COMPARING THE EFFECTIVENESS OF DIFFERENT DAMPERS PLACEMENT IN FRAMED BUILDINGS

In the present paper different viscous dampers placements are compared through an analytical design procedure, developed in order to easily evaluate the performances in terms of cost and effectiveness. Once the performance objective is imposed through a target damping ratio and the corresponding reduction in seismic response of the structure, by assuming a specific deformed shape it is possible to evaluate the period of vibration of an Equivalent Single Degree of Freedom system, from which the structure peak response under earthquake levels can be estimated. From these, the total cost expressed in terms of maximum required damper forces and its effectiveness as the ratio of the total cost and the benefit in base shear reduction are evaluated for each dampers configuration chosen. The analytical steps of the procedure are specified for the case of linear along-the-height displacement profile for three specific dampers configurations: (i) dissipative tower DT; (ii) inter-storey placement, referred to as Stiffness-Proportional Damping (SPD); (iii) fixed-point placement, referred to as Mass-Proportional Damping MPD. The actual seismic behaviors of the design solutions studied are verified through non-linear time-history analyses.