How to calculate wind loads from wind speeds

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Wind load is a determination of the amount of stress a structure experiences at a given wind speed. This calculation is important when determining the height of a building, antenna or even the mast on a sailboat. Determining actual wind load for even a simple structure is a complex process and should be done by a design engineer. The generic formula given below should be used only for rough estimates, not for final building designs. If you are building a tall structure, consult an engineer for accurate calculations. Contact a marine architect if you are designing a sailboat.

Calculate the force exerted by the wind at your target speed by squaring the speed in miles per hour and multiplying the answer by .00256.

For a 30mph wind the calculation would be

30 * 30 * .00256 = 2.304.

This is the amount of pressure, per square foot, a 30mph wind exerts.

Multiply the force determined Step 1 by the structure's surface area. With a 30mph wind and a structure with a surface area of 100 square-feet, the calculation is

2.304 * 100 = 230.4.

Multiply your answer from Step 2 by the structure's drag coefficient. For a flat square structure, multiply by 2.0. For a rounded structure, use 1.2.

For flat structure with a surface area of 100 square feet, a 30mph wind would create a wind load of

230.4 * 2.0 = 209 Kilogram.

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