Modelling piled foundations by the macro-element concept

This work applies the concept of macro-element to the problem of piled foundations under vertical eccentric load. The constitutive equations are developed in the framework of strain-hardening elasto-plasticity under the assumption of associated flow rule. The collapse domain is approximated by a parabolic equation while the yield surface has the same shape of the collapse surface and is scaled homothetically through a hardening function accounting for the past load history of the foundation. The proposed approach is validated against data from centrifuge experiments on pile groups embedded in kaolin clay. The macro-element model can be utilized directly to predict the response of piled foundations along with any load path in the axial load-moment plane. By contrast, it cannot predict the response to cyclic loads. An example for the practical application of the proposed approach is finally provided.