Wind Loading per TIA-222-H
TowerPlot calculates wind loads following ANSI/TIA-222-H (2018) methodology.
Design Wind Force on Structure
FST = qz × Gh × (EPA)S
Where:
- qz = Velocity pressure at height z
- Gh = Gust effect factor
- (EPA)S = Effective Projected Area of the structure
Velocity Pressure
Per ANSI/TIA-222-H Eq. 2-1:
qz = 0.613 × Kz × Kzt × Ks × Ke × Kd × V² [N/m²]
| Factor | Name | Source |
|---|---|---|
| Kz | Velocity pressure exposure coefficient | TIA-222-H Table 2-3 |
| Kzt | Topographic factor | TIA-222-H Section 2.6.6 |
| Ks | Rooftop speed-up factor | TIA-222-H Section 2.6.6 |
| Ke | Ground elevation factor | TIA-222-H Table 2-2 |
| Kd | Wind directionality factor | TIA-222-H Table 2-6 |
| V | Basic wind speed | User input / local codes |
TIA-222-F
TIA-222-F does not use Kd, Kzt, Ks, or Ke factors. The velocity pressure simplifies to qz = 0.613 × Kz × V².
EPA Per Section
(EPA)s = Cf × [Df × Af + Dr × Ar × Rr]
| Variable | Meaning |
|---|---|
| Cf | Force coefficient for flat members (from solidity ratio, TIA-222-H Table 2-8) |
| Af | Projected area of flat/angular members |
| Ar | Projected area of round members |
| Df, Dr | Direction factors for flat and round members per TIA-222-H Table 2-7 |
| Rr | Round member reduction factor |
Solidity Ratio
The solidity ratio determines the force coefficient:
ε = (Af + Ar) / Ag
Where Ag is the gross area of the tower face (panel height × panel width).
- Lower solidity → higher Cf (less shielding)
- Higher solidity → lower Cf (more shielding)
- TowerPlot interpolates Cf from TIA-222-H Table 2-8 based on the calculated solidity ratio
Wind Directions
| Cross Section | Total Directions | Description |
|---|---|---|
| Triangular | 9 | 3 faces × 3 approach patterns per face |
| Square | 8 | 4 faces × 2 approach patterns per face |
The governing direction (producing highest member forces) is automatically identified.
See also: TIA-222-H Reference for the complete standard mapping.