Wind Load (Generic Formula) Formula |
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| \( F \;=\; A \cdot p_w \cdot C_d \) |
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| Symbol | English | Metric |
| \( F \) = Wind Load | \(lbf\) | \(N\) |
| \( A \) = Area of the Object Perpendicular to the Wind | \(ft^2\) | \(m^2\) |
| \( p_w \) = Wind Pressure | \(lbf\;/\;in^2\) | \(Pa\) |
| \( C_d \) = Drag Coefficient, which Depends on the Shape of the Object | \(dimensionless\) | \(dimensionless\) |
Wind load is the dynamic forces or pressures exerted by wind on a building, bridge, or other structure, including its exterior walls, roof, and individual components. This is a critical dynamic load that structures must be designed to withstand to prevent collapse, excessive movement (sway), or failure of cladding and roofing materials. The magnitude of the wind load is not uniform and depends on several factors, primarily the "basic wind speed" for the structure's location (derived from historical weather data), its "exposure category" (which classifies the roughness of the surrounding terrain, such as open fields versus dense urban areas), and the "building's geometry" (its height, shape, and stiffness).
Wind creates a positive, pushing pressure on the windward face of a structure and a significant negative pressure, or suction, on the side and leeward faces and on the roof, which creates an uplift force. Structural engineers use established building codes, like those from the American Society of Civil Engineers (ASCE 7) or the historical Uniform Building Code (UBC), which provide detailed formulas and coefficients, such as the Gust Effect Factor and Pressure Coefficients to accurately calculate the total design wind load that the entire structure, and every component within it, must safely resist.
