Numerical aspects of coupling strongly frequency-dependent soil-foundation models with structural finite elements in the time-domain

In the literature relevant to soil–foundation–structure interaction problems a lot of results for the dynamic stiffness in the interface between the soil–foundation part and the structure have been published. However, in order to deal with transient excitations, a transformation into the time-domain is necessary. This contribution uses a well-described Padé-like rational representation, but adds some improvements concerning robustness, optimized treatment of spurious modes and numerical effectiveness. The benefits of the new findings are demonstrated by means of a typical application from foundation-engineering: very well prepared dynamic stiffness coefficients for groups of piles are used in order to treat transient excitations caused by an unbalanced rotor during running-up.