The Smile

By Luca Maria Francesco Fabris - 7 December 2017

The installation The Smile - brainchild of Alison Brooks and Arup for the London Design Festival that closed last October - demonstrated to the world the construction possibilities of hardwood. The Smile’s disarming simplicity conceals years of research into the cross-lamination of hardwood fibers and is the first structure built with industrial-sized panels of hardwood CLT. This 34 m rectangular-section “mega-tube” was arced so that the open ends of the two raised extremities became vantage points from which to view the surrounding area. The structure itself comprises just 12 prefabricated engineered tulipwood CLT panels 4.5 m wide and up to 14 m long. Assembled on site with 6,000 self-tapping screws, this huge tunnel is only an incredible 10 cm thick yet boasts higher structural resistance than reinforced concrete. Access to The Smile is via a large opening in the center of the structure, the only point where it touches the ground. Visitors were able to walk from the parapet at one end to the parapet at the other to see the view from opposite sides. Small oval-shaped openings - 12 to 20 cm in diameter - in areas of the walls subject to lower stresses create patterns of light inside the timber tube during the day. To ensure against rocking, The Smile is stabilized with a 20 t counterweight concealed under the structure and linked to a series of invisible stiffening beams in the roof above the panels. The Smile’s length, its capacity to withstand 10 t of wind loading, and a maximum dead load equivalent of 60 visitors means it has the strength of a 5-story lift shaft core. The only difference is its much smaller structure: elegant proof of real strength.