Sliding and rocking response of rigid blocks due to horizontal excitations

To study the dynamic response of a rigid block standing unrestrained on a r igid foundation which shakes horizontally, four modes of motion can be iden tified, i.e., rest, slide, rock, and slide and rock. The occurrence of each of these four modes and the transition between any two modes depend on the parametric values specified, the initial conditions, and the magnitude of ground acceleration. In this paper, a general two-dimensional theory is pre sented for dealing with the various modes of a free-standing rigid block, c onsidering in particular the impact occurring during the rocking motion. Th rough selection of proper values for the system parameters, the occurrence of each of the four modes and the transition between different modes are de monstrated in the numerical examples.