Conversion of the Reichstag Building into the German Bundestag in Berlin
The conversion of Paul Wallot's Reichstag building into a modern parliament building is the central symbol of the German capital's relocation. Alongside the internal reorganization and redesign of the building, the fully glazed dome above it plays a key role in the building's concept. The steel structure, with a base diameter of 38 metres and a height of 23.5 metres, is a highly visible sign of the renewal of the building, which remains largely unchanged externally. It is publicly accessible via a double-helix ramp and a viewing platform 16 metres above the base, and a glass ceiling allows a view into the plenary chamber. A conoid-shaped steel structure inside the dome, fitted with mirrors, directs daylight into the plenary chamber and simultaneously serves as the central element of the heating and ventilation system. A rotating shading element around the conoid protects against glare. The 24 dome ribs, with triangular cross-sections of varying depths, are supported on the building's roof by a ring-shaped box girder. They are connected via welded cast steel nodes with 17 horizontally circumferential profiles and welded to a ring girder at the top. Ramps with trapezoidal cross-sections and internal sound-absorbing panels, suspended from every other dome rib, act as additional ring girders. Thanks to new welding techniques and computer-aided manufacturing, the supporting structure could be produced without additional rework or cladding. The shingle-like glazing of the entire dome surface consists of 24 mm thick laminated safety glass in aluminium frames with maximum dimensions of 1.7 x 5.1 m, supplemented by horizontal panes of glass. One hundred panels with photovoltaic cells on the building's roof power the ventilation systems and the dome's sunshade. Inside, the understated detailing underscores the design's focus on openness and transparency, and the intention to integrate the public into the legislative work of parliament.
