Foundation, Concrete and Earthquake Engineering

Fire Resistant Construction

It is encouraged to use non-combustible materials in construction to have a fire resistant structure. All the structural elements such as beams, columns, lintels, arches, floors and roofs, load-bearing walls or partition walls etc. should be constructed in such a way that they should continue to function as structural members at least for the period which may be sufficient for the occupants to escape. The following additional points should be kept in view while designing a fire-resistant structure:
a. The load-bearing walls or columns of masonry should be thicker in section so that they may successfully act as fire barrier for a considerable time.
b. As far as possible resisting material should be used in the construction of flooring. If the usage of material which is likely to be damaged cannot be avoided either due to financial or other considerations, the following precautions should be observed:
1. In case of wooden floor, thicker joists spaced at a greater distance apart should be used.
2. Fire stops should be provided in the wooden floors at suitable intervals.
3. Flooring made from materials like concrete, brick, ceramic tiles etc., is considered to be most suitable for fire-resistant construction. In case, cast iron, wrought iron or combustible materials like rubber, cork, carpet etc. have to used in flooring, such materials should be protected by covering of insulating material like ceramic tiles, terracotta, bricks etc.
c. Reinforced concrete framed structures should be preffered to steel structures. As steel is liable to twist, sag or distort under heavy fire, the metal shoild be protected by using concrete, hollow clay tiles, bricks, metal lath and plaster, etc. the treatment given to steel column is shown in fig-1. The cover of the protected material like tiles or bricks etc. all around the steel members should be at least 10 cm. from all sides. In any case, the metal flages should be protected with not less than 5 cm. layer of conrete. The cover of concrete for reinforced concrete members, like beams, or columns should be sufficient to enable the members function satisfactorily, under fire for maximum time. The concrete cover outside the main reinforcement should be at least 5 cm. for very important structural members, like columns, girder, trusses etc. 38 mm for ordinary beam, or long span slabs, arches etc. and 25 mm. for partition walls and short span slabs.

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