AS/NZS 1170.2:2011

AS/NZS 1170.2:2011 STRUCTURAL DESIGN ACTIONS - WIND ACTIONS

PREFACE

CONTENTS

SECTION 1 GENERAL

1.1 SCOPE

1.2 APPLICATION

1.3 NORMATIVE REFERENCES

1.4 DETERMINATION OF WIND ACTIONS

1.5 UNITS

1.6 DEFINITIONS

1.7 NOTATION

SECTION 2 CALCULATION OF WIND ACTIONS

2.1 GENERAL

2.2 SITE WIND SPEED

2.3 DESIGN WIND SPEED

2.4 DESIGN WIND PRESSURE AND DISTRIBUTED FORCES

2.4.1 Design wind pressures

2.4.2 Design frictional drag force per unit area

2.5 WIND ACTIONS

2.5.1 General

2.5.2 Directions to be considered

2.5.3 Forces on surfaces or structural elements

2.5.4 Forces and moments on complete structures

2.5.5 Number of stress exceedences 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 debris

SECTION 3 REGIONAL WIND SPEEDS

3.1 GENERAL

3.2 REGIONAL WIND SPEEDS (VR)

3.3 WIND DIRECTION MULTIPLIER (Md)

3.3.1 Regions A and W

3.3.2 Regions B, C and D

3.4 FACTORS FOR REGIONS C AND D (FC, FD)

SECTION 4 SITE EXPOSURE MULTIPLIERS

4.1 GENERAL

4.2 TERRAIN/HEIGHT MULTIPLIER (Mz,cat)

4.2.1 Terrain category definitions

4.2.2 Determination of terrain/height multiplier (Mz,cat)

4.2.3 Averaging of terrain categories and terrain-height multipliers

4.3 SHIELDING MULTIPLIER (Ms)

4.3.1 General

4.3.2 Buildings providing shielding

4.3.3 Shielding parameter (s)

4.4 TOPOGRAPHIC MULTIPLIER (Mt)

4.4.1 General

4.4.2 Hill-shape multiplier (Mh)

4.4.3 Lee multiplier (Mlee)

SECTION 5 AERODYNAMIC SHAPE FACTOR

5.1 GENERAL

5.2 EVALUATION OF AERODYNAMIC SHAPE FACTOR

5.3 INTERNAL PRESSURE FOR ENCLOSED RECTANGULAR BUILDINGS

5.3.1 Internal pressure

5.3.2 Openings

5.3.3 Text deleted

5.3.4 Internal walls and ceilings

5.4 EXTERNAL PRESSURES FOR ENCLOSED RECTANGULAR BUILDINGS

5.4.1 External pressure coefficients (Cp,e)

5.4.2 Area reduction factor (Ka) for roofs and side walls

5.4.3 Action combination factor (Kc)

¿5.4.4 Local pressure factor (K¿) for cladding

5.4.5 Permeable cladding reduction factor (Kp) for roofs and side walls

5.5 FRICTIONAL DRAG FORCES FOR ENCLOSED BUILDINGS

SECTION 6 DYNAMIC RESPONSE FACTOR

6.1 EVALUATION OF DYNAMIC RESPONSE FACTOR

6.2 ALONG-WIND RESPONSE OF TALL BUILDINGS AND FREESTANDING TOWERS

6.2.1 General

6.2.2 Dynamic response factor (Cdyn)

6.3 CROSSWIND RESPONSE

6.3.1 General

6.3.2 Crosswind response of tall enclosed buildings and towers of rectangular cross-section

6.3.3 Crosswind response of chimneys, masts and poles of circular cross-section

6.4 COMBINATION OF ALONG-WIND AND CROSSWIND RESPONSE

APPENDIX A - DEFINITIONS

A1 Aerodynamic shape factor

A2 Annual probability of exceedence of the action

A3 Aspect ratio

A4 Awning

A5 Canopy

A6 Cladding

A7 Design wind speed

A8 Discharge coefficient

A9 Downdraft

A10 Drag

A11 Dynamic response factor

A12 Eccentricity

A13 Effective surface

A14 Elevated building

A15 Enclosed building

A16 Escarpment

A17 First mode shape

A18 First mode natural frequency

A19 Force coefficient

A20 Free roof

A21 Freestanding walls

A22 Frictional drag

A23 Gable roof

A24 Hill

A25 Hip roof

A26 Hoardings

A27 Immediate supports (cladding)

A28 Lag distance

A29 Lattice towers

A30 Lift

A31 Mansard roof

A32 Monoslope roof

A33 Obstructions

A34 Permeable

A35 Pitched roof

A36 Pressure

A37 Pressure coefficient

A38 Rectangular building

A39 Reynolds number

A40 Ridge (topographic feature)

A41 Roughness length

A42 Scruton number

A43 Shelter room

A44 Solidity (of cladding)

A45 Structural elements, major

A46 Structural elements, minor

A47 Terrain

A48 Topography

A49 Tornado

A50 Tributary area

A51 Tropical cyclone

A52 Troughed roof

A53 Turbulence intensity

APPENDIX B - NOTATION

APPENDIX C - ADDITIONAL PRESSURE COEFFICIENTS FOR ENCLOSED BUILDINGS

C1 ADDITIONAL PRESSURE COEFFICIENTS

C2 MULTI-SPAN BUILDINGS ( 60°)

C3 BUILDINGS WITH CURVED ROOFS

C4 MANSARD ROOFS

C5 CIRCULAR BINS, SILOS AND TANKS

C5.1 General

C5.2 Isolated circular bins, silos and tanks

APPENDIX D - FREESTANDING WALLS, HOARDINGS, CANOPIES AND SOLAR PANELS

D1 GENERAL

D1.1 Application

D1.2 Area reduction factor (Ka)

D1.3 Local net pressure factor (K)

D1.4 Net porosity factor (Kp)

D2 FREESTANDING HOARDINGS AND WALLS

D2.1 Aerodynamic shape factor for normal net pressure on freestanding hoardings and walls

D2.2 Aerodynamic shape factor for frictional drag

D3 FREE ROOFS AND CANOPIES

D3.1 Aerodynamic shape factor for net pressure on free roofs

D3.2 Aerodynamic shape factor for frictional drag and drag on exposed members for free roofs

D4 ATTACHED CANOPIES, AWNINGS AND CARPORTS (ROOFS)

D4.1 Aerodynamic shape factor for net pressure on attached canopies

D4.2 Aerodynamic shape factor for frictional drag and drag on exposed members of attached canopies

D5 CANTILEVERED ROOFS

D6 SOLAR PANELS

APPENDIX E - AERODYNAMIC SHAPE FACTORS FOR EXPOSED STRUCTURAL MEMBERS, FRAMES AND LATTICE TOWERS

E1 GENERAL

E2 AERODYNAMIC SHAPE FACTORS FOR INDIVIDUAL MEMBERS AND FRAMES

E2.1 Simple shapes and individual members

E2.2 Single open frame

E2.3 Multiple open frames

E3 DRAG FACTORS FOR STRUCTURAL MEMBERS AND SIMPLE SECTIONS

E3.1 Rounded cylindrical shapes, sharp-edged prisms and structural sections

E3.2 Rectangular prismatic sections

E4 LATTICE TOWERS

E4.1 General

E4.2 Drag force coefficient

APPENDIX F - FLAGS AND CIRCULAR SHAPES

F1 GENERAL

F2 FLAGS

F3 CIRCULAR SHAPES

APPENDIX G - ACCELERATIONS FOR WIND-SENSITIVE STRUCTURES

G1 ACCELERATION FOR SERVICEABILITY

G2 PEAK ALONG-WIND ACCELERATION FOR SERVICEABILITY

G3 CROSSWIND ACCELERATION FOR SERVICEABILITY OF TALL BUILDINGS AND TOWERS OF RECTANGULAR CROSS-SECTION

G3.1 General

G3.2 Peak crosswind acceleration for serviceability