Sliding-uplifting response of rigid blocks to base excitation.

In the present paper a two-degree-of-freedom system is considered which allows the simulation of rigid blocks uplifting and sliding on frictional foundations; the monolateral constraint between block and base is schematized by means of a joint model which allows the contact problem to be discretized. The joint model is governed by normal and shear constitutive laws, which have been derived by the phenomenological behaviour of stone blocks and rock joints, as given by rock mechanics. Furthermore, a numerical procedure has been developed in order to solve the nonlinear equations governing the motion of the block-base system, and to analyze the dynamic response of this system under seismic excitation; particulare attention has been paid to the influence of the vertical displacement on the slip response.