Soil-Structure Interaction aspects for ultimate limit state design of complex foundations

Compound foundations like Combined Pile-Raft Foundations (CPRFs) exhibit a com- plex interaction behaviour which is a prime example of soil-structure interaction. This complex inter- action can rarely be comprehended by means of analytical or empirical methods; in fact, usually nu- merical methods like the Finite Element Method (FEM) have to be applied. These numerical methods are -in geotechnical engineering up to now - commonly focussed on serviceability, environmental or groundwater topics and the majority of the research activities, which are running on the application of numerical methods for ultimate limit state investigations, concentrate on the stability of slopes or ex- cavations. Complementing this, in this paper a concept for ultimate limit state design of complex foundations is presented.