September 23, 2011
Of all the environmental loads on buildings and structures, wind is perhaps the most damaging. Almost three-fourths of all catastrophe claims paid by insurance carriers in the last 20 years have been for hurricane and tornado damage.
When wind is obstructed by a building or structure, it must change direction, resulting in a force being applied to the obstacle. The nature and magnitude of wind forces on structures are complex functions of shielding, stagnation, vortex shedding, and other phenomena. Building codes provide approximate relationships between wind speed and wind pressure on building and structure components that are intended to be used for design. More precise mapping of actual wind pressures requires wind-tunnel testing, or in some circumstances, computer modeling of the wind flow. However, experience shows that wind pressures are typically highest at architectural discontinuities high on the structure, such as roof eaves, dormers, or parapet corners, and wind damage often starts at these locations.
Exponent provides holistic wind engineering solutions to help our clients understand the wind hazard, the mechanisms and contributing cause(s) of wind damage, and the best measures to mitigate risk of future damage. We have helped owners of facilities in areas of high wind hazard quantify and mitigate their risks, and we have helped insurance carriers investigate the cause(s) and differentiate damage mechanisms after storms (including hundreds of structures after Hurricane Katrina).