Fire Protection & Steel Space Frames: How to Safeguard Your Structure Against Fire

 Steel space structures offer the advantages of long spans, lightweight construction, and high strength. However, in a fire environment, steel's strength rapidly decreases as temperatures rise. Without proper fire protection design and materials, structural stability and safety can be seriously compromised. This article will introduce the fire protection principles, common fire protection methods, design considerations, and practical recommendations for steel space frames.

Fire Behavior of Steel & Why Protection Matters

Steel's strength decreases significantly at high temperatures. For example, at temperatures of approximately 550-600°C, steel's yield strength may only be approximately 40-60% of its original strength.

Fire protection codes typically require structural steel to provide a fire resistance rating of a certain number of hours (e.g., 1 hour, 2 hours, or more) to ensure evacuation, fire control system response, and prevent premature structural failure.

Common Fire Protection Methods for Steel Space Frames

Passive Fire Protection (PFP)

Steel components are protected passively to maintain their strength and stability during a fire. Common methods include:

Spray-applied fire-resistant materials (SFRMs)—such as mineral fibers, cement-based materials, or lightweight aggregate mixtures.

Intumescent coatings: These expand at high temperatures to form a char layer, providing thermal insulation and fire resistance while also offering a good appearance, making them suitable for exposed steel structures.

Fire-rated boards or board insulation: Fire-rated boards are applied to steel beams or joints to provide a longer-lasting fire barrier.

Active Fire Protection Measures

While passive fire protection is critical, active protection systems should not be neglected, especially in large public or high-risk buildings. These include sprinkler systems, fire detectors and alarm systems, and fire suppression equipment.

Structural Design for Fire Resistance

Select steel components with large cross-sections, good cross-sectional mass, and slow thermal conductivity to provide better inherent fire resistance.

Consider the thickness of the fireproofing layer in the design and determine the thickness of the coating or cladding material on the component to meet code requirements.

Consider fire loads, fire exposure time, and temperature curves (standard fire curves or performance-based fire design) to verify the deformation and load-bearing capacity of the component under fire conditions.

Environmental & Durability Considerations

When selecting fireproofing materials, consider their durability in outdoor or harsh environments (such as humidity, corrosion, and temperature fluctuations). Tropical or exposed locations may have additional requirements for fireproofing coatings and cladding panels.

Design & Implementation Best Practices

Clarify the required fire protection rating (e.g., 1 hour, 2 hours, or more) and determine it based on factors such as application, building height, occupancy density, and evacuation needs.

Combining multiple fireproofing methods in accessible and difficult-to-access areas of steel components, such as cladding at joints and spraying or applying intumescent coatings on beam webs.

Strictly control the quality of fireproofing materials during the construction phase to ensure that coating thickness, adhesion, and coverage meet design requirements.

Regularly inspect and maintain the fireproofing layer. Damage to the coating, sheet metal joints, etc. caused by exposure to wind and rain, mechanical damage, or sunlight should be promptly repaired.

When designing a space structure grid, fire protection and aesthetics should be considered comprehensively. Fire protection treatment of exposed steel joints or exterior eaves should especially balance appearance and performance.

Conclusions & Call to Action

Steel space grids offer excellent structural performance, but the potential risks and subsequent costs of neglecting fire protection design and protective measures are significant. Using passive fireproofing materials, selecting appropriate components, combining active protection measures, and strictly adhering to standards during construction and maintenance can ensure the safety and durability of the structure in fire situations.

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