Visitors enter the building at the highest point of the foyer, descending dramatically via broad steps to a large cube inserted into the space. Images are constantly projected onto the upper part of the wall. Inside the cube is a presentation of shop concepts and product ranges; the interior is divisible into three sections by sliding partition walls.
Above ground the entire building was constructed from prefabricated components. The need to keep the sharply angled rigid glass skin as free as possible from large wind loads and movements in the 10,000 square-metre roof surface prompted the idea of decoupling the roof from the facade for expansion movements, but enabling wind loads to be directed from the glass skin into the roof structure. Hydraulic shock-absorbers are used here as connecting elements (see p. 818).
Continuous wind loads on the facade
A constant light wind on the facade cannot be avoided. It was therefore necessary to decide at which wind speed the system would couple the glass envelope to the roof. The facade stays have to be able to take the occurring loads when decoupled, for which the structure had to be appropriately dimensioned. The hypothetical breaking load was calculated and the shock-absorbers correspondingly adjusted. The effect of different loads on the system was tested using case data of medium wind speeds from the last 50 years.
Peak wind loads on the facade
By their very nature, strong gusts of wind happen quickly and suddenly. The delicate, sharply angled facade construction with laminated glass fins and glass corners did not permit the use of expansion joints. Thus it cannot take strong wind loads and has to direct these instead into the steel roof frame. The hydraulic shock-absorbers for the facade react to a combination of strong wind forces and high speed, by coupling the facade and the roof frame together to form a rigid connection. In this case the head of the facade meets a support in the roof.
Movements in the roof frame
Temperature changes lead to considerable movements in the steel roof frame. Warmer temperatures cause expansion, while cold causes contraction. These movements in the roof construction should not be allowed to impact on the glass facade, as otherwise it could lead to gaping joints and cracks. The glass facade continues upwards to form the edge of the roof, with the roof frame moving in this case under the corner formed by the facade. Hydraulic shock-absorbers integrated between the roof and the facade take up the movements. The roof and the facade are thus decoupled.
