DESIGN PRINCIPLES OF FIRE RSISTANT WALLS

• FIRE RESISTANCE:

• Fire resistance is a property of an element of building construction and is the

measure of its ability to satisfy for a stated period, some or all of the following

criteria:

• Resistance to collapse,

• Resistance to penetration of flame and hot gases and

• Resistance to temperature rise on the unexposed face upto a maximum of

180°C and/or average temperature of 150°C.

FIRE RESISTANT WALLS:

DEFINITION:

It is a fire resistance rated wall, having protected openings, which restricts

the spread of fire and extends continuously from the foundation to at least

1m above the roof.

GENERAL:

• The design and type of materials determines the fire resistivity of a

building element.

• Fire resistance is expressed in hours against a specified fire load

expressed in kcal/m² and against a certain intensity of fire.

AIMS IN FIRE SAFETY DESIGN

• To prevent fire.

• To safeguard the lives of occupants and fire fighters.

• To reduce damage on the building, its contents and on surrounding

buildings.

BASIC PRINCIPLES

• Fire avoidance

• Fire detection

• Fire growth restriction

• Fire containment

• Fire control

• Smoke control

• Escape provisions

CHOICE OF MATERIAL AND MATERIAL PERFOMANCE

1. CONCRETE• High Fire resistance• Disintegrates at 400 – 500°C • Holes in concrete walls will expose steel structural members2. STEEL• Does not burn.• may buckle in fire.• High conductivity spreads heat• Losses half its strength in 550°C

3. TIMBER• Combustible• Little loss of strength as charcoal formed insulates wood core.• Spreads flames.4. MASONRY• High fire resistance.• Crack at 575°C• Are subjected to high temperature during manufacture.5. CALCIUM SILICATE• Excellent thermal shock resistant upto 1000°C• Suitable for cladding structural members.6. GLASS• Standard float, toughened and laminated glass panels do not provide any fire

resistance.

CONSTRUCTION

• No wood frame is impervious to fire damage.• Using the right material and techniques add precious

minute to the amount of time the wall can withstand fire.• Keeping the wall material intact for as long as possible is

the effective way to increase fire resistance.

FIRE RESISTANT WALL BOARD

• It helps protect the interior wooden structures of the wall from damage.

• Gypsum fire board designed specifically to be fire resistant incorporates chemical additives and glass fibers that make the board more dimensionally stable when exposed to high heat.

• Fire resistant wall board is thicker than standard wallboard and the extra thickness lessens the transfer of heat through the board.

WALLBOARD ATTACHMENT

• Fastening the wallboard to studs via metal channels rather than screwing it directly to studs also help wallboard to remain in place longer during fire.

• The wallboard is not attached directly to the studs, any movement in the studs caused by fire is not transmitted directly to wallboard, and the board is less likely to pull away from fasteners holding it on the wall.

SHEAR WALL CONSTRUCTION

• A Shear wall is a wall that is designed to withstand lateral forces applied to the wall.

• Shear walls are constructed with plywood attatched over studs to supply lateral support which adds to the fire resistance.

• A wall constructed with wallboard over plywood provides to mins more fire resistance than a wall constructed with wallboard alone.

APPLICATIONS

• Can be used to subdivide a building into separate fire areas and reconstructed in accordance with locally applicable building codes.

• Can be used to separate high value transformers at electrical substation in the event of a mineral oil tank rupture and ignition.