The document will also offer guidance on the fire resistance of: Fire Doors This should highlight the period of time a door can hold back the spread of fire. A fire door in the UK usually has a fire rating of 30 minutes. Glazing Glazing should be able to hold back the fire and restrict any heat transfer.
Fire-resistant glass can help in the restriction of fire and heat transfer. Structural elements should be able to resist: • Collapse
• Fire and Smoke Penetration • Transfer of Excessive Heat
Resistance to Collapse Resistance to collapse, under fire conditions, refers to the ability of an element of a structure not to fail or collapse when a load is bearing on it. It therefore only applies to load-bearing elements of the structure. The unprotected metal used to carry a load presents an even more serious danger of rapid collapse when excessively heated. Structural steel, for example, loses two-thirds of its strength at 593°C and, in proportion to the amount and direction of the load to which it is subjected, begins to sag, and twist. This is by no means an abnormal temperature in even a moderate fire, the danger of the failure of unprotected load-bearing metalwork cannot be over- emphasised. A 10-metre steel joist, for example, will expand 60mm for a 500°C rise in temperature, and where it is built into a load-bearing wall, such expansion can lead to the collapse of the structure. Concrete is a commonly found material used in building structures and is inherently non-combustible. Indeed, it may have been fabricated to meet specific fire resistance standards. Concrete can be produced having a wide range of properties such as high compressive strength, durability, thermal insulation, and fire protection. In the case of a fire when concrete is heated, it expands due to thermal expansion of the materials, but the hardened cement paste also shrinks because of loss of moisture by drying out and internal stresses can be set up within the
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