Infinity on the Kirchberg plateau in Luxembourg
INFINITY’s LIVE.SHOP.WORK. triptyque comprises around 20,000 m² of high-quality housing, a 6,500 m² shopping centre with 23 shops, restaurants and themed cafés, and a 6,800 m² office building.
The project is based on a foundation system in direct contact with the underlying consistent sandstone. The sandstone roof level varies across the site and is weakened by the presence of fractures. A campaign of +/- 100 diagraphic drillings has enabled to refine the knowledge of these variations and to determine the foundation system more precisely.
In the areas where the sandstone level is lower than the bottom of the excavation, foundation wells were built down to the healthy sandstone to guarantee the homogeneous behaviour of the tower’s foundations. The fractures are partially filled in and bridged with extra width of the footings.
The office structure is mainly prefabricated. The central core consists of three shafts in the upper levels, only one of which extends to the foundations.
Inclined columns generate significant bending and torsional forces on the first three levels above ground. Tie rods (prestressing bars), placed in the cast-in-place slabs of the relevant floors, allow the transmission of the deflection forces to the central core.
The floors of the tower are made of prestressed precast slabs (Cofloor) of 25 cm thickness.
These floor elements are supported by beams with low height, either in concrete or made of metal profiles in order to facilitate the passage of techniques. For the intermediate axes, the floor elements are supported by prefabricated twin walls working as wall beams.
The basement floors are made of prestressed hollow core slabs resting on prefabricated beams, following the same principle as for the office areas.
The piers of the tower form the supporting columns.
At the foot of the residential tower, the columns made of high-performance concrete (C80/95) are laid on bound footings of lower strength concrete (C30/37).
The central core consists of three sections connected by metal lintels.
Structural optimisation and detailed design