Dynamic and Seismic Protection of Rigid-Block-Like Elements and Structures on Deformable Ground with Mass-Damper Dynamic Absorbers

Some elements and structures can be modeled as rigid blocks. To reduce their likelihood of overturning such block-like elements, structures can be coupled with safety devices. In this paper, a model of a rigid block placed on a deformable soil is coupled with a pendulum working as mass-damper dynamic absorber. The deformable ground is modeled as a continuous bed of vertical linear springs and dashpots. To assess the effectiveness of the mass-damper dynamic absorber, a parametric analysis is performed by numerically integrating the equations of motion and considering one-sine pulse and seismic excitations. In the analyses, the geometrical characteristics of the block, the mass and length of the pendulum, and the stiffness of the soil are taken as variable parameters. Under one-sine excitation, the comparison of overturning spectra obtained for blocks with and without a mass-damper dynamic absorber demonstrates the effectiveness of the chosen protection device, especially for soils characterized by high stiffness. The beneficial effect of the mass-damper dynamic absorber on the dynamics of the rigid block under seismic excitations is evaluated by comparing the rocking maps obtained for blocks that are and are not equipped with mass-damper dynamic absorbers. In addition to the reduction of the overturning events of the block, the results show that the protection device has the positive effect of reducing the amplitude of the rocking angle.