Abba Arena Auditorium
DEMOUNTABLE CLT THEATRE STRUCTURE
The ABBA Arena Auditorium forms the seating areas for the ABBA Voyage concerts, as well as incorporating entrance and bar areas, vertical circulation, fire escape corridors, and technical zones. It has a footprint of about 80 x 50m, is four storeys tall, and consists of 1650 unique cross laminated panels of dimensions up to 9.9m long. It sits within, and structurally independent of, the steel-framed enveloping walls and roof of the arena.
Xylotek joined the project team during its design development, initially as design consultants, to develop a solution wholly in mass timber (as an alternative to a steel framed approach). Having proven the viability for a cost-effective, demountable, scheme in cross laminated timber, we then were appointed for its full design, fabrication and installation. We worked with CLT supplier Hasslacher who produced and machined each of the unique panels which were delivered, just-in-time, in batches to the Stratford site.
The original scheme had around 144 tonnes of steel + 630m3 of CLT; our scheme has 900m3 of CLT which approximately halves the embodied carbon
The project presented exciting challenges. The non-orthonogal design – derived from the overall hexagonal form of the Arena - added significant geometric complexity compared to more conventional regular orthogonal CLT structure. We therefore established a rigorous process of 3d geometric modelling and data handling, integrating fabrication and install-sequence information into the model from the outset, and working closely with Hasslacher to provide CADCAM ready data. Given the geometric complexity, it was decided that a separate installation drawing was needed every panel. These were produced with programming help from Mule Studio.
Another challenge was to maximise the ease of disassembly of the structure to allow for its future relocation. CLT panels are typically joined together with lots of large screws which are challenging to remove. To address this, we developed – with our subconsultant engineers Corbett & Tasker - a system that mainly uses bolted connections. The use of glulam ‘ledger’ elements and ‘Idefix’ recessed connectors –combined to enable adjoining CLT panels to be structurally joined, even when one face is inaccessible. We believe this approach has broader potential for lifecycle considerations of CLT buildings in making dismantling and reuse of CLT panels possible (and so keep its captured carbon out of the atmosphere for longer).
The 600 tonne auditorium structure has no groundworks! Driven again by the need for demountability, the CLT structure is carried on over 300 JackPad portable foundations which sit directly on the tarmac of the existing car park on the site. Each JackPad wast adjusted vertically to account for variation in the carpark level and keep the CLT structure level. The large number of pads means that bearing pressures are kept low. The auditorium is thus wholly demountable.
The fire protection of the CLT was of critical importance and was achieved through spray-applied spread-of-flame treatments (applied by ATOL Construction). This was applied partly in-situ on the assembled structure, and partly onto panels pre-assembly (in a neighbouring marquee) for panels where accessibility would be difficult when assembled.
The Arena, located in Stratford, London, hosts the virtual ABBA Voyage concerts, and is designed to be demountable for future relocation. Xylotek also carried out the production of the external timber raincreen.
