Analytical and Numerical Study of a Smart Sliding Base Isolation System for Seismic Protection of Buildings

Madden, Glenn J.; Wongprasert, N.; Symans, Michael D.

doi:10.1111/1467-8667.00296

Cited by 34 publications

(12 citation statements)

References 21 publications

(29 reference statements)

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“…Acceptable control performance was shown under moderate excitations, while lower control performance was exhibited under severe excitations. Madden et al (2003) investigated the combination of an adaptive hydraulic damper and a sliding base isolated building. The sliding bearings in this study used the BoucWen hysteretic model.…”

Section: Smart Base Isolationmentioning

confidence: 99%

Multiaxial active isolation for seismic protection of buildings

Chang

Spencer

Shi

2013

Struct. Control Health Monit.

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Structural control technology has been widely accepted as an effective means for the protection of structures against seismic hazards. Passive base isolation is one of the common structural control techniques used to enhance the performance of structures subjected to severe earthquake excitations. Isolation bearings employed at the base of a structure naturally increase its flexibility, but concurrently result in large base displacements. The combination of base isolation with active control, i.e., active base isolation, creates the possibility of achieving a balanced level of control performance, reducing both floor accelerations as well as base displacements. Many theoretical papers have been written by researchers regarding active base isolation, and a few experiments have been performed to verify these theories; however, challenges in appropriately scaling the structural system and modeling the complex nature of control-structure interaction have limited the applicability of these results. Moreover, most experiments only focus on the implementation of active base isolation under unidirectional excitations. Earthquakes are intrinsically multi-dimensional, resulting in out-of-plane responses, including torsional responses.Therefore, an active isolation system for buildings using multi-axial active control devices against multi-directional excitations must be considered.The focus of this dissertation is the development and experimental verification of active isolation strategies for multi-story buildings subjected to bi-directional earthquake loadings. First, a model building is designed to match the characteristics of a representative full-scale structure.The selected isolation bearings feature low friction and high vertical stiffness, providing stable behavior. In the context of the multi-dimensional response control, three, custom-manufactured actuators are employed to mitigate both in-plane and out-of-plane responses. To obtain a highiii fidelity model of the active isolation systems, a hybrid identification approach is used which combines the advantages of the lumped mass model and nonparametric methods. Controlstructure interaction (CSI) is also included in the identified model to further enhance the control authority. By employing the H 2 /LQG control algorithm, the controllers for the hydraulic actuators promise high performance and good robustness. The active isolation is found to possess the ability to reduce base displacements, as well as producing comparable accelerations over the passive isolation. The proposed active isolation strategies are validated experimentally for a sixstory building tested on the six degree-of-freedom shake table in the Smart Structures Technology Laboratory at the University of Illinois at Urbana-Champaign.iv ACKNOWLEDGMENTS

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Section: Smart Base Isolationmentioning

confidence: 99%

Multiaxial active isolation for seismic protection of buildings

Chang

Spencer

Shi

2013

Struct. Control Health Monit.

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“…Deviations between predicted and measured maximum and cumulative sliding displacement response are considerably reduced when a spring connects the rigid block with the shaking table. Inverted pendulum sliding isolators, apart from sliding, possess such a spring balancing force property [14][15][16]. Based on these observations, the investigation is next extended to deal with the more complex dynamic system described in Section 2; that is the 2-D.O.F.…”

Section: Test Employing Simulated Earthquake Excitation Without Springmentioning

confidence: 99%

The response of a two-degree-of-freedom dynamic sliding system subjected to uni-directional horizontal dynamic and seismic excitations

Manos¹,

Koidis²,

Demosthenous³

2013

Int. J. CMEM

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An investigation is presented that studies the response of a two-degree-of-freedom dynamic sliding system; that is a single-degree-of-freedom oscillator being fi xed on top of a rigid block that can slide on its supporting shaking table along a horizontal axis when subjected to unidirectional dynamic or earthquake excitations along this horizontal axis. This problem appears to be of interest in predicting the dynamic and earthquake response of superstructures supported on a large foundation block capable of horizontal sliding by means of seismic sliding isolators. Special mock-ups are tested at the shaking table of Aristotle University for this purpose utilizing horizontal simulated earthquake excitations based on prototype earthquake ground motion recordings. The numerical results, which were obtained by a computer software developed for this purpose, are compared with the corresponding experimental measurements. The measured acceleration and displacement responses of the mock-ups appear to be, in all the examined cases, in reasonably good agreement with the numerical predictions. However, in certain cases, the numerically predicted sliding displacement of the rigid block appears to have an offset that differs from the sliding response that was observed during the experiments. This is more pronounced when there is no spring linking the rigid block with the shaking table and must be attributed to manufacturing tolerances of the mock-ups. It is demonstrated that the developed software, although it tries to represent such a rather complex problem in a simplifi ed manner, can be useful at the preliminary design stage of structural systems resting on sliding isolators. Results from various experimental and numerical tests demonstrate that the oscillator's response is generally made smaller by the sliding of the rigid block. This is true for a wide range of frequencies; however, there is a relatively narrow frequency window in which the oscillator's response is amplifi ed. This frequency window has a peak value that is slightly higher than the oscillator's eigen-frequency when it is considered to be a single-degree-offreedom system fi xed at its base.

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“…Some of these strategies combine conventional isolation system with actively or semiactively controllable devices. [7][8][9][10][11][12][13][14][15][16] Furthermore, control strategies using adaptive neural networks and their application in various types of structural systems, including seismically isolated structures, have been extensively studied during the last two decades. [17][18][19][20][21][22][23][24] Although varying levels of response reduction have been demonstrated by means of active control strategies, there is still a need to develop efficient, consistent, and robust techniques to address the issues stated earlier.…”

Section: Introductionmentioning

confidence: 99%

Active neural predictive control of seismically isolated structures

Khodabandehlou

Pekcan

Fadali

et al. 2017

Struct Control Health Monit

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SummaryAn online identification and control scheme based on a wavelet neural network (WNN) and model predictive control (MPC) are presented. The WNN comprises a backpropagation neural network with wavelet activation functions and a parallel feedforward term. The WNN is used to identify the structural system, and the model is used to provide the predictions for MPC. The backpropagation network parameters and the controller are trained by the gradient descent algorithm to minimize performance indices. The feedforward component is trained using recursive least squares. The latter is found to drastically reduce the number of hidden layer neurons and significantly reduce the computational load of the neural network. Due to the general structure of the controller, its performance is satisfactory even under the strict condition imposed by a fixed learning rate. The efficacy of the control was demonstrated through a series of computational simulations of a 5-story seismically isolated structure with conventional lead-rubber bearings. Significant reductions of all response amplitudes were achieved for both near-field (pulse) and far-field ground motions, including reduced deformations along with corresponding reduction in acceleration response. In particular, the controller effectively regulated the apparent stiffness at the isolation level.

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Analytical and Numerical Study of a Smart Sliding Base Isolation System for Seismic Protection of Buildings

Cited by 34 publications

References 21 publications

Multiaxial active isolation for seismic protection of buildings

Multiaxial active isolation for seismic protection of buildings

The response of a two-degree-of-freedom dynamic sliding system subjected to uni-directional horizontal dynamic and seismic excitations

Active neural predictive control of seismically isolated structures

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