An elasto-plastic macro-element for pile groups under inclined and eccentric loads

A new macro-element for pile groups under monotonic loading is presented herein, built on the classical theory of isotropic strain-hardening plasticity. The main assumption is that the yield surface in the generalized force space has a fixed shape and expands homothetically with respect to the axes origin util reaching the failure locus. Plastic displacements are developed according to a non-associated flow rule along with a hardening law derived by reproducing the behaviour of pile groups under monotonic loading observed in field tests. A few parameters are needed to calibrate the model, most of which are required in routine design. The performance of the macro-element is validated against data from centrifuge tests.