While steel itself is non-combustible, it loses its structural strength significantly at elevated temperatures (typically around 550°C / 1000°F), which can lead to deformation and collapse during a fire. Therefore, fire prevention and protection measures for steel structures focus on preventing the steel from reaching these critical temperatures or ensuring structural integrity for a sufficient period to allow for evacuation and firefighting.
Steel Structures Prevention Measures
Passive Fire Protection (PFP): Insulating the Steel
The primary goal here is to insulate the steel members to slow down the rate at which their temperature rises during a fire.
Spray-Applied Fire Resistive Materials (SFRM): These are cementitious or gypsum-based plasters sprayed directly onto steel members. They are cost-effective but can be fragile and aesthetically unpleasing if left exposed.
Intumescent Coatings: These paint-like coatings swell and char when exposed to heat, forming an insulating layer. They offer a more aesthetic finish and are often used where steel is exposed.
Concrete Encasement: Encasing steel columns and beams in concrete provides excellent fire resistance. This can be done with cast-in-place concrete or precast concrete sections.
Fire-Resistant Boards and Cladding: Gypsum boards, calcium silicate boards, or mineral wool boards can be used to box in steel members, creating a fire-resistant barrier.
Blockwork/Brickwork Encasement: Similar to concrete encasement, masonry can be built around steel members.
Filling Hollow Sections: Hollow structural sections (HSS) can be filled with concrete or other fire-resistant materials to improve their fire performance.
Active Fire Protection (AFP): Detecting and Suppressing the Fire
These systems aim to detect a fire early and suppress it or control its spread.
Sprinkler Systems: Automatic sprinklers are highly effective in controlling or extinguishing fires, thereby limiting the heat exposure to the steel structure.
Fire Detection and Alarm Systems: Smoke detectors, heat detectors, and flame detectors provide early warning, allowing for timely evacuation and firefighter response.
Fire Suppression Systems (Gaseous, Foam, etc.): Used in specific areas where water might be unsuitable (e.g., server rooms, areas with flammable liquids).
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