Exposure model for wind loading of buildings

Previous studies on the variation of wind mean speed profile with inhomogeneous terrain usually assumed that wind speed profiles sense the roughness averaged in a large-scale terrain-grid, so terrain roughness patches of different distance to the site are regarded of equal importance. Recent studies have pointed out the significance of local, small-scale roughness changes in terrain-grid of the order of 100 m. The paper investigates the variation of wind speed profile above inhomogeneous terrain with small-scale upstream roughness changes, especially those close to the site. Both wind tunnel experiments and numerical simulations are carried out. The experimental findings are used to formulate an easy to use wind speed model, which provides results in good agreement with a limited set of full-scale data. The comparison of this model with ESDU model is also discussed. The proposed model may better describe the building exposure in terms of upstream terrain conditions closer to the site of study, and help on the terrain-related code specifications.