Isolation or Damping? A Soil-dependent approach based on the KDamper concept

I. A. Antoniadis, K. A. Kapasakalis, E. J. Sapountzakis

Contemporary seismic isolation systems provide drastic reduction to the structure’s interstorey drifts and absolute accelerations. However, their major drawback is the large increase at the same time of the base displacement. Due to the high equivalent damping ratio, the novel KDamper concept can provide an alternative approach, taking into consideration the soil properties. The KDamper is based on the optimal combination of appropriate stiffness elements, which include a negative stiffness element. The main advantage of the KDamper over other similar concepts including negative stiffness elements, is that no reduction in the overall stiffness of the system is required. This paper considers the application of a KDamper system to a single degree of freedom system with a natural frequency of 2 Hz. The system is subjected to artificial accelerograms designed to match the EC8 elastic response spectra for ground type C. The KDamper is designed to the same or/and higher frequencies compared to the isolated system with a linear oscillator, exploiting the extraordinary damping properties it offers. A comparison with a base isolated structure using a linear oscillator (conventional seismic isolation bearings) designed to greatly decrease the eigenfrequency of the system (0.4-0.5 Hz), confirms that KDamper base seismic absorption designs can provide great reduction to the interstorey drifts and absolute accelerations reducing at the same time the base displacement.
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