ASCE 7-22
ASCE 7-22 Chapter 26 | General Wind Load Requirements
Wind exerts a dynamic pressure against a building based on the wind's speed, the terrain roughness, and the height above the ground. Taller structures in open terrain attract much higher wind pressures.
Governing Formula
Variables
Velocity pressure evaluated at height z
psf
Velocity pressure exposure coefficient
unitless
Topographic factor
unitless
Wind directionality factor
unitless
Basic wind speed (3-second gust)
mph
Quick Example
1
Determine basic wind speed
Look up V based on Risk Category and location mapping (e.g., V=115 mph).
2
Find exposure factors
Based on height (z) and Exposure Category (e.g. C), look up Kz.
3
Calculate velocity pressure
Multiply constants together.
When does this govern?
Wind load design directly dictates the lateral bracing system for most low-to-mid rise buildings outside of active faults, and dominates cladding design.
Common Mistake
Using the wrong exposure category. Using Exposure B (suburban) when there is a large open clearing or body of water immediately upwind that warrants Exposure C.