Windlast

Windlast, literally meaning wind load, is the external force exerted by wind on structures. It is a central concept in structural engineering and is used to assess the stability, safety, and performance of buildings, bridges, towers, and other constructions. Wind loads act as pressure on exposed surfaces, with positive pressures on the windward side and suction on the leeward side or roofs, depending on shape and orientation. Local effects at edges and corners can amplify the pressure.

Calculation of wind loads depends on wind speed, exposure, terrain roughness, and height. The dynamic pressure q = 0.5*rho*v^2 is distributed over surfaces using pressure coefficients or wind-flow models to obtain surface pressures, which are integrated to yield force results or pressure distributions. Because wind is gusty and turbulent, designers also apply gust factors and consider dynamic effects such as buffeting. Windloads are specified as load cases in structural analyses and are combined with other actions (live load, earthquake, etc.) to assess performance.

Standards: In Europe, wind actions are treated in EN 1991-1-4 (Eurocode 1), which defines basic wind speeds, exposure categories, and methods to compute wind loads. National annexes tailor these rules to local conditions. Similar frameworks exist worldwide, including ASCE 7 in the United States.

Applications: Windlast informs the design and assessment of buildings, bridges, towers, masts, wind turbines, and façades. Proper treatment ensures safety, serviceability, and durability under wind events.