Advanced Negative Stiffness Vibration Absorbers Coupled With Soil-Structure Interaction for Seismic Protection of Buildings

Abstract

Throughout the past decades, seismic isolation of structures has been studied rigorously as an approach to reduce seismic demand and mitigate structural damage. Research in this field has progressed significantly, starting from the use of simple elastomeric bearings for the decoupling of the superstructure from the base, to more complex devices that incorporate the use of an additional oscillating mass and negative stiffness elements. Characteristic examples of these devices are the Tuned Mass Damper (TMD) and the Quasi-Zero oscillators (QZSs). The KDamper is a novel passive vibration absorption concept, based essentially on the optimal combination of appropriate stiffness and mass elements, which include a negative stiffness element. The concept can be implemented using a system of prestressed elements in order to obtain the negative stiffness effects and might prove to achieve a significant advantage for seismic retrofitting.In this paper, the extended KDamper system is placed at the ground level and the soilstructure interaction (SSI) between the building foundations and superstructure is utilized as a means to effectively transfer the dynamic forces of the KDamper to the building and to distribute the required displacements between the structural elements and foundation, thus leading to absorption of the vibration energy. The configuration of the KDamper properties and tuning of its stiffness elements are studied herein. The effectiveness of the KDamper is subsequently investigated in view of the performance of a 4-storey building. A series of artificial accelerograms and real earthquake time histories are used as excitation. Results indicate the beneficial role of SSI on the reduction of the spectral acceleration and displacements, hence placing the concept as a compelling alternative to existing seismic protection technologies.

A negative stiffness dynamic base absorber for seismic retrofitting of residential buildings

“…Schematic dependencies of K 1 with SSI (horizontal and rotational stiffness of the soil–foundation) and column stiffness for horizontal displacement at the top of the base‐level columns 35 …”

“…[27][28][29] In addition, the proper allocation of the stiffness-mass elements of the device leads to a system that is both statically and dynamically stable; the properties of the KDamper can be designed in order to maintain the initial/static stiffness of the structure and, hence, avoid potential instabilities. This vibration control system has been examined for the protection of bridges 30,31 wind turbines, 32,33 and structural systems, [34][35][36] achieving reduction of the displacement demand at the base level. Specifically, Kapasakalis et al 34 introduced the extended version of the KDamper concept as a vibration absorber for low-rise buildings; the system was applied supplementary to conventional base isolation for a typical RC structure.…”

3d Numerical Investigation of an Extended Kdamper Absorber for Seismic Retrofitting of Low-Rise Buildings

“…To achieve this, a lumped parameter model (LPM) is utilized for modelling the controlled structure. Contrary to the previous investigations [14,17] that the ground motion excited the structure only in one direction, here a more realistic examination is conducted, assuming that the seismic waves act obliquely to the structure. Hence, two LPMs are required to describe the in plane and out of plane response of the building.…”

“…Figure 2: A simplified approach to account for the SSI effects (horizontal and rotational stiffness of the soil) for horizontal displacement at the top of each column [17] The equivalent first floor stiffness is calculated as:…”

Vibration Control of Wind Turbine Towers With Kdamper-Based Designs

“…Instead of increasing the additional mass, the vibration isolation capability of the KDamper can be increased by the NS, overcoming the sensitivity problems of TMDs as the tuning is mainly controlled by the NS. Thus, the KDamper always indicates better isolation properties than a TMD with the same mass, finding numerous applications for vibration absorption in structural systems [15][16][17][18][19][20][21][22][23][24]. Although the KDamper incorporates a NS element, it is designed to be statically and dynamically stable.…”