Date: 17 September–12 October 2016
Company Name: American Hardwood Export Council (AHEC)
The American Hardwood Export Council (AHEC) has collaborated with Alison Brooks Architects, Arup and the London Design Festival to present a cross-laminated tulipwood structure, ‘The Smile’ at the Chelsea College of Arts’ Rootstein Hopkins Parade Ground from 17 September until 12 October 2016.
The Smile is an urban pavilion that can be inhabited and explored by the public. The tubular timber structure measures 3.5 metres high, 4.5 metres wide and 34 metres long and is effectively a beam curving up at both ends. Showcasing the structural and spatial potential of cross-laminated American tulipwood, Alison Brooks’ concept is the first ever ‘mega-tube’ made with construction-sized panels of hardwood CLT.
CLT, which stands for ‘cross laminated timber’, is an engineered timber that can be used to make the walls and floors of entire buildings. CLT is commonly created using spruce, but The Smile pioneers the use of cross-laminated tulipwood, a fast-growing North American hardwood that offers greater strength and a more attractive finish. The fabrication of tulipwood panels in a CLT production plant helped to showcase how the material could be used for commercial projects.
Structure
The Smile’s two ends are viewing platforms that take in the sky and reach out to neighbouring buildings. Entering the pavilion through an opening where the curved form meets the ground, visitors can walk from end to end of the tube to discover a new kind of space that gradually rises toward light.
The walls are perforated with oval holes, measuring between 12 and 20 centimetres, which allow daylight to filter in and track across the interior space throughout the day. At night, The Smile emits beams of light from each end, elongating the structure. It is a play between a landscape structure and a building.
The Smile cantilevers from a single point in the centre. With its giant curved shape, it appears as though it may rock side-to-side. Making sure that it doesn’t happen even when the weight of 60 visitors is at one end has been just one of the challenges for Arup, the project’s engineers. The massive timber structure is screwed to a large wooden box that is hidden under the ground and filled with 20 tonnes of steel weights to prevent if from tipping over. The structure is designed to resist approximately 10 tonnes of wind loading.
Andrew Lawrence, global timber specialist at Arup, says, “The Smile is the most challenging structure ever constructed in CLT. Every aspect is pushed to the absolute limit. It really shows the potential for hardwoods in construction.”
For AHEC, ‘The Smile’ is one of the most important developments in a decade of research and development into structural timber innovation with Arup, and one that could broaden the use of CLT in the construction industry.”
