Control Of Civil Engineering Structures Research Articles

Radial Basis Function Neural Network in Vibration Control of Civil Engineering Structure

Abstract This article uses the radial basis function artificial neural network and the MATLAB toolbox to study the vibration control of civil engineering structures. The article proposes a dynamic structure design method based on a generalized radial basis function neural network. Furthermore, the RBF neural network theory is used to optimize the structure-related controller parameters in geotechnical engineering. The research results show that RBF neural network can more accurately predict the vibration response of civil engineering. It can effectively solve the time lag problem in vibration control.

Machine Learning Enhanced Dynamic Response Modelling of Superelastic Shape Memory Alloy Wires.

Superelastic shape memory alloy (SMA) wires exhibit superb hysteretic energy dissipation and deformation capabilities. Therefore, they are increasingly used for the vibration control of civil engineering structures. The efficient design of SMA-based control devices requires accurate material models. However, the thermodynamically coupled SMA behavior is highly sensitive to strain rate. For an accurate modelling of the material behavior, a wide range of parameters needs to be determined by experiments, where the identification of thermodynamic parameters is particularly challenging due to required technical instruments and expert knowledge. For an efficient identification of thermodynamic parameters, this study proposes a machine-learning-based approach, which was specifically designed considering the dynamic SMA behavior. For this purpose, a feedforward artificial neural network (ANN) architecture was developed. For the generation of training data, a macroscopic constitutive SMA model was adapted considering strain rate effects. After training, the ANN can identify the searched model parameters from cyclic tensile stress–strain tests. The proposed approach is applied on superelastic SMA wires and validated by experiments.

Performance analysis for an improved strategy in optimal control of civil engineering structures

Civil Engineering structures are already an important part in the Smart Cities concept. In connection to this, integration of new technologies is under way in the field of Structural Engineering as in all Civil and Buildings/Bridges Engineering. One of the main goals is to protect structures from possible harm from earthquakes. In order to achieve this goal, Optimal Active Control has been proposed and used with a high degree of success. However, the application strategies are continuously improving. A strategy consisting in simplifying the Optimal Active control for full states has been proposed by the authors and relatively recently modified for an increased efficiency. That was a theoretical research taking into account the possibility to reduce the order of magnitude of matrices involved in computations. The present paper is assuming the previous theoretical result and simulates its application to the structural model of a ground floor plus ten floors building specially designed for this purpose. The reinforced concrete frame building’s behaviour is analysed under seismic actions. Efficiency and the control strategy are observed in different scenarios. The structural response is revealing that the new strategy is working faster in limiting the effects of earthquake input. In addition, the reduced computational time leads to a faster control and smaller phase-shift in practical use.

CANFIS‐Based Semi‐active Vibration Control of Stochastically Excited High‐Rise Civil Engineering Structures with Nonlinearities and Uncertainties

AbstractThis study introduces a co‐active neuro‐fuzzy inference system (CANFIS) based vibration control strategy for high‐rise civil engineering structures, such as buildings, wind turbines and towers. The proposed approach uses semi‐active dampers, which are distributed in the structure. Attached to the structural members, semi‐active dampers generate adaptive restoring forces to reduce the structural vibrations by autonomously tuning their parameters. The nonlinear behavior and the uncertainties involved in the mathematical models of both the semi‐active dampers and the structures require sophisticated control strategies. Previous studies have shown that fuzzy logic controllers (FLCs) can overcome these challenges and perform effectively with semi‐active dampers to mitigate the structural vibrations. Nevertheless, FLCs require a predefined parameter tuning of their fuzzy rules and membership functions, which must be performed based on the knowledge of a human expert. Combining FLCs with artificial neural networks (ANNs), hybrid systems are proposed, which can determine the parameters of FLCs by using learning based training and adaptation strategies of ANNs. However, there is only limited research investigating the performance of these adaptive systems in the field of vibration control of civil engineering structures. The present work is concerned with a numerical formulation of such an adaptive system, in particular the CANFIS, and its implementation on a non‐linear seismically excited three‐story steel benchmark building with semi‐active dampers. To determine the premise parameters of the membership functions and the consequent parameters of the fuzzy rules a hybrid training method is performed using the recursive least‐square algorithm and the steepest descent method. Investigations with historic earthquakes show a significant reduction of the roof displacements of the building. For instance, during the Hachinohe earthquake the peak value of the displacement is reduced by 87 %.

Improved strategy for optimal control of Civil Engineering structures

Inside the Industrial Revolution 4.0, the concepts as Smart Cities and Smart Society are important parts in protection of humans against natural disasters, as strong earthquakes. Older or newer protection strategies of Civil Engineering structures (bridges, buildings) must be updated with elements of the actual technological revolution as sensors, drones, robots, nanotechnologies, AI, big data, cloud computing and so on. This paper is focused on a optimal structural active control of buildings started by many researchers during the last decades. Now, the target is to improve an optimal strategy developed by authors by proposing a more efficient use of computation. The success of this strategy leads to a faster response of computers that direct the control devices. This provides the ground for a larger range of control devices based on a larger number of sensors and, therefore, a better energy use together with a more precise anti-seismic structural protection

Robust Design Strategy for Multiple Tuned Mass Dampers with Consideration of Frequency Bandwidth

The tuned mass damper (TMD) has been widely used in vibration control of civil engineering structures after numerous analytical studies and experimental verifications. A large number of TMDs have been implemented in real structures against natural and man-made excitations since the early 1970. From field observations, it was found that the control efficacy of a TMD may decay significantly when its frequency is not well tuned to the desired value. A multiple TMD (MTMD) system was proposed to tune a band of frequencies, thereby enhancing the vibration control efficiency. Frequency detuning usually results from structural system variations due to errors in modeling, construction, and system parameter identification. In this study, the frequency detuning effect due to uncertainties of the controlled system parameters on the performance of the MTMDs is investigated. A sensitivity analysis was first carried out to evaluate the control effectiveness of a MTMD system designed by a conventional method. A new robust design method with account taken of frequency bandwidth is proposed to alleviate the detuning effect. Numerical analysis is performed to verify the applicability and efficacy of the proposed robust design method.

Vibration control performance of tuned mass dampers with resettable variable stiffness

Vibration control of civil engineering structures using tuned mass dampers (TMDs) is a widely acknowledged control strategy based on numerous analytical and experimental verifications. Although the design and application of traditional linear TMD systems are well established, nonlinear TMD systems that may have better control performance remain in the developmental stage. The TMD systems have two main problems, i.e. detuning effect and excessive TMD’s stroke. To improve the overall performance of TMD systems, a novel semi-active TMD named resettable variable stiffness TMD (RVS-TMD), is proposed. The RVS-TMD consists of an undamped TMD and a resettable variable stiffness device (RVSD). This RVSD is composed of a resettable element and a controllable stiffness element. By varying the stiffness of controllable stiffness element in the RVSD, force produced by the RVSD can be controlled smoothly through a semi-active control law. By operating the resettable element, the hysteretic loops of the RVSD can cover all four quadrants in the force–deformation diagram and, thus, increases energy dissipation. In other words, both stiffness and damping of the RVS-TMD are adjustable via only the RVSD device. The harmonic and seismic responses of a building equipped with the RVS-TMD were investigated. Numerical results show that the proposed RVS-TMD system can avoid detuning effect automatically and assure the optimal control performance as desired when the frequency of primary structure is changed.

An improved tuned mass damper (SMA-TMD) assisted by a shape memory alloy spring

The tuned mass damper (TMD) is a well acclaimed passive control device for vibration control of structures. However, the requirement of a higher mass ratio restricts its applicability for seismic vibration control of civil engineering structures. Improving the performance of TMDs has been attempted by supplementing them with nonlinear restoring devices. In this regard, the ability of shape memory alloy (SMA) in dissipating energy through a hysteretic phase transformation of its microstructure triggered by cyclic loading is notable. An improved version of TMD assisted by a nonlinear shape memory alloy (SMA) spring, referred as SMA-TMD, is studied here for seismic vibration mitigation. Extensive numerical simulations are conducted based on nonlinear random vibration analysis via stochastic linearization of the nonlinear force–deformation hysteresis of the SMA. A design optimization based on minimizing the root mean square displacement of the main structure is also carried out to postulate the optimal design parameters for the proposed system. The viability of the optimal design is verified with respect to its performance under recorded earthquake motions. Significant improvements of the control efficiency and a reduction of the TMD displacement at a much reduced mass ratio are shown to be achieved in the proposed SMA-TMD over those in the linear TMD.

Stochastic seismic response analysis and reliability assessment of passively damped structures

Viscous dampers have demonstrated their value for vibration control of civil engineering structures subjected to seismic excitations due to their effective energy dissipation capabilities and excellent durability characteristics. In most existing designs of practical applications on structural control with viscous dampers, just several ground motions with different risk levels are included. Logical treatment on the randomness inherent in the occurrence and propagation of earthquakes has still not received sufficient appeal. In this paper, stochastic seismic response analysis and reliability assessment of passively damped structures are carried out through experimental investigations and numerical simulations. Complete shaking-table tests on a framed structure with viscous dampers are involved, where the base excitation is represented by a physical stochastic ground motion model. For the numerical analysis and reliability assessment, the probability density evolution method and the theory of extreme value distribution are employed. Experimental and numerical investigations indicate that the seismic performance of the controlled structure with viscous dampers is significantly improved compared with that of the uncontrolled structure, and the structural safety is essentially enhanced.

Active and semi-active vibration control of buildings in Japan—Practical applications and verification

During the last two decades, active and semi-active vibration control of civil engineering structures has attracted growing worldwide interest as an innovative technology in the earthquake and wind engineering fields. In Japan, there has been rapid progress in research and development in the construction and mechanical industries and at universities, because the concept of active control is widely expected to exceed the performance limitations of conventional earthquake-resistant structures. As a result, about 70 active and semi-active control systems have already been applied to actual buildings in Japan since 1989. The 1995 Kobe Earthquake opened a door to positive development of semi-actively controlled structures against large earthquakes. Semi-active control research affects both conventional seismic-resistant structures and passively controlled structures. At present, structural control includes not only active and semi-active control but also passive control. Vibration problems in civil engineering structures are examined again from the standpoint of control engineering. Practical applications of structural control encourage monitoring and system identification research with recently advanced information technology. The observation records of buildings and controllers under dynamic loadings have been analyzed to confirm the effectiveness of the installed control systems. This paper introduces practical applications of active and semi-active control of buildings in Japan and reports control verification methods through observation data recorded in controlled buildings. The state of the art proves that structural control and its related monitoring technologies are growing as general design items for tall buildings and flexible structures. Copyright © 2009 John Wiley & Sons, Ltd.

선형 구조물의 능동 진동 제어를 위한 포화 제어기의 안정성

Control input`s saturation of active control devices for large structures under large external disturbances are often occurred. It is more difficult to obtain the exact values of mass and stiffness as structures are higher. The modelling errors between mathematical models and real structures must be also included as parameter uncertainties. Therefore, in active vibration control of civil engineering structures like buildings and bridges, the robust saturation controller design method considering both control input`s saturation and parameter uncertainties of system is needed. In this paper, stabilities of linear optimal controller LQR, modified bang-bang controller, saturated sliding mode controller, and robust saturation controller among various controllers which have been studied and applied to active vibration control of buildings are investigated. Especially, unstable phenomena of the LQR, the modified bang-bang controller and the saturated sliding mode controller when the control input is saturated or parameter uncertainties exist are presented to show the necessity of the robust saturation controller. The robust stability of the robust saturation controller are shown through a numerical example of a 2DOF linear vibrating system and an experimental test of the two-story structure with an active mass damper (AMD).

H∞-based control strategies for civil engineering structures

Two H∞-based control strategies are proposed for application to civil engineering structures. The first strategy deals with a class of excitations with a specified ‘energy’ bound (H∞B-EB), whereas the second strategy addresses a class of excitations with a specified peak bound (H∞B-PB). Both control strategies are derived by minimizing an upper bound of the H∞ performance (i.e. energy or L2 gain) with the constraints (or penalties) on the peak values of another set of quantities, such as the control resources. These control strategies are formulated within the framework of linear matrix inequalities (LMIs), so that the LMI toolbox in MATLAB can be used effectively and conveniently. These control techniques are applied to a wind-excited 76-storey benchmark building and a long-span cable-stayed benchmark bridge subject to earthquakes to illustrate their effectiveness for practical problems, such as control of civil engineering structures. Copyright © 2004 John Wiley & Sons, Ltd.

ACTIVE AND SEMI-ACTIVE CONTROL OF BUILDINGS IN JAPAN

During the last two decades, active and semi-active control of civil engineering structures has made rapid progress in Japan. This technology has become widely used in earthquake engineering design, and more than 50 control systems have already been applied to buildings in Japan. The 1995 Hyogo-ken Nanbu Earthquake opened a door to positive development of semi-actively-controlled buildings against large earthquakes. This paper reports the state of the art by introducing practical applications, and describes future perspectives.

Multi‐objective optimal design of FLC driven hybrid mass damper for seismically excited structures

AbstractStructural vibration control using active or passive control strategy is a viable technology for enhancing structural functionality and safety against natural hazards such as strong earthquakes and high wind gusts. Both the active and passive control systems have their limitations. The passive control system has limited capability to control the structural response whereas the active control system depends on external power. The power requirement for active control of civil engineering structures is usually quite high. Thus, a hybrid control system is a viable solution to alleviate some of the limitations. In this paper a multi‐objective optimal design of a hybrid control system for seismically excited building structures has been proposed. A tuned mass damper (TMD) and an active mass driver (AMD) have been used as the passive and active control components of the hybrid control system, respectively. A fuzzy logic controller (FLC) has been used to drive the AMD as the FLC has inherent robustness and ability to handle the non‐linearities and uncertainties. The genetic algorithm has been used for the optimization of the control system. Peak acceleration and displacement responses non‐dimensionalized with respect to the uncontrolled peak acceleration and displacement responses, respectively, have been used as the two objectives of the multi‐objective optimization problem. The proposed design approach for an optimum hybrid mass damper (HMD) system, driven by FLC has been demonstrated with the help of a numerical example. It is shown that the optimum values of the design parameters of the hybrid control system can be determined without specifying the modes to be controlled. The proposed FLC driven HMD has been found to be very effective for vibration control of seismically excited buildings in comparison with the available results for the same example structure but with a different optimal absorber. Copyright © 2002 John Wiley & Sons, Ltd.

REAL-TIME IDENTIFICATION OF MAGNETO-RHEOLOGICAL DAMPERS

Modeling of magneto-rheological dampers to be used in semi-active control of civil engineering structures is addressed. The behavior of this kind of dampers is modeled through a first order Lugre dynamic friction model whose structure is analytically simpler than other dynamic friction models used in the literature. With this structure real-time parametric identification of the magneto-rheological damper is possible. Forces obtained with this modeling approach are in good agreement with those produced by other models.

Experimental Verification of Multiinput Seismic Control Strategies for Smart Dampers

This paper documents the results of an experimental study conducted to demonstrate the capabilities of multiple magnetorheological (MR) devices for seismic control of civil engineering structures. A six-story test structure in the Washington University Structural Control and Earthquake Engineering Lab is considered, and four parallel-plate, shear-mode MR dampers are used to control this test structure. Two control devices are installed in the test structure between the base and first floor, and two are installed between the first floor and second floor. A phenomenological model of the shear mode MR damper is proposed and verified. A nonlinear system identification method, appropriate for multi-input/multi-output systems, is used to develop a model of the integrated structural system. Experimental transfer function data corresponding to one system input are used to update the eigenvalues of an analytical model. Two semiactive control algorithms, including a Lyapunov algorithm and a clipped-optimal algorithm, are considered. An El Centro earthquake example is used to disturb the system at three amplitude levels. The results indicate that high performance levels can be achieved, and the responses of the semiactive system are significantly better than that of comparable passive systems.

Placement of sensors/actuators on civil structures using genetic algorithms

AbstractThe optimal design and placement of controllers at discrete locations is an important problem that will have impact on the control of civil engineering structures. Though algorithms exist for the placement of sensor/actuator systems on continuous structures, the placement of controllers on discrete civil structures is a very difficult problem. Because of the nature of civil structures, it is not possible to place sensors and actuators at any location in the structure. This usually creates a non‐linear constrained mixed integer problem that can be very difficult to solve. Using genetic algorithms in conjunction with gradient‐based optimization techniques will allow for the simultaneous placement and design of an effective structural control system. The introduction of algorithms based on genetic search procedures should increase the rate of convergence and thus reduce the computational time for solving the difficult control problem. The newly proposed method of simultaneously placing sensors/actuators will be compared to a commonly used method of sensors/actuators placement where sensors/actuators are placed sequentially. The savings in terms of energy requirements and cost will be discussed. Copyright © 2001 John Wiley & Sons, Ltd.

Generalized minimum variance control for buildings under seismic ground motion

AbstractThe generalized minimum variance (GMV) algorithm for the control of civil engineering structures is developed and presented in this paper. This algorithm needs the knowledge of the seismic excitation model to derive the autoregressive moving average exogen model of the structure. Then the GMV control is applied. The control is designed such that the variance of the generalized cost function is minimized. To demonstrate the effectiveness of this control technique, simulation tests using a single‐degree‐of‐freedom structure are performed. The results show that the relative displacement of the structure and the control effort are significantly reduced. Copyright © 2001 John Wiley & Sons, Ltd.

Compensation of time-delay for control of civil engineering structures

Time-delay is an important issue in structural control. Applications of unsynchronized control forces due to time-delay may result in a degradation of the control performance and it may even render the controlled structures to be unstable. In this paper, a state-of-the-art review for available methods of time-delay compensation is presented. Then, five methods for the compensation of fixed time-delay are presented and investigated for active control of civil engineering structures. These include the recursive response method, state-augmented compensation method, controllability based stabilization method, the Smith predictor method and the Pade approximation method, all are applicable to any control algorithm to be used for controlled design. Numerical simulations have been conducted for MDOF building models equipped with an active control system to demonstrate the stability and control performance of these time-delay compensation methods. Finally, the stability and performance of the phase shift method, that is well-known in civil engineering applications, have also been critically evaluated through numerical simulations. Copyright © 2000 John Wiley & Sons, Ltd.

Optimal Noise Rejection in Structural Analysis by Means of Generalized Sampled-Data Hold Functions

In this paper, a technique for optimal noise rejection, based on generalized sampled-data hold functions is applied to the control of civil engineering structures. The technique consists in suitably modulating the sampled outputs of the system under control by periodically varying functions in order to attenuate the effect of the disturbances on the system states to an acceptable level, by minimizing a quadratic cost function. This minimization is performed by feeding back the outputs of the system, which are assumed to be corrupted by measurement noise. Moreover, in the present paper, the robustness properties of the GSHF based optimal regulator is analyzed and guaranteed stability margins, expressed in terms of elementary cost and system matrices, are proposed for such a type of optimal regulators. The effectiveness of the method is demonstrated by various simulation results. The results of the paper can be used to assess the detrimental effect of noise on the closed-loop system and the tradeoff involved in assuring good sampled-data performance and sufficient robustness.