Semi-active Tuned Mass Damper Research Articles

Semi Active Tuned Mass Dampers of Buildings: A Simple Control Option

The present study investigates the effectiveness of a Proportional-Integral-Derivative (PID) controlled Variable Damping Semi-Active Tuned Mass Damper (VD-STMD) on reducing the vibration response of an earthquake excited multi-storey structure. The effectiveness of the controlled system is evaluated by comparing the structure’s overall dynamic behavior against that of an equivalent similar structure equipped with a conventional optimally designed passive Tuned Mass Damper (TMD). The numerical simulations show that the structure equipped with the PID controlled VD-STMD has improved vibration attenuation metrics when compared to the one equipped with the optimal TMD. From the numerical simulations, it was also evident that when material degradation and structural damage is considered, the TMD becomes instantly de-tuned resulting in reduced vibration mitigation performance. On the contrary, the VD-STMD controlled system remains insensitive to the stiffness parametric variation, suggesting the suitability of such systems in structural applications sustaining damage or in general change.

Shaking table tests of a plate‐column structure with semi‐active tuned mass damper

AbstractThis paper presents selected results of experimental tests carried out on the three‐storey plate‐column structure, which is a physical model of a building. On the top floor the semi‐active tuned mass damper (STMD) is installed. That device is a kind of harmonic oscillator with a variable stiffness characteristic. The tuning of STMD is possible in the frequency range from 0 to 5 Hz, which allows to counteract the resonant vibration of plate‐column structure for the three basic frequencies. The model's vibration are kinematically excited by using the earthquake simulator. It is assumed that during an experimental tests the plate‐column structure's vibration are only excited by horizontal component of base motion (dominant influence on building's vibration). The aim of the experimental analysis presented in this paper is to verify the effectiveness of the semi‐active tuned mass damper in vibration's amplitude reduction of the main structure. The tested device is prototype of STMD, which uses a competitive constructional solution of stiffness parameter control. By reason of above, special attention is focused on the testing of vibration eliminator in two aspects: change of stiffness characteristic (the rate of change), and the accuracy of tuning to the resonant frequencies. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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.

A novel semi-active TMD with folding variable stiffness spring

An innovative variable stiffness device is proposed and investigated based on numerical simulations. The device, called a folding variable stiffness spring (FVSS), can be widely used, especially in tuned mass dampers (TMDs) with adaptive stiffness. An important characteristic of FVSS is its capability to change the stiffness between lower and upper bounds through a small change of distance between its supports. This special feature results in lower time-lag errors and readjustment in shorter time intervals. The governing equations of the device are derived and simplified for a symmetrical FVSS with similar elements. This device is then used to control a single-degree-of-freedom (SDOF) structure as well as a multi-degree-of-freedom (MDOF) structure via a semi-active TMD. Numerical simulations are conducted to compare several control cases for these structures. To make it more realistic, a real direct current motor with its own limitations is simulated in addition to an ideal control case with no limitations and both the results are compared. It is shown that the proposed device can be effectively used to suppress undesirable vibrations of a structure and considerably improves the performance of the controller compared to a passive device.

On a combination of ground-hook controllers for semi-active tuned mass dampers

This study proposes a semi-active on-off damping controller that is a mix of three conventional ground-hook controllers for semi-active tuned mass damper systems. Three conventional ground-hook controllers are shown to be effective only in a certain frequency range. By taking advantage of all three ground-hook controllers, the mixed controller shows its better performance. More-over, we found an analytical solution of the harmonic vibration of the semi-active controlled system. The accuracy of the analytical solution and the superior performance of the proposed controller are verified by the numerical simulations.

A frequency tracking semi-active algorithm for control of edgewise vibrations in wind turbine blades

With the increased size and flexibility of the tower and blades, structural vibrations are becoming a limiting factor towards the design of even larger and more powerful wind turbines. Research into the use of vibration mitigation devices in the turbine tower has been carried out but the use of dampers in the blades has yet to be investigated in detail. Mitigating vibrations will increase the design life and hence economic viability of the turbine blades and allow for continual operation with decreased downtime. The aim of this paper is to investigate the effectiveness of Semi-Active Tuned Mass Dampers (STMDs) in reducing the edgewise vibrations in the turbine blades. A frequency tracking algorithm based on the Short Time Fourier Transform (STFT) technique is used to tune the damper. A theoretical model has been developed to capture the dynamic behaviour of the blades including the coupling with the tower to accurately model the dynamics of the entire turbine structure. The resulting model consists of time dependent equations of motion and negative damping terms due to the coupling present in the system. The performances of the STMDs based vibration controller have been tested under different loading and operating conditions. Numerical analysis has shown that variation in certain parameters of the system, along with the time varying nature of the system matrices has led to the need for STMDs to allow for real-time tuning to the resonant frequencies of the system.

The Influence of Changing Stiffness Characteristic of a Semi-active Tuned Mass Damper onto the Effectiveness of Vibration Reduction in a Plate-column Structure

This paper presents selected results of experimental and computational analysis concerning the influence of changing stiffness characteristic of a semi-active tuned mass damper (STMD) onto the effectiveness of vibration reduction in a building's model. The discussed STMD is installed in a laboratory model of three-storey building, which consist of aluminum plates and columns. The model's vibration are caused by kinematical excitation with using the earthquake simulator. The first three eigenfrequencies of the model, corresponding to the lateral eigenforms, are in the frequency range, which STMD can be tuned. This device is a harmonic oscillator with two movable spring elements and thanks to the change of their angle; it is possible to control the stiffness of STMD. Applied, original design solution of STMD allows tuning the vibration eliminator in the frequency range from 0.2Hz to 4.7Hz.

Precise stiffness and damping emulation with MR dampers and its application to semi-active tuned mass dampers of Wolgograd Bridge

This paper investigates precise stiffness and damping emulation with MR dampers when clipping and a residual MR damper force constrain the desired control force. It is shown that these force constraints lead to smaller equivalent stiffness and greater equivalent damping of the constrained MR damper force than desired. Compensation methods for precise stiffness and damping emulations are derived for harmonic excitation of the MR damper. The numerical validation of both compensation methods confirms their efficacy. The precise stiffness emulation approach is experimentally validated with the MR damper based semi-active tuned mass damper (MR-STMD) concept of the Wolgograd Bridge . The experimental results reveal that the precise stiffness emulation approach enhances the efficiency of the MR-STMD significantly when the MR-STMD is operated at reduced desired damping, where the impact of control force constraints becomes significant.

Study on semi-active tuned mass damper with variable damping and stiffness under seismic excitations

SUMMARY In the present study, a semi-active tuned mass damper (STMD) with variable damping coefficient and stiffness is evaluated under seismic excitations. Variation of the damping ratio of the STMD is implemented through tracking the displacement of the STMD.If the tracked amplitude of the STMD is increasing, damping ratio of the STMD is set to zero, or else it is set to an appropriate nonzero value. Stiffness of the STMD is tuned through tracking the displacement of the primary structure, which is analyzed using a short-time Fourier transform-based control algorithm. Both far-field and near-fault ground motions are used to examine the effectiveness of the STMD and the control algorithm. Displacement time history and response (displacement and acceleration) spectra are obtained for the cases of an optimal passive TMD and an STMD. It is found that the STMD with variable damping ratio and frequency can effectively attenuate the seismic responses and outperform the optimal passive TMD. In addition, results are obtained for the case that damage occurs to the primary structure during an earthquake. The study indicates that the STMD controlled by the proposed algorithm can rapidly capture the variation of the structure and remains tuned with the primary structure, whereas the optimal TMD becomes off-tuned when damage occurs. Copyright © 2013 John Wiley & Sons, Ltd.

Recent Advances on Vibration Control of Structures Under Dynamic Loading

In this paper, a review of recent journal articles on passive, active, semi-active, and hybrid vibration control of structures subjected to dynamic loading is presented. Passive systems reviewed include tuned mass damper (TMD), tuned liquid column damper (TLCD), tuned liquid column ball damper (TLCBD), circular TLCD (CTLCD), and pendulum TLCD (PTLCD). Active control systems include active tuned mass dampers (ATMD) and piezoelectric actuators. Semi-active systems include magnetorheological (MR) damper, negative stiffness devices (NSD), magneto-rheological damper TMD (MR-TMD), variable stiffness semi-active TMD (VS-STMD), variable damper STMD (VD-STMD), and recentering variable friction device (RVFD). Hybrid systems include active base isolation system and semi-active MR dampers with nonlinear base isolators. The current frontier of research is semi-active control of structures as well hybridization of various control systems. The problem is complex requiring integration of several different hardware and software technologies with structural design such as smart materials, adaptive dampers, actuators, sensors, and control and signal processing algorithms. This complexity also makes it an exciting area of research and development.

Semi-active tuned mass dampers with phase control

The present study aims at proposing an innovative phase control methodology for semi-active tuned mass dampers (SA-TMDs) that intend to minimize the off-tuned problems associated with passive tuned mass dampers (P-TMDs). The phase control algorithm is first developed, the essential of which is to apply the variable friction force to slow down the mass block at specific moments when the phase lag of the SA-TMD with respect to the structure is different from 90°, resulting in the SA-TMD back to the desired phase lag, i.e., −90° phase deviation, so that the SA-TMD has the maximum power flow to reduce the structural vibration. The feasibility of the application of the phase control in SA-TMDs is verified by performing numerical analyses of a simplified Taipei 101 structure model with a SA-TMD subjected to sinusoidal loads and design level wind loads. The numerical simulation results show that the SA-TMD implemented with phase control can enable the mass block to vibrate in a manner with a phase lag close to the −90° when the structure model is under sinusoidal excitations with frequencies different from the structural fundamental mode. The SA-TMD with phase control not only exhibits better performance than the optimal P-TMD in terms of suppressing the structural vibration, but also enhances its robustness, particularly when the SA-TMD is off-tuned to the structure.

Hardening Düffing oscillator attenuation using a nonlinear TMD, a semi-active TMD and multiple TMD

This paper investigates the response attenuation of a hardening Düffing oscillator utilizing a Nonlinear Tuned Mass Damper (NTMD), a Semi-Active Tuned Mass Damper (STMD), and a multiple TMD (MTMD) consisting of the two in parallel. A high amplitude “detached” solution branch in the frequency-response of the primary structure is observed in the case of an NTMD. By adding an STMD to the NTMD in parallel, the study indicates that the high amplitude detached resonance can be significantly attenuated. The MTMD (NTMD+STMD) is found effective in suppressing both the steady-state and transient responses. A parametric study of the design parameters of the MTMD is conducted. It is found that the addition of an STMD with a small mass ratio and small damping ratio in parallel with an NTMD results in significant reduction of steady-state response. For transient response reduction, the study shows that the damping ratio of NTMD has a significant effect while the other parameters have minimal effects. Increasing the damping ratio of the NTMD (up to a critical value) increases the decay rate of the transient responses. These results indicate that the design parameters for the MTMD should be appropriately selected to ensure that the MTMD attenuates both the steady-state and transient response effectively.

The Application of Resettable Device to Semi-Active Tuned Mass Damper Building Systems for Multi-level Seismic Hazard Mitigation

An innovative multi-story Semi-Active Tuned Mass Damper (SATMD) building system is proposed to control seismic response of existing structures. The application of adding new stories as large tuned mass and semi-active (SA) resettable actuators as central features of the control scheme is derived. For the effective control of the structures, the optimal tuning parameters are considered for the large mass ratio, for which a previously proposed equation is used and the practical optimal stiffness is allocated to the actuator stiffness and rubber bearing stiffness. A two-degree-of freedom (2-DOF) model is adopted to verify the principal efficiency of the suggested structural control concept. The simulations for this study utilizes the three ground motions, from SAC project, having probability of exceedance of 50% in 50 years, 10% in 50 years, and 2% in 50 years for the Los Angeles region. 12-story moment resisting frames, which are modified as '12+2' and '12+4' story structures, are investigated to assess the viability and effectiveness of the system that aims to reduce the response of the buildings to earthquakes. The control ability of the SATMD scheme is compared to that of an uncontrolled and an ideal Passive Tuned Mass Damper (PTMD) building system. From the performance results of suggested '12+2' and '12+4' story retrofitting case studies, SATMD systems shows significant promise for application of structural control where extra stories might be added.

Attenuation of a linear oscillator using a nonlinear and a semi-active tuned mass damper in series

In this paper, the behavior of a three degrees-of-freedom system is examined, consisting of a linear primary structure (PS), a tuned mass damper with a small cubic stiffness nonlinearity and a semi-active tuned mass damper (STMD) connected in series—each element with a mass approximately two orders of magnitude smaller than the previous. Using numerical simulations, it is determined that an STMD with a mass four orders of magnitude smaller than the PS is able to greatly reduce the amplitude of the PS response by acting to keep the nonlinear tuned mass damper within its linear range. Effective attenuation is dependent on appropriate selection of design parameters—selecting an appropriate STMD mass ratio given its damping, the strength of the stiffness nonlinearity, and the largest forcing amplitude expected. Using a standard tuning approach for the STMD (modulating its stiffness to match the natural frequency of the STMD to the excitation frequency) and comparing its performance with an optimal passive linear tuned mass damper (TMD), the STMD provides a wider-band frequency-response amplitude reduction but often increases the response amplitude slightly above the resonance frequency. A piecewise linear tuning approach for the STMD is proposed which combines the performance benefits of the STMD and the TMD to improve performance and further reduce power requirements.

Enhancement of a tuned mass damper for building structures using fuzzy logic

Over the past 10 years there has been a growing need to introduce closed-loop control technology for vibration suppression of buildings subject to wind or earthquake disturbances. This paper deals with the investigation of the effectiveness of a fuzzy logic based time variable damping tuned mass damper (TMD) on a building structure undergoing free and forced vibrations. The uniqueness of this approach is the application of a robust, nonlinear fuzzy based controller to emulate a time-optimal control strategy. Fuzzy logic based time variable damping is introduced into a semi-active TMD in order to enhance its performance in the vibration suppression of buildings. First, a single story structure for three different vibration suppression approaches is studied. The fuzzy logic based time variable damping TMD (fuzzy TMD) is compared to the baseline passive TMD as well as a conventional proportional-derivative (PD) controller. Forced vibration is introduced using a resonant harmonic sinusoidal excitation (i.e. same frequency as the fundamental frequency of the structure). Finally, the fuzzy TMD is compared to the baseline for the free vibration of a 15 story structure. For both structures studied, MATLAB® based simulation results show that the passive TMD and the PD, both constant gain approaches, provide similar results whereas the fuzzy TMD yields half the settling time. This effort clearly demonstrates the potential of a variable gain (damping) strategy for the vibration suppression of buildings.

Semi-active fuzzy control of a wind-excited tall building using multi-objective genetic algorithm

In this study, a multi-objective optimal fuzzy control system for the response reduction of a wind-excited tall building has been proposed. A semi-active tuned mass damper (STMD) is used for vibration control of a 76-story benchmark building subjected to wind load. An STMD consists of a 100kN magnetorheological (MR) damper and its natural period is tuned to the first-mode natural period of vibration of the example building structure. The damping force of the MR damper is controlled by a fuzzy logic controller. A multi-objective genetic algorithm is used for optimization of the fuzzy logic controller. Both the 75th floor acceleration response of the structure and the stroke of the STMD have been used as the objective functions for this multi-objective optimization problem. Because a multi-objective optimization approach provides a set of Pareto-optimal solutions, an engineer is able to select an appropriate design for the specific performance requirement. For a comparative study, a sky–ground hook control algorithm is employed for control of the STMD. Based on numerical results, it has been shown that the proposed control system can effectively reduce the STMD motion as well as building responses compared to the comparative sky–ground hook control algorithm. In addition, the control performance of the STMD controlled by the optimal fuzzy controller is superior to that of the passive TMD and is comparable to an active TMD, but with a significant reduction in power consumption.

Frequency and damping adaptation of a TMD with controlled MR damper

This paper describes the new concept of a semi-active tuned mass damper with magnetorheological damper (MR-STMD). The real-time controlled MR damper force emulates controlled damping and a superimposed controllable stiffness force to augment or diminish the force of the passive spring stiffness which enables us to control the MR-STMD natural frequency. Both the damping and natural frequency are tuned according to Den Hartog’s formulae to the actual dominant frequency of the main structure irrespective of whether it is a resonance or a forced frequency. The MR-STMD is experimentally validated on the Empa bridge with a 15.6 m main span for different added masses to shift its resonance frequency −12.2% and +10.4% away from its nominal value. The experimental results are compared to those obtained when the MR-STMD is operated as a passive TMD that is precisely tuned to the nominal bridge. The comparison shows that the MR-STMD outperforms the TMD both in the tuned and all de-tuned cases by up to 63%. Simulations of the MR-STMD concept point out that the proposed semi-active control algorithm is most suitable for MR-STMDs due to the small amount of clipped active forces. A sensitivity analysis demonstrates that the real MR-STMD could be even more powerful if the force tracking errors in the MR damper force due to the current driver and MR fluid dynamics and remanent magnetization effects could be further reduced. The MR-STMD under consideration represents the prototype of the 12 MR-STMDs that have been running on the Volgograd Bridge since late fall 2011.

Research on Control Effectiveness of Semi-Active MR-TMD to some Coal Gas Manufacturing Plant

A new semi-active MR-TMD control device, which is consisted of TMD which take the gasifier as the damper mass and a magneto-rheological damper, was proposed to solve the problem of factory building vibration when the gasifier is working in it. The feasibility and effectiveness of semi-active MR-TMD control system for structural vibration control under rectangular periodic excitations were simulated and analyzed by adopting one semi-active control algorithm proposed by the author. The control effect of semi-active MR-TMD, passive TMD and active AMD were compared by adopting the same model structure. Numerical simulations show that the damping performance of using semi-active MR-TMD control is better than that of using passive TMD control and active AMD control; the displacement and acceleration of the structure’s each floor have decreased significantly. It also indicates that the semi-active controlling method is available.

Seismic response control of elastic and inelastic structures by using passive and semi-active tuned mass dampers

In this study, the performances of a passive tuned mass damper (TMD) and a semi-active TMD (STMD) were evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for damped structures with a passive TMD and with a STMD proposed in this study. The displacement spectra confirmed that the STMD provided much better control performance than passive TMD and the STMD had less stroke requirement. Also, the robustness of 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 hysteresis described by the Bouc-Wen model. The results indicated that the performance of the passive TMD whose design parameters were optimized for an elastic structure considerably deteriorated when the hysteretic portion of the structural responses increased, and that the STMD showed about 15-40% more response reduction than the TMD.

A Comparison between a New Semi-Active Tuned Mass Damper and an Active Tuned Mass Damper

Reducing structural vibrations is one of the main concerns in structural control. Different control techniques are proposed for this purpose. Among the variety of control methods, semi-active ones are very attractive and beneficial in that they require minimum amount of energy but they are very capable to reduce structural displacements. In this paper, the behavior of a structure equipped with a new type of semi-active tuned mass damper called SADA-TMD is compared to the behavior of a structure equipped with active tuned mass damper (ATMD). SADA-TMD is a TMD equipped with semi-active damper actuator (SADA). This device can absorb energy transferred to the ordinary TMD during earthquakes and use it like an actuator; it can also dampen any part of this absorbed energy. For the purpose of comparison a multi story building has been modeled numerically. The performance of SADA-TMD and ATMD is controlled by fuzzy logic controller (FLC). Advantages of employing SADA-TMD to reduce structural responses are shown through illustrations and numerical results. However, the results come from applying SADA-TMD can be compared to that of active tuned mass dampers (ATMD), because SADA-TMD is a semi-active device, the power requirements is significantly lower than those of ATMD. It is worth to be mentioned that because SADA-TMD can work on battery power, it is more reliable than ATMD during strong earthquakes; because the source of energy which is necessary for active actuator could be failed during those earthquakes.