Description
CargoLifter AG was founded in 1996 for the development, construction, operation and marketing of cargo airships. The CargoLifter was intended to become a new means of worldwide transportation of large and heavy goods; its dimensions required a new scale of thinking. A suitable “air-shipyard” was needed. The enterprise, including take-off and landing areas, a visitors’ centre, and facilities for suppliers, is situated on a former military airfield in Brand, 60 km south of Berlin.
The heart of the complex is the hangar for the construction and maintenance of the airships, which are roughly 260 m long. Size and shape of the hangar are determined by the space required by two airships docked side by side: the building is 107 m high and spans a floor area of 66,000 m². At 210 m in width and 360 m in length, the hall is one of the world’s largest free-spanning structures. In order to create enough space for the simultaneous assembly of two cargo airships, the entire floor area is free of installations. Therefore, some of the design offices and staff rooms are situated at the perimeter of the hall between the base points of the large arched trusses.
The hangar consists of a central section with a compass dome and two domed gates at its ends. In terms of geometry, the elevation and plan of these main elements is based on a circle. In order to achieve the requisite opening angle for the airships to pass through, both gates are supported by a rigid central section. When the gates are closed, their quarter-spherical shape supports the aerodynamic performance of the building.
The load-bearing structure of the central section, which is 144 m long and 210 m wide, is based on five arched tubular steel trussed girders with a radius of approximately 100 m, and a structural membrane spanning between the arches. The steel trusses are restrained by approximately 9 m high reinforced concrete abutments, thus creating a rigid semi-cylindrical shell. The arched trusses are positioned at 35 m centers. They are coupled by reinforcing members accepting wind and torsion loads. At their vertices, the trusses are linked by a continuous ridge girder whose butt ends also provide the connecting joints for the gate structure. Ridge girder and arched trusses are four-chord trusses with a structural height of 8 m.
The semicircular shape of the hangar requires an outer building envelope that performs both as a roof and a wall. The membrane freely spanning between the arched trusses accepts wind and snow loads and transmits them to the top chords of the trusses. This membrane, developed for the project, is a four-layered system with the two outer layers accepting the non-permanent loads. The two inner layers create air cushions and exclusively serve as thermal insulation. Daylight enters the hangar through the highly translucent membrane and the fully glazed exterior and interior façades of the office zones.
Both gates consist of eight segments each. When the gates are opened, four segments slide behind each other on either side. The structural system of the individual gate elements is composed of trapezoid profiles on a latticed shell of vertical and diagonal members. Perimeter arches with a height of 3 m accept the loads from the shell segments. When opened, the gate segments can slide neatly behind the fixed segments. In this way, the huge opening ratio of the gates (200 m wide and 100 m high) is made possible.
After CargoLifter AG went bankrupt, a new investor was found for the hall and the entire premises. The Malayan Tanjong Corporation plans to turn the hangar into a holiday park including a tropical rainforest. The conversion of the hangar is scheduled for completion in autumn 2004.
Drawings
Originally published in: Jürgen Adam, Katharina Hausmann, Frank Jüttner, Industrial Buildings: A Design Manual, Birkhäuser, 2004.