º£½ÇÊÓƵ

RISE – Hofpleintoren (Hofplein Tower)

Rotterdam, Netherlands

º£½ÇÊÓƵ has supported the development of one of the European Union’s future landmark buildings. At 286m tall, the RISE tower will not only swiftly become the most familiar building in Rotterdam when it is completed, it is also set to become the tallest inhabited building in the European Union.

The new development is located on the south-east corner of Hofplein, Rotterdam’s bustling central square. It consists of three towers – the two other ones at roughly 150m and 160m – with the central tower standing at nearly twice the height.

The vibrant mixed-use development will include a combination of retail, cafes, a hotel, a health centre, office space and residential apartments – of which a large percentage will fall into the category of affordable housing, opening-up high-rise city centre living to all.

Challenge

The Netherlands does not have a history of building (super) high rise towers. The tallest existing tower in the country before 2022 was only 165m, so the new structure will nearly double that height.

º£½ÇÊÓƵ was engaged to provide consultancy around the structural engineering of the Hofplein tower building up to building permission, bringing significant experience in working on tall towers around the world.

The design envisions a reinforced concrete structure, with a central core and walls prolonged towards the facades to give the required stability as well as daylight requirements. The project would need to be delivered within a relatively tight construction budget, and solutions needed to be found to ensure the construction phase could be achieved rapidly and efficiently.

Post Covid-19, the design also needed to retain fluidity, to incorporate the post-pandemic societal changes that could emerge from a constantly shifting situation. It required the design team to ask deeper questions of the plans, such as whether post-lockdown, people would see more value in larger apartment spaces, or whether the hotel facility would require fewer rooms if the hospitality industry was still in turmoil with restrictions on people’s movements and longer-term changes in mind-set towards travel.

Solution

º£½ÇÊÓƵ’s team of experts conducted a series of rapid digital prototyping experiments to demonstrate to the client amendments to the design that could save money, construction time and reduce the building’s carbon footprint by lessening the materials required.

The process created a raft of alternative options, using the latest digital tools to examine and tweak multiple details of the initial architectural design.

Using computational design tools, including Grasshopper, BIM360, Revit and Robot structural analysis software, the team was also able to generate different scenarios around more nuanced elements such as the size of the core, the potential use of the facade as a structural element, as well as the formation of 10-storey cross-shaped bracing options that were to be a feature of the facade.

We initially optimised the efficiency of this bracing by demonstrating that adjusting the angles of the architectural crosses could have a dramatic impact in terms of stability and construction materials required.

We later supported the client and architect to further optimise the design by redesigning the apartment grids to enable a stability system focused purely on the concrete core. This allowed the additional bracing to be removed entirely from the design, reducing the materials required and significantly reducing the project costs. The rapid prototyping process demonstrated a pathway that would save the client an enormous 20% in building costs of the stability system while still maintaining the architectural vision of the design.

Opting for a single construction material – reinforced concrete, rather than the steel and concrete combination of the original sketch design – further positively impacted the project efficiency by speeding up construction times and simplifying construction processes.

We developed digital models, using computational fluid dynamics (CFD) technology, and conducted a series of wind tunnel tests, which helped to reduce the wind load by approx. 25% – further lessening the materials required in the stability system. This in turn, further lowered environmental impact, together with changing the 10-story plinth from concrete into a wooden structural system, as well as project costs for the client, on the other hand rising the benefits by increasing the floor area of the apartments.

We also worked closely with our local partner Tielemans and the project’s geotechnical engineers, to ensure careful analysis had been given to the formation of the piling used within the foundations, as these have significant implications for the integrity of the wider structure.

The city centre location means the ground is already busy with historical infrastructure, as well as being just 10m away from one of the city’s main underground railway lines. To bear the loads required for a 286m tower, around 300 piles needed to be installed to a depth of NAP -65,00m within a highly constrained plot. Any piles that needed to be moved or missed as a consequence of complications with the ground works, would have a direct impact on the structure, with the structural design needing to be adjusted accordingly.

Value

The new development will replace an out-dated 10-storey complex of retail and social housing, with all residents planned to be offered a social housing apartment in the new scheme. It will create a vibrant new district for the city centre.

The ambitious scale of the building means that structural engineering is at the forefront of the project’s success. The º£½ÇÊÓƵ team oversaw the structural engineering on the Hofpleintoren, the largest of the three towers on the plot, up to building permission (Developed Design stage) in late 2023, where our local partner Tielemans led the structural design of the other 2 Towers and wooden plinth buildings, at which point another local firm took on the tender and construction phase. Full completion is expected to take six years.

º£½ÇÊÓƵ’s history of taking on the challenges dictated by high rise towers, as well as our broad experience of working on complex, multi-stakeholder projects, brought a considerable value to driving the scheme forward. The process of rapid digital prototyping revolutionised the design – cutting construction costs, and helping to shape a striking, efficient and sustainable landmark for the 21^st century city.