The damped cable system (DCS) represents an innovative seismic protection strategy, especially
attractive for retrofitting existing reinforced concrete structures. This technology is based on inseries
coupling of fluid viscous re-centring dampers and pre-stressed steel cables. The cables go
through the building stories and exert reaction forces on the floor-slabs, which are in opposite
direction to the earthquake loads. Since each cable makes sliding contact with the slabs, its reaction
includes the damping force component supplied by the fluid viscous device connected to it. The
combination of cable elasticity and device energy dissipation gives rise to a highly performing
protection system, characterised by lower architectural intrusion and installation work as compared
to traditional rehabilitation techniques. The DCS is currently the subject of a Research and
Technological Development Project funded by the European Community. The previous stages of
the planned research programme resulted in the assessment of system feasibility, as well as of its
preferable fields of application. Afterwards, attention has been devoted to the structural design
aspects. Relevant developments, presented in this paper, concern: (a) a mixed deformation/strengthbased
evaluation of system performance, with careful control of local stress states, besides member
and story drifts; (b) the assumption of an enhanced design objective, according to advanced
guidelines for the seismic rehabilitation of buildings; and (c) direct comparisons between the
response of frame structures retrofitted by DCS and different protection strategies. These three
points are herein discussed with special reference to a four-story frame, selected as one of the basic
case study structures in this section of the research programme.