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# Eurocode 1 Wind load on free-standing walls and parapets (net pressure coefficients)

Description:
Calculation of wind load action effects on free-standing walls and parapets. The net wind pressure for zones A, B, C, D along the length of the structure are calculated from the net pressure coefficients corresponding to the overall effect on the front and back faces
According to:
EN 1991-1-4:2005+A1:2010 Section 7.4.1
Supported National Annexes:
A) Calculation of pressure coefficients: Only countries that adopt CEN recommended values for section 7.4.1 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).
Input

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.
m/s
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.
kPa
m
m
m
For walls standing on the ground hbase = 0. For parapets on buildings hbase is the height of the building
m
Length of return corner, approximately perpendicular to the wall face, as shown in EN1991-1-4 Figure 7.19
Solidity ratio φ = 1.0 corresponds to solid walls. Solidity ratio φ = 0.8 corresponds to walls with 20% openings. Solidity ratios less than 0.8 are not supported in this calculation

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.
Nationally Defined Parameters
kg/m3
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 the National Annex to EN1991-1-4 §7.4.1(1).
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.