Commerzbank Arena

In order to prepare the stadium for the Football World Championship in 2006 and provide a roofing system quickly adaptable to changing weather conditions, a membrane construction has been selected, which when "parked" is folded together in the centre of a tensile cable structure. The material saving principle of this "gather-up roof" was developed by the engineers Schlaich Bergermann und Partner and has been tested in a smaller scale for several years.

Despite the complete stand roofing, the steel cable membrane roof with spans of up to 240 m ensures a perfect growth of the grass. The outer roof edge and the contour of the stands are in plan geometrically identical. This results in an ideal roof area and simultaneously an optimized roof load transfer into the supporting structure of the stands. Similar to a spoke-wheel, a steel element forms the outer compressive ring, the hub. Two tension rings are positioned at the inner roof edge and kept apart by 12 m long struts. The connections between tension and compressive rings consist of 2 x 44 radial cables, which together with six suspended ropes form the rope girders.

Another 2 x 36 radial cables are positioned between the tension rings and the central knot. Located centrally above the pitch a multimedia cube is suspended from this central knot, which simultaneously houses the inner roof membrane. The cylindrical drum protects the folded up membrane and opens and closes like a blossom, when the roof is extended.