Snow and Wind Effects on Steel Structures in Canada: Design Considerations

Canada’s vast geography results in extreme snow loads, high winds, and regional climate variations, making steel structure design critical for safety and durability. Below is a detailed breakdown of key factors, codes, and solutions.

1. Snow Load Effects on Steel Structures in Canada

A. Regional Snow Load Variations

Canada’s snow loads vary dramatically by province:

B. Key Snow Load Design Factors

• Snow Drifting: Accumulates near parapets, roof steps, and adjacent structures.

• Sloped Roofs: Steeper roofs (≥30°) shed snow but require snow guards.

• Thermal Effects: Heated buildings can cause ice dams, increasing loads.

C. Canadian Snow Load Standards

• National Building Code of Canada (NBC 2020) – References CSA S16 (Steel Design) and CSA O86 (Snow & Wind Loads).

• Calculation Method:

  $$S=I_s[S_s(C_b{C}_w{C}_s{C}_a)+S_r]$$

  • $S_s$ = Ground snow load (site-specific)

  • $C_b$ = Roof slope factor

  • $C_w$ = Wind exposure factor

  • $C_a$ = Shape factor (for drifting)

D. Structural Solutions for Snow Loads

✔ Stronger Purlins & Girts – Thicker steel sections (e.g., C200x20 vs. C150x15).
✔ Roof Reinforcement – Additional bracing for unbalanced snow loads.
✔ Snow Retention Systems – Bars/clips to prevent sliding snow hazards.

2. Wind Load Effects on Steel Structures in Canada

A. Regional Wind Speed Variations

Canada’s wind loads depend on exposure, topography, and storm frequency:

B. Wind Load Design Factors

• Exposure Category: Open terrain vs. urban areas (NBC defines Exposure A, B, C).

• Dynamic Effects: Vortex shedding on tall, slender structures.

• Uplift Forces: Wind can rip off roofing if not properly anchored.

C. Canadian Wind Load Standards

• NBC 2020 & ASCE 7-22 – Used for reference in Canada.

• Calculation Method:

  $$P=q\cdot C_e\cdot C_g\cdot C_p$$

  • $q$ = Wind pressure (depends on $V$, air density)

  • $C_e$ = Exposure factor

  • $C_g$ = Gust factor

  • $C_p$ = Pressure coefficient

D. Structural Solutions for Wind Loads

✔ Moment-Resisting Frames – For lateral stability in high-wind zones.
✔ Enhanced Anchorage – Larger base plates (e.g., 400x400mm) with epoxy bolts.
✔ Aerodynamic Shapes – Sloped roofs, rounded corners to reduce drag.
✔ Wind-Resistant Cladding – Screwed (not just nailed) metal panels.

3. Combined Snow & Wind Load Considerations

• Unbalanced Loads: Wind can redistribute snow, creating uneven stresses.

• Uplift + Snow Weight: Simultaneous loads require stronger connections.

• Dynamic Effects: Blizzards combine heavy snow with high winds.

Case Study: Steel Warehouse in Toronto

• Snow Load: 2.2 kPa (NBC) → Reinforced purlins (C250x30).

• Wind Load: 1.1 kPa → Cross-bracing and hurricane ties.

• Result: 15% heavier steel framing than a comparable U.S. Midwest building.

4. Future Trends in Canada

• Climate-Adaptive Design: Accounting for increased snowfall/wind in some regions.

• Smart Sensors: IoT monitoring of snow accumulation and wind stress.

• Hybrid Materials: Steel-glulam composites for eco-friendly designs.

5. Conclusion

For Canadian steel structures, engineers must:
✅ Follow NBC 2020 + CSA S16 for snow/wind loads.
✅ Reinforce roofs and frames in high-snow regions (Quebec, Atlantic).
✅ Anchor securely in high-wind zones (Prairies, Atlantic).
✅ Monitor climate trends for future-proofing.