Mitigation of amplified response of restrained rocking walls through horizontal dampers

Failure mechanisms in masonry walls are commonly due to the low tensile strength of masonry that could cause overturning or pounding due to the interaction with transverse walls. In this paper, the influence of dissipative devices easing the dynamic stability of rocking blocks is studied considering the main parameters affecting the response. Normalized rotation time-histories are obtained for six geometrical configurations under several acceleration records in order to analyse possible resonant effects and beneficial reductions due to the presence of a damper, accounted for in the equation of motion of the one-sided restrained rocking block. Rocking response spectra obtained for undamped systems show that possible beat phenomena may arise for certain geometrical configurations and restraint stiffness values. A design equation for the damping coefficient is proposed for the anti-seismic device and its influence on restrained façade walls under real strong motions is analysed.