Added viscous dampers in shear type structures: the effectiveness of mass proportional damping

In this paper the authors investigate the dynamic performances of multi-degree-of-freedom shear-type structures equipped with manufactured viscous dampers. The system of added viscous dampers that leads to a mass proportional damping (MPD) matrix is identified as the one providing the best overall performance in terms of minimum top-storey response variance to a Gaussian band limited white noise input within the class of classically damped systems. A performance index developed by the authors and based upon modal damping ratios confirms that, within the class of Rayleigh damping systems, the MPD limiting case provides the largest damping effect. For a 6-d.o.f. system, comparison with results available in literature also shows that the MPD system provides better performance than optimised (as suggested by other research works) non-classical damping schemes. A physical explanation for the optimum damping performance offered by MPD systems is also provided herein, together with clear indications about how to implement MPD systems in real building structures. A check on the applicability of MPD systems to real structures and its effectiveness is also carried out successfully through the development and study of a realistic finite element model of an actual 18-storey building.