Abstract
Underground structures can be vulnerable during strong earthquakes, and seismic mitigation systems designed for these structures are instrumental in improving multiple aspects of seismic performance. To deal with this problem, a novel isolation system is proposed for underground structures, employing the incorporation of a negative-stiffness amplification system (NSAS) and an isolator. The proposed NSAS consists of the subconfiguration of a spring with positive stiffness in parallel with a dashpot, which is then in series with a negative-stiffness device. The mechanical model and physical realization of the NSAS are presented, based on which the energy-dissipation-enhancement mechanism of NSAS is detailed. On this basis, comprehensive parameter analyses were conducted between the NSAS isolation system and a conventional isolation system. Analysis results showed that the NSAS exhibited a significant energy-dissipation-enhancement effect, in which the series connection of the negative and positive stiffnesses amplified the dashpot’s deformation for enhanced energy-dissipation capacity and efficiency. Compared with a conventional isolator, the NSAS isolation system provided the underground structure with a multiperformance and multilevel mitigation effect, particularly yielding lower responses of displacement and shear forces at the same time. More vibration energy could be dissipated by NSAS, thereby alleviating the energy-dissipation burden of underground structures.
Highlights
Underground structures are essential infrastructure of modern metropoles that can be vulnerable to strong earthquakes [1,2,3]
Taking Daikai station as a typical example, comprehensive comparative analyses were conducted for the underground structure controlled with the negative-stiffness amplification system (NSAS) and conventional isolation systems, of which the key performance, including the relative displacement of the central column, shear force and plastic-energy dissipation, was fully investigated
The the histograms of plastic-energy proportion the uncontrolled underground and the structures controlled by the isolation system under seismic excitation, structure and the structures controlled by the conventional isolation systems (CISs) and NSAS isolation system under seismic with increased illustrated
Summary
Underground structures are essential infrastructure of modern metropoles that can be vulnerable to strong earthquakes [1,2,3]. There is a broad need to improve the seismic safety of underground structures and develop innovative seismic-vibration control devices to protect underground structures from destruction during strong earthquakes [10,11,12]. Departing from the widely analyzed negative-stiffness effect, variants of negative-stiffness-based systems and the potential for improved energy-dissipation efficiency both remain unclear, especially in the vibration control of underground structures, which is of concern in this study. Taking Daikai station as a typical example, comprehensive comparative analyses were conducted for the underground structure controlled with the NSAS and conventional isolation systems, of which the key performance, including the relative displacement of the central column, shear force and plastic-energy dissipation, was fully investigated. On the basis of the parametric analysis results, the effectiveness and suggested design parameters of the NSAS are provided for the seismic-vibration control of underground structures
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