Shake table testing of a passive negative stiffness device with curved leaf springs for seismic response mitigation of structures

Past research has shown that negative stiffness may be used to good effect in mitigating the response of seismically excited structures. This has led to the emergence of several new negative stiffness devices of varying sizes, complexity, effectiveness, and practicality. In this study, a passive negative stiffness device composed of curved leaf springs using geometric nonlinearity is presented. The proposed device is designed to be simple and compact so as to be easily installed and exhibits approximately constant negative stiffness over a large range of displacements. Beyond these displacements, the negative stiffness produced by the device increases, which can help to limit the transmission of large damper forces at peak structure displacements. At displacements approaching the deformation limit of the device, the device produces positive stiffness so that stability of the structure is ensured. The objective of the research presented herein is to investigate the basic behavior of the device. Shaking table tests on specimens consisting of a vibrating part and the prototype passive negative stiffness device subjected to sinusoidal and simulated earthquake waves were conducted. The results revealed that the specimens exhibited negative restoring force characteristics, and due to the effect of the negative stiffness, an increase in the apparent period was demonstrated. Moreover, reduction of the response acceleration was shown without remarkable increase of the response displacement under the simulated earthquake inputs. Also, a numerical analysis to simulate the shake table testing and evaluate the control effect for a full-scale building model was carried out.

Automated summary

This study introduces a passive negative stiffness device composed of curved leaf springs using geometric nonlinearity to mitigate the response of seismically excited structures. Experimental results demonstrate the device's effectiveness in reducing response acceleration within a certain range while ensuring structural stability.