Snow Load and Wind Load in Steel Frame Structures: Key Considerations

Steel frame structures must be designed to withstand environmental loads, particularly snow and wind, to ensure safety and longevity. Here’s a breakdown of their impact and how they influence steel frame design.

1. Snow Load on Steel Structures

Definition: The weight of accumulated snow on a roof, measured in kN/m² or psf (pounds per square foot).

Factors Affecting Snow Load

• Geographic Location – Heavier snow in northern Europe, Canada, and mountainous regions.

• Roof Slope – Steeper roofs shed snow more easily (reducing load).

• Roof Shape – Curved or sawtooth roofs may accumulate snow unevenly.

• Thermal Properties – Insulated roofs retain snow longer (higher load).

• Drifting – Snow accumulates near parapets, roof steps, and valleys.

Design Considerations

• Minimum Snow Load – Building codes (e.g., Eurocode 1 (EN 1991-1-3), ASCE 7 (USA) specify regional requirements.

• Partial Loading – Engineers must account for uneven snow distribution.

• Snow Guards – Prevent sudden sliding (important for steep roofs).

Typical Snow Loads (Examples)

2. Wind Load on Steel Structures

Definition: The force exerted by wind, causing lateral pressure, uplift, and dynamic effects on the structure (measured in kN/m² or psf).

Factors Affecting Wind Load

• Wind Speed – Higher in coastal, open, or hurricane-prone areas.

• Building Height & Shape – Taller buildings face greater wind forces.

• Topography – Hills and valleys can funnel wind, increasing loads.

• Exposure Category – Open terrain vs. urban areas (more obstructions reduce wind impact).

• Dynamic Effects – Vortex shedding can cause oscillations in slender structures.

Design Considerations

• Wind Zone Maps – Codes (e.g., Eurocode 1 (EN 1991-1-4), ASCE 7) classify regions by wind speed.

• Pressure Coefficients – Account for suction (uplift) on roofs and walls.

• Cladding & Fasteners – Must resist wind-induced vibrations.

• Aerodynamic Shapes – Sloped or rounded roofs reduce wind drag.

Typical Wind Loads (Examples)

3. Combined Load Effects on Steel Frames

• Dead Load + Snow/Wind – Structures must handle simultaneous loads (worst-case scenarios).

• Uplift Risk – Strong winds can lift roofs if not properly anchored.

• Deflection Limits – Excessive movement can damage cladding.

Structural Solutions

✔ Stronger Connections – Bolted/welded joints to resist wind uplift.
✔ Bracing Systems – Diagonal bracing or moment frames for lateral stability.
✔ Roof Pitch Optimization – Sloped roofs (≥10°) reduce snow accumulation.
✔ Wind & Snow Drift Analysis – Advanced software (e.g., STAAD.Pro, RFEM) ensures compliance.

4. Key Design Codes & Standards

5. Conclusion

• Snow Load → Dictates roof strength, slope, and insulation needs.

• Wind Load → Impacts bracing, cladding, and foundation design.

• Combined Loads → Must be analyzed for structural integrity.

Best Practice: Work with a structural engineer to perform site-specific load calculations and ensure compliance with local codes.