Soil-structure interaction analysis in a study of an offshore extension

This paper studies the seismic non-linear soil-structure interaction effects on an offshore extension under construction in Monaco, which is a seismic area. The extension consists in backfillings enclosed by precast concrete caissons. Piled foundations are embedded in the backfillings, supporting several buildings. A non-classical design method is required to account for different phenomena such as the dynamic soil-piles-caissons-building interactions, nonlinear soil (backfill) behavior and the tridimensional behavior of the extension. Due to computational limitations the calculation method is split in two parts: first bidimensional transient nonlinear dynamic analyses, then a tridimensional pseudo-static analysis. The bidmensional analyses give the local soil accelerations, which are then introduced into the tridimensional pseudostatic global model. This modeling optimization allows for an efficient solution of the tridimensional dynamic non-linear soil-structure interaction problem. The soil pressure applied to the caissons obtained by the bidimensional and tridimensional analyses are finally compared.