This paper presents a new dynamic actuator useful to study soil-structure interactions in a centrifuge. This new dynamic apparatus is based on an amplified piezoelectric actuator. Using this device it is possible to create vibrations in the soil sample of different frequencies and amplitudes. The dynamic actuator consists of a set of weights in a single degree of freedom system plus a piezoelectric actuator and a piezoelectric load cell, which measures the dynamic load. A description of the dynamic actuator and its application to dynamic soil-structure interaction under wind turbines is presented. The calibration of the dynamic actuator and some results of centrifuge tests for shallow and embedded foundations are presented.