Wind Speed Structural Damage Risk Calculator
Estimates structural damage risk and expected damage level based on wind speed, building characteristics, and site exposure using ASCE 7 wind load principles and Beaufort/Saffir-Simpson damage correlations.
3-second gust speed at 33 ft (10 m) above ground
Mean roof height above ground
Older buildings may have lower resistance
Results will appear here.
Formulas Used
Velocity Pressure Coefficient (ASCE 7-22 Eq. 26.10-1):
Kz = 2.01 × (z / zg)2/α
Velocity Pressure:
qz = 0.00256 × Kz × Kzt × Ke × V² (lb/ft²)
Design Wind Pressure:
p = qz × G × Cf × I (lb/ft²)
where G = 0.85 (gust factor), Cf = 1.3 (force coefficient), I = importance factor
Demand-to-Capacity Ratio:
DCR = p / Capacityadjusted
Capacityadjusted = Capacitybase × (1 − 0.003 × Age), min 70% of base
Risk Score:
Risk = min(100, (DCR / 2.0) × 100)
Assumptions & References
- Wind speed is the 3-second gust speed at 33 ft (10 m) above ground, consistent with ASCE 7-22 Section 26.5.
- Topographic factor Kzt = 1.0 (flat terrain assumed). Hilly or escarpment sites require higher values.
- Ground elevation factor Ke = 1.0 (sea level). Adjust per ASCE 7-22 Table 26.9-1 for high elevations.
- Gust factor G = 0.85 applies to rigid structures (natural frequency ≥ 1 Hz). Flexible structures require dynamic analysis.
- Force coefficient Cf = 1.3 is a simplified value for enclosed rectangular buildings. Actual values vary by geometry.
- Building resistance capacities are representative typical values; actual capacity depends on specific structural design.
- Age degradation of 0.3%/year is an approximation; actual degradation depends on maintenance, materials, and environment.
- Saffir-Simpson and Beaufort classifications are used for contextual reference only, not for structural design.
- References: ASCE 7-22 (Minimum Design Loads for Buildings and Other Structures); Saffir-Simpson Hurricane Wind Scale (NHC); Beaufort Wind Scale (WMO).
- This calculator provides a simplified risk estimate only. Always consult a licensed structural engineer for design, retrofit, or safety decisions.