Construction Technology Flashcards
What is the elemental build-up of Superstructure in construction?
Frame Upper Floors Roof Stairs External Walls Internal Walls Internal Doors
What are the benefits of a concrete frame?
Good fire resistance
Thermal massing – stores heat
Long service life with low maintenance cost
Can be the most economical structural material (dams and piers)
Can be precast off site
What are the disadvantages of a concrete frame?
Low tensile strength (pulling apart strength) Requires mixing, casting and curing Can crack Very heavy Can’t be recycled less uniform in behaviour
What are the benefits of a steel frame?
High strength to weight ratio Predictable properties Speed of erection Ease of repair Can be prefabricated off site Can be recycled Bolt together so can be used to expand existing structures
What are the disadvantages of steel frames?
Effected by currency fluctuations more
Requires fireproofing
Can rust so requires maintenance
longer lead time
How is slip resistance measured?
R – Rating
9 to 13, 13 being high
What size is a brick?
215x102.5x65mm
How many bricks are there m2?
60
What are Foundations?
Function to safely sustain and transmit to the ground the combined dead, imposed and wind loads of the structure above
What are some types of foundations?
Pad – lighter or wide span lightweight buildings - warehouses
Raft – concrete slab for good soil
Pile – for weak or cohesive, water bearing soils
Strip – for houses where loads are transferred to the ground from the perimeter walls
What are some types of piles?
Pre-cast Bored piles CFA piles Secant piles Sheet piling
How does Continuous Flight Augured piling work?
Augur is used to extract the soil then the concrete is poured in from the bottom
A reinforced steel cage is then dropped into the wet concrete and the casing removed
How does Rotary Bored piling work?
Used for the highest load carrying capacity is required
Augers and buckets used to excavate the soil
Steel casing is inserted to hold the shape of the hole
Concrete poured on top of a reinforcement cage
What are the benefits of RBP?
Minimal ground disturbance / damage to surrounding structures
Suitable for all soil types
Can drill through most obstructions
What are the negatives of RBP?
Most expensive
requires bitumen which is then contaminated so expensive disposal
Types of Waterproofing in basement?
Tanking – asphalt or bitumen applied internally or externally to create a continuous membrane
Cavity drain – moisture below the concrete slab is drained into a sump then pumped or discharged away
What is composite decking?
Profiled steel decking forms permanent formwork and adds sheer strength
In-situ reinforced concrete poured on top
Generally used in steel frames but not limited to
What is an alternative to composite decking on a steel frame?
Pre-Cast concrete planks
What is top down construction?
Used to speed up construction
Ground floor slab is cast with an access hatch
Below grand is excavated whilst the core is built upwards
The piles form the retaining wall
Allows building to be constructed simultaneously above and below ground
What is bottom up construction?
Where the basement is formed the work proceeds upwards, simpler but slower
Which building regulations refer to Noise and vibrations?
Part E – Resistance to Sound
Which building regulations refer to Fire?
Part B – Fire Safety
What is intumescent paint?
Fireproofing to steel – applied in the factory, manually touched up
What is the build-up of a stud partition?
Baseplate and top plate
Vertical and horizontal timber or metal studs
Plasterboard or gyroc boards screwed and fixed into studs
Firestop and smoke seal added to the top of the partition
What is a suspended ceiling made up of?
A bracket is fixed to the soffit
Metal grid or beams are fixed to the brackets
Tiles or panels are then installed within the grid
Variety of M&E or acoustic or fire barriers can be filled in the plenum
What types of bearings were used in Soho Place theatre?
Pad bearings – similar to rubber cushions in the main frame
Spring bearings on the auditorium concrete box
How does a Fan coil unit work?
2 or 4 pipe heat exchange coil and a fan (AHU) to draw air across the coil
Controlled by manual / automatic switches or thermostats
Thermostat controls the through flow of water to the heat exchanger using control valve / fan speed
What is an AHU?
Air handling unit
Responsible for drawing air into the building an disposing of exhaust air
Controls air intake and distribution of into ductwork
What are Soft spots?
An area of RC slab with a prescribed rebar layout and reduced rebar
Means a future tenant can knock through a panel a link between floors if required
How would you price a sedum roof?
RC roof slab Insulation Waterproof membrane Gravel drainage layer / attenuation layer Soil Sedum roofing – Plants £400/m² roughly
What type of heating / cooling did they have on Soho Place?
Fan Coil Units
What are the different types of FCUs?
2 pipe – cooling only
4 pipe – heating and cooling
Name some alternatives to FCU?
Chilled beam
displacement
What are the advantages of an FCU system?
Good control of air movement
Quick installation
High cooling capacity
What are the disadvantages of an FCU system?
Air filter requires maintenance
Fan can be noisy
How does chilled beams work?
HVAC system designed to heat or cool large spaces
Pipes of water pass through the beam which is integrated into the suspended ceiling or just above it
Active chilled beams use fans to draw air across it
Passive chilled beams rely on convection
What are acoustic barriers?
Installed in voids below RAF or above suspended ceilings (plenums)
Rockwool or acoustic material like autex
On Soho Place, what was the saving going from S2S partitions to using acoustic / fire barriers?
£30/m² saving however total once barriers paid for (£30/m) – total saving approximately £40k
What is the difference between stick and unitised facades?
Stick – site assembled, frame first (the sticks) then windows slotted in – requires scaffolding
Unitised – prefabbed, installed via hoists
What are the benefits of stick facades?
Economically friendly (smaller volumes) Shorter lead times
What are the benefits of unitised facades?
High quality as factory prepared environment
Quick installation
Shifts labour to a safer and cheaper environment – factory not site
Higher performance spec.
No scaffolding
What are British standards?
Publications issued by British Standard Institution
Give recommended minimum standards for materials, components, design and construction practices
What are building regulations?
Statutory instructions setting minimum standards for performance and specs for design and construction of buildings
What are the disadvantages of stick facades?
Longer installation times
Significant space required for installation and storage on-site
What are the disadvantages of unitised facades?
Longer lead times to prepare in factories
Typically more expensive
What is post-tensioned concrete?
Steel tendons are laid through the slab
Concrete poured
Once cured a stressing jack used to tension the slab
Stronger that RC slab as concrete is under compression
What is pre-tensioned concrete?
Steel tendons laid through the slab and stressed with a jack (tightened)
Concrete is poured
Once concrete is cured and bonded the tendons the anchors are cut
Transfers the compressive strength to the concrete
Good for pre-cast concrete
What are the difference types of screed?
Bonded – laid straight onto concrete base
Unbonded – laid onto bitumen damp proof membrane
What’s a steel table?
Blue book
Gives information on steel in tabulated form
Only for serial size and universal types (standard forms)
What is an alternative to a visual Mock-Up?
Bim / Virtual Reality
What is the build-up to a stick system facade?
Transfom and mullions fixed into floor slab
Glazing fixed to transfoms and mullions
Aluminium cap over glazing to hold it in place
What is the build-up of a brick cavity wall?
Brick or masonary
Cavity board
Insulation
blockwork
How would you cost an FCU?
Ductwork Fancoil BMS control Power supply approx. £6k/unit
What surveys would you expect to be carried out on site?
As-Built drawing validations RAD survey (refurbishment and demolition asbestos survey) 3D Laser / point cloud survey Obstruction survey (ground conditions) Utility mapping survey
Who defines the Fit-Out Terminology?
BCO – Guide to Specification 2019
Shell & Core
Fully furnished – entrance / reception, staircase, WC, common areas, lift and core
Shell finished – base services for plant / equipment, terminated at breakout point to floor, basic life safety equipment installed
Cat A Works
Shell and core
Floor plate finishes – suspended ceilings, internal partitions, RAF, basic M&E (heating, lighting), finishes to cores and WCs, carpet, power to each floor
Cat B works
Fully fitted out for occupation
How much do the active Fan tiles used in the Coworking cost?
c.£1,000 each
Why did you use fan tiles in the coworking?
The base build CAT A ventilation system is a simple underfloor ducted displacement system with perimeter heating via radiators. This was okay for an occupancy of 1/8m2 but coworking requires 1/6m2 so needed to improve it.
Fan tile system meant that central plant kept as per base scheme, DFU’s needed to be replaced for ones that ‘talked’ to the air tiles which are individually controlled and replaced the original floor grilles.
What work was carried out under the cat a plus?
Drainage & HCWS to tea points DFU’s and fan tiles Modifications to CAT A LTHW distribution Omission of CAT A underfloor ductwork Modification to CAT A containment Partial omission of CAT A Lighting, addition of client supplied lighting Supplementary fire detection BMS controls
What would you include if you were costing piling?
Piling mat Piling rig Concrete Steel cage Disposal of material Surveys - UXO (unexploded ordinance survey) - sonar / ground penetration
