Semi-active Tuned Mass Damper Research Articles

Fuzzy hybrid control of a wind-excited tall building

A fuzzy hybrid control technique using a semi-active tuned mass damper (STMD) has been proposed in this study for mitigation of wind induced motion of a tall building. For numerical simulation, a third generation benchmark is employed for a wind-excited 76-story building. A magnetorheological (MR) damper is used to compose an STMD. The proposed control technique employs a hierarchical structure consisting of two lower-level semi-active controllers (sub-controllers) and a higher-level fuzzy hybrid controller. Skyhook and groundhook control algorithms are used as sub-controllers. When a wind load is applied to the benchmark building, each sub-controller provides different control commands for the STMD. These control commands are appropriately combined by the fuzzy hybrid controller during realtime control. Results from numerical simulations demonstrate that the proposed fuzzy hybrid control technique can effectively reduce the STMD motion as well as building responses compared to the conventional hybrid controller. In addition, it is shown that the control performance of the STMD is superior to that of the sample TMD and comparable to an active TMD, but with a significant reduction in power consumption.

Mitigation of wind response of a tall building using semi‐active tuned mass dampers

AbstractIn this study, the effectiveness of semi‐active tuned mass dampers (STMDs) for the response control of a wind‐excited tall building was investigated. To this end, a 76‐storey, 306 m benchmark building proposed for the city of Melbourne, Australia was used. Across wind load, data from wind tunnel tests were employed as excitation. A variable damping device and a magnetorheological (MR) damper were used to compose STMDs. A groundhook control algorithm was used to appropriately modulate the damping force of the semi‐active damper. The control performance of the STMD was compared to that of a sample TMD, an active TMD (ATMD) and a semi‐active variable stiffness TMD. The robustness of the STMD was investigated through the uncertainty in the building's stiffness. This study also investigated whether each of the mass dampers could satisfy the design requirements and constraints. The numerical studies show that the STMD can reduce the structural responses similar to an ATMD, but with a significant reduction in power consumption. It is also shown that the STMD with a 50 kN capacity MR damper can effectively control a full‐scale tall building subjected to wind excitation, and it can satisfy the design requirements and constraints of the benchmark problem. Copyright © 2010 John Wiley & Sons, Ltd.

Control of flapwise vibrations in wind turbine blades using semi-active tuned mass dampers

The increased size and flexibility of modern multi-Megawatt wind turbines has resulted in the dynamic behaviour of these structures becoming an important design consideration. The aim of this paper is to study the variation in natural frequency of wind turbine blades due to centrifugal stiffening and the potential use of semi-active tuned mass dampers (STMDs) in reducing vibrations in the flapwise direction with changing parameters in the turbine. The parameters considered were the rotational speed of the blades and the stiffness of the blades and nacelle. Two techniques have been employed to determine the natural frequency of a rotating blade. The first employs the Frobenius method to a rotating Bernoulli-Euler beam. These results are compared with the natural frequencies determined from an eigenvalue analysis of the dynamic model of the turbine including nacelle motion, which is developed in this paper. The model derived considers the structural dynamics of the turbine and includes the dynamic coupling between the blades and tower. The semi-active control system developed employs a frequency-tracking algorithm based on the short-time Fourier transform technique. This is used to continually tune the dampers to the dominant frequencies of the system. Numerical simulations have been carried out to study the effectiveness of the STMDs in reducing flapwise vibrations in the system when variations occur in certain parameters of the turbine. Steady and turbulent wind loading has been considered. Copyright © 2010 John Wiley & Sons, Ltd.

Using upper storeys as semi-active tuned mass damper building systems

This paper presents an exploratory case study based analysis of the seismic performance of multi-storey passive and semi-active tuned mass damper (PTMD and SATMD) building systems are investigated for 12-storey moment resisting frames modelled as ‘10+2’ storey and ‘8+4’ storey. Segmented upper stories of the structure are isolated as a tuned mass, and a passive viscous damper or semi-active resetable device is adopted for energy dissipation. Optimum TMD control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two degree of freedom (2-DOF) system. Log-normal statistical performance results are presented for 30 probabilistically scaled earthquake records. The time history analysis and normalised reduction factor results show the response reductions for all seismic hazards. Thus, large SATMD systems can effectively manage seismic response for multi degree of freedom (MDOF) systems across a broad range of ground motions in comparison to passive solutions. This research demonstrates the validity of the TMD building systems for consideration in future design and construction. It also provides a template for the design and analysis of passive or semi-active TMD buildings utilising large masses, or more efficiently, added storys, for improving seismic response performance.

Compensation of Time Delay Effect in Semi-active Controlled Suspension Bridges

In order to increase the critical wind speed to avoid galloping of flexible suspension bridges, it is necessary to introduce additional damping. One of the feasible methods of introducing additional damping to suspension bridges is using semi-active tuned mass damper control mechanisms. The time delay in generating the active control action due to the actuator’s dynamics is, however, a major practical problem which may destabilize the semi-active controlled structure. In this paper, the effect of the time delay on the stability of a semi-active controlled suspension bridge is investigated. It is shown that when the time delay for the semi-active controlled suspension bridge is considered, the critical wind speed will be less than that determined when the time delay is neglected. The reduction in the critical wind speed due to time delay might cause the suspension bridge to gallop at normal wind speeds. The paper shows how to compensate for the time delay effect in order to ensure the galloping suppression. The time delay compensation is treated by two methods: the first method expresses the delayed control action using a truncated Taylor’s series in terms of the current control action and its derivatives1 the second method expresses the delayed control action as feedback of the delayed state variables. Both methods are applied on a linear model derived from the actual nonlinear model. The controlled response considering the delay is obtained by applying the designed active control on the actual nonlinear model. The results of both methods of time delay compensation are discussed and compared using a numerical example.

Semi‐active tuned mass damper building systems: Application

AbstractSeismic performance attributes of multi‐story passive and semi‐active tuned mass damper (PTMD and SATMD) building systems are investigated for 12‐story moment resisting frames modeled as ‘10+2’ stories and ‘8+4’ stories. Segmented upper portion of the stories are isolated as a tuned mass, and a passive viscous damper or semi‐active resetable device is adopted as energy dissipation strategy. The semi‐active approach uses feedback control to alter or manipulate the reaction forces, effectively re‐tuning the system depending on the structural response. Optimum tuned mass damper control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two‐degree‐of‐freedom system. Statistical performance metrics are presented for 30 probabilistically scaled earthquake records from the SAC project. Time history analyses are used to compute response reduction factors across a wide range of seismic hazard intensities. Results show that large SATMD systems can effectively manage seismic response for multi‐degree‐of freedom systems across a broad range of ground motions in comparison to passive solutions. Specific results include the identification of differences in the mechanisms by which SATMD and PTMD systems remove energy, based on the differences in the devices used. Additionally, variability is seen to be tighter for the SATMD systems across the suites of ground motions used, indicating a more robust control system. While the overall efficacy of the concept is shown the major issues, such as isolation layer displacement, are discussed in detail not available in simplified spectral analyses, providing further insight into the dynamics of these issues for these systems. Copyright © 2009 John Wiley & Sons, Ltd.

Loading models and response control of footbridges excited by running pedestrians

New trends in the architectural design of footbridges feature an unprecedented slenderness, especially when these are located in the urban environment. For this reason, static analyses and a design towards the ultimate limit state have proven inadequate in many circumstances, and the main objective in the structural design is becoming that of assessing the serviceability limit state through dynamic analyses. On the other hand, the key issue of dynamic analyses is the availability of reliable models for the structure and for loads, and in the particular case of pedestrian action the lack of commonly accepted models for walking, running and jumping has become the weak link in the whole structural design process. In a first stage of the present work, vibration measurements were taken on a recently built cable-stayed footbridge, whose second vibration mode was excited by runners. As a second step, a dynamic loading model for the vertical component of the running-induced force was developed, which was used for the finite element analyses of the footbridge. Finally, tuned mass dampers (TMDs) represent a quite mature technology for reducing the resonant response of flexible structures, but their effectiveness is heavily dependent on the tuning ratio. In the case of footbridges, pedestrians can act as a significant part of the vibrating mass; thus, varying the vibration frequency, which makes it difficult to properly tune the damper frequency. Semi-active TMDs can be looked at as passive devices able to adjust their dynamic parameters according to a given control logic. A physical description of a control algorithm is given in the paper, and its performance is discussed. Copyright © 2008 John Wiley & Sons, Ltd.

Nonlinear vibration of shallow cables with semiactive tuned mass damper

The nonlinear vibration of shallow cables, equipped with a semiactive control device is considered in this paper. The control device is represented by a tuned mass damper with a variable out-of-plane inclination. A suitable control algorithm is designed in order to regulate the inclination of the device and to dampen the spatial cable vibrations. Numerical simulations are conducted under free spatial oscillations through a nonlinear finite element model, solved in two different computational environments. A harmonic analysis, in the region of the primary resonance, is also performed through a control-oriented nonlinear Galerkin model, including detuning effects due to the cable slackening.

Velocity adjustable TMD and numerical simulation of seismic performance

A new type of velocity adjustable tuned mass damper (TMD) consisting of impulse generators and clutches is presented. The force impulse is generated by a joining operation of electromagnets and springs and MR dampers are used as clutches. Rules for velocity adjustment are established according to the working mechanism of TMD. The analysis program is developed on a VB platform. Seismic response of SDOF structures with both passive TMD and velocity adjustable TMD are analyzed. The results show that (1) the control effectiveness of passive TMDs is usually unstable; (2) the control effectiveness of the proposed semi-active TMDs is much better than passive TMDs under typical seismic ground motions; and (3) unlike the passive TMD system, the proposed velocity adjustable TMDs exhibit good control effectiveness even when the primary structure performance becomes inelastic during severe earthquakes.

준능동 동조질량감쇠기의 탄성 및 비탄성 지진응답 제어성능 평가

본 연구에서는 지진하중을 받는 탄성 및 비탄성 구조물에 대하여 수동 및 준능동 TMD의 지진응답제어성능을 평가하였다. 먼저 기존의 연구에서 제안된 식을 사용하여 최적 설계된 수동형 TMD와 본 연구에서 제시된 준능동 TMB가 설치된 탄성 구조물의 변위스펙트럼을 구하였으며, 준능동 TMD가 TMD보다 작은 스트로크를 가지고도 최대변위응답제어에 있어 우수함을 확인하였다. 또한 구조물의 주기와 TMD의 주기가 일치하지 않은 경우의 성능저하에 대한 TMD의 강인성을 평가하였다. 최종적으로 Bouc-Wen 모델을 사용하여 모사된 비탄성이력 특성을 가지는 구조물에 대한 수치해석을 수행하였으며, 이를 통해 탄성구조물에 대하여 최적화된 수동형 TMD의 성능은 구조물 응답의 비탄성이력 부분이 증가함에 따라 크게 저하되는 반면 준능동 TMD는 수동형 TMD보다 약 15-40% 정도의 더 많은 응답감소효과를 가짐을 확인하였다. In this study, tile performance of a passive tuned mass damper (TMD) and a semi-active tuned mass damper (STMD) was evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for the damped structures with a passive TMD, which was optimally designed using the frequency and damping ratio presented by previous study, and with a STMD proposed in this study. The displacement spectra confirm that STMD provides much better control performance than passive md with less stroke. Also, the robustness or the TMD was evaluated by off-tuning the frequency of the TMD to that of the structure. Finally, numerical analyses were conducted for an inelastic structure of which hysteresis was described by Bouc-Wen model and the results indicated that the performance of the passive TMD of which design parameters were optimized for a elastic structure considerably deteriorated when the hysteretic portion or the structural responses increased, while the STMD showed about 15-40% more response reduction than the TMD.

준능동 TMD를 이용한 메가골조구조물의 진동제어

메가골조시스템은 사용되는 구조재료를 절약하면서도 구조물의 강성을 효과적으로 높일 수 있는 장점 때문에 고층건물의 설계에 많이 사용되고 있다. 이러한 메가골조시스템이 주로 적용되고 있는 초고층건물의 구조설계에서는 횡하중에 대한 거주자의 불안감을 최소화시키는 것이 주요한 관심사중의 하나이다. 따라서 본 연구에서는 메가골조구조물의 사용성을 향상시키기 위한 방법으로 일반적인 수동 TMD의 제어성능을 개선한 준능동 TMD(STMD)를 사용하였다. 이를 위하여 TMD에서 일반적으로 사용되고 있는 수동감쇠기 대신 준능동 MR 감쇠기를 사용하여 STMD를 구성하였다. 메가골조구조물의 일반적인 유한요소해석모델은 매우 많은 수의 자유도로 구성되어 있기 때문에 원형모델을 사용하여 STMD의 제어성능을 검토하는 것은 현실적으로 불가능하다. 따라서 메가골조구조물의 동적 거동을 정확하게 표현할 수 있는 최소한의 자유도를 가진 응축모델을 행렬응축기법을 이용하여 제안하였다. 또한 일반적인 행렬응축기법의 효율성을 향상시키기 위하여 메가골조구조물의 특성을 활용한 다단계 행렬응축기법을 제안하였다. 본 연구에서 제안된 응축모델을 사용한 제어의 효율성과 정확성 및 메가골조구조물에 대한 STMD의 제어성능을 예제해석을 통하여 검증하였다. The mega frame system is becoming popular for the design and construction of skyscrapers because this system exhibits structural efficiency by allowing high rigidity of the structure while minimizing the amount of structural materials to be used. Since the mega frame system is usually adopted for super high-rise buildings, the comfort of occupants may be main concerns in the practical application of this system. For the enhancement of the serviceability of mega frame structures, a semi-active tuned mass damper (STMD) is developed in this study. To this end, a Magnetorheological (MR) damper is employed replacing passive damper as a semi-active damper to improve the control effect of a conventional TMD. Since a conventional finite element model of mega frame structures has significant numbers of DOFs, numerical simulation for investigation of control performances of a STMD is impossible by using the full-order model. Therefore, a reduced-order system using minimal DOFs, which can accurately represent the dynamic behavior of a mega frame structure, is proposed in this study through the matrix condensation technique To improve the efficiency of the matrix condensation technique, multi-level matrix condensation technique is proposed using the structural characteristics of mega frame structures. The efficiency and accuracy of the reduced-order control proposed in this study and the control performance of a STMD were verified using example structures.

Control of Wind-induced Nonlinear Oscillations in Suspension Bridges using a Semi-Active Tuned Mass Damper

In this article, the along-wind and across-wind response of the suspended cables and the bridge deck response of a suspension bridge subjected to wind loading are studied. The mean wind direction is assumed to be perpendicular to the planes of the suspended cables. It is shown that the suspended cable, if constructed alone, will gallop in the across-wind direction when the mean wind speed exceeds a certain critical wind speed. Similarly the bridge deck, if constructed alone, will gallop when a critical wind speed is exceeded. The construction of a suspension bridge, through coupling the bridge deck with the suspended cables via vertical hangers, increases the critical wind speed at which galloping occurs. However, the increase in the critical wind speed of a suspension bridge over a normal bridge is not sufficient to prevent galloping at moderate wind speeds. This article investigates the use of a passive or semi-active tuned mass damper control mechanism to increase critical wind speed for a flexible suspension bridge without changing the shape or size of the bridge deck cross section.

Control of Wind-induced Nonlinear Oscillations in Suspension Bridges using Multiple Semi-active Tuned Mass Dampers

The effectiveness of using Multiple Tuned Mass Dampers (MTMD) to increase the critical wind speed of a flexible long span suspension bridge subjected to wind loading is studied. The mean wind direction is assumed to be perpendicular to the plane of the suspended cable. The along-wind response and across-wind response of the suspended cables and the bridge deck response due to wind are studied, and it is shown that using a single passive or semi-active tuned mass damper (STMD) with a large mass at the mid-span of the bridge raises the critical wind speed of the suspension bridge. As the installation of a single large passive or semi-active tuned mass damper is problematic, we investigate the effectiveness of using multiple tuned mass dampers (MTMD) with small masses located at various positions along the bridge deck. In order to further increase the critical wind speed, the passive MTMD are supplemented by velocity feedback active control forces. The effects of the dampers’ locations, the mass ratio and the damping ratio on the critical wind speed are also investigated.

다양한 하중의 진동제어를 위한 준능동 TMD의 이용

To dale, lots of types of tuned mass dampers are developed and investigated to reduce dynamic responses of a structure due to various causes. In this study, control performance of semi-active tuned mass damper(STMD), that can change the damping of tuned mass damper in real time based on structural responses, was investigated with respect to various types of excitation employing numerical simulation. Skyhook control algorithm was used to appropriately modulate the damping ratio of semi-active damper that composes STMD. The control effectiveness of a STMD under harmonic and random excitation were evaluated using a single-degree-of-freedom (SDOF) structure in comparison with a conventional passive tuned mass damper (TMD). The robustness of a STMD and a passive TMD were compared along with the variation of the mass of a SDOF structure. The control performance of STMD using magnetorheological (MR) damper was also investigated in this study. Based on the numerical studios, it was shown that the control effectiveness of the STMD was significantly superior to that of a passive TMD with respect to harmonic and random excitation.

Semiactive Fuzzy Logic Control of Suspension Bridge Flutter

A semiactive tuned mass damper (STMD) system with variable damping is used to control the flutter instability of long-span suspension bridges. For this purpose, a combined vertical and torsional model of a TMD system, which is placed at the middle of the center span, is used. This system has two degrees of freedom, which are tuned close to the frequencies corresponding to vertical and torsional symmetric modes of the bridge, that get coupled during flutter. The variable damping of the system is chosen through a fuzzy logic controller using the displacement and velocity at the center of the bridge as the inputs. The transient response of the bridge due to a given initial condition in presence of the wind self-excited forces is controlled so that critical flutter wind speed for the bridge is enhanced. The methodology is applied to increase the flutter wind speed of the Thomas Suspension Bridge. Also, a numerical study is conducted to investigate the effectiveness of the semiactive control scheme.

Semiactive Control of Building Structures with Semiactive Tuned Mass Damper

Abstract: This study proposed a new semiactive control device for building control. Semiactive tuned mass damper (STMD) combine a tradition tuned mass damper (TMD) and a semiactive damper. The property of semiactive damper can be adjusted online to produce the desired control force. In the present year, many types of semiactive dampers are proposed. In this study, the variable damping device and MR damper are used to illustrate the control effect of STMD. In addition, the control effect of the TMD and active tuned mass damper are also compared. The numerical simulation results show that the STMD can greatly improve the control efficiency of TMD.

Optimal control of structures with semiactive-tuned mass dampers

In this paper, the optimal performance of a magnetorheological (MR) damper which is used in a tuned mass damper in reducing the peak responses of a single-degree-of-freedom structure subjected to a broad class of seismic inputs including the harmonic, pulse, artificially generated and recorded earthquake excitations are studied. The optimal semiactive control strategy minimizes an integral norm of the main structure squared absolute accelerations subject to the constraint that the non-linear equations of motion are satisfied and is determined through a numerical solution to the Euler–Lagrange equations. The optimal performance evaluated for an MR damper is compared to an equivalent passive-tuned mass damper with optimized stiffness and damping coefficients. It is shown numerically that the optimal performance of the MR damper is always better than the equivalent passive-tuned mass damper for all the investigated cases and the MR damper has a great potential in suppressing structural vibrations over a wide range of seismic inputs.

Seismic structural control using semi-active tuned mass dampers

This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping. An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD system by considering the damping as an assumptive control action. The damping modification of the SATMD is carried out according to the proposed OTE algorithm, which is formulated based on analysis of the structural movement under external excitations, and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey and a ten-storey shear structures with a SATMD on the roof are conducted. The effectiveness on vibration reduction of MDOF systems subjected to seismic excitations is discussed. Analysis results show that the behavior of the structure with a SATMD is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also verified.

Floor vibration control using semi-active tuned mass dampers

This paper discusses the application of a new class of semi-active tuned mass dampers, called ground-hook tuned mass dampers (GHTMD), for the reduction of floor vibrations due to human movements. The TMD introduced uses a continuously variable semi-active damper (ground-hook damper) to achieve reduction in the floor acceleration. Here, the GHTMD is applied to a single degree of freedom system representative of building floors. The GHTMD design parameters are defined in terms of non-dimensional values. The optimum values of these parameters are found based on the minimization of the acceleration response of the floor for different GHTMD mass ratios and floor damping ratios. The performance of the GHTMD is compared to that of the equivalent passive TMD. In addition, the effects of off-tuning due to variations in the mass ratios and frequency ratios of the TMD and GHTMD are studied. Comparison of the results demonstrates the efficiency and robustness of GHTMD with respect to equivalent TMD. Finally, a guide for the design of GHTMDs is presented.Key words: floor vibrations, semi-active tuned mass dampers, tuned vibration absorbers, vibration control, ground-hook dampers, human-induced vibrations, annoying vibrations, optimum design parameters.

Control of wind-induced vibrations of long-span bridges by semi-active lever-type TMD

With the rapid increase of bridge spans, research on controlling wind-induced vibration of long-span bridges has been a problem of great concern. In view of the fact that the vibration frequencies and damping of long-span bridges vary with wind speed, and the variation characteristics could not be accurately known even if through wind tunnel experiments, a concept of semi-active (SA) control of wind-induced vibration of long-span bridges is put forward in this paper. A new SA lever-type TMD with an adjustable frequency and the corresponding control strategy are primarily developed. A case study of the Yichang bridge, a suspension bridge with a main span of 960 m, shows that the SA lever-type TMD device is much superior to passive TMD in control efficiency and robustness.