For 50 years Buckminster Fuller’s ideas about lightweight structures have been fascinating people, and not just structural engineers and architects. He showed how to create a stable geodesic structure in which non-contiguous elements subject to pressure are combined with contiguous tensioned elements.
In keeping with this principle of “tensegrity”, the office of Grand Architects spanned the elliptical floor space of the velodrome in Aigle with a support-free double layer pneumatic membrane structure. With a diameter of 70m x 90m and a PVC-PES membrane area of almost 5,000sqm, the membrane cushion is among the largest of its type in the world-
On the ground, the steel structure consists of three adjacent compressed rings, which are connected by spokes made of round tube profiles. The outer ring is in the form of a three-dimensional structure. Suspended in between are vertical “air supports”, which run up and down in the shape of a pyramid, attached by four tension rods each. In addition, the entire steel structure is undergirded by tie rods which run from the edge beams across the air supports to the inner tension ring.
The pneumatic cushion is composed of two layers of membrane, manufactured from PVC-coated polyester material, which is assembled and mounted in a single unit. The lower membrane is supported at the edge by 56 air supports and a cable grid, while the central area with a diameter of 40m is an unsupported span.
The upper membrane stretches across the entire ellipse. It is held in place by 28 radial cables that rest on the outer membranes. These cables are protected from the weather by sleeves. Two blower stations keep the air pressure at 379Pa. Sensors mounted inside the membranes respond to weather conditions and control the pressure in the membrane up to a maximum of 1,000Pa. The attic’s circumferential aluminium cladding forms the outer end of the roof.
The displacements are controlled by an automatic system to adjust the internal pressure.