Building and Structures Flashcards
Why is timber often far superior to other materials when involved in a fire?
The build up of charcoal on the surface of burning timber limits the availability of oxygen, thereby insulating the remainder of the section.
Timber also does not expand significantly under the influence of heat, therefore sudden collapse is unlikely.
What are the disadvantages of aluminium in construction?
Very rapid loss of strength in fire (stability is affected at 100-225 degrees centigrade.
High expansion rate, twice that of steel.
Very low melting point (pure aluminium melts at 660 degrees centigrade).
What do intumescent materials do and where are they found?
They swell with the application of heat, forming a seal against the passage of flame and hot gases.
They can be found in fire doors or around structural members of a building, like steel work.
They can be in sheet form or sprayed on.
What factors determine the stability of a brick/stone wall when exposed to fire?
Its thickness in relation to height.
Whether or not proper bonding has been used (sufficient headers to tie the wall together).
To some extent on its age (disintegrating mortar).
Any horizontal pressure or levering effect which may be exerted on it.
The burning away of floors and cross walls, leaving a high wall without side support.
Expansion of beams built into walls pushing it outwards, throwing it out of equilibrium.
What are the 2 main functions of a fire door?
To protect escape routes from the effects of fire so that occupants can safely reach a final exit.
To protect the contents and/or structure of the building by limiting the spread of fire.
They will also contain the outbreak of a fire.
Protect from the penetration of toxic smoke and fumes into otherwise unaffected parts of the building for a short while.
Restrict the flow of oxygen, helping to starve the fire when the door is closed.
What happens to concrete at high temperatures?
Concrete is non-combustible and will not ignite. But it will lose load bearing strength both during and after exposure to high temperatures.
It will spall and split into pieces, especially when cooled with water.
What type of roof did Hibs build but doesn’t know the name of?
Monitor roof
What factors influence the performance of timber floors in a fire?
Whether the floor is plain edged (butted, tongue and grooved) or is chipboard or plywood.
The thickness of the flooring.
The load bearing capacity of the joists and the load imposed.
