A novel structural seismic protection system with negative stiffness and controllable damping

Abstract

In this paper, an innovative controllable negative stiffness system (CNSS) integrating adaptive negative stiffness and controllable damping characteristics is proposed to realise desirable vibration protection and improve adaptability, hence being effective to various earthquakes. The force-displacement relationship of the CNSS is derived as the forward model to describe its nonlinear properties. Three representative control algorithms, i.e., Linear Quadratic Regular (LQR) control, H∞ control and Sliding Mode (SM) control, are utilised for the CNSS to attain optimal control force. Based on the Takagi-Sugeno-Kang (TSK) Fuzzy inference system optimised by Non-Dominated Sorted Genetic Algorithm II (NSGAII), a novel inverse model is proposed accordingly to obtain input current according to the required control force and real-time system responses. To demonstrate the feasibility and efficiency of the CNSS for structural seismic protection, a numerical case study is conducted on a three-storey building model with CNSS installed on its first floor. Four scaled benchmark earthquakes are employed as excitations for the case study. Ten evaluation criteria are adopted to assess and verify the performance of the CNSS, and comparisons are made with that of uncontrolled and passive controlled systems. The numerical results indicate that the proposed CNSS can significantly improve the vibration control performance on all evaluation criteria simultaneously in comparison with the other two conventional systems. In addition to having good suppression effects on peak floor displacement and peak inter-storey drift, the CNSS with the SM controller demonstrates superior performance on mitigating peak structure shear and peak acceleration response of the first floor.

Pseudo‐active actuators: A concept analysis

“…Then a specific pseudo‐active actuator, the negative stiffness damper, is realized. Such a new concept of actuators with the combination of (variable) damping and (variable) negative stiffness was presented by Iemura and Pradono, 20,21 Weber and his associates, 22,23 Shi and Zhu, 24 and later Li's group 25,26 . All the theoretical results of their studies on the applications indicated that the new actuator could provide significant improvement on vibration attenuation, which is comparable to the system using an active actuator.…”

“…A schematic of the force transition of a controllable damping actuator via a linear the combination of (variable) damping and (variable) negative stiffness was presented by Iemura and Pradono, 20,21 Weber and his associates, 22,23 Shi and Zhu, 24 and later Li's group. 25,26 All the theoretical results of their studies on the applications indicated that the new actuator could provide significant improvement on vibration attenuation, which is comparable to the system using an active actuator. Prototype realization of the new actuators with "controllable damping + negative stiffness" was only provided by Shi and Zhu 24 and Yang et al 27 A permanent magnet or an electromagnetic device was used for the negative stiffness capacity for such actuators.…”

A Half-Cycle Negative-Stiffness Damping Model and Device Development

“…Numerous studies have been conducted on negativestifness damping devices and associated design theory. For instance, Li et al [49][50][51][52] analyzed the mechanism of negative stifness and proposed a novel controllable negative-stifness system using active control technology that can simultaneously achieve negative stifness and controllable damping properties. Using control algorithms (LQR control, H ∞ control, and sliding mode control), a controllable system based on full-state feedback was created, which improved vibration control performance on all evaluation criteria.…”

Performance of a passive rate‐independent damping device in a seismically isolated multistory building

“…A small-scale coil spring unit and oil damper were designed and fabricated to build the Maxwell element. Because the negative stiffness devices that have been developed exhibit nonlinear behavior especially against large deformation, [44][45][46][47] we reduced the isolator stiffness instead.…”