At the "Königsallee" in Dusseldorf
Between 1985 and 1987, the city-centre Kö-Galerie was built in a joint venture in Düsseldorf’s most expensive shopping street. It consisted of four deep basement floors, three shopping floors and five office floors. Due to the short construction period and the close proximity of neighbouring buildings, the so-called “top-down method” was used in Germany for the first time (Düsseldorfer Deckel - Düsseldorf cover slab). In this construction method, a concrete roof slab is built at road level on an earth model and the construction works are then simultaneously carried out using the mining technique downwards and conventionally upwards. This top-down method has two decisive advantages which compensate for the additional costs: settlements of neighbouring buildings are close to zero and the reduction in construction time is enormous, in the case of Kö-Galerie it was 35%.
Before concreting the roof slab, diaphragm walls were built up to the level of watertight tertiary layers. After that the prefabricated composite steel supports (primary columns) were installed to bear the loads of the buildings in liquid-supported boreholes. Each further slab that was concreted below the upper roof slab on the earth model served as reinforcement for the diaphragm walls and as the roof slab for the next basement floor.
Further details:
- 6,500 m² plot area
- 240,000 m³ building volume
- 9,400 m² diaphragm walls th = 80 cm
- 16.5 MN maximum column loads