Level 3 - Lydden Road Frames Flashcards
What where the various frame options you advised on on Lydden Road?
Steel Frame with Composite metal deck
Steel Frame with CLT slab
RC Frame with PT slab
RC frame with CLT Slab
What was your advice to the Client on the different frame options for Lydden Road
Frame options were ranked from most cost effective to least cost effective
Best - RC Frame & PT Slab - £73/ft2
Worst - Steel Frame & CLT Slab - £96/ft2
Key metrics were identified including:
Design efficiencies
Net:gross
Pros & Cons of each option
What was the most cost effective frame option for Lydden Road?
RC frame with PT Slab = £73/ft² on the GIA
£4.8m total cost
What was the least cost effective frame solution for Lydden Road?
Steel Frame with CLT Slab hybrid = £96/ft² on the GIA
£6.4m total cost
What were some of the pros and cons you advised on the frame costs for Lydden Road?
RC frame with PT Slabs
Pros - most cost efficient
Cons - Thicker slabs than composite deck and reduced floor to ceiling
Steel with Composite deck
Pros - Wider spans with uninterrupted floor plates improved the NIA, lighter frame could result in reduced foundation costs
Cons - Not as cost effective as RC frame and PT slab and prices of steel being volatile
CLT Slab solutions
Pros - Increased sustainability credentials
Cons - Bespoke, most expensive solution and limited supply chain. Deep floor build ups reducing floor to ceiling heights
What is a post tension slab?
Concrete slab with steel cables running through it that are tensioned to make the concrete stronger and help reduce cracking.
How did you cost the PT slab
Rate builder:
Concrete = £185/m3 Formwork Allowance for post tensioning Allowance for paint to tendons Sundries Prelims OHP
£240 to £360/m2 depending on slab size
Whats the difference between pre and post tensioning concrete?
Pretension is the technique in which we are imparting tension in strands before placing the concrete.
Post tensioning is done by forming a duct in which strands are pulled (tensioned) after the concrete gains it’s full strength
What determines the choice between a steel and concrete frame?
- Building type i.e. offices might want long spans = steel frame or Resi might want thermal properties = concrete frame
- Client Type i.e. Commercial client may want quick installation = steel frame
What is the cost difference between a steel and concrete frame?
It depends on a number of factors as one can be more cost efficient than the other dependent on:
- Site Logistics = deliveries may be more difficult in a tight site
- Market conditions = steel can be more expensive
- Programme Benefit/ Time related prelims = concrete has more as more time on site and requires more material storage and quality control
- Standard steel or bespoke specified = bespoke are more expensive
- Spec of Concrete = certain grades are more expensive
Which would you say is stronger out of steel and concrete?
- Concrete has better compressive strength, but steel is stronger in tensile strength.
- This is why steel is used to reinforce concrete.
- Concrete without rebar is not very strong!
What are the main components of a steel frame?
- Steel beams
- Steel columns
- Bracing
- Connector Plates
What are some different types of steel sections?
- I beam = I shape
- PFC = Parallel Flange Channel = U shape
- Angled Sections = L shape
- CHS =Circular Hollow Sections = O shape
What are the main components of a concrete frame?
- Concrete beams and columns
- Formwork
- Rebar
How much would you expect to pay for a concrete frame?
- Completely depends on the building, where it is, spec etc.
- But I would expect to pay around £160 - £190/m3 for concrete
