Summary The KDamper is a novel passive vibration absorption concept based essentially on the optimal combination of appropriate stiffness elements, one of which has a negative value. In this paper, the implementation of the KDamper as a seismic Absorption Base (KDAB) is considered. The performance of the KDAB is assessed in three characteristic test cases, namely, a rigid body and two flexible buildings with fundamental periods of 0.5 and 1.0 s, respectively. In all three cases, the structures are excited by real and artificial accelerograms. The performance of the KDAB is compared not only with the original structure but also with the cases of conventional and highly damped base isolation systems, as well as with the case of a tuned mass damper inerter. Alternative options for the selection of the KDamper nominal frequency are considered, leading to two cases. In the first one, the nominal KDamper frequency is selected equal to the low frequency of a conventional base isolation system, resulting in a drastic improvement of the overall structural performance (i.e., superstructure accelerations and base drifts). In the second one, the KDAB is implemented with a much higher nominal frequency, leading to a drastic reduction of the relative base displacement, in the order of few centimeters, combined with acceptable structural performance. As a consequence, the KDamper can be implemented as a supplement of a conventional base isolation system or, alternatively, as a “stiff absorption base,” overcoming the disadvantages of seismic isolation approaches, leading towards new seismic protection technologies.

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Contemporary seismic isolation systems for building structures provide drastic reduction to the structure's interstorey drifts and absolute accelerations. However, their major drawback is the large increase of the base displacement. Due to the high equivalent damping ratio, the novel KDamper passive vibration isolation and damping concept can provide an alternative approach for seismic protection. 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 3 storey concrete building structure. A dynamic system consisting from a simplified flexible structure model and KDamper devices is considered and is subjected to artificial accelerograms designed to match the EC response spectra. The KDamper is designed to higher frequencies compared to the isolated system with seismic isolation bearings, exploiting the extraordinary damping properties it offers. A comparison with a base isolated structure using Lead Rubber Bearings designed to greatly increase the fundamental period of the system (2.0-2.5 sec), 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.

Abstract. A novel passive vibration isolation and damping concept is implemented to