Eurocode 1 Wind load on monopitch canopies (net pressure coefficients and overall force coefficient)

Calculation of wind load action effects on monopitch canopies (i.e. roofs of structures not enclosed with permanent side walls). The net effect of the wind pressure on the upper and lower surface for zones A, B, C on the roof surface are calculated from the corresponding net pressure coefficients. The overall effect of the wind action on the structure is also calculated from the corresponding force coefficient.
According to:
EN 1991-1-4:2005+A1:2010 Section 7.3
Applicable for:
Roofs of structures not enclosed with permanent side walls such as petrol stations, dutch barns etc. Monopitch slope between 0 and 30°
Supported National Annexes:
A) Calculation of pressure coefficients: Only countries that adopt CEN recommended values for section 7.3 of EN1991-1-4 are supported. B) Peak velocity pressure: The value of the peak velocity pressure can be specified manually. Otherwise automatic calculation of peak velocity pressure is supported, in addition to countries that adopt the CEN recommended values for NDPs, also for the following National Annexes: Finland, Portugal. The National Annexes of Germany, Norway, Spain, Sweden, Switzerland are NOT supported (enter peak velocity pressure manually).
All Calculations

Hint: Select 'Custom peak velocity pressure' in the terrain category dropdown in order to manually specify the peak velocity pressure.

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. For a description of the terrain categories 0, I, II, III, IV see Calculation of peak velocity pressure.
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. Altitude correction may also be specified in the National Annex for EN1991-1-4 §4.2(2)P. The directional and season factors are generally cdir = 1.0 and cseason = 1.0. For particular cases values smaller than 1.0 may be specified in the National Annex for EN1991-1-4 §4.2(2)P.
The pitch angle value is given positive. Both wind directions are examined.
The ratio of the area of feasible, actual obstructions under the canopy divided by the cross sectional area under the canopy, both areas being normal to the wind direction. A value of φ=0 represents an empty canopy, and φ=1 represents the canopy fully blocked with contents to the down wind eaves only (this is not a closed building). See figure below.
Definiton of blockage factor for canopy roofs
Definiton of blockage factor for canopy roofs (see also EN1991-1-4 Figure 7.15)

Orography factor larger 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.
Nationally Defined Parameters
According to EN1991-1-4 §4.5(1) and the National Annex.
According to the National Annex to EN1991-1-4 §4.1(1), §4.2(1)P, §4.2(2)P, §4.3.1(1), §4.3.2(1), §4.3.5(1), §4.4(1), §4.5(1).
According to EN1991-1-4 §7.3(6) and the National Annex. The default value is 0.25 (i.e. center of pressure at d'/4, where d' is the inclined width of the rectangular plan parallel to the wind direction).
Note: Always verify the validity of the Nationally Defined Parameters (NDPs). Please inform us of any discrepancy using our Contact Form. The NDP value is left blank for all NDPs that we do not have this information available. Interested users who have access to the corresponding NDPs can notify us using our Contact Form to fill-in the missing information.