AI struct-retard Flashcards
What do Building Regulations and National Codes require regarding building stability in the event of fire?
Buildings shall be designed and constructed to maintain stability for a reasonable period to allow occupant escape and fire service access.
What materials are commonly used for structural frames in buildings?
- Concrete
- Timber
- Steelwork
Do most concrete frames require additional passive fire protection measures?
Generally, no, as they are designed to achieve a specified fire resistance period.
Under what circumstances might additional passive fire protection measures be required for concrete frames?
In cases like road tunnels where spalling of concrete may be an issue.
What are the two broad categories of timber framed buildings in terms of fire protection?
- Heavy timber construction (e.g., ‘Glulam’)
- Lightweight timber framing
How does heavy timber construction provide fire resistance?
Through a sacrificial layer of wood that chars in a fire.
What is typically used for fire protection in lightweight timber framing?
A board system, such as plasterboard.
What is a common method to limit the rise in temperature of steel frames?
Insulating with proprietary passive fire protection products.
What types of products can be used for passive fire protection on steel frames?
- Reactive (intumescent) paint coatings
- Plaster or cementitious-based spray/trowel coating systems
- Dry cladding systems
What must be considered when applying fire protection to steel frames?
The issue of corrosion protection to the steelwork.
What must loadbearing testing demonstrate during fire resistance evaluations?
That structural elements can carry the load without collapsing for the duration of the fire test.
What formula is used to calculate the fire resistance period for steel frames?
The ‘Section Factor’ (A/V), where A is surface area and V is volume.
What happens to heavily loaded steel at approximately 550°C?
It loses about 40% of its design margin of safety.
What factors influence the limiting temperature of a structural steel member?
- Temperature profile
- Load depending on building use
- Structural model used for the steel frame
What effect does a concrete slab have on the fire resistance of steel beams?
It protects the upper surface from fire and acts as a heat sink, causing temperature differences.
What is the typical limiting lower flange temperature for fully loaded non-composite beams carrying concrete slabs?
About 620°C.
What is a cellular beam characterized by?
Web openings that allow for longer spans and service installations.
What are the two methods used to create cellular beams?
- Cutting along the web of a hot rolled section
- Welding three plates together with apertures cut into the web
What is the main failure mode of cellular beams in fire conditions?
Web post buckling.
What is a sacrificial layer in timber frame construction?
Additional timber designed to char and protect inner material from fire damage.
What are the two subcategories of reactive (intumescent) paint coatings?
- Thin film coatings
- Thick film coatings
What is the application method for thin film coatings?
Applied by airless spray, brush, or roller in multiple coats.
What is the fire resistance range for thin film coatings?
Generally up to 1 hour, with some systems offering up to 2 hours.
What is the primary difference between thin and thick film coatings?
Thick film coatings use epoxy formulations designed for hydrocarbon fire conditions.
