CONSTRUCTION TECHNOLOGY Flashcards
What are the different types of foundations?
Strip, pile, raft and pad
What are the advantages of strip foundations?
Useful to transfer continuous loads
good for clays and seasonally changing soils
useful where ground conditions are good
What are the disadvantages of strip foundations?
Not conducive for taller buildings of a heavier load
Due to excavation and curing time it takes a lot of time
Requires a lot of concrete so can be high cost
Complicated formwork
What are the advantages of pile foundations?
Useful for large structures
Well suited for very poor ground conditions
CFA is as quick as excavation and consecutive pouring
What are the disadvantages of pile foundations?
Expensive
Can be noisy and intrusive
Plant hire required is additional costs
Needs piling mat and rig
Bored piles takes a long time
Transferring pre-cast piles is difficult
What are the advantages of raft foundations?
Good for poor ground conditions and small buildings
What are the disadvantages of raft foundations?
Not suitable for large loads
Requires lots of concrete
Requires sturdy formwork
What are the advantages of precast concrete?
Better QAQC in the factory
reduced time on site and associated preliminaries cost
Reduces the time you need to wait for it to cure on site, better programme
What is substructure?
All elements of work that are undertaken below the damp proof course that provides the basis for the superstructure to be constructed upon (Foundations)
What is the purpose of soil investigation and ground conditions surveys?
To determine the suitability of the site for the proposed works and determine and adequate and economically viable foundation design.
The investigation should determine the potential difficulties associated with the ground conditions (which may need to be allowed for in the cost plan).
Assist with identifying a suitable foundation solution.
What are the main components of concrete?
Cement
Aggregate (natural rock, crushed stone, gravel)
Water
What is a borehole?
This can be used to investigate soil or for a geothermal heating solutions.
Boreholes are the most suitable method of soil investigation when foundations are over 3m deep.
Geothermal boreholes are permanent boreholes that use the Earth’s natural heat to raise the temperature of circulated water.
This is a closed system and can be used to heat the building above which is adopted as a sustainable technology.
What are piles?
A series of columns constructed or inserted into the ground to transmit the load of a structure to a lower level of subsoil.
They are used where no suitable foundations conditions are present nearer to ground level or in areas where there is a high water table.
What are the different types of piles?
Sheet
Secant
Bored
Pre-cast
Sheet Piles
A deep trench is excavated and concrete is poured in situ.
The piles can be used to form basement walls or act as retaining walls.
Secant Piles
Interlocking piles of different hardness and diameters, bored to provide a combination of foundations and basement walls.
They support in providing a waterproof structure and are often seen when a top down construction method is used.
Bored Piles
An auger is used to excavate the soil and then concrete is poured in once complete.
Pre-cast Piles
Piles are hammered into the ground. This is not often favoured due to the high noise levels associated with installation and the lack of flexibility in terms of depth required.
What are the different ways that piles transfer their load to the surrounding ground?
End bearing piles: transfer load through low bearing capacity soil to a strong stratum such as rock/dense sand
Friction piles: bear on frictional resistance between their outer surface and the soil in contact.
Settlement reducing piles: incorporated beneath the central part of a raft foundation in order to reduce differential settlement to an acceptable level.
Tension piles: resist uplifting forces that might otherwise cause the structure to be extracted from the ground due to uplifting forces such as hydrostatic pressure, seismic activity or overturning movement.
Do you know any modern methods of construction (MMC)?
MMC includes any modern construction methods and includes eg: solar panels, green roofs, air source heat pumps and modular construction
Can you name any building regs?
O - Overheating in buildings
B - Fire
M - Access to and use of buildings
L - conservation of fuel and power
What are the advantages of pre cast concrete?
Better QAQC in factory, reduces time on site and associated preliminary costs, reduces the time needed to cure on site improving overall programme
How big is a window board?
This is dependent on the design, size of the window opening and how thick the wall is
What are section 38 works?
Construction of new estate roads that will be adopted by the public highway
What is S278 works?
These consist of alterations to existing highways
Are you aware of any RICS literature relating to MMC?
I am aware of the report prepared by RICS on MMC looking at the forward lookahead for MMC
What are the British standards? BS
Recommendation to minimum standards for construction and design
What are the International standards? ISO?
Same as above but international and compatible with BS
Are you aware of SUDs?
These are sustainable urban drainage systems. I am aware of them eg ponds and swales however I have never personally wored with them. I have experience of more traditional drainage systems comprising of pipes, manholes etc.
A Client has a large area of land and is looking to develop a warehouse, how would you advise him between using a Concrete structural frame or a steel structural frame.
a. I would advise the client of the advantages and disadvantages of both. However a steel portal frame would traditionally suit a warehouse.
b. This is because of the long spans able to be achieved with steel as well as its quick erection on site, thus reducing cost of preliminaries
c. Steel is lightweight also, meaning it can support its own weight and the roof structure, whereas concrete would not achieve this.
d. A warehouse requires large open spaces (tall) for racking, which concrete could not do.
e. Steel is stronger, more tensile and compressive
f. Lighter so requires smaller foundations
Steel vs concrete frame?
a. Steel is more Lightweight
b. Steel has better Large spans
c. Steel is Recyclable/sustainable
d. Both can be prefabricated and have quality control (moreso steel)
e. Steel is erected quicker on site, no drying time
f. Steel requires less foundation as its lighter
g. Concrete requires lots of maintenance, can be damaged just from air
h. Concrete is fireproof, steel needs protection
i. Concrete can usually be more local (steel from abroad)
j. Concrete has better sound and heat insulation
k. Cost – it depends!
talk me through the different options of foundations and when you’d advise a client to use them?
a. Foundations are the concrete mass in which a building sits on, between the ground, transferring the lode of the building into them.
b. The different types and when they’d be used are:
i. Strip foundations, I would advise a client to use these where the building is at a certain size (small) as they are usually not suited to larger building lodes. Where there is horizontal or continuous loading to be spread by external and internal loadbearing walls, and where the ground conditions are suitable for them. If the ground conditions are a bit poorer, I would advise deep strip.
ii. Piled foundations (CFA, bored, driven and sheet). I would advise to use these where ground conditions are poor and a suitable stratum needs to be reached in order to spread the lode, I would also advise this when the building is very large as there would be a massive amount of lode imposed which needs distributing deep into the ground and surrounding earth.
iii. Pad foundations. I would advise the use of pad where the building construction calls for point lodes, such as steel columns in a warehouse, usually cheaper than strip as it isn’t used across the entire perimeter
iv. Raft foundations. I would advise on the use of these where the building needs to spread the lode over the whole area, this is good for smaller buildings or very poor ground conditions, this can also act as a floor slab, saving on additional cost and time
What is your current industry knowledge of the building regs?
a. New process in place October 2023
b. Additional requirements being set out for higher risk buildings that are 18+ metres in height or have 7 or more storeys and have at least two residential dwellings
You have worked on projects where planning was involved, do you know what reserved matters are?
They are essentially a planning application with increasing detail on the project, taking into account any conditions that have been incorporated.
What is substructure?
All elements of work that are undertaken below the damp proof course that provides the basis for the
superstructure to be constructed upon
What is the external envelope?
*The materials and components that form the external shell or enclosure of a building.
* These may be load or non-load bearing
What are the approved documents?
A. Structure.
B. Fire safety.
C. Site preparation and damp proofing.
D. Toxic substances.
E. Sound proofing.
F. Ventilation.
G. Hygiene.
H. Drainage and waste disposal.
I. Not in use.
J. Heating appliances.
K. Protection from falling, collision and impact.
L. Conservation of fuel and power.
M. Disabled access and facilities.
N. Glazing.
O. Not in use.
P. Electrical safety.
What are British Standards?
- Publications issued by the British Standards Institution prefixed BS.
- They give recommended minimum standards for materials, components, design and construction
practices.
What are international standards?
- Publications issued by the International Organisation for Standardisation – prefixed ISO.
- They are compatible with and complement the British Standards
What is superstructure?
- All internal and external works items above the damp proof course.
- This is made up of:
o External walls.
o Stairs.
o Roof.
o Structural walls.
o Suspended ceilings.
o Raised floors.
What are the typical components of site investigations?
- Their objective is to collect and record data to help with the design and construction process. This
should include matters in relation to the site that may impact the development for example:-
o Boundary hedges & fencing.
o Existing trees.
o Size, depth and location of services including gas, telephone, electricity, water & drains.
o Existing buildings.
o Ground water conditions.
o Soil investigations.
o Trial pit information
What is the purpose of soil investigations?
- Their purpose is to determine the suitability of the site for the proposed works and determine adequate
and economic foundation design. - The investigation should determine the potential difficulties associated with the ground conditions and
assist with identifying a suitable foundation solution.
What are the main site considerations?
- Access considerations.
- Storage considerations.
- Accommodation.
- Temporary services.
- Plant.
- Fencing & hoarding.
- Health & Safety risks.
What is a retained façade?
- The facade of the building is retained whilst everything behind the front wall is demolished.
- Allowances needs to be made for a temporary support structure and also cleaning & restoration works
to the retained façade. - Retained facades are often required as a result of listed building requirements.
What are temporary works?
- Temporary works do not normally appear on construction drawings but may be required depending on
the construction methodology being used. - Temporary works may also be required as a result of health and safety requirements to ensure a safe
method of construction for example temporary propping
What is a tower crane and what are some considerations during its erection and operation?
- A tower crane is a tall crane used for lifting objects into high places.
- The boom allows a longer reach with 360° access.
- A longer boom reduces the payload capability.
- You would usually use a smaller crane to erect a tower crane.
- Weather conditions could prevent it from working, in particular high, strong winds
What is a scaffold?
- Scaffold is a temporary working platform erected around the perimeter of a building or structure to
provide a safe working place at a convenient height. - Scaffold is usually required for work 1.5m above ground level.
What is shoring?
- Shoring is a form of temporary support given to existing buildings.
- Its purpose is to provide a precaution against damage or injury due to collapse of the structure.
What are the main components of concrete?
- Cement.
- Aggregate (natural rock, crushed stone, gravel).
- Water.
What is a borehole?
- A borehole can be used for soil investigation or for geothermal heating solutions.
- Boreholes are the most suitable method of soil investigation when foundations are over 3m deep.
- Geothermal boreholes are permanent boreholes that use the Earth’s natural heat to raise the
temperature of circulated water. - This is a closed system and can be used to heat the building above which is adopted as a sustainable
technology.