THE SQUAIRE Frankfurt am Main

Structural flights of fancy

A 660 m long, 65 m wide, nine storey high shopping and office centre with two hotels and event locations rests atop the roof of the mainline station at Frankfurt Airport—at least so it seems. In fact, this futuristic superstructure, weighing a total of 350,000 tonnes, is borne aloft by a fish-belly truss construction and the steel columns of the station underneath.

KREBS+KIEFER used complex non-linear calculations to verify the stability of the existing structure. By exploiting all system and cross-sectional reserves, it was possible to extend the superstructure to the maximum, with only a few local reinforcements.

The main elements of the existing structure are 43 steel frames spanning the tracks and platforms—column-free—at intervals of 15 metres. A 30 cm thick, highly reinforced concrete slab connects the upper chords of the fish-belly truss girders without joints over the entire length. 15 x 15 cm small steel blocks deflect the loads from the superstructure into the posts of the truss.


  • Structural Engineering
  • Rehabilitation & Preservation