Practical seismic design of structures equipped with viscous dampers: procedure and application

Viscous dampers have widely proved their effectiveness in mitigating the effects of the seismic action upon building structures. In view of the large impact that use of such dissipative devices is already having and would most likely have soon in earthquake engineering applications, this paper presents a practical procedure for the seismic design of structures equipped with viscous dampers. The four-step procedure is evolved from the today’s knowledge of manufactured viscous dampers and aims at guiding the professional engineer from the choice of an appropriate target damping ratio to the final design technical specifications of non-linear commercially available viscous dampers. A numerical application of the procedure is then provided with reference to a two-storey precast reinforced-concrete shopping mall building. Noticing that precast concrete structures (commonly assembled at construction site) are not capable of transmitting bending moments at joints and show a relatively large flexibility with respect to lateral seismic loads, the use of added viscous dampers turns out to be strongly recommended (with respect to traditional lateral-resisting bracing systems) to keep, at the same time, inter-storey drifts within the limitations imposed by seismic codes, and actions in the dissipative braces, in the structural elements and at foundation level within acceptable levels.