Foundations

When building the foundations, which were completed within a year, the plan had been to raise the structure to a height of 705 m, 544 m using reinforced concrete and 161 m using steel. The overall mass was about 500,000 t, equivalent to the take-off weight of about 900 fully-occupied Airbus A380s.

Pile foundations were laid, comprising 194 reinforced concrete skin-friction piles, each 50 m long and 1.5 m in diameter and connected into loadbearing sandstone at a depth of 50 m. A 3.7 m petal-shaped concrete slab was then poured over them (cf. Fig.). The extensive podium surrounding the tower on the lower floors stands on 650 piles, each 90 cm in diameter. Since the highest safety margins were factored in from the very beginning, there was sufficient certainty that the foundations could cope with the change in height. Furthermore, the additional 100 metres would result in a comparatively small increase in the structure's deadweight because of the tower's tapering design.