The effects of temperature on the energy dissipation of viscoelastic dampers (VED) for seismic mitigation of structures are investigated. In order to simulate the damper behaviour, 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. The heat losses of the material due to radiation and conduction are neglected in the evaluation of the increase of temperature of the damper during operation. Thermorheologically simple materials are considered and the influence of the deformation frequency on the storage and loss moduli is modelled using fractional derivatives operators. The effect of material temperature on the force-deformation relation is modelled 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 VED 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.
Evolutionary Model of Viscoelastic Dampers for Structural Applications
APRILE, Alessandra;
1997
Abstract
The effects of temperature on the energy dissipation of viscoelastic dampers (VED) for seismic mitigation of structures are investigated. In order to simulate the damper behaviour, 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. The heat losses of the material due to radiation and conduction are neglected in the evaluation of the increase of temperature of the damper during operation. Thermorheologically simple materials are considered and the influence of the deformation frequency on the storage and loss moduli is modelled using fractional derivatives operators. The effect of material temperature on the force-deformation relation is modelled 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 VED 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.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
