Eurocode 1 Wind load on signboards (force coefficient)

Calculation of wind load action effects on signboards with rectangular surface area. The total horizontal force, horizontal eccentricity, and base overturning moment are calculated from the force coefficient corresponding to the overall effect of the wind action on the structure
According to:
EN 1991-1-4:2005+A1:2010 Section 7.4.3
All Calculations
The basic wind velocity is given as vb = vb,0cdircseason where the fundamental value of basic wind velocity vb,0 is defined in EN1991-1-4 §4.2(1)P and its value is provided in the National Annex. The directional and season factors are generally cdir = 1.0 and cseason = 1.0. Values different than 1.0 may be specified in the National Annex for EN1991-1-4 §4.2(2)P
The terrain categories are illustrated in EN1991-1-4 Annex A. The transition zones between terrain categories are specified in EN1991-1-4 §A.2.
Wind terrain category 0 Wind terrain category I Wind terrain category II Wind terrain category III Wind terrain category IV
Illustration of Terrain categories reproduced from EN1991-1-4 Annex A
Notation for wind load on signboards according to EN1991-1-4
Notation for signboards, reproduced from EN1991-1-4 Figure 7.21

Orography factor different than 1.0 may be applicable over isolated hills and escarpments. See EN1991-1-4 §4.3.3 and §A.3 for more details.
Structural factor cscd in accordance with EN1991-1-4 Section 6. A value of cscd = 1.0 is generally conservative for small structures not-susceptible to wind turbulence effects such as buildings with height less than 15 m.