THE ROLE OF FRICTION IN THE DYNAMIC BEHAVIOUR OF FREESTANDING MARBLE OBJECTS

Nowadays, millions of art works exhibited are not always adequately protected against possible dangers and hazards, as the artifacts exhibited in churches and in small museums. An artifact can be in fact successfully modelled as a rigid body, in other word a body that does not undergo changes in shape if subjected to ground shaking due to seismic actions. In this paper the response of two marble elements in contact under sliding conditions is investigated. It is shown that the friction coefficient between object base and the supporting plane plays a key role in the overall behaviour of the rigid object during an extreme event. The experimental campaign is focused on the evaluation of the static and kinematic friction coefficient between marble specimens with two different shapes (cubic and prismatic) and three different surface roughnesses: bush-hammered, sanded and polished. The determination of the static friction coefficient has been made through a motorized plane with variable inclination angle. The influence of the friction coefficient on the dynamic behaviour of the specimens has been examined by means of dynamic tests with a unidirectional shaking table.