Abstract:

ESDU 84011 provides a simplified method of estimating the variation of design wind speed (mean-hourly or gust values) with height about the ground and with terrain roughness. The data for flat terrain (which are based on relationships given in ESDU 82026 and 83045) are presented in the form of tables giving a factor (K) by which a wind speed at 10 m (33 ft) over open country terrain must be multiplied to give the wind speed at the required height over the site in question. K-factors are provided for a range of heights up to 400 m (1310 ft), gust averaging times and combinations of terrain roughness at the site with a single change in roughness at varying distances upwind of the site. It is also shown how the tabulated data can be used to generate wind speed profile data for multiple changes in terrain roughness. ESDU 84030 complements ESDU 84011 by providing values of turbulence intensity for all cases for which ESDU 84011 provides wind speed data.