At the heart of Stockholm's new Hagastaden district, one of the world's leading areas for life sciences, the eye-catching Forskaren building is emerging. The round office building, which consists of a steel column-beam system, is located on the overpass of the E4/E20 highway, which placed great demands on the distribution of loads. The structural engineering company Sitowise (formerly BTB), which was commissioned to design the frame, used its advanced Tekla Structures environment for the complex frame design.
Forskaren is a collaboration between Tekniska museet, Karolinska Institutet and Vectura Fastigheter that will be a meeting place between academia, industry, research and the public. On the ground floor, there are plans for exhibitions and meetings with current names in the life science field. The rest of the building will house offices, co-working spaces and a restaurant when it is completed at the end of 2023.
The building's frame consists of a radial column-beam system in steel with a hollow deck floor and three stabilizing stairwells in prefabricated concrete. The frame rests on prefabricated concrete beams and steel trusses, which in turn rest on the overlay constructed over the tunneled parts of the E4/E20 and the Värtabanan that cross the area. Because the tunnel roof must not be loaded at all, the loads have been transferred down to the tunnel walls via the concrete beams and steel trusses.
- The trusses were the most challenging parts to make due to high loads and complicated geometries, especially as they weigh up to 30 tons and are almost 30 meters long. The glazed steel structure on the roof was also complicated, as it is both round and has a slope and needed to be adapted to strict deformation requirements from the glass roof," says Hampus Hällgren, designer at Sitowise.
Installations required 'cracked' steel beams
The building's façade is clad in accoya (wood modified by acetylation to prevent it from absorbing water) and inside, oak veneer has been used to clad the interior walls and mezzanine railings.
At an early stage, Sitowise worked with a typeface through the building, dividing the building into sections vertically so that all floors are visible. This was to make it easier to see how the radial steel beams, which run from the center of the building out to the facade, would be aligned with installations in the ceilings and floors.
- "We had to adjust the steel beams quite a lot in terms of height, which meant that they had to be 'cracked' a couple of times on the way out to the facade. This required a great deal of coordination with the other disciplines and took a large part of the design time," says Hampus Hällgren.
Well-developed Tekla environment
Tekla Structures has been a basic prerequisite for the design of the frame and the production of manufacturing drawings where many different assemblies would be synchronized.
- At Sitowise, we work in a well-developed proprietary Tekla environment that is adapted to our customers' wishes and requirements. Having this environment as a base saves a lot of time and makes the work much more efficient and better. For a complex project like this, it has been essential to have a ready-made environment from scratch," says Hampus Hällgren.
For the transfer of elements to the frame contractor Contiga, Impact Tekla Base Tool has been used to link to the planning program Impact. This has then formed the basis for Contiga's planning in the factory and storage of building materials. Carl Lagerstedt, Assembly Manager at Contiga, sees great advantages in working with buildable 3D models when it comes to work environment and logistics:
- This makes it easier to detect and prevent work environment risks at the design stage, such as high heights and hard-to-reach places to assemble. In the assembly phase, our site managers use the model as an aid to determine assembly orders and which concrete elements should be delivered on which loads.
To share buildable data, Contiga's supervisors have used Trimble Connect, primarily on their computers. On site, the installers have then had access to the model on iPads or on their phones.
What has been the cooperation with other stakeholders?
- "We started early with joint design meetings, where we addressed the problems that we knew would be big and take a long time, such as the trusses under the building. Close cooperation is a prerequisite for avoiding problems at a later stage," concludes Hampus Hällgren.
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