shall be used to calculate the exposure multipliers for site conditions related to terrain/height (Mz,cat), shielding (M,) and topography (MJ. The design shall take account of known future changes to terrain roughness when assessing terrain category and to buildings providing shielding when assessing shielding. 4.2 Terrain/height multiplier (Mica) 4.2.1 Terrain category definitions Terrain, over which the approach wind flows towards a structure, shall be assessed on the basis of the following category descriptions @ Terrain Category 1 (TC1) — Very exposed open terrain with very few or no obstructions, and all water surfaces (eg. flat, treeless, poorly grassed plains; open ocean, rivers, canals, bays and lakes). (6) Terrain Category 2 (TC2) — Open terrain, including grassland, with well-scattered obstructions having heights generally from 1.5 m to 5 m, with no more than two obstructions per hectare (eg. farmland and cleared subdivisions with isolated trees and uncut grass). 0 Terrain Category 2.5 (TC2.5) — Terrain with some trees or isolated obstructions, terrain in developing outer urban areas with scattered houses, or large acreage developments with more than two and less than 10 buildings per hectare. @ Terrain Category 3 (TC3) — Terrain with numerous closely spaced obstructions having heights generally from 3 m to 10 m. The minimum density of obstructions shall be at least the equivalent of 10 house-size obstructions per hectare (e.g. suburban housing, light industrial estates or dense forests). © Terrain Category 4 (TC4) — Terrain with numerous large, high (10 m to 30 m tall) and closely- spaced constructions, such as large city centres and well-developed industrial complexes. Selection of the terrain category shall be made with due regard to the permanence of the obstructions that constitute the surface roughness. NOTE The aerodynamic roughness length, zo, in metres, is related to the terrain category number by the following relation: xq =2x10(™ =~) 4.2.2. Determination of terrain/height multiplier (Mzcat) ‘The variation with height (2) of the effect of terrain roughness on wind speed (terrain and structure height multiplier, Mz,cat) shall be taken from the values for fully developed profiles given in Table 4.1. For intermediate values of height and terrain category, use linear interpolation. (© Standards Australia Limited/Standards New Zealand 2021,Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 2 2 8 6 2 3 2 5 5 8 3 6 ° & g 3S é § 3 = a 3 8 3 a 2 a 2 = 5 fra 5 2 z B g < s 2 6 2 g 8 8 3 8 3 o z 6 2 B 2 8 Copyrighted material aL AS/NZS 1170.2:2021 Table 4.1 — Terrain /height multipliers for gust wind speeds in fully developed terrains — All regions except AO ‘Terrain/height multiplier (Mzcad) Height (2) Terrain Terrain Terrain Terrain Terrain j@) Category2 | Category2.5 | Category | Category 4 <3 097 ost 087 0.83 075 5 LoL ost 0.87 (ce 10 1.08 1.00 092 0.83 075 15 412 105 097 0.89 075 20 14 1.08 1.01 094 075 30 118 uz | «106 1.00 080 40 121 16 10 | 08 0.85 50 1.23 118 113 | 1.07 090 5 1.27 4.22 7 iz 098 100 131 124 1.20 116 1.03 iso | «136 127 124 121 iit 200 139 129] 827. 124 | 16 NOTE In Region A0, use Maca forall 100 m nal terrains, For 100 m <2: 200.m, tke Mya as 1.24 all terrains. INOTE2 Forall other regions, for intermediate terrains use linear interpolation. INOTE 3 _Forintermediate values of height z, use linear interpolation. 4.2.3 Averaging of terrain categories and terrain-height multipliers When the upwind terrain varies for any wind direction, an averaging of terrain-height multipliers shall be adopted. The terrain-height multiplier, M,,cat, shall be taken as a weighted average over an averaging distance, xa, depending on the height, z. NOTE zis equal to the average roof height, h, ofa building, when its less than, or equal to, 25 m. ‘The averaging distance, x,, shall be the larger of 500 m or 40z, Terrain shall be assessed after ignoring the terrain immediately upwind for a lag distance, xy, where xj istaken as 202. ‘An example of this averaging procedure is given in Figure 4.1. Wind direction > To4 = eb ES oe _— , LH Xe | bagdistance | x= 202 Ms eata Xz * Mca Xia + Macs M, for the case illustrated NOTE The terrain within the lag distance, x, is ignored when averaging terrain-helght multipliers. Figure 4.1 — Example of averaging of terrain-height multipliers © Standards Australia Limited /Standards New Zealand 2021, storage or use on a network is prohibited. production, distribution u urther reprodi Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 ) Ply Ltd F icensed to SAI Global'Jacobs Group (Australia| : = E 3 2 a 8 8 AS/NZS 1170.2:2021 32 43 SI ding multiplier (Mz) 43.1 General Shielding may be provided by upwind buildings or other structures. Shielding shall not be provided by trees or vegetation, An upwind building shall not be used to provide shielding on a slope with a gradient that is greater than 0.2, unless its overall height above a common datum, such as mean sea level, exceeds that of the subject building (see Figure 4.2) The shielding multiplier (M,) that is appropriate to a particular direction shall be as given in Table 4.2 for structures with h = 25 m in height (h is defined in Figure 2.1). The shielding multiplier shall be 1.0 for structures with h greater than 25 m, where the effects of shielding are not applicable for a particular wind direction, or are ignored. NOTE To accurately determine shielding and interference effects between buildings with h greater than 25 m, wind-tunnel testing is needed. Attention should be given to possible combinations of tall buildings placed together, which can lead to local and overall increases in wind actions. A shielding building as elevation | exceeds building being shiclded (not a shisiaing buitaing as average slope 0.2 ana 7 ao Slovation is Tess than building Zs %, L being shielded QED s 20m J- Shielding building as height 2 h rs v and the average slope < 0.2 we | \ t RX KS COR TITIRTIRIR RATATAT NEST t Average gtound slope 2 0.2 Nota shielding building as height I 045 (see Figure 4.5): () —_ Within the rectangular peak zone (see Figure 4.5), use Equation 4.4(4): My vor{s-Hl] 440) (i) _Elsewhere within the local topographic zone (see Figures 4.3 and 4.4), My shall be as. given in Equation 4.4(3). where H = height ofthe hil, ridge or escarpment ly = _ horizontal distance upwind from the crest of the hill ridge or escarpment to a level half the height below the crest x = horizontal distance upwind or downwind of the structure to the crest of the hill, ridge or escarpment 1, = length scale, to determine the vertical variation of My, to be taken as the greater of 0.36 Ly or 0.4 H 1z = _ length scale, to determine the horizontal variation of My, to be taken as 4 Ly upwind for all types, and downwind for hills and ridges, or 10 Li downwind for escarpments z = reference height on the structure above the average local ground level NOTE Figures 4.3, 44 and 4.5 are cross-sections through the structure's site fora particular wind direction, For the case where x and zare zero, the value of Mh is given in Table 4.3, Irrespective of the provisions of this Clause, the influence of any peak may be ignored, provided the crest is distant from the site of the structure by more than 10 times its crest elevation above sea level, and any intervening valley is more than 10 times the distance of the valley floor below the crest. For escarpments, the average downwind slope, measured from the crest to a distance of the greater of 3.6 ly or 4 H shall not exceed 0.05. © Standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited, p (Australia) Pty Ltd.Further reproduction, distribution. Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global"Jacobs Grou 35 AS/NZS 1170.2:2021 Local topographic zone 44L, or 6H Lz = 1.4L, oF 1.6H (whichever is greater) (whiche Figure 4.3 — Hills and ridges Local topographic zone wes oY Lye 14d, or .6H Ly = 3.6L, or 4H (whichever is gr ter) Figure 4.4 — Escarpments Local topographic zone “uw GZ po Slope > 0.45 7 Figure 4.5 — Hills and escarpments having upwind slopes greater than 0.45 Peak zone with ‘constant Mf, (© standards Australia Limited/Standards New Zealand 202136 Table 4.3 — Hill-shape multiplier at crest (|x|=0),z=0 (for gust wind speeds) Upwind slope (H/2t) = 0.05 0.05 0.10 0.20 0.30 | 205 , storage or use on a network is prohibited. 44.3 Lee multiplier (Mice) The lee (effect) multiplier (Mieg) shall be evaluated for New Zealand sites in the lee zones as shown in Eigure 4.6, For all other sites, the lee multiplier shall be 1.0. Within the lee zones, the lee multiplier shall apply only to wind from the cardinal directions nominated in Table 4.4. Each lee zone shall extend by the distance as specified in Table 4.4, this distance is measured from the leeward crest of the initiating range, downwind in the direction of the wind nominated, The lee zone comprises— @ _ashadow lee zone, which extends from the crest ofthe initiating range (the upwind boundary ofthe lee zone); (0) anouter lee zone over the remainder of the lee zone; and (© _ lateral transition zones, which extend from the lateral edges of the shadow zone by x/4, where xis the distance from the initiating crest along the edge of the shadow zone and by R/4 for the Tateral edges of the outer zone, where R is the distance from the initiating crest to the leeward edge of the shadow zone. The coordinates of the initiating crests are shown in Table 4.5. ia) Pty Ltd, Further reproduction, distribution, y: [manh.tran@jacobs,com] @ 2021-11-14 The lee multiplier for shadow zones shall be as specified in Table 4.4. Within the outer lee zone, %5 the lee multiplier shall be determined by linear interpolation with horizontal distance, from the ZB shadow/outer zone boundary (where Mice is from Table 4.4) to the downwind boundary of the outer “ag zone (where Miee = 1.0). Within the lateral transition zone, the lee multiplier shall be determined by 2° linear interpolation along a line parallel to the crest from the value at the point at the lateral edge of the SS shadow and outer zones to a value of 1.0 at the far edge of the lateral zone. 6 8 Ss s g 2 o z 6 2 3 2 8 NOTE Nolee zones have been identified in Australia. Printed (© Standards Australia Limited/Standards New Zealand 2021, Copyrighted material|, storage or use on a network is prohibited. istribution, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 (Australia) Pty Ltd.Further reprodu: g. 2 5 g 3 8 3s s 8 2 5 z 6 2 2 5 Copyrighted material 37 AS/NZS 1170.2:2021 Table 4.4 — New Zealand lee zones direction and extent of shadow and outer zones uter ‘| Range Direction Mice Shadow Outer (im) Gam) North stand 1, |Kaimai [Ease 1.20 fotos ‘8to 20 2, [Taranaki ‘Any,takentobe (1.35 loto1z 120030 '90° sector from ‘mountain top downwind to location | 3./Ruapehu [NW and SE [135 Ovi2 [12 to30 4. Tararua SE [1.20 (0to8 81020 5.|fararuaand [NW 1.20 (0t08 ‘8020 ‘Orongorongo | 6.[Coastal Wairarapa NW a [South Istana - 7, [West Coast North [E and SE 1.20 (ots 81020 8.|West Coast Alps _|SE [2.35 (Oto 12 121030 9. Awatore Nw 1.35 (Oto 12 (vithin Inland Kaikoura) 10.[iniand Kaikoura [NW 135 [oto 12 (within Southern Alps) 11,|Southern Alps [NW 1.35 looiz 121030 412. Hunter Isw 1.20 0t08 ‘Bt020 | 13. akataramea [NW 1.20 0t08 Bto20 14, |StMary’s sw 1.20 0t08 81020 15, Pisa NW 1.20 (0to8 81020 16. Dunstan NW. 1.20 oto8 81020 [Ear Rock ana Pilar — NW 120 dt08 ~[st020 © Standards Australia Limited/Standards Now Zealand 2021AS/NZS 1170.2:2021, 38 Psi ou Onakune 7 rston North Key: Loe multiplier, Moy (ownwind fram initiating crest) BI Shadow zone § outer zone BS WG Lateral transition zone NOTE 1 Some outer and lateral transition zones are not shown. NOTE2 For numbers shown, see the first column of Table 4.4. Figure 4.6 — Locations of New Zealand lee zones Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 (© Standards Australia Limited /Standards New Zealand 2021 Copyrighted material licensed to SAI Global*Jacobs Group (Australia) Pty Ltd.Further reproduction, distribution, storage or use on a.network is prohibited.ia) Pty Ltd.Further reproduction, distribution, storage or use on a network is prohibited Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global’Jacobs Group (Austr 39 AS/NZS 1170.2:2021 Table 4.5 — New Zealand lee zones, coordinates (WGS 84 datum) along initiating crests [Range Coordinates [South Island [Southern Alps (NW) JAwatere (NW) lintand Kaikoura (NW) Hunter (SW) st Mary’s (SW) Hakataramea (NW) Pisa (NW) Dunstan (NW) [Rock and Pillar (NW) |West Coast Alps (SE) |West Coast North (E&SE) (169.773, ~44.324}, (170.061, ~44.022] (170.668, ~43.943}, [170.797, ~43.843] (171.401, ~43.589], (172.222, ~43.029] 172.27, ~42.868], 172.629, ~42.668) (172.657, ~42,510}, [172.764, ~42.480] 172.948, 42.487), 173.138, 42.451] [173.710, -42,198}, 173.759, ~42.118] (173.861, ~41.687], (173.798, ~41.754] (173.187, ~42.082), (172.954, -42.106] [173.953, ~41.827], (173.433, ~42.147] [173.270, -42.179] [170.926, ~44.670), (170.922, ~44.657] {170.851, ~44,568}, (170.801, ~44.464] [170,769, ~44.441], [170.676, 44.301] [170.389, ~44.859}, (170.322, ~44.644] [170.343, ~44.806], [170.302, -44.777] (170.291, -44.717] (170.464, ~44.616], (170.515, -44.546] (170.580, -44.480},[170.561, ~44.474] (169.119, -44.994}, (169.141, ~44930] [169.189, ~44.872), (169.261, -44.27] (169,348, -45.064],[169.568, ~44.957] (169.718, -44,840) (169.979, ~45.570},[170.009, ~45.516] (170.173, -45.317],[170.209, ~45.248] [170.241, -43.51], (170.478, ~43.434] [171.564, ~42,785}, (171.694, -42.646] (172.195, ~42.382] [171.339, ~42.390},[171.651, ~41.891] [172.059, -41.618}, (172.227, 41.410] [172.213, ~40,964], [172.377, -40.910] |[172.459, -40.792] North Island ITararuas and Orongorongo (NW) (0743923, -41.423}, (175.001, -41.345] (175.017, ~41.349],[175.266, ~41.084] 175.267, ~40.995}, (175.284, ~40.956] (175.361, ~40.873], (175.418, -40,878} 175.509, -40.665},[175.691, 40.447) NOTE World Geodetic System 1984 (WGS 84). (© Standards Australia Limited Standards New Zealand 2021AS/NZS 1170.2:2021 40 Section5 Aerodynamic shape factor 5.1 General This Section shall be used to calculate the aerodynamic shape factor (Cshp) for structures or parts of structures. Values of Csip shall be used in determining the pressures applied to each surface. For calculating pressures, the sign of Cshp indicates the direction of the pressure on the surface or element Gee Figure 5.1), positive values indicate pressure acting towards the surface and negative values Indicate pressure acting away from the surface (less than ambient pressure, ie. suction). The wind action effects used for design shall be the sum of values determined for different pressure effects such as the combination of internal and external pressure on enclosed buildings. , storage or use on a network is prohibited, Clauses 5.3, 5.4 and 5.5 provide values for enclosed rectangular buildings. For the purposes of this Standard, rectangular buildings include buildings generally made up of rectangular shapes in plan. Methods for other types of enclosed buildings, exposed members, lattice towers, free walls, free roofs and other structures are given in Appendices A to E. ve Si External pressures Internal pressures x 2g 2 2 gt gs 3 3 3 8 5 8 3 2 5 Z 3g > é NOTE: Cy, is used to give a pressure on one face of the surface under consideration, Positive value of Cj, indicates pressure acting towards the surface, negative acting away from the surface (2) Pressures normal to the surtaces of enclosed buildings Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11- NOTE: C,, is used to give a frictional drag on external surfaces of the structure only. Load per unit area aéts parallel to the surface. z 3 < 2 g 8 ° 3a 3 8 8 s 8 3 o z a 2 3 2 8 (©) Frictional drag on enclosed buildings Figure 5.1(A) —Sign conventions for Csup (© Standards Australia Limited/Standards New Zealand 2021 Copyrighted materiPrinted / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI GlobalJacobs Group (Australia) Ply Ltd.Further reproduction, distribution, storage or use on a network is prohibited. a NOTE: Cy, is used to give a net pressure normal to the wall’derived from face pressures on both ‘upwind and downwind faces, The net pressure always acts normal to the longitudinal axis of the wall (c) Pressure normal to the surfaces of walls and hoardings NOTE: Cy, is used to give net pressure normal to the roof'derived from face pressures on both upper and lower surfaces. The net pressure always acts normal to the surface and positive indicates downwards (c) Pressure normal to the surtaces freestanding roots AS/NZS 1170.2:2021 a~ SS NOTE: C,, is used to give frictional drag on both sides of the wall. Load per unit area acts parallel to both the surfaces of the wall (4) Frictional drag on walls and hoardings NOTE: Cj, is used to give the tots! frictional drag forces derived from face frictional forces on both upper and lower surfaces. Load per unit area acts parallel to both the surfaces of the roof. () Frictional drag on freestanding roots Figure 5.1(B) — Sign conventions for Cshp 5.2. Evaluation of aerodynamic shape factor The aerodynamic shape factor (Csnp) shall be determined for specific surfaces or parts of surfaces as follows: @ Enclosed buildings — use Equations §.2(1), 5.2(2) and $.2(3): Coup =Gpj KejKy for internal pressures 5.2(1) Coup =Spe KaKcek ‘Ky » for external pressures 5.202) Coup = C(KaK9: for frictional drag forces 5.203) (6) Circular bins, silos and tanks — see Appendix A. © Standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited, ution, @jacobs.com] @ 2021-11-14 imanh.tran@jacobs.com] @ 2021~ r ) Ply Ltd.Further reproduction, dist ted / viewed by: [ Copyrighted material licensed to SAl Global’Jacobs Group (Australia) AS/NZS 1170.2:2021 2 oO Freestanding walls, hoardings, canopies and roofs — see Appendix B and Equations 5.2(4) and 5.2(5): Coup = Opn Ka KK » for pressure normal to surface 5:24) Copp = Cf, for frictional drag forces 5.2(5) @ —_ Exposed structural members, frames and lattice towers — see Appendix. @ Flags and circular shapes — see Appendix D. where Cpe = external pressure coefficient pj = internal pressure coefficient Cy = frictional drag force coefficient Con = net pressure coefficient acting normal to the surface for canopies, freestanding roofs, walls, and the like area reduction factor Ke = combination factor Ke = combination factor applied to external pressures Ke, = combination factor applied to internal pressures Ke = local pressure factor K, = open area/internal volume factor for internal pressures Kp = porous cladding reduction factor 5.3 Internal pressure for enclosed rectangular buildings 5.3.1 Internal pressure 5.3.1.1 General Internal pressure is a function of the external pressures, and the leakage and openings in the external surfaces of the building or an isolated part of a larger building, and for some large buildings, the internal volume. The open area of a surface shall be calculated by adding areas of opening to areas of permeability or leakage on that surface of the building (e.g. vents and gaps in the building envelope). The height at which the design wind speed is determined for calculation of internal pressures shall be the average roof height (h), as defined in Figure 2.1. However, for the cases of windward wall leakage or openings on a building greater than 25 m in height, the design wind speed at the height of the opening, shall be used. Pressure coefficients for internal pressure (Cp, shall be determined by either Clause 5.3.1.2 or S.3.1.3. NOTE 1 Damage inspections after wind storms, in Regions C and D, have shown that large openings are very likely to occur accidentally due to failure of elements under direct wind pressure, or in the lower levels of a building envelope, by debris impact: Large openings can also accur in Regions A (0 t0'5), B (1 t0 2) and NZ (1 to.4) under the same circumstances, although openings produced by debris impact are less likely. NOTE 2, The equivalent free area of a ventilator (e.g. ridge or under-eave ventilators) can be determined from the product of discharge coefficient and throat area. (© Standards Australia Limited/Standards New Zealand 2021n, distribution, storage or use on a network is prohibited. ° ) Pty Ltd.Further reproduc Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 licensed to SAl Global“Jacobs Group (Australia) a AS/NZS 1170.2:2021 5.3.1.2 Internal pressure coefficients for all cases, except ultimate limit states for parts of buildings below 25 m in Regions Cand D * Clause 5.3.1.1 applies to buildings in all regions for serviceability limit states. For ultimate limit states, it applies to all buildings in Regions A (0 to 5), B (1 to 2) and NZ (1 to 4), and parts of buildings higher than 25 m above ground level in Regions Cand D. Pressure coefficients for internal pressure (Cp;) shall be determined from Tables 5.1(A) or 5.1(B). ‘Table 5.1(A) shall be used for the design case where there are no potential openings in any surface with a combined area greater than 0.5 % of the total area of that surface, and the leakage in the walls lead to internal pressures. Table 5.1(B) shall be used for the design case where there are openings in any surface greater than 0.5 % of the total area of that surface, or they can be created accidentally. 5.3.1.3 Internal pressure coefficients for ultimate limit states for parts of buildings below 25 m in Regions Cand D Pressure coefficients for internal pressure (Cp,) for parts of a building in Regions C and D below 25 m for ultimate limit states, shall be determined from Table 5.1(B) only. ‘The ratio of the sum of opening areas on one surface to total open area of other walls and roof surfaces as defined in Table 5.1(B) shall not be taken to be less than two unless — @ _itcan be demonstrated that an opening will not be created in the building envelope as a result of impact loading from the windborne debris defined in Clause 2.5.8; or (0) a permanently-open roof ventilator, such as a ridge ventilator, has been installed with equivalent total area (see Clause 5.3.1.1 Note 2) of at least that of the largest areas of any potential accidental openings in the walls, considering the combined area of wall openings in each wall surface one at a time; or 0 permanently-open, wall ventilators have been installed on atleast two walls, with equivalent total area (see Clauise 5.3.1.1 Note 2) of the ventilators on each wall at least that of the largest of any potential accidental openings in the walls, considering the combined area of wall openings in each wall surface one at a time. NOTE 1 Low-tise buildings in Regions C and D should be designed for the high internal pressures resulting from large openings, for ultimate limit states. Even in cases where the opening is small or there is no opening, ‘Table 5.1(A) is not intended to be used for low-rise buildings in Regions Cand D for ultimate limit states. NOTE 2 To date, the majority of windborne debris in Regions C and D in Australia has not often impacted at heights on buildings above 25 m. This is not the case in other parts of the world and could change in the future ‘with increasing numbers of high-rise buildings. 5.3.2. Openings 5.3.2.1 General Openings shall be determined according to either Clause 5.3.2.2 (Regions A (0 to 5), B (1 to 2) and NZ (1 to 4), and Regions C, D at heights of 25 m or above) or Clause 5.3.2.3 (Regions C, D below 25 m).. Subject to Clauses 5.3.2.2 and 5.3.2.3, combinations of openings and open area shall be assumed to give internal pressures, which, together with external pressures, give the most adverse wind actions. NOTE Potential openings include doors or windows that are left open or may fail, vents that are normally open and holes in cladding caused by impacts by windborne debris during a major wind event. Openings can be doors (including balcony doors) or windows that are left open, open under pressure, or open due to the failure of latches or hinges. When determining internal pressures, consideration should be given to scenarios in which large openings may develop. Openings may also be generated by debris impacts, particularly in Regions C and D (Gee Clause 2'5.8) (© Standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited, ution, 4, Bo BE 5 8 & ® E 8 g g 8 § £ S & = 3 g 3 2 ip (Australia) Pty Ltd.Further reproduction Copyrighted material licensed to SAI Global’Jacobs Grou AS/NZS 1170.2:2021 “ 5.3.2.2 Openings in buildings in Regions A (0 to 5), B (1 to 2) and Nz (1 to 4), and parts of ‘buildings at heights of 25 m or above in Regions C and D ‘The full area of doors, including large access doors (e.g. roller doors), and windows that are normally closed, shall be regarded as openings, unless they are demonstrated to be capable of resisting the applied wind pressures. NOTE 1 When assessing internal pressures, designers should consider the principles of robustness, Le. to avoid situations where the failure of a single component such as a door or window could lead to consequent and disproportionate failure of other elements, or even complete fallure of the structure. NOTE 2 The structural assessment of doors that are assumed to remain closed and intact should include elements such as supports, frames, jambs, roller door guides, wind locks, latches and hinges, and fixings, where the resistance of doors relies on those. This assessment of roller doors and their supporting structural elements should also account for any structural resistance to any catenary actions developed by the door under wind load. 5.3.2.3 Openings in buildings for ultimate limit states for parts of buildings below 25 min Regions Cand D Doors (including large access doors) and windows that are normally closed, and cladding elements, shall be regarded as openings with an area equal to the greater of — @ the full area of the element, where it has not been demonstrated that it can resist the applied wind pressures; or (6) the area of opening that results from debris impact, where the debris impact loading criteria are defined in Clause 2.5.8, 5.3.3 Internal walls and ceilings Internal walls and ceilings that enclose a space adjacent to an external wall and provide an effective seal between spaces within buildings shall be subject to the pressure derived for the space adjacent to an external wall, determined in accordance with Clauses 5.3.1 and 5.3.2. The known and likely ‘openings in the external wall, in combination with a pressure coefficient of +0.2 or ~0.2 on the other side, shall be taken into account to give the largest magnitude pressure difference across the wall or ceiling with a minimum net pressure coefficient of 0.4. Other internal walls that provide an effective seal between spaces within buildings shall be designed for a minimum net pressure coefficient of 0.4. Internal walls and ceilings which do not form a permanent seal shall be designed for a net differential pressure coefficient of 0.3. NOTE Ceilings may also be subjected to wind-induced pressures, depending on factors such as roof leakage, proximity to rooms with potential large external openings, and the location of manholes. (© Standards Australia Limited/Standards New Zealand 2021ibution, storage or use on a network is prohibited. Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 ensed to SAI Global'Jacobs Group (Australia) Pty Ltd.Further reproduction, di Copyrighted material 45 AS/NZS 1170.2:2021 ‘Table 5.1(A) — Internal pressure coefficients (Cp,i) for buildings — Cases for walls without openings greater than 0.5 % of the wall area and an impermeable roof Condition [One wall permeable, other walls impermeable: l@) Windward wall permeable i Cpe for the windward wall Examples showing, permeability and wind direction (®)__ Windward wall impermeable -03 lnwo or three walls permeable, other lwalls impermeable: |(@® Windward wall permeable 041,02 (i) Windward wall impermeable 0.3 [All walls permeable 0.3 0r 0.0, whichever is the more severe for combined actions [A building effectively sealed and having non-opening windows 0.2 0r 0.0, whichever is the more severe for ‘combined actions INOTE Where two values are shown, these are provided as separate load cases. In regard to Table 5.1(A), an impermeable surface means a surface having a ratio of total open area to total surface area of less than 0.1 %. A permeable surface means a surface having a ratio of total open area, including leakage, to total surface area between 0.1 % and 0.5 %. Other surfaces with open areas greater than 0.5 % are deemed to have large openings and internal pressures shall be obtained from Table 5.1(B), (© Standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited. up (Australia) Pty Ltd.Further reproduction, distribution Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 icensed to SAI Global"Jacobs Grou AS/NZS 1170.2:2021 46 Table 5.1(B) — Internal pressure coefficients (Cp,i) for buildings with openings greater than 0.5 % of the area of the corresponding wall or roof Ratio of area of | openings on one surface to the sum ofthe total open | Largest opening on Largest opening on | Largest opening on area (including | windward wall | leeward wall side wall roof permeability) of other wall and roof surfaces O5 orless 03,00 =03, 00 T0300 | 1 01,02 =0.3,0.0 ~0.3,0.0 2 0.7 Kae Cpe Keke Cpe Ks Ke Cpe 3 0.85 Ka Ke Coe Kake Coe Kake Cpe | Gormore Kake Cpe KaKelpe | KakeCre | 5-1(b}1 rt 15-1(b) a NOTE 1 Gye is the relevant external pressure coefficient at the location of the largest opening, For example, lin Column 2, Cp,» means the windward wall pressure coefficient obtained from Table 5.2(A); in Column 3, S| lmeans the leeward wall pressure coefficient obtained from Table 5.2(B), in Column 5, Cpe means the roo Jpressure coefficient for that part of the roof containing the opening. INOTE 2 _ Ky is the area reduction factor related to the total area of the opening(s), A, on the surface under| consideration treating the “tributary area’ as the area ofthe opening. See Clause 5.4.2. JNoTE 3 Xe is the local pressure factor, based on the area and location of the opening on the surface under| Jconsideration, treating the “Area, A” asthe area ofthe opening. See Clause 5.4.4. INOTE4 Surfaces with openings have a ratio of total open area, A, to the total area ofthat surface related to the| internal volume (Vol) under consideration, greater than 0.5 % 5.34 Open area/volume factor, Ky When the largest opening in a building is on a wall, and the open area is greater than the sum of the total open area on the roof and other wall surfaces by a factor of six or more, then the following Equation 5.3(1) applies: A Ae . <— <— |< 3 010.18] log,9| 1007 || for 0.09<| 1005 |<3 5.3() Alt K, = 0.85, for | 100“— |< 0.09 Vol 095 for [fmf 7 Vor where A is the open area on the wall and Vol is the internal volume. Forall other cases, Ky shall be taken as 1.0. NOTE 1 Openings on side walls exposed to relatively small volumes (e.g. partially enclosed balconies on high- rise buildings) may generate significant cavity pressure oscillations, NOTE2 Internal volume means the volume of the enclosed space exposed to the opening, (© Standards Australia Limited/Standards Nev Zealand 2021a AS/NZS 1170.2:2021 5.4 External pressures for enclosed rectangular buildings 5.4.1 . External pressure coefficients (Cp,e) The external pressure coefficients (Cp«) for surfaces of rectangular enclosed buildings shall be as given in Tables 5,2(A), 5.2(B) and S.2(C) for walls and Tables 5.3(A), 5.3(B) and 5.3(C) for roofs and for some special roofs as given in Appendix A. The parameters (ie. dimensions) referred to in these Tables are set out in Figure 5.2. nsed to SAI Global" Jacobs Group (Australia) Pty Ltd. Further reproduction, distribution, storage or use on a network is prot Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 (© Standards Australia Limited,/Standards New Zealand 2021 Copyrighted materialAS/NZS 1170.2:2021 2 os Ne , storage or use on a network is prohibited, ler reproduction, distribution, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 p (Australia) Pty Ltd.Furthe ~ a For windward wall, W, use V varying with height for bulidings > 25 m high Indicates wind [> direction W-= Windward U = Upwind root slope rosswind root slope ownwind roo! slope worage root height ensed to SAI Global'Jacobs Grou; R L = looward =D h Figure 5.2 — Parameters for rectangular enclosed buildings For leeward walls, side walls and roofs, wind speed shall be taken as the value at z = h. The reference height (h) shall be taken as the average height of the roof. (© Standards Australia Limited Standards New Zealand 2021 Copyrighted materialited, Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 8 g 2 z § 2 s 5 z 5 3 2 2 § 2 3 2 5 a 2 8 8 3 5 @ g > @ a 3 < 2. 3 3 oO a 8 os g 3 oO z Fs 2 5 Copyrighted material 9 AS/NZS 1170.2:2021 Where two values of Cpe are listed, roofs shall be designed for both values. In these cases, roof surfaces may be subjected to either value due to turbulence. Alternative combinations of external and internal pressures (see also Clause 5,3) shall be considered, to obtain the most severe conditions for design. For roofs, the following alternative load cases should be considered: @ When using Table 5.3(4), for the appropriate roof type, slope and edge distance— 0 apply the more negative value of Cp,. to all pressure zones and surfaces; and (i) apply the less negative (or most positive) value of Cpe to all pressure zones and surfaces. wy When using both Tables 5.3(B) and 5.3(C), and for the appropriate parameters— @ apply the more negative value of Cp. from Table 5.3(B) to the upwind slope together with the value from Table 5.3(C) to the downwind slope; and (i) apply the less negative (or positive) value of Cpe from Table 5.3(B) to the upwind slope together with the value from Table §.3(C) to the downwind slope. © When using Table 5.3(C) only, for steeper crosswind slopes on hip roofs, apply the appropriate Cpe value to both slopes. For the underside of elevated buildings, Cpe shall be taken as 0.8 and -0.6. For buildings with less elevation above ground than one-third of the height, use linear interpolation between these values and 0.0, according to the ratio of clear unwalled height underneath first floor level to the total building height. For the calculation of underside external pressures, wind speed shall be taken as the value at h. Under-eaves pressures shall be taken as equal to those applied to the adjacent wall surface below the surface under consideration. Table 5.2(A) — Walls — External pressure coefficients (Cp ¢) for rectangular enclosed buildings — Windward wall (W) External pressure coefficients (Cp,.) id speed varies with height) For buildings on ground— 0.8, when wind speed varies with height; or <25.0m 0.7, when wind speed is taken for 2=h For elevated buildings— 0.8 (wind speed taken at fi) © Standards Australia Limited /Standards New Zealand 2021AS/NZS 1170. 2021 50 — Leeward wall (L} ‘Table 5.2(B) — Walls — External pressure coefficients (Cp.<) for rectangular enclosed buildings , Storage or use on a.network is prohibited. Tadao Sdegresice | mootshape | Poynton | do Bera resure a —e 0 tiporgabie “10 2 i 0 Hiporaab D 0 Hip or gable 15 Allvalues ° tipo gable » aa 0 tiporsable 225 sot ai 90 | ableeeNotes) | alates 2 M NOTE Porinvrmediat vauesotd/band a inet inerpoltion Bou Beas Nove2 The design wind speedtobe used wth thes pressure coefficient shouldbe taken a the average oof] sae NOTE. Forhiproofuse the same ves ss ford" Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global’Jacobs Group (Australia) Pty Ltd.Further reproduction, distribution, — Side walls (8) Table 5.2(C) — Walls — External pressure coefficients (Cp,<) for rectangular enclosed buildings Horizontal distance from | External pressure coefficients windward edge Coe) Oto th ~0.65 Thto2h 2hto3h -03 >3h I -0.2 NOTE The design wind speed to be used with these pressure [coefficients should be taken at the average roof height (z= h). (© Standards Australia Limited Standards New Zealand 2021 In regard to Tables 5.3(A), 5.3(B) and 5,3(C), for intermediate values of h/d ratios, linear interpolation shall be used, Interpolation shall only be carried out on values of the same sign.Printed / viewed by: [manh.tran@jacobs.com] @ 2021-11-14 Copyrighted material licensed to SAI Global"Jacobs Group (Australia) Ply Ltd.Further reproduction, distribution, storage or use on a network is prohibited. 51 AS/NZS 1170.2:2021 Table 5.3(A) — Roofs — External pressure coefficients (Cp,<) for rectangular enclosed buildings — For upwind slope (U), and downwind slope (D) and (R) for roofs with a < 10°, and monoslope roofs Roof type and slope |__External pressure coefficient (Gp) Crosswind slopes fer gable roofs, and sey Horizontal distance from indstopes | slope,(U), windward edge of roof hid sos haz 1.0 monoslope roofs slope, (D) ® | Ot 05h 0.5 to 1h _ 1.7, -0.3 Alla acto | into 2h (0.7), 0.3) 2hwo ah SS | see Note [NOTE The values given in parentheses are provided for interpolation purposes. Table 5.3(B) — Roofs — External pressure coefficients (Cp,«) for rectangular enclosed buildings — Upwind slope (U) a2 10° - External pressure coefficients (pa) upwind patio b/d Roof pitch (a) degrees ’ [2% | 2s 3 | Bas z025 03,02 | 02,03 00,01 a2 10° [02,04 | 0,0.8sina =02,03 Table 5.3(C) — Roofs — External pressure coefficients (Cp,«) for rectangular enclosed buildings —Downwind slope (D), and (R) for hip roofs, for a2 10° Rooftypeand slope | T External pressure coefficients (Gp. Eeesewind pownwind | Ratioh/d Roof pitch (a), degrees coors ce)” slope (D) 10 13 | zm) 03] 0S) 08 Forb/dsa ew | aw os | -05 | -0s | -o6 | Fagen: 21.0 =0.7 -0.6 0.6 Forb/d=8;-09 _ 5.4.2 Area reduction factor (Ka) for roofs and walls For roofs and walls of enclosed buildings, the area reduction factor (K,) shall be as given in Table 5.4. For ll other cases, Ka shall be taken as 1.0. Tributary area (4) is the area contributing to the force being considered. For intermediate values of A, linear interpolation shall be used. ‘Table 5.4 — Area reduction factor (Ka) Tebuaryare ant | RoRandatiewall | Windward val) Tawwardals zo 10 10 | 70 25 09 I _ 095 [ 10 2100 I 08 09 l 0.95 (© Standards Australia Limited/Standards New Zealand 2021, storage or use on a network is prohibited. }) Pty Ltd. Further reproduction, distribution, manh.tran@jacobs.com] @ 2021-11-14 Printed / viewed by: Copyrighted material licensed to SAI Global’Jacobs Group (Austr AS/NZS 1170.2:2021, 52 5.4.3 Action combination factor (Kc) Where wind pressures acting on a combination of surfaces of an enclosed building (e.g. windward wall, roof, side wall, leeward wall, internal surface)-contribute simultaneously to a structural action effect, (e.g. member axial force or bending moment) on a structural, or cladding element, combination factors (Kee and Ke,), less than 1.0, may be applied to the external and internal surfaces when calculating the combined actions. Asurface shall be either a windward wall, a side wall, a leeward wall, a roof (the upwind and downwind roof are treated together as a single surface), or the internal surfaces of the building treated as.a single surface. An internal surface shall not be treated as an effective surface if C,)|<0.4 Where pressures on two contributing surfaces act together in combination to produce a structural action effect, Kze and Kei may be taken as 0.9. Where three (or more) contributing surfaces act in combination, Kee and Ke; may be taken as 0.8. Examples of appropriate combination factors (Kee and Ke,) are given in Table 5.5. ‘The product K%. Ke, shall not be less than 0.8. NOTE Action combination factors less than 1.0 account for the non-simultaneous action of peak pressures on effective surfaces, ‘Table 5.5 — Examples of action combination factors Ke.e and K., for action effects on structural elements from wind pressure on effective surfaces External [Internal Desigacase | Example diagram feral [Intern fe) Sefectve 08) 20 surfaces \ 4 fy Pressures from cS {notan windward and va effective Teeward wall — ~ surface) incombination with root Zoro or emall internal proseure | pressures | | (b) 4effective 08 08 surfaces | Pressures from 4 windward and Ieeward walls SS in combination with roof | pressures &nd internal pressures _ (@ sefective 1 ; Pressures from (notan side walls in effective combination surface) with roof & pressures | zer0 or small internal pressure 08 (© Standards Australia Limited/Standards New Zealand 2021