Rocking response of rigid blocks subjected to ground motion

This work deals with the rocking response of a rigid free-standing block under the action of ground motion, as basic reference for the seismic analysis of masonry structures. A new computational strategy for representing the seismic input is suggested in order to define such an amplitude resonance as representing the most disadvantageous conditions for the block. The rocking response to artificial accelerograms is then analysed by means of a simplified equation of motion between two impacts. The coefficient of restitution is assumed as a variable of the problem to account also for other damping effects (e.g. local plastic deformations). A stabilised phase of the motion is identified for which an upper-bound of the maximum rotation angle of the block can be defined in closed form. The results are plotted in a kind of resonance spectra which point out the influence of such meaningful parameters as the coefficient of restitution and the size and slenderness of the block.