Office building Elsässertor
Basel, Switzerland
Competition 1st prize 1990
Project 2000
Realisation 2002-2005
Elsässertor.
Overview
Client
Batigroup AG, Totalunternehmer, im Auftrag der Schweizerischen Bundesbahn SBB, Schweizerischen Unfallversicherung SUVA und PUBLICA, Switzerland
Architecture
Herzog & de Meuron, Basel, Switzerland
Team ZPF
Hans-Peter Frei, Alfred Männel
Awards
Auszeichnung Guter Bauten Kanton Basel-Landschaft Kanton Basel-Stadt 2008
At a key urban development location, the Elsässertor building extends along the railway line towards France, between the railway station, city centre and historical buildings.
Relatively large businesses and restaurants are situated on the ground floor, while spatially flexible offices and business premises are on the upper floors. Three interior courtyards provide optimal light conditions for the office workplaces. The innovative glass facade meets the strictest of requirements in terms of structural physics. The building envelope has two layers, whereby the outer glass elements were mounted on an angle as specified by the architects. Depending on the time of day and incident light, the facade's appearance and colour change, displaying a fractured reflection of the surrounding buildings. In darkness, this effect is reversed and the interior structures become visible.
Elsässertor is a floating body of flat slabs and prefabricated spun-concrete columns with varying diameters of 300-500 mm in a dynamic column grid measuring 6.50 x 8.00-8.80 m. Only sprinklers, lighting and some of the sanitary pipes are integrated into the concrete slabs, while the rest of the building services equipment runs through the locally and statically activated hollow floor. The horizontal reinforcement is provided solely by the eccentrically arranged continuous cores serving as lift shafts and stairwells. Due to the layout, which is unfavourable in principle, but advantageous in terms of usage, the concrete cores have a wall thickness of 40 cm. This support structure is very economical and enabled the construction work to proceed quickly because of the minimal number of walls. The lack of a column for the projecting corner of the building on the ground floor is compensated for by a steel framework with a diagonal support passing through all upper floors and a tension girder in the top slab. Despite the building's length of 140 m, it was possible to dispense with dilatation joints.