682 research outputs found

    Neural Network Based Vibration Control of Seismically Excited Civil Structures

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    This study proposes a neural network based vibration control system designed to attenuate structural vibrations induced by an earthquake. Classical feedback control algorithms are susceptible to parameter changes. For structures with uncertain parameters they can even cause instability problems. The proposed neural network based control system can identify the structural properties of the system and avoids the above mentioned problems. In the present study it is assumed that a full state of the structure is known, which means the at each floor horizontal displacements and rotations about the vertical axis are measured. Additionally, it is assumed the acceleration signal coming from the earthquake is also available. The proposed neural control strategy is compared with the classical linear quadratic regulator (LQR) not only in terms of displacement responses, but also required control forces. Moreover, the influence of different weighting matrices on performance of the proposed control strategy has been presented.The effectiveness of the neuro-controller has been demonstrated on two numerical examples: a simple single degree of freedom (DOF) structure and a multi-DOF structure representing a twelve story building. Both structures under consideration have been excited with El Centro acceleration signal. The results of numerical simulations on the SDOF system indicate that using neuro-controller it would be possible to obtain smaller amplitudes as compared with the LQ regulator, but it would require higher control effort

    Lyapunov Based Control Algorithm for Seismically Excited Buildings

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    Several different seismic active control algorithms have been proposed in the last decades, most of these studies are based on the applications of the traditional linear quadratic regulator control (LQR). This paper develops a new control algorithm for SDOF structures based in Lyapunov method. This algorithm uses Lyapunov’s direct approach for stability analysis in design of feedback controller. The approach requires the use of Lyapunov function candidate, which must be a positive definite function of the states of the system. The controller is designed so as to make the derivative of the Lyapunov function negative semi-definite. Numerical simulations using one story frame structure modeled as shear building structure subjected to earthquake excitations have been performed to evaluate the effectiveness of the proposed algorithm

    Data Mining Technology for Structural Control Systems: Concept, Development, and Comparison

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    Structural control systems are classified into four categories, that is, passive, active, semi-active, and hybrid systems. These systems must be designed in the best way to control harmonic motions imposed to structures. Therefore, a precise powerful computer-based technology is required to increase the damping characteristics of structures. In this direction, data mining has provided numerous solutions to structural damped system problems as an all-inclusive technology due to its computational ability. This chapter provides a broad, yet in-depth, overview in data mining including knowledge view (i.e., concept, functions, and techniques) as well as application view in damped systems, shock absorbers, and harmonic oscillators. To aid the aim, various data mining techniques are classified in three groups, that is, classification-, prediction-, and optimization-based data mining methods, in order to present the development of this technology. According to this categorization, the applications of statistical, machine learning, and artificial intelligence techniques with respect to vibration control system research area are compared. Then, some related examples are detailed in order to indicate the efficiency of data mining algorithms. Last but not least, capabilities and limitations of the most applicable data mining-based methods in structural control systems are presented. To the best of our knowledge, the current research is the first attempt to illustrate the data mining applications in this domain

    NDM-522: DECENTRALIZED SEMI-ACTIVE CONTROL FOR MULTI-PERFORMANCE-BASED DESIGN

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    Traditional performance-based design (PBD) that has a single performance level has been widely researched by changing section sizes of structural members or material properties to resist single hazard levels. However, this approach has limitations in terms of achieving performance and alternative design options for the owner. To overcome these limitations of the traditional PBD method, a multi-performance-based control design (MPBCD) methodology is newly proposed. The MPBCD integrates a decentralized semi-active control algorithm with semi-active smart damping devices and an advanced multi-objective optimization method. The multi-objective optimization is used to achieve various sets of performance-based control designs. The control designs satisfy multiple performance levels under multiple hazard levels without changing cross-section sizes or material properties of structural members. This MPBCD provides multiple sets of control designs (i.e., control device layouts with control design variables) to minimize design costs and maximize control effectiveness. The multiple sets of designs offer optimal performance-based control design covering a broad range of hazard levels with various performance levels. This numerical study uses an advanced decentralized semi-active controller and large-scale 200-kN magnetorheological (MR) dampers installed in a nine-story moment-resisting frame (MRF) building. From the multi-objective optimization technique, multiple layouts of control devices and controller parameters for multiple performance levels under multiple hazard levels are investigated

    A semi-active H∞ control strategy with application to the vibration suppression of nonlinear high-rise building under earthquake excitations

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    Different from previous researches which mostly focused on linear response control of seismically excited high-rise buildings, this study aims to control nonlinear seismic response of high-rise buildings. To this end, a semi-active control strategy, in which H∞ control algorithm is used and magneto-rheological dampers are employed for an actuator, is presented to suppress the nonlinear vibration. In this strategy, a modified Kalman–Bucy observer which is suitable for the proposed semi-active strategy is developed to obtain the state vector from the measured semi-active control force and acceleration feedback, taking into account of the effects of nonlinearity, disturbance and uncertainty of controlled system parameters by the observed nonlinear accelerations. Then, the proposed semi-active H∞ control strategy is applied to the ASCE 20-story benchmark building when subjected to earthquake excitation and compared with the other control approaches by some control criteria. It is indicated that the proposed semi-active H∞ control strategy provides much better control performances by comparison with the semi-active MPC and Clipped-LQG control approaches, and can reduce nonlinear seismic response and minimize the damage in the buildings. Besides, it enhances the reliability of the control performance when compared with the active control strategy. Thus, the proposed semi-active H∞ control strategy is suitable for suppressing the nonlinear vibration of high-rise buildings

    Hysteretic active control of base-isolated buildings

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    In this work, an active control law for base-isolated buildings is proposed. The crucial idea comes from the observation that passive base-isolation systems are hysteretic. Thus, an hysteretic active control strategy is designed in a way that the control force is smooth and limited by a prescribed bound. Furthermore, given a specific actuator with a physically limited maximum force and maximum rate of change, it is proven that the design parameters in the contributed control law can be chosen such that the control signal inherently satisfies the actuator constraints. Eight different ground-acceleration time-history records and a model of a 5-story building are used to study and compare the performance of a passive pure friction damper alone, with the addition of the proposed active control. Numerical analysis demonstrates that our control strategy effectively mitigates base displacement and shear without an increase in superstructure drift or acceleration.Peer ReviewedPostprint (author's final draft
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