Effects of the filtering action exerted by piles on the seismic response of RC frame buildings

The inertial interaction analysis of a structure founded on piles is usually performed assuming the free-field motion as seismic action at the foundation level, thus neglecting the filtering action often exerted by piles. By contrast, the existence of frequency filtering is confirmed through works referring to theoretical and experimental studies, even if this effect is generally neglected in design practice. In this paper the seismic performance of frame buildings, excited by filtered and free-field input motions is evaluated. The results of these analyses, expressed in terms of top displacement and base shear, allow for assessing the importance of the beneficial effect coming from the piles on the inertial response of the superstructure.