Tuned Mass Damper or Viscoelastic Damper?

Abstract

Within this report, an analytical research will be performed on the effectivity of Tuned Mass Dampers (TMDs) and Viscoelastic Dampers (VEDs), and a conclusion will be drawn as to which is most effective in damping the oscillations of an earthquake. First of all, a simple model of second-order differential equations describing the oscillations of each floor within a building of n floors is derived, in which no frictional forces are taken into account. The solution to this model is derived for a building of two floors, which demonstrates the characteristics of oscillations in this model and which shows how resonance is represented mathematically, and what patterns of oscillations look like. Then, a TMD and VED are added to the model of one floor to expose what their working principles are. Subsequently, the methods of adding these dampers to the models for two, five and ten floors are given. For varying earthquake-frequencies, the maximum displacement within 5 seconds is determined, which shows the effect of TMDs and VEDs for different positions within the building. The conclusion from these results is that the effect of the TMDs is always that at the eigenfrequencies, the oscillations of the building are no longer resonating. However, the building will start resonating for other eigenfrequencies due to the TMD. The VED is more consistent, though its damping-effect on resonating frequencies is smaller than for the TMDs. The conclusion is that VEDs are most effective, though more dampers have to be added to improve its effectiveness. After this, a new model is introduced, which does contain a friction force: air resistance. Based on the new model, it is concluded that even oscillations for resonating frequencies are eventually damped out, though they do still grow large. Again, TMDs and VEDs are added to the model, and similar conclusions about the effectivity of the dampers as for the first model were drawn.