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Wind zones map - Belgium

What are the Belgian wind zones according to Eurocode 1 ?

On the map of the national annex, the Belgian area is divided into four wind zones.
Fundamental value of the basic wind velocity vb,0 23m/s 24m/s 25m/s 26m/s
Eurocodes - Wind zones map - Belgium (2010-2023) Wind zoning of Belgium (2010-2023)

How to adjust the basic wind velocity for each direction of wind and according to return period in Belgium ?


A variation have to be considered with the probability factor cprob.

When the wind comes from a direction where the probability of occurrence of strong winds is less, a reduction can be considered with the directional factor cdir.

You should also take in account the effect of the roughness of the terrain (vegetation / urbanization) and the effect of orography (terrain relief) to accurately determine the peak velocity pressure for each wind direction.

Which are the terrain categories in Belgium ?

Example of results given by the software

See the features of Eurocodes Zoning for wind analysis in Belgium
Available in English/French, otherwise «Google Translate»!

B1 - Localization

Belgian flag
4.9053° , 50.2445°
688279m , 603864m
Large map
Simple map
Rondchêne, 5500 Dinant, Wallonie

B2 - Elevations

Elevation map to calculate orography factor
Coordinates 4.9013°, 50.241° 4.9044°, 50.2436°
Elevations 96m 189m
Obstacle effective height H 93m
Slope actual length Lu / Ld 361.4m
Slope angle Φ 25.7%
Horizontal distance site/top x 121.2m
Elevation at the place of construction 197m

B3 - Building

common building with floors (apartments and/or office spaces)
100years
7.0m
35°

B4 - Terrain categories

Terrain map
Sectors 1 2 3 4
Categories II II III II
Radius R of the angular sector : 300m

C1 - Snow NBN EN 1991-1-3 ANB (october 2007)

Belgium (sk,0 = 0.5kN/m2)
Dinant, Namur
sk,197m = 0.613 kN/m2

s100ans = 0.695 kN/m2

C2 - Wind NBN EN 1991-1-4 ANB (december 2010)

24 m/s
Dinant, Namur
Belgium
Sectors 1 2 3 4
Sector definition from 350° to 80° from 80° to 170° from 170° to 260° from 260° to 350°
Fundamental value of the basic wind velocity vb,0 24.0m/s
Shape parameter K 0.2
Exponent n 0.5
Annual probability of exceedence p 0.01
Probability factor cprob 1.038
Directional factor cdir 1.0 0.983 1.0 1.0
Basic wind velocity vb 24.9m/s 24.5m/s 24.9m/s 24.9m/s
Reference roughness length z0,II 0.05m
Roughness length z0 0.05m 0.05m 0.3m 0.05m
Terrain factor kr 0.19 0.19 0.215 0.19
Height above ground z 7.0m
Minimum height zmin 2.0m 2.0m 5.0m 2.0m
Roughness factor cr(z) 0.939 0.939 0.678 0.939
Obstacle type cliffs
Exposure type - - downwind -
Factor depending on the type and dimensions of the obstacle s max 0.0 0.0 0.598 0.0
Orography factor* co(z) 1.0 1.0 1.308 1.0
Mean wind velocity vm(z) 23.4m/s 23.0m/s 22.1m/s 23.4m/s
Turbulence factor kl 0.995 0.995 1.247 0.995
Standard deviation of the turbulence σv 4.713m/s 4.634m/s 6.696m/s 4.713m/s
Turbulence intensity Iv(z) 0.201 0.201 0.303 0.201
Air density ρ 1.25kg/m3
Exposure factor ce(z) 2.124 2.124 2.456 2.124
Peak velocity pressure qp(z) 824.7N/m2 797.5N/m2 953.3N/m2 824.7N/m2
Peak wind velocity for Serviceability Limit States vp(z),SLS 130.8km/h 128.6km/h 140.6km/h 130.8km/h
Peak wind velocity for Ultimate Limit States vp(z),ULS 160.2km/h 157.5km/h 172.2km/h 160.2km/h
* The orography factor is calculated for a well individualized obstacle (an emergent zone compared to a general ground without marked relief)

C3 - Seism NBN EN 1998-1 ANB (october 2011)

1 (0.39m/s2)
Dinant, Namur
A seismic analysis may be required for this building.