Importance of kinematic interaction in the seismic vulnerability assessment of pile-supported buildings

This paper reviews some aspects of pile-soil kinematic interaction in light of recent research findings. First, kinematic pile bending is examined, recalling some of the relevant contributions on the subject, and then comparing available methods with recent advanced numerical and experimental studies. A general procedure for the practical application of simplified formulae, taking into account nonlinear soil behavior, is discussed, and it is shown that the above formulae compare well with the available benchmarks. Based on the accumulated theoretical and experimental evidence, some suggestions for future code revision are also provided. Second, the paper focuses on the change of the free-field motion generated by pile-soil kinematic interaction, pointing out that the presence of piles usually leads to a reduction of the seismic demand in the structure, and simple procedures to account for this effect are also suggested. Slender tall structures supported by small pile groups may represent an exception to this general trend, due to the rotational component of the Foundation Input Motion induced by piles.