3. Fire resisting walls, floors and ceilings and fire-resistant glazing Flashcards
Question 14 a) Explain how composite floors behave in a fire. (4 marks) b) Describe the factors affecting the fire resistance of concrete. (2 marks)
Composite floors consist of a profiled metal deck upon which concrete is poured with additional steel reinforcement. In fire conditions the lower profiled metal deck performs differently to the concrete above. The metal deck will transfer heat laterally and expand at a different rate to the concrete above. Steam released from the concrete can force out the metal decking causing it to deform and sag under the load of the concrete.
Factors that affect the fire resistance of concrete:
Extent of concrete cover over reinforcement, the thicker this cover is the more insulation is provided to the reinforcement.
Thickness of concrete
Concrete density, higher density concrete is more thermally conductive than lower density concrete. Concrete make up aggregates etc.
load applied to the concrete
Question 15 Describe four factors that influence the fire resistance of glazing systems when used as nonloadbearing compartment walls. (4 marks)
All components of a glazing system must be compatible and reference fire test evidence.
Type of glazing. The type of glazing used in a compartment wall will affect its fire resistance. Integrity only glass, such as, toughened, borosilicate, and glass ceramic offer integrity only so radiated heat be transferred to an adjoining compartment; insulation rated glass can reduce the amount of radiated heat.
How the glazing is supported affects a glazed non-loadbearing compartment wall’s fire resistance.
Aspect ratio and maximum pane area – relationship between width and height and overall area must not exceed that stated by the manufacturer
The type of glazing seal – the glazing seal is sited between the bead and glazing
The type of frame material must be tested with the system as a whole
The type and shape of beads – must be as specified by manufacturer and as tested
Extent of glass edge cover – modified toughened and heat soaked toughened soda lime glass requires a minimum distance of glass edge cover as specified by manufacturer.
Type of fixings and location of fixings to frame and beads
Question 16 a) Explain how fire resisting ceilings contribute to the fire resistance of a building. (2 marks) b) State the performance requirements of a fire resisting ceiling installed below a cavity. (3 marks)
Fire resisting ceilings contribute to the fire resistance of a building by containing a fire within the compartment of origin for a given period of time. Protecting the void or ceiling above
Integrity (E) Insulation (I)
Reaction to fire – fire resisting ceilings should not contribute to the growth of fire
Impact resistance
Access to services if the void contains them,Unsure of this question
Stiffness, damage by impact
Question 17 State five performance factors that are taken into account when determining whether or not fire resisting partitions are fit for purpose. (5 marks)
Partition stiffness
Damage by impact from large soft body
Surface damage by small body impact resistance
Perforation by small body impact resistance
Resistance to structural damage by multiple impacts from a large soft body
Effects of door slamming
Resistance to crowd pressure
Anchorage pull out and pull down resistance
Heavyweight anchorage eccentric downward load resistance
