Damage limit states for artistic assets from cyclic and dynamic tests on plastered masonry walls

Recent earthquakes have dramatically demonstrated the consequences of the seismic vulnerability of cultural heritage assets worldwide. Nevertheless, this critical issue still needs to be fully explored, as earthquake engineering efforts have been mostly devoted to structural performance and life safety rather than to non-structural response and damage control in the past. The protection of artistic assets to seismic actions requires the identification of the main damage mechanisms and the definition of proper limit states depending on the different asset typology, which can be either movable (such as paintings and statues) or unmovable (e.g. frescos, stuccoes, pinnacles, and balconies). Experimental tests conducted at the University of Pavia and at the EUCENTRE Foundation allowed investigating the correlation between the response of structural masonry walls and the damage to non-structural unmovable artistic assets attached to them. The testing campaign included in-plane quasi-static cyclic shear-compression tests on individual piers and shake-table tests on a half-scale building prototype. The specimens were constructed with double-leaf stone masonry made of undressed blocks and river pebbles. The walls were plastered on one side to simulate the presence of unmovable cultural heritage features. The tested prototypes were monitored by potentiometers, accelerometers, and an optical acquisition system, that allowed monitoring the response of both structural and nonstructural elements. Different limit states of both masonry walls and attached plaster were defined based on the damage level recorded at each stage of testing. Analysis of the experimental results permitted correlating some engineering demand parameters, such as interstorey drift ratios and deformations of structural elements, to the damage extent identified on the plastered surfaces for each limit state of interest.