The dawn of digital fabrication
Inside the DFAB HOUSE – the world’s first house to have been digitally planned and constructed largely digitally.

The dawn of digital fabrication

For some time now, it has been widely acknowledged that the construction industry is lagging behind other sectors in terms of productivity and it has also been singled out as the least digitized industry. As the industry strives to redress the balance, lets examine what contribution the BBR Network have made and how they continue to adapt their approach to increasingly demanding customers and the fast-evolving digital environment.

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1966: A BBR post-tensioned prefabricated component of a car park overbridge is lifted into place in Zürich. All components were manufactured in a controlled factory environment, transported and, finally, placed into position during a single night-time road closure.

BBR has always been a pioneer of new technologies to support the construction industry – in fact, this is the very reason the business was created. When the three BBR founders began their work to develop the then new technology of post-tensioning, they were driven by a materials shortage and need for speed in the post-war reconstruction process. Their investment quickly extended to securing factory facilities where some of the earliest modern prefabricated post- tensioned structural components were produced. They also invested in developing leading edge specialist equipment to measure and test structural integrity and to facilitate their work. This commitment to improving construction with latest technology, over 75 years on, is still a cornerstone of the BBR business.

Optimized technology

Over the years there have been many new BBR developments, but in the context of today’s market the continual drive to optimize BBR technologies is perhaps the most relevant. Recognizing that ease of on-site installation is a crucial factor in achieving greater productivity, our R&D team has focused on refining our post-tensioning systems and accessories to promote program savings.

Reduction of up to 36% in the amount of concrete used, plus reduced CO2 emissions and related impacts.

For example, with the introduction of the BBR slab post-tensioning systems, an advanced generation of unbonded and bonded flat post-tensioning which features the lowest minimum center spacing and slab thickness at low concrete strength for all sizes on the market. This translates into a reduction of up to 36% in the amount of concrete used, thus cost saving on materials, plus reduced CO2 emissions and related impacts on the environment.

Prefabricated Prefinished Volumetric Construction (PPVC)

PPVC is a construction method whereby free-standing 3-dimensional modules are completed with internal finishes, fixtures and fittings in an off-site fabrication facility, before it is delivered and installed on-site. Among the initiatives undertaken in the BBR Network has been the venture into PPVC in Singapore, whereby the prefabricated approach to housing is thought to increase productivity by up to 50%.

Increase productivity by up to 50%

BBR Construction Systems (Singapore) in conjunction with BBR Holdings’ subsidiary Moderna Homes, were the first in Singapore to complete a residential project under the Government Land Sales (GLS) scheme using PPVC technology.

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2018: BBR Construction Systems (Singapore) in conjunction with BBR Holdings’ subsidiary Moderna Homes, were the first in Singapore to complete a residential project under the Government Land Sales (GLS) scheme using PPVC technology.

Precast segmental construction

Meanwhile, for many years now, the BBR Network has been carrying out projects where precast post-tensioned segments have be used to create viaducts for metro rail systems. Off-site segment manufacture creates a greater opportunity for quality control, while just-in-time delivery promotes more effective working and less congestion on site.

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2013: BBR Malaysia used prefabricated segments to form the viaduct for the extension to the Kelana Jaya Metro system. Off-site manufacture of the segments allowed greater quality control and just-in-time delivery promoted more effective working during night-time road closures.


Digital fabrication

Robotics have been used for years in other industries – for example the automotive industry – and now, combined with other technologies, this has been extended to the construction sector. In the last 12 months we have seen the creation of the DFAB HOUSE.

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2019:Digitallyplannedandlargelydigitally constructed, the three storey DFAB HOUSE building sits on the NEST research and innovation building belonging to EMAP and Eawag in Dübendorf, near Zurich.

The project is a collaborative demonstrator of the Swiss National Centre of Competence in Research (NCCR) Digital Fabrication and is sited on top of the NEST Building of Empa and Eawag. NEST (Next Evolution in Sustainable Building Technologies) is the world’s first mod- ular research and innovation building aimed at accelerating the innovation process in the construction sector.

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2019: A segment of Smart Slab for the DFAB HOUSE being lifted into place, ready for stressing with BBR VT CONA CMI internal PT tendons.

As part of the full-featured building project, the DFAB HOUSE initiative has brought research- ers from eight different disciplines within the Swiss Federal Institute of Technology (ETH Zurich) together with industrial partners and planning professionals in a unique way to not only digitally design and plan the buildings but also build using predominantly digital processes, both on-site and off-site with the help of robots and 3D printers.

70% less than a conventional concrete slabs

BBR monostrand post-tensioning tendons were installed into the ‘Smart Slab’ – a 80m2 post-tensioned concrete slab made up of eleven 7.4m-long segments. Every segment is unique and was prefabricated, using the 3D printed formwork, with special interface features which facilitated on-site connection through post-tensioning tendons. The Smart Slab’s geometry is structurally optimized for its challenging load-case, involv- ing cantilevers of up to 4.5m. The material is distributed in a hierarchical grid of curved ribs, which vary between 30 and 60cm in depth. In addition, the interstitial surfaces stabilize the grid and are only 1.5cm thick. Consequently, the slab only weighs 15t – almost 70% less than a conventional solid concrete slab.

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2019: The structural principle of the 80m2 Smart Slab for the DFAB HOUSE is a hierarchical grid of post-tensioned ribs cantilevering from the curved Mesh Mould Wall.

As well as a delicate concrete ceiling – cast in 3D printed formwork, the house features a curved concrete wall created by a construction robot, plus voice-activated domestic installations. Although analysis of the DFAB HOUSE will be ongoing for some time yet, it is a foretaste of what our industry can and will achieve. It is significant that the project owes its reality to a cross-functional team and wider collaboration with industry.

The construction industry is at the dawn of digital fabrication, the widespread use of these novel techniques is still some way off in the future, however it can be envisaged that they will eventually extend to all types of structure. As we regard an increasingly digital outlook, the team at BBR Headquarters will always be ready to pioneer yet further new technologies and techniques to drive the agenda for improvements and optimization in the construction industry, while maximizing the benefits for the BBR Network, its customers and the society.

References

  • CONNAECT: https://www.bbrnetwork.com/downloads/connaect/
  • DFAB HOUSE: www.dfabhouse.ch
  • Image courtesy of ETH-Bibliothek Zürich, Bildarchiv, photographer Kurt Salvisberg, licensed under CC BY-SA 4.0, Com_L15-0555-0007-0002 / Roman Keller, NCCR Digital Fabrication / Digital Building Technologies Group, ETH Zurich.

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