WIND FRENCH NORM NV65 I – General points 1. Definitions Hypothesis : for all buildings, the direction of the wind is horizontal.. Def1: Mater couple : orthogonal projection of the wind surface on a perpendicular surface to the wind direction. Elements to determine : − − −

Def2 : Dynamic pressure :

dynamic pressure q proportions (ratios λ et φ) ν and c

pressure exercised on a flat surface perpendicular to the wind, so as the wind speed become null.

The wind force is perpendicular to the structure and depends on the wind speed V, the properties of the structure, its orientation in relation to the wind and its form and dimensions. In Dynamics is defined a normal pressure qn and an extremal pressure qext such as : qext =1.75 qn

Def3 : Nominal pressure : for a classic location, without any area effect or mask effect, for every element which higher dimension is higher than 0.5m, the basic pressures qn and qext qre those calculated 10 m above the ground level. Those pressures are defined in tables and maps (see pp 47-52 NV 65 for France). They will be called qn10 and qext10 or more easily q10 when formulas will be set for both. Def4 : Permeability of the walls : the permeability µ of a structure is defined as the ratio of the total surface opened to the wind on the global surface of the structure. A structure is called 'closed' if µ