Predicting the displacement of triple pendulum™ bearings in a full‐scale shaking experiment using a three‐dimensional element

Dao, Nhan D.; Ryan, Keri L.; Sato, Eiji; Sasaki, Tomohiro

doi:10.1002/eqe.2293

Cited by 84 publications

(65 citation statements)

References 8 publications

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“…On the other hand, changes in both sliding velocity and instantaneous vertical force parameters cause variations to the coefficient of friction, which in turn changes the shear force. Hence, the proposed behavior model by Dao was used to model the coefficient of friction. In this model, the coefficient of friction was experimentally calculated for different sliding velocities and eight vertical forces.…”

Section: Studied Modelmentioning

confidence: 99%

Assessment of sliding‐rubber isolator effect in progressive collapse of bridges under two scenarios

Havaei

Moayyedi

2017

Structural Design Tall Build

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Summary In this study, performances of 2 types of bridges, with and without seismic isolation, are addressed in 2 damage analysis scenarios, where, in the first, the side column and, in the second, the middle column are removed from the bridge piers. The performance was assessed using nonlinear dynamic analysis, and the time history and maximum structural responses were evaluated. Initially, sliding‐rubber isolators were designed according to AASHTO guide specifications, and then the bridges were modeled in OpenSees software package. Additionally, the coefficient of friction for the isolator was considered as a variable due to sudden removal of the columns and the consequent changes in the sliding velocity and axial forces. The results indicate that use of seismic isolation systems caused an increase in all maximum structural responses except that of the base shear. Considering the frictional performance of the isolators, slides in the deck are not caused by yielding of seismic isolators, and the reason for permanent displacements of the deck may be attributed to bridge instabilities in the first scenario. However, decrease in the horizontal stiffness results in increased maximum permanent displacement. In the first scenario, uplift of the deck occurred in the case of isolated bridge.

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Section: Studied Modelmentioning

confidence: 99%

Assessment of sliding‐rubber isolator effect in progressive collapse of bridges under two scenarios

Havaei

Moayyedi

2017

Structural Design Tall Build

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“…Among the various techniques for enhancing the safety and functionality of structures subjected to earthquake excitation, base isolation is 1 of the most successful and widely applied techniques. [1][2][3][4] Base isolation was developed to control the acceleration of the structure in an earthquake event by isolating the superstructure from the ground with a natural period that is much longer than the dominant periods of the ground motion. A long natural period generally results in small floor acceleration but causes large displacement at the base isolation floor.…”

Section: Discussionmentioning

confidence: 99%

Second‐mode tuned mass dampers in base‐isolated structures for reduction of floor acceleration

Shi

Saburi

Nakashima

2018

Earthq Engng Struct Dyn

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Summary To reduce floor acceleration of base‐isolated structures under earthquakes, a tuned mass damper (TMD) system installed on the roof is studied. The optimal tuning parameters of the TMD are analyzed for linear base isolation under a generalized ground motion, and the performance of the TMD is validated using a suite of recorded ground motions. The simulation shows that a TMD tuned to the second mode of a base‐isolated structure reduces roof acceleration more effectively than a TMD tuned to the first mode. The reduction ratio, defined as the maximum roof acceleration with the TMD relative to that without the TMD, is approximately 0.9 with the second‐mode TMD. The higher effectiveness of the second‐mode TMD relative to the first‐mode TMD is attributed primarily to the unique characteristics of base isolation, ie, the relatively long first‐mode period and high base damping. The modal acceleration of the second mode is close to or even higher than that of the first mode in base‐isolated structures. The larger TMD mass ratio and lower modal damping ratio of the second‐mode TMD compared to the first‐mode TMD increases its effect on modal acceleration reduction. The reduction ratio with the second‐mode TMD improves to 0.8 for bilinear base isolation. Because of the detuning effect caused by the change in the first‐mode period in bilinear isolation, the first‐mode TMD is ineffective in reducing roof acceleration. Additionally, the displacement experienced by the second‐mode TMD is considerably smaller than that of the first‐mode TMD, thereby reducing the installation space for the TMD.

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“…The friction force on the pendulum f p is assumed to be known at installation and is taken as a constant value. Equation (5) can readily be transferred into the state space forṁ…”

Section: Magnetic-rheological Damper Properties and Modelingmentioning

confidence: 99%

LQR control with frequency‐dependent scheduled gain for a semi‐active floor isolation system

Shi

Becker

Furukawa

et al. 2013

Earthq Engng Struct Dyn

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SUMMARYFloor isolation is an alternative to base isolation for protecting a specific group of equipment installed on a single floor or room in a fixed‐base structure. The acceleration of the isolated floor should be mitigated to protect the equipment, and the displacement needs to be suppressed, especially under long‐period motions, to save more space for the floor to place equipment. To design floor isolation systems that reduce acceleration and displacement for both short‐period and long‐period motions, semi‐active control with a newly proposed method using the linear quadratic regulator (LQR) control with frequency‐dependent scheduled gain (LQRSG) is adopted. The LQRSG method is developed to account for the frequency characteristics of the input motion. It updates the control gain calculated by the LQR control based on the relationship between the control gain and dominant frequency of the input motion. The dominant frequency is detected in real time using a window method. To verify the effectiveness of the LQRSG method, a series of shake table tests is performed for a semi‐active floor isolation system with rolling pendulum isolators and a magnetic‐rheological damper. The test results show that the LQRSG method is significantly more effective than the LQR control over a range of short‐period and long‐period motions. Copyright © 2013 John Wiley & Sons, Ltd.

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Predicting the displacement of triple pendulum™ bearings in a full‐scale shaking experiment using a three‐dimensional element

Cited by 84 publications

References 8 publications

Assessment of sliding‐rubber isolator effect in progressive collapse of bridges under two scenarios

Assessment of sliding‐rubber isolator effect in progressive collapse of bridges under two scenarios

Second‐mode tuned mass dampers in base‐isolated structures for reduction of floor acceleration

LQR control with frequency‐dependent scheduled gain for a semi‐active floor isolation system

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