What are the functional requirements of structural frames?
Strength - ability to carry, dead, live, imposed and wind loads
Stability - lateral stability
Durability and freedom from maintenance
What factors might effect the choice of frame and material?
- Site conditions
- Economics
- Availability of labour and materials
- Buildability
- Time
- Environmental preference
- Capital costs
- Maintenance
- Design flexibility
- Number of floors
- Use of the building
What are the advantages and disadvantages of timber frame construction?
Advantages:
- Fast to build
- Less wet trades - no drying out
- Lightweight structure
- Sustainability
- Good thermal performance
Disadvantages
- Limited to six storeys
What are the advantages of framed building as opposed to load bearing walls?
They can be taller
Open spans can be larger
Pre-fabrication can lead to faster erection
More design freedom on the outer skin
What types of structural frame are you aware of?
Steel
Reinforced concrete (in-situ or pre-cast)
Timber
How can you feel the difference visually between a steel frame and a concrete frame building?
Width of structural pillars
What are the advantages and disadvantages of concrete cast in-situ?
Advantages
- Versatility - can produce non-standard shapes
- Performance in fire
- Well established method
- Cost-effective
Disadvantages
- labour intensive
- slower to construct due to curing times
- potential quality issues on site
- high embodied carbon
What are the advantages and disadvantages of concrete pre-cast?
Advantages
- Quality assurance
- Fire performance
- Efficient use of reinforced concrete
- Speed
Disadvantages
- only cost effective for mass production
- modification - penetration through slab for services need to pre-formed
- High initial investment - steep cashflow
What are the advantages and disadvantages of steel frame?
Advantages
- Historically it has been cost effective due to material efficiency
- speed and ease of assembly
- high strength to weight ratio
- reliability due to factory manufacture
- circular economy
Disadvantages
- performance in fire -need fire proofing
- high thermal conductivity
- reduced flexibility on site
Why might you consider when choosing to construct a building with concrete rather than steel?
Weight
- steel lightweight and high strength to weight ratio
- concrete heavy
Speed of construction
- Steel off site manufacture and fast assembly without curing times required for concrete.
Fire performance
- Steel required additional fire protection as prone to becoming embrittled at high temperatures where concrete performance well.
Carbon/Sustainability
- steel has much lower embodied carbon than concrete
- steel can be disassembled and re-used as part of circular economy
Thermal performance
- Steel has high thermal conductivity resulting in reduced thermal performance
- Concrete has high thermal mass resulting in a more comfortable internal environment
Durability
- Concrete required less maintenance than steel as it is less susceptible to corrosion
What is the purpose of cores
Add stiffness to the structure
Provide stability for framed structures
Fire protection-particularly escape
Where can cores be located?
centrally
off centre
externally
What are the main methods of construction for cores?
Vertical panel
Jump form
Slip form
