Steel structure buildings must be designed to withstand wind and snow loads as specified by relevant building codes and standards (e.g., ASCE 7 in the US, Eurocodes in Europe, or GB 50009 in China). The specific requirements depend on the building's location, geometry, height, and exposure.

1. Wind Load

Wind load is the pressure exerted by wind on a structure. Key factors include:

Basic Wind Speed: Determined from wind maps based on geographic location and return period (e.g., 50-year or 100-year mean recurrence interval).

Exposure Category: Accounts for terrain roughness (e.g., open, suburban, or urban areas).

Building Height and Shape: Affects wind pressure distribution. Dynamic effects (gust factors, vortices) must be considered for tall or flexible structures.

Importance Factor: Adjusts for the building's occupancy category (e.g., higher for essential facilities).

Wind load calculations typically consider:

Design wind pressure on walls and roofs.

Uplift forces on roofs.

Internal pressure for enclosed or partially enclosed buildings.

2. Snow Load

Snow load is the weight of accumulated snow on the roof. Key factors include:

Ground Snow Load: Based on historical data for the location (often provided in code maps).

Roof Slope: Steeper roofs reduce snow accumulation.

Thermal Factor: Accounts for heat loss through the roof (e.g., unheated vs. heated buildings).

Exposure Factor: Wind exposure can scour or drift snow.

Importance Factor: Similar to wind load, based on building occupancy.

Special considerations include:

Snow Drifts: Accumulation near parapets, roof steps, or obstructions.

Unbalanced Loads: For sloped or curved roofs.

Rain-on-Snow Surcharge: In regions with heavy rain and snow.

Design Principles for Steel Structures

Load Combinations: Wind and snow loads are combined with dead, live, and other loads as per code requirements (e.g., 1.2D + 1.6S + 0.5L).

Structural System: Steel frames, trusses, and connections must be designed for these loads. Bracing systems resist lateral forces from wind.

Roof Design: Roof purlins, decks, and connections must handle uplift from wind and weight from snow. Ponding (water accumulation) should also be considered.

Fatigue and Durability: Cyclic wind loads may cause fatigue in connections. Corrosion protection (e.g., galvanizing) is critical in snowy climates.

Best Practices

Use updated code provisions and site-specific data.

Consider climate change effects on extreme weather loads.

Engage a qualified structural engineer for design and verification.

Regularly inspect and maintain the structure, especially after severe weather events.

Note: Always consult local building codes and a licensed engineer for project-specific requirements.