Past and recent earthquakes have shown that unreinforced masonry façades are among the most vulnerable structural elements. However, their assessment is usually performed resorting to simplified static analyses. On the contrary, the focus of this research has been on the non linear dynamic behaviour of masonry walls rocking out-of-plane, due to seismic ground motion. Emphasis has been put both on analytical modelling, and on the definition of significant intensity measure of ground motion. As for the first aspect, equations of motion for several boundary conditions have been derived. Moreover, the role of impact energy damping has been addressed, letting to explain previous experimental results. It has been shown that the addition of a lateral restraint, simulating transverse walls, can increase the vulnerability by bringing the rocking façade in phase with the excitation. The restraining of the top of the wall has an influence both on threshold acceleration, energy damping and period of vibration, as proven analytically. As for the second aspect, several intensity measures have been considered highlighting the correlation between overturning and velocity parameters. Such results can guide the selection of appropriate accelerograms for the time history analysis of façades.
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