During the redesign and expansion of the Hilti AG factory site at Feldkircher Strasse 100 in Schaan (FL), existing factory, warehouse and administration buildings were demolished and replaced by the Office Mitte and Office Nord buildings.
The Office Nord building is located between the park and Feldkircherstrasse and forms the northwestern end of the new Hilti Campus. The rectangular building has three floors above ground and one below ground, which is only partially integrated into the ground to the west due to the slope. The first floor has a park-side arcade with meeting rooms and a central restaurant, while the upper floors are used as office space. The central area spanning between the cores is formed by storey-wise stepped atriums for cenital lighting with bridge-like formulated ceiling connections (“decks”).
In order to ensure the greatest possible flexibility of use, the structure has no vertical structural elements in the area of the usable spaces that restrict the use of the floor plans. In the above-ground floors used for office purposes, columns are only placed along the facades and the inner courtyard. Wall plates are only found in the area of the two access cores.
Large floor spans of up to 11.1 m in combination with large distances between columns along the floor edge result in correspondingly high support reactions. In order to avoid critical points with high punching shear stresses and to limit the slab edge deformations according to the requirements of the façade, the slabs were largely supported linearly via beams and edge girders. To limit the deflections of the long-span slabs, they were prestressed.
The gravity-induced loads are transferred in a concentrated manner via a few vertical support elements. Due to the fair faced concrete requirements, the highly stressed columns were constructed using on-site concrete. The facade columns were connected to the edge beam in a stiff manner, resulting in a moderate framework effect. This reduces beam deflections, especially in the corner and edge areas. Due to the high loads, the columns were directed centrically down to the foundation.
The decks are accessed via steel staircases. These span from floor to floor as simply supported beams with intermediate landings. The stair stringers form the railing and constitute the main load-bearing element. The stair treads were made of steel sheets in the form of troughs which, in addition to carrying the live loads, stabilize the stringers horizontally.