Robustness Evaluation of Elastoplastic Base-Isolated High-Rise Buildings Subjected to Critical Double Impulse

Fujita, Kohei; Yasuda, Keisuke; Kanno, Yoshihiro; Takewaki, Izuru

doi:10.3389/fbuil.2017.00031

Cited by 10 publications

(8 citation statements)

References 21 publications

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“…An evaluation of the results of a few previous studies that investigated responses of relatively long-period structures under NF excitations illustrates that the values of the initial periods of the non-isolated and isolated counterparts are key parameters to predict the level of decrease/increase caused by seismic isolation in force and displacement demands (e.g., see examples presented in Takewaki, 2008;Ma et al, 2014;Fujita et al, 2017;Lagos et al, 2017;Anajafi and Medina, 2018;Naderpour et al, 2019). This evaluation shows that seismic isolation for NF excitations can, in many cases, reduce the mean force demands significantly (up to 70-80%).…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of Seismic Isolation for Long-Period Structures Subject to Far-Field and Near-Field Excitations

Anajafi

Poursadr²,

Roohi

et al. 2020

Front. Built Environ.

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This study evaluates primarily the effectiveness of seismic isolation for structures with intermediate and relatively long non-isolated periods (e.g., bridges with tall piers) subjected to near-field (NF) and far-field (FF) excitations. The inelastic response spectrum approach is used to systematically evaluate the effects of the two fundamental aspects of seismic isolation, i.e., period lengthening and lateral-strength reduction on the seismic responses (e.g., displacement, acceleration, and base shear) of isolated structures. To validate the results, the real-world isolated Rudshur bridge with a relatively flexible (long-period) substructure is studied. Additional isolated and non-isolated variants of the Rudshur bridge with different initial periods are also developed. 20 FF (non-pulse) and 20 NF (pulse type) ground motions are used for the non-linear response history analyses. The results illustrate that when designed properly, seismic isolation can effectively reduce the mean base shear and acceleration responses of structures with relatively long non-isolated periods under FF excitations. For these structures, seismic isolation does not significantly increase the mean displacement responses under FF excitations, and for particular cases, can even reduce them. For NF excitations, seismic isolation can significantly reduce the mean base shear responses of intermediate-to long-period structures. In some cases, this reduction is even more significant than that for FF excitations. However, when the initial period of the isolated structure is relatively long (e.g., greater than 2.5 s), NF excitations can impose significantly large mean displacement demands on the superstructure (i.e., as great as 1.0 m for the studied cases). For NF excitations, a range of initial period (e.g., 1.5-2.5 s for the studied ground motions) and lateral yield-strength (e.g., 10-15% of the seismically effective weight) exists for the isolation system parameters that can noticeably reduce mean acceleration and base shear responses while mean displacement responses of the isolated superstructure remain within ranges used in practice. The inelasticspectrum approach, as used in this paper, can reasonably predict these isolation system parameters.

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Section: Introductionmentioning

confidence: 99%

Effectiveness of Seismic Isolation for Long-Period Structures Subject to Far-Field and Near-Field Excitations

Anajafi

Poursadr²,

Roohi

et al. 2020

Front. Built Environ.

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“…It should be pointed out that their approach does not need to solve the equation of motion directly. These theories using double and multi impulses are expanded for the elastic-plastic model with linear viscous damping (Kojima et al., 2017; Hayashi et al., 2018, Akehashi et al., 2018), the elastic-plastic 2DOF model (Taniguchi et al, 2016) and the elastic-plastic base-isolated building model (Fujita et al, 2017; Takewaki et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Critical response of elastic-plastic SDOF systems with nonlinear viscous damping under simulated earthquake ground motions

Tamura

Kojima

Takewaki

2019

Heliyon

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Multi impulse with constant time interval is used as a representative of a long-duration earthquake ground motion. An analytical expression is derived for the elastic-plastic response of a single-degree-of-freedom (SDOF) model with nonlinear viscous damping subjected to the “critical multi impulse” which maximizes the response. The fact that only free vibration appears under such multi impulse enables the smart application of an energy approach in deriving the analytical expression for a complicated elastic-plastic response with nonlinear viscous damping. The nonlinear viscous damping characteristic for deformation is approximated in terms of a quadratic or elliptical function. The critical timing of the impulses is found to correspond to the zero restoring-force timing or the maximum velocity timing depending on the input level. It is shown that the nonlinearity in viscous damping causes a remarkable influence on the earthquake response in some cases. The reliability and accuracy of the proposed theory are investigated through the comparison with the results by the time-history response analysis to the tuned sine wave as a representative of the long-duration earthquake ground motion.

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“…Recent research trends of seismic isolation devices are as follows: Tomita and Fujita [4] studied the threedimensional seismic isolation system, and Auad and Almazán [5] developed a nonlinear vertical locking isolation system. Fujita et al [6] developed a new method of robustness evaluation for an elastoplastic base-isolated high-rise building considering simultaneous uncertainties of structural parameters.…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of Seismic Isolation System by Installation Location in Lighthouse Structures

Hur

Park

2018

Shock and Vibration

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The purpose of this study is to evaluate the applicability of seismic isolation devices for marine accidents under seismic loads. The lighthouse structure is a very important facility when the ship approaches the port. However, it is necessary to reinforce the structure to protect it from earthquake. This study presents isolation technology as a method to enhance the seismic performance of lighthouse structures built before seismic design criteria were established. This paper analyzed improvement of seismic performance in three cases of seismic isolation by applying the proposed method of isolation technology. In Case 1, the entire lighthouse structure is isolated, and in Case 2, only the lighthouse lens, the most important component of the lighthouse structure, has been isolated to assure constructability and economy. In Case 3, isolation effect was analyzed by comparing Case 1 and Case 2 with lighthouse structures.

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Robustness Evaluation of Elastoplastic Base-Isolated High-Rise Buildings Subjected to Critical Double Impulse

Cited by 10 publications

References 21 publications

Effectiveness of Seismic Isolation for Long-Period Structures Subject to Far-Field and Near-Field Excitations

Effectiveness of Seismic Isolation for Long-Period Structures Subject to Far-Field and Near-Field Excitations

Critical response of elastic-plastic SDOF systems with nonlinear viscous damping under simulated earthquake ground motions

Performance Evaluation of Seismic Isolation System by Installation Location in Lighthouse Structures

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