Design and Optimization of the KDamper Concept for Seismic Protection of Bridges

Abstract

The KDamper is a novel passive vibration isolation and damping concept, based essentially on the optimal combination of appropriate stiffness elements, which include a negative stiffness element. The KDamper concept ensures the static stability of the structure, does not require heavy masses, and can achieve better dynamic characteristics, compared to the “Quazi-Zero Stiffness” (QZS) isolators and the traditional Tuned Mass Damper (TMD). Contrary to the TMD and its variants, the KDamper substitutes the necessary high inertial forces of the added mass by the stiffness force of the negative stiffness element. Among others, this can provide comparative advantages in the very low-frequency range (Kapasakalis et al. in GRACM, 2018 [1]). The paper proceeds to a systematic approach for the optimal design and selection of the KDamper parameters, for a typical bridge structure. The design of the KDamper follows the scope of a general vibration isolation and damping concept considering Base Acceleration Excitation/Relative Structure Displacement Response Transfer Function and/or Base Acceleration Excitation/Absolute Structure Acceleration Response Transfer Function. Furthermore, an alternative design approach, incorporating an optimization algorithm is examined. The system is subjected to artificial accelerograms and real earthquake records. The proposed system is compared to the initial undamped model as well as similar structures employing other seismic isolation techniques. Comparative results prove the efficiency of the proposed KDamper system, used as an alternative or supplement to conventional seismic isolation techniques.KeywordsSeismic isolationNegative stiffnessKDamperDamping