Evolutionary model of viscoelastic dampers for structural applications

The effects of temperature on the energy dissipation of viscoelastic dampers for seismic mitigation of structures are investigated. To simulate the damper behavior, an evolutionary model is proposed to describe the dependence of the mechanical properties of the damper on the deformation frequency and the temperature increase due to dissipation. Thermorheologically simple materials are considered and the influence of the deformation frequency on the storage and loss moduli is modeled using fractional derivative operators. The effect of material temperature on the force-deformation relation is modeled using the concept of evolutionary transfer function, and the proposed model is implemented using a step-by-step technique in the frequency domain. The predictions of the proposed model in the case of sinusoidal and seismic deformations show good agreement with experimental results. Finally, the response spectra of single-degree-of-freedom structures with added vis-coelastic dampers and subjected to seismic excitation are computed using the proposed evolutionary model; the results obtained show that the thermal effect due to energy dissipation is not always negligible.