DAMPING REDUCTION FACTORS FOR ADJACENT BUILDINGS CONNECTED BY VISCOELASTIC DAMPERS

This work investigates the dynamic behaviour of a multi-storey frame building, assumed as the structure to be controlled, connected with an adjacent support structure by means of viscoelastic dampers (VEDs). The VED system has three main effects: (i) modes coupling effects between the two buildings due to the stiffness component of the VEDs, (ii) energy dissipation provided by the viscous component of the VED, (iii) energy transfer between modes leading to modes coupling effects between the two buildings without a significant dissipation of energy, due to the viscous component of the VED. The relative contribution of the three effects is highly dependent on the main properties of the coupled system, including the two buildings and the VED system. To investigate this complex behaviour, first the minimal coupled dynamic system composed by two Single-Degree-Of-Freedom systems connected by a VED is analysed. The theory of complex damping is used to determine complex frequencies and damping ratios, while analytical expressions of steady state response under harmonic excitation are determined to investigate the influence of the system parameters on the maximum dynamic amplifications. The seismic response is then investigated through a wide parametric study with the aim of evaluating the trends of peak floor displacement and acceleration reduction factors. Then, the analysis is extended to uniform multi-storey structures. The results can be useful for a preliminary design of the VED system and for the evaluation of its effectiveness based on the fundamental dynamic properties of the connected buildings.