Improving the performance of conventional base isolation systems by an external variable negative stiffness device under near-fault and long-period ground motions

Nepal, Sandhya; Saitoh, Masato

doi:10.1007/s11803-020-0609-3

Cited by 16 publications

(3 citation statements)

References 44 publications

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“…Negative stiffness can be physically realized by pre-compressed springs [37], convex-interface pendulums [38], inerter [39,40], and magnetic mechanisms [41]. With respect to the development of a negative stiffness device, Nepal et al [42] designed a device with both negative and positive springs to improve current base isolation systems. This device can avoid resonance to achieve controlled displacements and accelerations under various earthquake scenarios.…”

Section: Introductionmentioning

confidence: 99%

Developing and Applying a Double Triangular Damping Device with Equivalent Negative Stiffness for Base-Isolated Buildings

Sun,

Peng,

et al. 2023

Buildings

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A passive double triangular damping (DTD) device with equivalent negative stiffness is proposed in this study. The DTD device consists of transmission systems and triangular damping systems. A mechanical model was developed to describe the force–displacement relationship of a triangular damping system, while the feasibility of both the system and model was evaluated using experimental tests. The theoretical analysis demonstrated that DTD was a form of damping with equivalent negative stiffness, and the equivalent expressions were generated. Finally, the prospect of application in the DTD-controlled isolation system was explored using numerical simulation. The results revealed that DTD was more effective than a lead–rubber bearing in reducing isolator displacement and rooftop acceleration when subjected to ground motions.

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Section: Introductionmentioning

confidence: 99%

Developing and Applying a Double Triangular Damping Device with Equivalent Negative Stiffness for Base-Isolated Buildings

Sun,

Peng,

et al. 2023

Buildings

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“…However, as mentioned earlier, the approach of using fixed‐points theory could lead to some errors in determining the optimal parameters. Nepal and Saitoh 19 investigated the use of a negative stiffness device to improve the performance of traditional base isolation systems under near‐fault and long period ground records. A suitable range of damping values and slope, satisfying both the stability criteria and the permitted limits of displacement and acceleration responses, was proposed by the authors.…”

Section: Introductionmentioning

confidence: 99%

Optimum design of a tuned‐mass damper with negative stiffness device subjected to ground excitation

Zhang

Nyangi

2022

Structural Contr & Hlth

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In this study, a negative stiffness device based on the magnetic principle is presented and experimentally tested. Then, a tuned mass damper with a negative stiffness device (denoted as TMD_NSD) subjected to harmonic support excitation is optimized in terms of H ∞ optimization criterion, H2 optimization criterion, and stability maximization criterion (SMC). Closed-form expressions for the optimal tuning parameters are derived in terms of both H ∞ criterion and SMC, while the optimal tuning parameters are numerically determined in terms of H 2 criterion. The control performance of the TMD_NSD is compared with the classical TMD in terms of maximum dynamic amplification factor (DAF max ). It is found that the performance of the TMD_NSD based on these three optimization methods is superior to that of the classical TMD. Besides, the performance based on H ∞ and H 2 optimization is almost similar, while the performance based on SMC is less than the first two methods. Compared with the classical TMD, the TMD_NSD could significantly reduce the primary system's peak value and broaden the efficient frequency range of vibration mitigation. However, surprisingly, the DAF max decreases with the increase in the mass ratio of the classical TMD, while the DAF max for the TMD_NSD increases with the increase in mass ratio. Finally, the effectiveness of optimization methods in seismic response control is examined via time history analyses (THA) under 20 real earthquake excitations. The THA findings suggest that the TMD_NSD is superior to the TMD for seismic response mitigation for the three optimization methods. However, it is noted that the displacement response of TMD_NSD based on H ∞ and H 2 optimization is comparable but slightly better than that of the SMC method. Nevertheless, in terms of absolute acceleration control, it is shown that TMD_NSD performance based on the SMC method is better than that of the H ∞ and H 2 methods. Overall, the three optimization methods are validated to be effective for seismic mitigation of the un-damped single-degree-of-freedom (SDOF) primary structure subjected to real seismic excitations.

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“…Depending on the extent of damage under such strong events, isolated buildings need to be repaired to avoid damage accumulation or replaced after the event, incurring heavy costs [9,10]. Owing to the detrimental nature of pulse-type motions to amplify the overall response of the structure, their effects should be taken into consideration while designing site-specific response spectra [11,12]. Although base isolation is an effective way to control structural vibrations, its usage has serious limitations in the locality of the faults.…”

Section: Introductionmentioning

confidence: 99%

Performance of clutched inerter damper for base-isolated structures under near-fault motions

Barkale

Jangid

2022

Eng. Res. Express

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The performance of the supplemental clutched inerter damper (CID) for the base-isolated multi-story structures subjected to near-fault earthquakes is investigated. The isolation system is considered as lead-rubber bearings with bi-linear characteristics and viscous damping. The resisting force of the CID is proportional to the relative acceleration between two terminals under the attached condition and zero when detached. The governing equations of motion of base-isolated structure and the CID are derived and solved using numerical technique under seven near-fault ground motions data. The variation of peak bearing displacement, top floor absolute acceleration, total base shear, and the CID force is plotted against the inertance mass ratio of the CID. The above peak responses were also analyzed for different values of damping, period of isolation, yield strength of LRB, and superstructure stories. Application of the CID is observed to effectively facilitate the reduction in bearing displacement while the combined effect of isolation and the CID prevents the top floor acceleration to shoot up. The optimum value of inertance mass ratio is also determined by minimizing the total base shear which is the measure of equivalent lateral force on the structure. The optimum inertance lies in the range of 35-45% of the total mass of the isolated building under near-fault motions. In addition, the performance of the CID base-isolated structure subjected to cycloidal pulses is also investigated. It is observed that the CID is quite effective in controlling the displacement of the isolation system under cycloidal pulses.

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Improving the performance of conventional base isolation systems by an external variable negative stiffness device under near-fault and long-period ground motions

Cited by 16 publications

References 44 publications

Developing and Applying a Double Triangular Damping Device with Equivalent Negative Stiffness for Base-Isolated Buildings

Developing and Applying a Double Triangular Damping Device with Equivalent Negative Stiffness for Base-Isolated Buildings

Optimum design of a tuned‐mass damper with negative stiffness device subjected to ground excitation

Performance of clutched inerter damper for base-isolated structures under near-fault motions

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