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Specified Wind Load

CL 4.1.7.3 (NBC 2020)
v1.0.1
File:
Project:
Designer:
Date:

Climatic Data

Source
Region
Location
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Velocity Pressure
Return Period:
Reference Velocity Pressure
q:
kPa

Factors

Importance factor
Iw:
Limit state:
Building dimensions
Building height, H:
m
Building width parallel to wind direction,
D:
m
Midheight of dominant opening (for Cei)
Midheight, hi:
m (leave empty if no dominant opening.)
Input Parameters
Exposure Factor
Terrain:
Exterior gust factor,
Cg:
(to be 2.0 for the building as a whole and main structural members)
Interior gust factor,
Cgi:
Topographic factor,
Ct:
Internal pressure Category, Cpi:
info
Building Openings: [CL: 4.1.7.1]
Category 1: Uniformly distributed small openings amounting to less than 0.1% of the total surface area of the building.

Category 2: Non-uniformly distributed openings of which none is significant or significant openings that are wind-resistant and closed during storms.

Category 3: Large openings likely to remain open during storms.

For cladding on parapets use Category 3.
Specific design elevation above grade,
Z:
m
Number of design steps,
n:

Factors

User input values:
q: 1kPa
Importance Factor, ULS: Iw = 1.0
(Note: No load factors are applied to the results below.)
Ct = 1

External Wind Pressures

p = Iw*q*Ce*Ct*Cg*Cp

Windward Face

H/D = 1
Ce = Ce(Z)
Cp = 0.8

On Leeward Face

Ce(H/2) = Ce = (h/10)0.2 (but not less than 0.9) = 0.9
Cp = -0.5
p = Iw*q*Ce(H)*Ct*Cg*Cp = -0.9 kPa
 
Z (m) Ce(Z) p
(windward)
(kPa) 		p
(leeward)
(kPa) 		p
(combined)
(kPa)
roof:1 0.9 1.44 -0.9 2.34
0.75 0.9 1.44 -0.9 2.34
0.5 0.9 1.44 -0.9 2.34
0.25 0.9 1.44 -0.9 2.34
grade: 0 0.9 1.44 -0.9 2.34
specified: 0 0.9 1.44 -0.9 2.34

 

On Roof

Ce(H) = Ce = (h/10)0.2 (but not less than 0.9) = 0.9
Cp = -1
p = Iw*q*Ce(H)*Ct*Cg*Cp = -1.8 kPa

On Side Walls

Ce(H) = Ce = (h/10)0.2 (but not less than 0.9) = 0.9
Cp = -0.7
p = Iw*q*Ce(H)*Ct*Cg*Cp = -1.26 kPa

Internal Wind Pressure

Cgi = 2.0
Cpi = 0.3 to -0.45
Reference height (max H/2 or 6m)= 6 m
Cei = (hi/10)0.2 (but not less than 0.9) = 0.9
pi = Iw*q*Cei*Ct*Cgi*Cpi
pi = 0.54kPa to -0.81kPa

This information must be read or used in conjunction with Part 4 of the NBC 2020. In the event of discrepancies, Part 4 of the NBC 2020 shall govern.

© 2009–2025 Modulo Software Inc.
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