COMBINED PILED-RAFT FOUNDATION (CBRF),
Carsten Ahner1, Dmitri Sukhov1
There are no standards and no design rules for Combined Piled-Raft Foundation
available up to now. The investigation of this problem is just at the beginning.
The common reliability approach for the elaboration of a safety concept for
Combined Piled-Raft Foundation is proposed and future tasks are set.
The problem of design of Combined Piled-Raft Foundation have become more
and more important in the last years, when some skyscrapers were built in
Germany. Most of them located in Frankfurt Main, where the over soil layer
consists of settlement active clay. The rocky Frankfurt limestone is located at a
depth of 44 metres.
The Combined Piled-Raft Foundation could be a good economic decision for
heavy high buildings, because both the bearing capacity of the slab and the
1 Institut für Massivbau und Baustofftechnologie i. Gr., Universität Leipzig
bearing capacity of the piles will be fully used. Since 1984 the following projects
have been built or designed:
• Messetorhaus (Fair Gate House), Frankfurt/M.
• Messeturm (Fair Tower), Frankfurt/M.
• American Express High Rise Building, Frankfurt/M.
• Deutsche Postreklame, Frankfurt/M.
• Landeskreditbank Baden-Württemberg
• Südwestdeutsche Landesbank, Stuttgart
• High Rise Building Port of Singapur Authority
• High Rise Building of Trade Centre Landsberger Allee, Berlin
• Westendstr. 1, Frankfurt/M.
• Castor and Pollux, Frankfurt/Main.
Many projects already built or designed show an absolute necessity for
elaboration of a common design concept, which could be used by all specialists of
The Combined Piled-Raft Foundation acts as a composite construction consisting
of the three bearing elements: piles, slab and subsoil. In comparison with the
conventional foundation design the Combined Piled-Raft Foundation exhibits a
total new dimension fo