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Wind Loading

Background

Standards

Design

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Wind Loading

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Wind Loading

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Wind Loading

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Wind Loading

CP3: Chapter V: Part 2

Code of basic data for the design of buildings

Chapter V . Loadings Part 2. Wind loads

BS 6399-2:1997

Loadings for buildings Part2: Code of practicefor wind loads

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Wind Loading - CP3

Wind Speed - 3 second gust

Exposure

Open Country

Open Country, scattered wind breaks

Small towns, outskirts of cities

City centres

Building Height

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Wind Loading - BS6399

Standard Method

Directional Method

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Wind Loading - BS6399

Site Wind Speed

Vs= Vbx Sax Sdx Ssx Sp

VbBasic wind speed

SaAltitude factor

SdDirection factor

SsSeasonal factor

SpProbability factor

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Wind Loading - BS6399

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Wind Loading - BS6399

Altitude factor

Sa= 1+ 0.001x Height above sea level

If topography not significant

As a generalisation any building more than half-way up

a hill, or an on a ridge or cliff will have increase wind

loading and a more detailed calculation of Sa will berequired

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Wind Loading - BS6399

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Wind Loading - BS6399

SdDirection factor

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Wind Loading - BS6399

SsSeasonal factor = 1

SpProbability factor = 1

1 in 50 years storm

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Example calculation

Vs= Vbx Sax Sdx Ssx Sp

Sa =1.005

Sd =1

Ss = 1

Sp = 1

Vs = 16.63 x 1.01 x 1 x 1 x1 = 16.80 m/s

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Wind Loading - BS6399

Effective wind speed

Ve= Vsx Sb

Sb= Terrain & Building Factor

Site in town or country

Distance from the sea

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Wind Loading - BS6399

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Example calculation

Ve = Vs x Sb

Sb = 1.97 for distance 30 km from sea and He= 26.2 m

Ve = Vs x Sb = 16.80 x 1.932 = 32.5 m/s

Building size:

H = 26.2 mL = 44.3 m

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Wind Loading - BS6399

Dynamic Pressure

qs= 0.613 x Ve2

qs= 0.613 x (32.5)2 =647.5 N/m2

=0.65 kN/m2

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Wind Loading - BS6399

Pressure to structure

External pressure

pe= qsx Cpex Ca

Cpe is the external pressure coefficient

Cais the size effect factor = 1

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Wind Loading - BS6399

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Wind Loading - BS6399

Internal pressure

pi= qsx Cpix Ca

Cpi is the internal pressure coefficient

Cais the size effect factor = 1

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Wind Loading - BS6399

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Wind Loading - BS6399

Wind Loads

p = pe- pi

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Wind Loading - BS6399

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Wind Loading - BS6399

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Wind Loading - BS6399

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Wind Loading - BS6399

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Malaysia Wind Map

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Wind speed gust

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Page 34 *Sources of data: Razali A M et al Mapping of Annual Extreme Wind Speed