Asia’s largest arch support spanning
72 metres and constructed
with glulam, CLT BBS and solid
Republic of Singapore
Year of construction 2016
Technical University of Nanyang
Architect Toyo Ito & Associates
Struts Building Technology
Support structure planner
T.Y. Lin International Group
Technical adviser on statics
Ermanno Acler - Holzpak Engineering
Architects Toyo Ito & Associates were commissioned by the Technical University of Nanyang to design a new sports centre, and thus Asia’s largest glulam construction, clad in 3-ply solid wood panels. The trend for large-volume timber constructions has just started in Asia, where ecological construction is becoming increasingly important, above all in public buildings.
It is a non-air conditioned hall with a 9,800 m² playing surface. Cooling is provided by the optimum design of the hall and a sophisticated ventilation system that works without traditional cooling elements, saving significant cooling costs when the sports hall is used. The spectator seating provides space for 1,000 sports fans. The playing surface has space for 1 football pitch, 3 basketball courts or even 13 badminton courts – providing plenty of space for all students.
The Binderholz Group constructed the components from Austrian wood and supplied them together with the necessary knowledge and expertise to Singapore in conjunction with its partner Holzpak Pte. Ltd. As the components already fitted perfectly, the roof was completed in record time with only 14 workers over a period of three weeks. If other materials had been used, it would have taken 30 workers and a construction period of two to three months.
The NTU sports hall was designed using a 3-point arch support. It is important to choose a system that permits the surface and side joints to be easily moved for such a large span without putting additional load on the wood components. The 72-metre roof consists of seven wooden arches, supported by vertically positioned steel A-frames, which were constructed to minimise lateral movement of the side joints. It was also necessary to reduce the lateral movement of the steel frame surfaces to restrict the deflection of the roof to a minimum.
For logical reasons, each of the two halves of the arch were split into three separate components, which had previously been joined by a temporary connection – a combination of full-thread bolts and custom-made steel plates. This meant that it was possible to obtain a high degree of rigidity and restore the structural behaviour of the two halves of the arch. The vaulted roof was stabilised with a rigid layer of cross-layered wooden panels. The binderholz CLT BBS elements are 60 mm thick and were bent over the glulam to guarantee optimum adjustment to the curvature of the roof.
Thanks to this outstanding solution, it was possible to achieve the aim of a consistent rigidity ratio across the entire roof and, at the same time, accelerate the construction process of the Roof. The wood can support a weight several times heavier than concrete or steel in relation to the ratio of thickness and weight. No columns or beams are thus needed in the interior to support the seven wooden arches weighing a total of 440 tonnes.
There are other benefits apart from the structural benefits: Wood has excellent fire resistance as a product. Instead of burning, it only carbonises at a speed of 0.75 mm per minute. Wood therefore offers an additional buffer of 50 mm, which allows a whole hour for evacuation. The carbonised layer also acts as an insulator so that the inner core is protected from heat. This was further supported by a sprinkler system to extinguish individual components in risk areas. The wood is also resistant to moisture and termites, meaning that no special conservation system is needed, a factor ensured by annual controls. And it also benefits the environment as the wood solely comes from sustainable forest management, i.e. a new tree is planted for each felled tree.
Photos: © Holzpack, binderholz