Utilisateur Story
Dans cet exemple, nous allons calculer des valeurs de force moyennes pour une section de pont, telles que celles applicables aux sections structurelles dans le processus de vérification basées sur WTG-merkblat-M3
This example belongs to Group 1 according to Figure 2.2 in WTG-Merkblatt-M3 is:
- G2: Absolute values with medium accuracy requirements. The area of application can include parameters or preliminary studies when later investigations with higher accuracy are planned (e.g., wind tunnel examination of class G3).
- R2: Solitary, all relevant wind directions with sufficiently fine directional resolution.
- Z1: Statistical mean values, provided they concern stationary flow processes where fluctuations (e.g., due to approaching flow turbulence) can be sufficiently captured by other measures.
- S1: Static effects. It is sufficient to represent the structural model with the necessary mechanical detail, but without mass and damping properties.
Les dimensions de l'exemple sont indiquées sur la Figure 01 et l’hypothèse d’entrée est illustrée dans le Tableau 1 :
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Tableau 1 : Données d’entrée de l’exemple de vérification d’une section de pont
| Model | Bridge Section |
|---|---|
| Vitesse de référence du vent | V = 30 m/s |
| Densité de l'air | ρ = 1.225 kg/m³ |
| solveur | Pressure-Based |
| Modèle de turbulence | Steady k-ω SST |
| Type of wind velocity profile | Constant in height |
| Intensité de la turbulence | 27% |
| Numerical algorithm | SIMPLE algorithm |
| Discrétisation | Second ordre |
| Pression résiduelle | 10⁻⁴ |
| Viscosité cinématique | ν = 1.5 × 10⁻⁵ |
Also, the computational mesh study needs to be performed according to the following link:
Dans cet exemple, nous allons comparer la valeur moyenne de la force du vent en direction x entre l’EN 1991-1-4 et RWIND. The force coefficient cfx,o for bridge sections can be obtained using Figure 8.3 in EN 1991-1-4:
Force en direction X - Méthode simplifiée
Where it has been assessed that a dynamic response procedure is not necessary, the wind force in the x-direction may be obtained using Expression (8.2) in EN 1991-1-4:
vb=30 m/s is the essential wind speed
C is the wind load factor. C=ce⋅cf,x=1.425×1.3=1.85 , where ce is the exposure factor given in 4.5 and cf,x is given in 8.3.1(1)
Aref,x=5 m2 is the reference area given in 8.3.1
ρ=1.225 kg/m3 is the density of the air
Force Results in RWIND and Comparison to Eurocode
Dans RWIND, les résultats des forces totales du vent sont disponibles dans l’onglet « Informations » dans Modifier le modèle, comme le montrent les Figures 2 et 3. The difference between critical wind direction scenario RWIND (θ=0°) and Eurocode is about 5.36% (less than the criteria in WTG = 10%), which shows acceptable agreement:
