Effects of taking into consideration realistic force-velocity relationship of viscous dampers in the optimisation of damper systems in shear-type structures

In previous works, the authors have investigated the advantages offered by inserting added viscous dampers into shear-type structures and have identified a special damper scheme based upon the mass proportional damping component of Rayleigh damping matrices (referred to as MPD system) which is capable of providing good overall dissipative performances. All these analyses were performed using a linear force-velocity relationship to model the constitutive law of the damping devices. This paper investigates how the use of a more accurate non-linear modelling of the dampers affects those findings. The numerical simulations here illustrated (performed with reference to a 6-storey shear-type structure subjected to a series of 40 historical records of earthquake ground motions) confirm the effectiveness and the robustness of MPD systems with respect to other damping systems. The results also point out how special attention must be paid in the identification of the correct relationship existing between the linear modelling of viscous dampers and their non-linear actual behavior, as this may lead to large over- or under-estimations of their dissipative effectiveness.