Applicative solutions for the seismic improvement of a hospital building with the use of viscous dampers

A direct procedure for the seismic design of regular multi-storey frame structures with added viscous dampers is recalled in this paper and applied for the seismic improvement of a reinforced concrete frame structure. The application is carried out with reference to the real case-study of a five-storey hospital building located in Bologna. Three different solutions of seismic retrofit are presented and analyzed in terms of both performances and costs. They differ in terms of viscous dampers used, either Stiffness Proportional Dampers (SPD) or Mass Proportional Dampers (MPD), and number of external towers built, to provide an indirect implementation of the MPD system. The applied design procedure is based on the so-called “direct five-step procedure” which is intended to guide the structural engineer from the choice of a target reduction in the seismic response of the structural system to the identification of the corresponding damping ratio and the mechanical characteristics of the commercially available viscous dampers.