The Portalen pavilion is a double-layered deployable timber gridshell in the tradition of Frei Otto and his team, and it serves as meeting space and venue for the community centry of Hageby in the city of Norrköping, Sweden. The shell is constructed as a simple flat mat of timber laths, and then bent into its three-dimensional form. Once positioned onto the glued laminated timber arches, the shell is braced by cables and covered by polycarbonate sheets.
A group of architects and engineers who had recently immigrated to Sweden wished to create a community centre for Portalen in Hageby, Norrköping. Portalen is a centre for labour-market integration and a place to make new contacts and find employment. In the Summer of 2016, in collaboration with Spanish architects Map13 Barcelona, they used experimental, vaulted brick work, to explore the potential nature of this meeting place. As a first step towards a community centre, the intent was to build a pavilion, initially envisioned as a large masonry vault.
Summum Engineering along with Edyta Augustynowicz were then invited to assist with parametric modelling and structural engineering. Due to poor soil conditions, the pavilion was then re-imagined as a more modestly sized timber structure, and the decision was made to build a deployable gridshell. We proceeded with the structural design on that basis.
The gridshell was parametrically modelled by first generating a surface that met architectural and constructional constraints. A grid was mapped onto this surface using the compass method in order to create a so-called Chebyshev net – a network in which each edge has the same length – to guarantee that the curved form could be built using a square, flat mat of timber laths. This discrete network was then altered using form finding to improve its structural and constructional performance, before being analyzed. The structural model included various aspects including joint slip of the timber connections, higher-order geometric nonlinearity as well as material properties according to Eurocode. The analysis was approached in two different ways: first, similar to seminal structures in the UK, such as the Weald & Downland Gridshell by viewing the actively bent gridshell as a set of curved glulam beams (advice was sought from the original engineers from Buro Happold and builders from Green Oak Carpentry), and second, by taking the residual bending stresses from deployment into account in combination with material creep. The gridshell was evaluated with respect to deflection, material strength and global buckling; the latter by comparison with buckling factors achieved for Frei Otto’s Multihalle gridshell in Mannheim, Germany.
The resulting structure, once deployed, braced and clad, will serve as a permanent pavilion for Sweden’s newest citizens making their way to Portalen and finding their place in their new home country.
Joanna Zawieja et al. | Public Art Agency Sweden (Statens Konstråd)
Project architect and client
Design and modelling team
Marta Domènech Rodríguez, David López López, Mariana Palumbo Fernández, Teresa del Pozo Lérida, Delfina Capiglioni, Antonio (Toni) Planas Portas, Alejandro Caballero | Map13 Barcelona
Diederik Veenendaal, Sjef Brands | Summum Engineering
Diederik Veenendaal | Summum Engineering
Marcus Abrahamsson | Nyrens
Sveden Trä (timber laths)
Hasslacher Norica Timber (glulam arches)
Swans Mekaniska (steel connections)
Carl Stahl (steel wire bracing)
GOP (polycarbonate cladding)
SFS Intec (connections)
Steve Corbett, Andrew Holloway | Green Oak Carpentry