Gridwork domes made of double mesh grid shells of wooden laths, spanning up to 85 metres
Bundesgartenschau Mannheim GmbH
Carlfried Mutschler und Joachim Langer, Mannheim, D
Ove Arup & Partners, London
The Multihalle was built for the German National Garden Show that took place in 1975 in Mannheim as a temporary multi-purpose hall with café and restaurant. It is made of two fluidly connected gridwork domes that develop organically from an amorphous ground plan. The support structure consists of a gridshell that spans up to eighty-five metres, made of a double mesh of wooden laths with a 5 x 5-centimetre cross-section. This intrinsically soft shell is braced with stiff bolt connections as well as a cable net arranged diagonally to the gridshell fields. At their ends, the laths of the gridshell are braced by connected glulam beams. The PVC membrane covering the shell is thirty per cent light-permeable, so that the interior is suffused by a soft, even light. The design of the roof structure stemmed from research conducted on gridshells at the Institute for Lightweight Structures at the University of Stuttgart. Optimising the roof form in terms of structural engineeringwas a matter of painstaking trial and error using hanging models made of chains and nets, which, when turned upside down, generate filigree gridshells made exclusively of pressure-loaded laths. The hanging model for the Multihalle was measured using stereophotogrammetry, while computers were used in parallel to check the balance of forces in the structure numerically, determiningthe coordinates for the individual nodes. Using scale models, it was possible to test the structural calculations made by a programmefor computing non-linear frameworks. In erecting the roof, the gridshell was first laid out flat on the ground with loosely connected nodes and then pushed up into shape with the help of scaffolding towers. The bolts were then locked into place and the boundaries of the shell fixed so that the roof could bear its own weight. Finally, an asymmetric load test was carried out to ensure the building’s structural stability. The Multihalle attracted worldwideattention at the time of its construction as an architecturally outstanding pioneer project for several engineering disciplines.