Offsite, precast and BIM: The perfect trio
Frequently proclaimed as being the key to the construction industry’s future, Offsite Construction has certainly grown in popularity in recent years. While the offsite conversation may often focus largely on the use of light-gauge steel framing systems, precast concrete is just as significant – a great example of offsite manufacturing by its very nature.
Here, incorporating digital technology into the construction workflow can be a huge help, boosting precast concrete and the wider offsite industry’s efficiency and productivity benefits even further. Craig Johnson, Business Development Manager – Detailing & Manufacturing at Trimble (UK), explains more.
A solution for cost and time savings
With precast concrete being offered as a cost and time savings solution, while simultaneously maintaining the high production and finished aesthetics, time is always of the essence. As such, anything that contributes to an efficient manufacturing process and helps maintain the speed and quality of production is essential, ensuring that precast manufacturers can continue to offer improved building schedules and time savings to their clients.
This is where digital technology and BIM can come into play. By utilising a 3D model-based workflow, precast contractors can benefit from enhanced visualisation and accuracy, with great levels of detail contained within the central model. As well as offering automatic clash detection, helping to reduce the likelihood of rework being required further down the line, this digital approach can also help to facilitate greater data integration between different stages of a project.
For example, the data contained within the 3D model can be automatically fed into the fabrication machinery in accordance with the central model’s associated production schedule. This level of automation can be key, helping to reduce the likelihood of human error, increase rates of production and streamline the overall process, ensuring that the precast components are delivered to site right when they are needed.
Offsite manufacturing for onsite constraints
When it comes to offsite construction, you want offsite manufacturing that fits the on-site constraints. As well as ensuring just-in-time deliveries, considering the installation process is also important, with this final stage in many ways just as important and instrumental as the initial detailing and modelling. After all, one of the primary benefits of the offsite methodology is that it offers a simpler and more streamlined process, including a faster assembly process on site.
While precast concrete can bring with it the perceptions of excessive weight – in turn, translating into challenges when trying to manoeuvre and install on site - this certainly isn’t the case. With developments in digital technology helping to facilitate a smoother installation, BIM software can be used for planning crane layouts and assembly sequencing. As well as analysing the centre of gravity of concrete components and using this information to better plan crane lifts and crane locations, precast contractors can take this insight further still. In fact, as early as the detailing stage, teams can be planning ahead and considering the final assembly process during any design decision-making.
For example, there are Crane Tools available, such as those within Tekla Warehouse, that allow users to enter the specific crane type that will be used on site. Detailers can then use the tool to amend the panel or slab design accordingly, depending on the crane load capacity, such as by changing span lengths or weights.
Ready for anything
As a product, precast concrete is hugely adaptable, able to suit and fit a variety of applications and sectors. This is perhaps one of the reasons for its success within offsite, with the offsite process not limited just to student accommodation or hotels but instead covering the whole of the construction and wider infrastructure industries. As such, materials are needed that can keep up.
In much the same way as steel framing systems are used, precast concrete panels can help construct the external structure of a building and form its internal layout. Precast can even have some benefits over its steel equivalent when it comes to a building’s internal structure, with its self-supporting nature making it suitable for larger spans, helping to open up spaces and create a contemporary, open-plan look and feel.
Indeed, in many ways, precast concrete can be seen as a limitless material. Through the use of different aggregates, different colours and different textures, it can be used to achieve any shape and any finish – with precast panels even able to mimic brick or timber. This flexibility could perhaps be especially useful in helping combat one of the obstacles to the uptake of offsite and modular construction: mainly the perception that it leads to the creation of identical and uninspiring “boxes”.
Moulds modelled by RCDS NI (UK) for external precast facades on V&A, London.
Given this flexibility, mixed-material buildings can be a common occurrence within construction. For example, you may have a steel framed building but with a precast brick slip façade. In these situations, having a multi-material software can be hugely advantageous. Enabling project teams to consider, analyse and visualise both the steel and concrete structure within the same model, including how the different materials interact and connect with each other, can be key in helping to avoid structural clashes and facilitate more informed decision making.
Collaboration and visualisation
While important on any construction project, ensuring high levels of effective collaboration and visualisation is perhaps especially critically when it comes to offsite – particularly during the detailing and on-site installation phases of the construction sequence.
At the detailing stage of a project, 3D modelling software can offer first-hand, in-house visualisation direct from the drawing office to the shop floor, assisting with manufacturing confirmations and query resolutions. What’s more, prior to manufacturing, the use of cloud- based collaboration platforms (such as Trimble Connect) can offer enhanced insight towards the precast model for all parties involved within the approval process, from the client and architect through to the engineer, precast manufacturer and steelwork contractor.
This collaboration software can be just as valuable once the project reaches site, allowing site teams to ensure a streamlined and efficient installation and assembly. Before developments in digital technology, if a clash was identified on site, the site team would first have to make a call to the drawing office and explain the issue. They would then have to go through the model to try and identify the clash detected on site and report back. Now, with the rise of mobile tablets and mixed reality technology, such a lengthy and convoluted process is a thing of the past, with site teams able to access the model remotely, resulting in faster on-site resolutions.
As a material, concrete is still growing in popularity, favoured for its flexibility, thermal benefits, large spans and design possibilities. As offsite construction continues to grow, precast concrete is set to be an integral part of the movement, with digital technology sitting alongside it. Indeed, integrating all forms of BIM into the construction workflow can enable precast manufacturers to offer a fuller and more comprehensive precast package, further benefitting the offsite movement.