Seismic soil-structure interaction study of inclusion reinforced foundations with a macro-element

The reinforcement technique using rigid inclusions is a practical, cost-effective, and time-saving foundation solution. This technique has already proven successful in supporting structures that are subject to high seismic demands, such as the Rio-Antirrio bridge in Greece. In a performance-based design approach, it is important to consider the dynamic soil-structure interaction phenomenon, which is specially relevant when dealing with soft soils. Direct approaches simulating the whole soil-structure system within the same numerical model are still computationally expensive and the classic modal response spectrum analyses, based on the superposition principle, are not capable of taking into account most of nonlinear mechanisms. The macro-element approach is therefore a promising method, as it allows modelling of non-linear soil-structure interaction mechanisms at the base of the structure without increasing the numerical cost. This approach has shown particularly good performance in the dynamic analysis of shallow and piled foundations. The present paper aims to extend the application of the macro-element approach to foundations on rigid inclusions. To this end, the upper-bound kinematic exterior approach is employed to derive a yield surface corresponding to this type of foundation. Its potential application in the context of non-linear soil-structure interaction studies is also discussed.