Each country has set characteristic snow loads on the ground for each portion of its territory.
The division is usually specified in the national annex of Eurocode 1 part 1-3.
Each country has set fundamental value of the basic wind velocity for each portion of its territory. The reference velocity corresponds to the average wind velocity over 10 minutes, measured at 10m above ground level on an 'open country' site with a return period of 50 years. The division is usually specified in the national annex of Eurocode 1 part 1-4.
Each country has set reference peak ground acceleration on type A ground for each portion of its territory. The type A ground has a stratigraphic profile like rock or other rock-like geological formation, including at most 5m of weaker material at the surface. The division is usually specified in the national annex of Eurocode 8 part 1-1.
First, you need to calculate the value of snow on the ground at the relevant site :
Then, you can take into account the annual probability of exceedence by calculating the ground snow load with a return period equivalent to the design working life of your building.
The wind direction is to be considered for several reasons :
For the calculation of wind actions, only a few wind directions are considered; for example the normal directions to the facades in the case of buildings. To accurately determine the peak velocity pressure, you will have to take into account many parameters such as :
Then you can calculate the wind peak velocity pressure:
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Coordinates | 6.9536° 43.4972° |
6.9455° 43.4994° |
6.9455° 43.4994° |
6.9368° 43.5019° |
---|---|---|---|---|
Elevations | 9m | 244m | 244m | 54m |
Obstacle effective height H | 235m | 190m | ||
Slope actual length L_{u} / L_{d} | 698.4m | 754.4m | ||
Slope angle Φ | 33.7% | 25.2% | ||
Horizontal distance site/top x | 483.1m | |||
Elevation at the place of construction | 58m |
Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|
Categories | IIIb | 0 | 0 | IIIb |
NF EN 1991-1-3/NA (may 2007) + A1 (july 2011)
NF EN 1991-1-4/NA (march 2008) + A1 (july 2011) + A2 (september 2012) + A3 (april 2019)
Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|
Sector definition | from 330 ° to 60 ° | from 60 ° to 150 ° | from 150 ° to 240 ° | from 240 ° to 330 ° |
Fundamental value of the basic wind velocity v_{b,0} | 24.0m/s | |||
Shape parameter K | 0.2 | |||
Exponent n | 0.5 | |||
Annual probability of exceedence p | 0.02 | |||
Probability factor c_{prob} | 1.0 | |||
Directional factor c_{dir} | 1.0 | 0.85 | 0.85 | 1.0 |
Basic wind velocity v_{b} | 24.0m/s | 20.4m/s | 20.4m/s | 24.0m/s |
Reference roughness length z_{0,II} | 0.05m | |||
Roughness length z_{0} | 0.5m | 0.005m | 0.005m | 0.5m |
Terrain factor k_{r} | 0.223 | 0.162 | 0.162 | 0.223 |
Height above ground z | 8.0m | |||
Minimum height z_{min} | 9.0m | 1.0m | 1.0m | 9.0m |
Roughness factor c_{r(z)} | 0.645 | 1.193 | 1.193 | 0.645 |
Obstacle type | isolated hills | |||
Exposure type | - | upwind | - | downwind |
Factor depending on the type and dimensions of the obstacle s _{max} | 0.0 | 0.8 | 0.0 | 0.8 |
Orography factor ^{*} c_{o(z)} | 1.0 | 1.235 | 1.0 | 1.112 |
Mean wind velocity v_{m(z)} | 15.5m/s | 30.1m/s | 24.3m/s | 17.2m/s |
Turbulence factor k_{l} | 0.923 | 1.0 | 1.0 | 0.923 |
Standard deviation of the turbulence σ_{v} | 4.943m/s | 3.299m/s | 3.299m/s | 4.943m/s |
Turbulence intensity I_{v(z)} | 0.319 | 0.11 | 0.136 | 0.287 |
Air density ρ | 1.225kg/m^{3} | |||
Exposure factor c_{e(z)} | 1.347 | 3.84 | 2.774 | 1.55 |
Peak velocity pressure q_{p(z)} | 475.1N/m^{2} | 978.9N/m^{2} | 707.1N/m^{2} | 546.7N/m^{2} |
Peak wind velocity for Serviceability Limit States v_{p(z),SLS} | 100.3km/h | 143.9km/h | 122.3km/h | 107.6km/h |
Peak wind velocity for Ultimate Limit States v_{p(z),ULS} | 122.8km/h | 176.3km/h | 149.8km/h | 131.7km/h |
Code of the Environment - Article D563-8-1 (09/01/2015) JORF n°0248 of 24/10/2010 text N°5