Construction Technology Flashcards
(39 cards)
Types of Structural frames
- Concrete
- Timber
- Steel
Types of foundation
Strip foundations- A concrete base that is poured to a minimum depth of 225mm, upon which the walls of the foundation are built up to the level of the ground floor. Used when setting a building on firm, level ground that has been properly prepared.
Trench fill foundations- Similar to strip foundations, but with the trench filled with concrete. Typically used on sites with clay soils or where tree roots are a problem.
Raft foundations- Large, flat slab of concrete used to spread the weight of a building over a larger area. Raft foundations are typically used on soft, weak or waterlogged ground.
Pile foundations: Used on sites where the soil is unstable, or where the building is particularly heavy. Pile foundations involve the use of long, steel or concrete columns that are driven deep into the ground to support the weight of the building.
Pad foundations: Similar to strip foundations but consists of isolated footings that support individual columns or stanchions. Typically used on lightweight structures or on sites with a shallow layer of topsoil.
What is off-site manufacturing/ construction
Off-site construction is a construction procedure that involves the planning, designing, fabrication, transportation of fabricated building items and its assembling on the site.
Panelised (2D) construction- flat panel units used in the form of walls, floors or roof panes in order to create a complete structural shell. Built in the factory and transported to the site for assembling as a three-dimensional structure or to fit into an already on-site constructed structure. panel units can be made out of timber, insulated panels or light gauge steel or concrete.
Volumetric/ modular (3D) construction- three-dimensional units are produced in the factory and brought to the site and bolted together. The frames constructed can be either steel, timber or concrete. The modules can bought in different forms e.g. basic structural shell or with internal and external finishes and services.
Benefits of OSM
Speed, high degree of precision, cost savings, greater quality control
When is OSM suitable
Project has to meet tight deadlines, involves the construction of repetitive structures, space limitations on site, safety concerns.
RIBA Plan of Work 2020
RIBA is a framework explaining how a construction project should be organised.
Split into 8 stages from 0-7:
RIBA Stage 0
Strategic definition- Determining the best means of achieving the clients requirements, including undertaking early cost appraisals (which could be not build something new). QS involvement in reviewing budget as part of business case.
RIBA Stage 1
Preparation and brief- Developing detail of the brief to make sure everything needed for the design phases is in place (undertaking feasibility studies). Agree budget and produce initial cost plan/ estimate (e.g. based on unit rate)
RIBA Stage 2
Concept design- Getting a design concept that makes sure the look and feel for the building is in line with the clients requirements and budget. Cost plan update, e.g. ratio analysis.
RIBA Stage 3
Spatial coordination- Spatially coordinate the design before the detail required for construction is added e.g. the spaces required for any building systems – such as structural and building services have been determined. Cost plan can be updated to elemental cost plan.
RIBA Stage 4
Technical design- Developing the information required to manufacture and construct the building. Cost plan continue to be updated, with constant review against budget and analysis of design solution/ value engineering. Cost plan update to initially be updated with approximate quantities and developed to full BoQ with pre-tender estimate also produced. BoQ is then issued to tenderers to populate with rates and pricing document is then produced and negotiated to agree a contract sum.
RIBA Stage 5
Construction and manufacturing- Constructing/ manufacturing the building. The QS main involvement begins in regard to managing the construction contract (undertaking duties detailed in contract administration) monitoring and managing costs (as per project finance/ commercial management duties)
RIBA Stage 6
Handover- Closing out of defects and completing the handover tasks required to conclude the building contract (agree final account, undertaking analysis looking at final cost against initial budget, assessing lessons learnt)
RIBA Stage 7
Use- When the building is in use, this lasts until the building reaches the end of its life
Monitoring of MSE roof for loading
An automatic total station was installed on top of one of the precast concrete columns. Monitoring prisms were then installed throughout the precast structure which would feed information to the total station. Readings were taken automatically every hour to check if there was any movement in the structure.
This was required whilst the loading of the green roof took place due to previous deflection that had occurred on the structure
what were some of the OSR issues, how were they resolved?
Due to the location of the roundabout, in the centre of London with utilities, tram lines etc. underneath, although scanning was undertaken unforeseen ground conditions with various obstructions (Thames water chamber) and utility clashes (BT cable) were common.
During the weekly construction progress meetings these were discussed and solutions identified. EWNs would be raised for this and I would chair the EWN section of the meeting where mitigating actions would be discussed and determined (lower of cable) to prevent cost and time impact on the programme.
What is an IDR, what does it include?
IDR is an Independent Design Review which takes place a different stage of the design process. It involves multiple discipline engineers, project managers etc. from the business to come together and undertake a complete review of the design to date.
I attended the surrey quays 60% IDR which was undertaken at 60% completion of the design, some of the key elements reviewed included;
- review of site constraints e.g. existing retaining walls, station interface, trackside assets
- CDM plan overview and responsibilities
- Detail on safety procedures e.g. use of man safe harness system when accessing roof
- Whole life carbon modelling review
- Inclusive design considerations
- Acoustic modelling review
- Structural engineering model using BIM to review loading considerations, foundation arrangements etc.
What is acoustic modelling?
Acoustic models used to predict a wide range of acoustic characteristics within rooms and spaces
- help with the shaping of rooms
- selection of acoustic finishes,
- placement of speakers
This is important for TfL projects that involve refurbishment/ building of new stations as we have minimum standards we must comply with in regard to the acoustic levels of our audio information.
Acoustic performance of wall and ceiling finishes therefore need to be considered, e.g. use of acoustic panels in ceilings can help absorb unwanted noise and improve clarity of sounds
What is BIM?
BIM is a Building Information Modelling system which is capable of enabling designers to generate and optimise different 3D structural models. It helps them assess the structural integrity of buildings, simulate various load scenarios, and identify potential issues before the actual construction begins.
BIM enhances collaboration, provides enhanced visualisations, clash detection, improved cost estimation, sustainable design and efficient communication.
Trial holes vs scanning
Trial holes involved penetrating the ground in different locations to analyse the ground conditions whereas the use of ultrasonic scanning uses a scanning tool which can assess ground conditions non-intrusively. The scanning was less time consuming, and came with less risk due the non-intrusive methodology. Whilst it came with slightly more direct costs the reduced risk and time resulted in overall cost savings.
Construction methodology for ESS
The ESS location was surrounded by live tracks and therefore provided access constraints to the project. Access options were considered as part of the methodology review, my involvement in this was to review the costed programme and advise on cost savings based on a change to the construction methodology.
One option was to install an underpass, this would provide ease and safe access to the compound, however came with circa £500k of increased costs and a slightly increased programme duration. Even with the underpass weekend possessions would be required to undertake works with close vicinity to the tracks and therefore an additional number of possessions or a blockade would provide cost and programme advantages.
Advantages and Disadvantages of concrete frames
Advantages;
- durable
- low maintenance
- does not rust, rot, or burn
- effective soundproofing material
Disadvantages;
- can be more expensive than other products
- heavy, which may present transportation challenges
- Cannot be stored once it is mixed as the cement reacts with water and the mixture hardens.
Advantages and Disadvantages of timber frames
Advantages;
- light, and easy to work with,
- inexpensive,
- a natural resource
- good at absorbing sound inside a building
Disadvantages;
- cannot be easily used to build at height
- requires treatment and protection using chemicals often manufactured in energy-intensive processes.
- more susceptible to water damage, fire, decay, and termites.
Advantages and Disadvantages of steel frames
Advantages; Strong and cost effective, quick to erect, which can lead to labour savings, suitable for prefabrication and mass production, reusable after a structure is disassembled. Additionally, steel binds well to concrete, meaning reinforced concrete can be used to provide deep foundations and basement, making it a very popular building material
Disadvantages; steel is made using an energy intensive process, exposure to the environment can damage the material and cause corrosion and it has high manufacture and maintenance costs.
