Combined pile/slab foundations are defined in DIN 1054:2010-12 as geotechnical composites consisting of a foundation slab and piles or diaphragm wall elements. This form of foundation engineering is used to transfer very high building loads (e.g. from high-rises) into the subsoil and to limit or minimise settlement. The relative stiffnesses of the individual composite components and the subsoil involved influence the determination of the internal forces and moments so that the design must be created in an iterative fashion on the basis of the complete model.

Regulatory framework

The Technical Building Rules provide conclusive technical rules for the design and execution of pile/slab foundations. The passage referring to the need for a regulatory verification of fitness for use, currently still included in DIN 1054:201, will be removed with draft DIN 1054/A3:2020-02. DIBt does not grant general construction technique permits (aBG) for these applications.

The technically complex modelling of the foundation and soil and the iteration process require an excellent understanding of both geotechnical design and building construction. For the structural analysis and its review, sufficient expertise in both disciplines should be ensured. For instance, regarding geotechnical design, a design review expert for earth works and foundation engineering within the meaning of the Model Ordinance on design review engineers and experts in accordance with Section 85(2) MBO (M-PPVO, December 2012) could be involved in the design and review process.