Semi-active Tuned Mass Damper Research Articles

Semi-Active Groundhook Control of Offshore Tension Leg Platforms Using Tuned Mass Damper With Optimized Parameters and Magneto-Rheological Damper Under Multiple Hazards

Abstract The purpose of the current study is to recommend an offshore tension leg platform (TLP) semi-active control system to lessen vibrations caused by various risks, such as the wind load and regular and irregular waves. State-of-the-art indicates that there has not been much study on semi-active management of offshore TLPs exposed to numerous hazards while taking into account system nonlinearities and employing a control method that is resilient to uncertainty. An augmented velocity–displacement-based groundhook (AVDB-GH) semi-active control scheme using magneto-rheological (MR) dampers, which is an improvement over the displacement-based groundhook (DB-GH) control algorithm, is proposed. The proposed controller uses a semi-active tuned mass damper (SATMD) consisting of a passive tuned mass damper (TMD) and two semi-active MR dampers as the control devices. Constrained nonlinear optimization is used to determine the SATMD's optimized parameters in order to produce the best control performance. A significant reduction in surge response of TLP is observed both in the time domain and the frequency domain. Compared to the SATMD using the usual DB-GH algorithm, the suggested control strategy more successfully decreases the key response variables—deck displacement, power spectral density, and acceleration. The effectiveness of the controller is better for regular waves than for irregular waves and wind forces. Because the performance of the controller is unaffected by changes in the mass and stiffness of the TLP, the controller can be regarded as robust.

Random crowd-induced vibration in footbridge and adaptive control using semi-active TMD including crowd-structure interaction

A slender footbridge can suffer from a large vibration under vertical human-induced excitation. To improve its serviceability, a tuned mass damper (TMD) has a wide application. However, considering the randomness and synchronization of crowd-induced excitation and the effect of crowd-structure interaction (CSI), the control robustness of a passive TMD needs to be improved. To achieve a better performance, a semi-active TMD (STMD) with variable mass and damping (VMD-STMD) is presented in this paper, which can not only adjust the own mass and frequency in real time to adapt to the dynamic characteristics of the footbridge through the water pump and electromagnetic valve, but also adjust its damping to improve the effect of energy dissipation through changing the eddy current damping. The proposed VMD-STMD can maximize the absorption of structural kinetic energy and dissipate. The working mechanism and control algorithm of VMD-STMD are introduced first, and then, a Euler-Bernoulli simply supported beam is studied. To highlight the best control effect and robustness of VMD-STMD, an optimized passive TMD, variable mass STMD (VM-STMD) and variable damping STMD (VD-STMD) are compared, 100 calculations of them based on crowd probabilistic models are proposed. The influence of CSI is investigated and different crowd density and synergy rate are discussed in detail. Through the maximum, mean and standard deviation of the three comfort evaluation indexes of the 100 groups of acceleration, the control effect and robustness of different TMDs are analyzed. Results show that structural dynamic responses and TMD’s performance vary greatly due to the randomness of CSI. In general, VMD-STMD has the best control effect, and its standard deviation is also the smallest, indicating the best control robustness.

Calibration of Viscous Damping–Stiffness Control Force in Active and Semi-Active Tuned Mass Dampers for Reduction of Harmonic Vibrations

Tuned mass dampers (TMDs) are commonly used to mitigate vibrations in civil structures. There is a growing demand for new solutions that offer similar effectiveness as TMDs but with reduced mass. In this context, this paper investigates active (ATMD) and semi-active (STMD) tuned mass dampers with relative displacement and velocity feedback. The control force of the ATMD is assumed to be the sum of viscous damping and either positive or negative stiffness forces. This control force is calibrated for a specific parameter K such that the effectiveness of the ATMD in reducing harmonic vibrations matches that of the TMD with K times larger mass. The optimal calibration is derived based on the mathematical reformulation of an existing optimal acceleration feedback control algorithm. The control approach for the ATMD is then applied to the STMD. Subsequently, the sub-optimal STMD is analyzed, with a focus on its limitations arising from the clipping of active forces. Finally, the paper presents a calibration of the STMD using a numerical optimization method. It is demonstrated that the maximum achievable performance of the numerically optimized STMD matches that of the TMD with three times larger mass.

Vibration control of steel frames with setback irregularities equipped with semi-active tuned mass dampers

This paper presents a pioneering study on the seismic vibration control of steel moment-resisting frames (MRFs) with setback irregularities using semi-active tuned mass dampers (SATMDs). The research investigates the efficiency and the location of the SATMDs and compares their efficiency with traditional tuned mass dampers (TMDs) for the vibration control of setback structures with different vertical irregularities. To assess the nonlinear seismic performance of buildings with setbacks, various engineering demand parameters such as inter-story drift ratio, story displacement, story velocity, story acceleration, and base shear factor were analyzed under earthquake excitations. The results reveal that the use of SATMDs reduced the seismic response of irregular frames with setbacks. In addition, the efficiency of SATMDs in the control of setback frames was more than the regular frames. Also, the investigations showed that placement of the control systems at the roof level of the structure significantly reduced the structural vibration of irregular structures. It is noticeable that the use of these control devices requires more attention for structures with significant setbacks because, in some cases, the response of a structure with SATMDs can be greater than an uncontrolled structure.

Seismic Response Control of a Nonlinear Tall Building Under Mainshock–Aftershock Sequences Using Semi-Active Tuned Mass Damper

Under the excitation of strong mainshock (MS), the structure will enter the nonlinear stage, whose hysteretic characteristic can be well-simulated by the Bouc–Wen (BW) model. The accompanying aftershock (AS) may increase structural damage and cause the safety problem, therefore, the advanced structural control technology is worthy of being applied to nonlinear structure under MS–AS sequences. The tuned mass damper (TMD) is a popular vibrational absorber, however, it is sensitive to the frequency deviation and may lose its effect for nonlinear dynamic response control in this issue. To protect the nonlinear tall building under MS–AS sequences effectively, a semi-active TMD (STMD) is investigated in this study, which can vary its frequency and damping in real time simultaneously. It can adapt to structural nonlinear behavior in each time segment through varying its stiffness according to the wavelet transform (WT) based algorithm, and meanwhile, enhance the energy dissipation through switching its damping coefficient in real time. A 10-story nonlinear tall building is proposed as a case study and for comparison, a passive TMD (PTMD) is used. Nine MS–AS sequences are elected and nonlinear structural control performance of STMD is highlighted. Results show that STMD can control structural displacement responses and base shear effectively and performs better than PTMD in reducing the plastic development of the structure as well. Further, energy analysis is proposed and it is verified that STMD has an excellent effect in decreasing the structural input energy from MS–AS sequences and dissipating more energy than PTMD. Especially, it is found that a strong AS may cause a larger response to the nonlinear structure than MS, while the nonlinear control effect of STMD is still significant in that case.

Seismic control of cross laminated timber (CLT) structure with shape memory alloy-based semi-active tuned mass damper (SMA-STMD)

Cross laminated timber (CLT) is becoming increasingly popular for constructing multiple-story buildings due to its alignment with Sustainable Development Goals of United Nations. However, such structures can be susceptible to excessive vibrations during earthquakes. While tuned mass dampers (TMDs) can be used to control these vibrations in CLT structures, their effectiveness can be reduced due to the lightweight nature of CLT and changes in its structural mass or deterioration of the wood. To address this issue, this paper proposes the use of shape memory alloy-based semi-active tuned mass dampers (SMA-STMDs) for controlling vibrations in CLT structures. This study includes the design and experimental testing of a full-scale, novel spring-pendulum combined SMA-STMD system, which utilises the mechanical properties of SMAs that change with temperature to achieve semi-active control. Finite element method simulations demonstrate that the proposed SMA-STMD system can effectively reduce structural seismic vibrations in CLT structure. By adjusting the SMA temperature, the SMA-STMD system can effectively address the issue of TMD system off-tuning caused by changes in the CLT structural properties. Overall, the proposed SMA-STMD system offers a promising solution for seismic control in CLT structures and has the potential to promote the development of CLT structures.

Bi-directional semi-active tuned mass damper for torsional asymmetric structural seismic response control

Tuned mass damper (TMD) is a popular vibration absorber. To improve the seismic protection performance of a bi-directional passive TMD, a bi-directional semi-active TMD (BSTMD) with adaptive stiffness, variable mass and semi-active damping is proposed in this study. The BSTMD can adapt to structural X- and Y-directional instantaneous frequencies at the same time under bi-directional ground motions, which are identified through wavelet transform (WT), and the instantaneous angle of a diamond spring device is adjusted according to the instantaneous frequency ratio of two directions, which means that the stiffness ratio of two directions is retuned first. Then, the mass is retuned to match the exact instantaneous frequency. At last, the semi-active damping is realized according to an extended output signals-based control algorithm. A two-directional asymmetric torsional benchmark model is proposed as a case study. For comparison, two optimal passive TMDs implemented in X and Y directions separately and two unidirectional STMDs with variable stiffness and damping implemented in X and Y directions separately are investigated as well. Numerical results show that under bi-directional earthquake excitations in the benchmark problem, the two optimal passive TMDs have a good control effect. Two unidirectional STMDs have the best aseismic mitigation effect generally, in both lateral and torsional dynamic responses; while the BSTMD has a comparable control effect with less electromechanical devices, and can reduce the stroke of unidirectional STMD to a great degree. Though the BSTMD is aimed at X- and Y- directional dynamic responses, it can control torsional responses effectively as well, and when the eccentricity is enlarged to double, it remains effective for seismic mitigation.

Semi-active tuned mass dampers under combined variable actions of friction forces and external disturbances

Anti-seismic devices are employed to implement the best performance of the structures under earthquakes. In this paper, semi-active tuned mass dampers (SA-TMDs) are studied by considering several combinations of variable friction forces and external disturbances. The variable damping model is used, where the goal consists in estimating the external actions to find the best friction force for system dampening. In particular, general, sinusoidal, and Gaussian dynamic loadings are considered. To obtain the response of the structure and dampers, several numerical solutions have been implemented. Probabilistic and determines analyses have been also developed to study different damper characteristics. Results show that a SA-TMD can reduce the structure displacements up to ~ 70.0% indicating a good performance in controlling different oscillations. This technology not only preserves the integrity of a structure mitigating its vibrations but also improves the life of occupants and their safety and comfort. This is beneficial from the perspective of practical application, and it is an advancement with respect to this theme.

Study on a three-dimensional variable-stiffness TMD for mitigating bi-directional vibration of monopile offshore wind turbines

Bi-directional vibrations of offshore wind turbine (OWT) exist due to the misalignment of wind and wave loadings, which induces the structural fatigue failure. At present, monopile offshore wind turbine (MOWT) is widest utilized in worldwide, which is adopted as the research objective in this study. A novel semi-active three-dimensional magnetorheological elastomer (MRE) based tuned mass damper is proposed to suppress a MOWT bi-directional vibration under misaligned wind, wave, seismic loadings. The proposed MRE-based TMD is installed in the nacelle, which presents dual-directional controllable stiffness properties. Its nonlinear behavior is depicted by bi-lateral Bouc-Wen model. A semi-active control framework is developed, in which current-dependent stiffness of MRE-based TMD is tuned for tracing real-time dominant frequency of the MOWT. The numerical results reveal that MRE-based TMD can effectively attenuate the bi-directional dynamic responses of MOWT under various operation conditions. Additionally, the semi-active MRE-based TMD outperforms passive TMD in reducing the peak and RMS displacement of the tower top in both fore-aft (FA) and side-side (SS) directions, especially in operational state. MRE-based TMD also presents strong robustness under the condition of structural stiffness degradation.

Seismic control of a smart structure with semiactive tuned mass damper and adaptive stiffness property

AbstractTo reduce structural responses under earthquake excitations effectively and improve their resilience, a smart structure with a semiactive tuned mass damper (STMD) on the top story and a semiactive adjustable stiffness device (SASD) on the first story which contributes to the structural adaptive stiffness property is developed in this study. The SASD consists of a diamond spring device composed of four linear springs and an electromagnetic actuator, which can change the angle of the diamond device and therefore retune the stiffness. Two typical STMDs developed previously are reviewed first, which are diamond device‐based STMD with variable stiffness and damping and pendulum‐type STMD with variable frequency and eddy current damping, respectively. Numerical results show that the proposed STMD has a better control performance than passive‐tuned mass damper and STMD with variable stiffness or damping acting independently. To enhance the seismic protection of the structure with an STMD on the top story further, based on the principle of base isolation, a diamond device‐based SASD is applied to the first story. The linear quadratic Gaussian‐based variable stiffness algorithm for SASD is proposed. A 10‐story building is presented as a case study. The variable stiffness range of SASD is discussed in detail, while it is found that a ±50% variable stiffness range achieves the best earthquake mitigation. Control effects of different numbers of SASD implemented along the height of the building are compared as well. Numerical results show that with the increase in the number of SASDs, the earthquake mitigation effect is better; however, the magnitude of the increase is decreasing. The smart structure with the combined SASD and STMD has an excellent seismic protection performance and is better than with SASD or STMD acting independently. Meanwhile, it is found that the proposed combination has a similar control effect to four SASDs installed from the first story to the fourth story, respectively, while it can reduce the number of additional electromechanical systems and the influence on the use function of the building.

Machine learning driven damper for response control in vehicle–bridge interaction systems

The implementation of machine learning for the real-time prediction of the suitable value of the damping ratio of a semi-active tuned mass damper (SA-TMD) is investigated to ensure enhanced vibration control in vehicle–bridge interaction (VBI) problems. The response assessment of the uncontrolled, tuned mass damper (TMD)-controlled, and SA-TMD-controlled bridge models is performed under the Japanese Shinkansen (SKS) train model. The energy-based predictive (EBP) control algorithm is implemented for the bridge fitted with the SA-TMD. The EBP algorithm-controlled SA-TMD results in more effective suppression of the bridge vibration as compared to the passive TMD. However, the effectiveness of the EBP algorithm reduces for more complex VBI systems because of the increased computational time delay. To circumvent the effect of the delay, a control strategy is proposed based on the weighted random forest (WRF) algorithm. The WRF algorithm is trained based on the data obtained from the EBP algorithm-controlled bridge and implemented to suppress the vehicle-induced vibration of the bridge using SA-TMD. The results demonstrate that the implementation of the newly proposed WRF algorithm-based control strategy nullifies the effects of the computational time delay. Furthermore, it is established that the WRF algorithm suppresses the bridge vibration more effectively than the EBP algorithm.

Semi-active Groundhook Control of Offshore Tension Leg Platforms Using TMD with Optimized Parameters and MR Damper Under Regular waves

The motivation and objective of the present study are to propose a semi-active control system for offshore tension leg platforms (TLPs) to mitigate the vibrations induced by regular wave loads. State-of-the-art indicates that not much work is reported on semi-active control of offshore TLPs considering potential nonlinearities for multiple hazards using a control algorithm, which is robust against uncertainties. A displacement based groundhook (DB-GH) control algorithm using tuned mass damper (TMD) and magneto-rheological (MR) damper is employed for the semi-active controller because of its robustness against parametric uncertainties and reliability. Optimized parameters of the semi-active TMD (SATMD) are obtained using constrained nonlinear optimization to achieve the best control performance. The flexibility of the groundhook control lies in its simplicity of implementation, computational efficiency and its demand for only two sensors in order to achieve the calculations of control forces. The scope of the present study is to demonstrate the efficiency of the proposed controller and investigate the effects of different influencing parameters. A TLP, reported in literature, is taken as an illustrative example. The non-linearly coupled dynamic responses of the structure-damper system is analysed and solved in time domain using MATLAB SIMULINK. The results show the SATMD performs quite satisfactorily in reducing the responses of the TLP in different critical conditions.

Seismic performance improvement of base-isolated structures using a semi-active tuned mass damper

Base isolation can achieve a reduction in floor acceleration and inter-story drift. However, it may suffer from excessive displacements under near-fault and far-field earthquakes. To improve the aseismic performance of passive base-isolated structures, in this paper, a semi-active tuned mass damper (STMD) with variable stiffness and damping is presented. A combined control algorithm based on output signals only is developed for the STMD first. Then, the STMD is applied to an eight-story linear base-isolated structure and also a nonlinear one. As for the linear model, which represents a theoretical benchmark, an optimized passive TMD (PTMD) is used for comparison. As for the nonlinear model, lead rubber bearing (LRB) is considered and simulated using the well-known Bouc-Wen model. Eight earthquakes with different spectral characteristics and peak ground amplitudes are chosen, and two PTMDs are optimized for comparison, while one is tuned to the pre-yield period of the base-isolated model and the other is tuned to the post-yield period of the base-isolated model. Numerical results show that, generally, STMD has the best control effect in both linear and nonlinear models. For displacement responses, because STMD can vary its stiffness and damping, it can mitigate the structural first-mode response effectively, and can achieve both top story and isolated level responses reduction. As for acceleration responses of the top story, STMD achieves excellent performance in the structural second-mode acceleration response mitigation. Therefore, STMD can improve both displacement and acceleration performances of both linear and nonlinear base-isolated structures effectively.

A novel semi-active tuned mass damper with a continuously tunable stiffness

A passive tuned mass damper can only be designed to have a good damping effect near the resonance frequency of the primary structure. To overcome this limitation, a novel semi-active tuned mass damper with continuously tunable stiffness is proposed in this paper. The proposed design features a compact mechanism that can vary its stiffness by changing the number of active coils in parallel and series configurations of helical springs. The real-time control of the stiffness is achieved by designing and implementing a driving system for this mechanism. The motion characteristics and required driving torque for the designed prototype are also examined during the stiffness tuning process. It is demonstrated that the novel semi-active tuned mass damper can tune its stiffness over a wide range, and consequently tune its working frequency band to a desirable region with a proper control law. The effectiveness of the proposed prototype was investigated numerically and experimentally with respect to one-degree-of-freedom harmonic excitations in the frequency ratio range of 0.8–1.2. The results indicate that the prototype preserves optimal vibration suppression performance across a broad frequency range. Thus, the proposed semi-active tuned mass damper can provide a simple and effective in-situ tunable tool for suppressing primary structure vibration in the presence of non-stationary vibratory excitations.

Seismic Performance Assessment of Semi Active Tuned Mass Damper in an MRF Steel Building Including Nonlinear Soil–Pile–Structure Interaction

Seismic Performance Assessment of Semi Active Tuned Mass Damper in an MRF Steel Building Including Nonlinear Soil–Pile–Structure Interaction

Vibration control of midrise buildings by semi-active tuned mass damper including multi-layered soil-pile-structure-interaction

Semiactive tuned mass dampers (STMD) can be used in mid-rise buildings to control seismic excitations during continuous operation. Numerous studies have been conducted to investigate the performance of STMDs without considering the soil-pile-structure interaction (SPSI). When modeled with a fixed base, the characterization of STMD can be significantly misleading and doesn’t necessarily result in a conservative design. In order to evaluate the impact of SPSI on the performance of STMD under seismic loading, mid-rise steel buildings on layered soil were analyzed using the three-dimensional finite element software Opensees. The effects of changes in geotechnical parameters such as shear strength and stiffness were also studied. The results showed that the efficiency of STMD is significantly reduced and the structural accelerations and displacements are increased with the inclusion of SPSI. A progressive increase in the displacements of the top storeys were also observed when the SPSI effect was considered. The reduction in the base shear was attributed to the mobilised passive force around the piled foundations when SPSI was considered in the analysis models.

Hybrid experimental investigation of MR damper controlled tuned mass damper used for structures under earthquakes

This paper aims to investigate the performances of a semi-active tuned mass damper (STMD) used to reduce the vibrations of buildings under different seismic excitation by the real-time hybrid simulation (RTHS) method. In the STMD, the MR damper is used as a control element with a variable damping feature. The RTHS method is an alternative to experimentally studying the STMD system. MR damper is critically significant for the system and is experimentally installed. At the same time, the other parts are designed in numerical simulation and tested simultaneously. MR damper is a control element whose damping value can change according to the amount of voltage transmitted. Therefore, the groundhook control method determines the MR damper voltage variations. The results show that the control method applied to MR damper-controlled STMD effectively suppresses structural vibrations.

Design of a Semiactive TMD for Lightweight Pedestrian Structures Considering Human–Structure–Actuator Interaction

Lightweight pedestrian structures constructed with high strength-to-weight ratio materials, such as fiber-reinforced polymers (FRP), may experience large accelerations due to their lightness, thus overcoming the serviceability limit state. Additionally, uncertainties associated with human–structure interaction phenomena become relevant. Under these circumstances, variations in pedestrian actions could modify the modal properties of the coupled human–structure system and classical approaches based on passive Tuned Mass Dampers (TMD) do not offer an effective solution. An alternative solution is to use a Semiactive TMD (STMD), which includes a semiactive damper that, when properly designed, may be effective for a relatively broad frequency band, offering a robust solution when significant uncertainties are present. Thus, this paper presents a design methodology for the design of STMDs applied to lightweight pedestrian structures including human–structure and actuator–structure interaction. A multiobjective optimization procedure has been proposed to simultaneously minimize structure acceleration, inertial mass, and maximum damper force. The methodology has been applied to a lightweight FRP footbridge. Realistic simulations, including system uncertainties, interaction phenomena, nonlinear damper model, noise-contaminated signals, and the practical elements (in-line digital filters) needed for the successful implementation of the control law, validate the methodology. As a conclusion, the STMD is more effective than its passive counterpart in both, canceling the response or achieving similar performance with significant lower inertial mass.

Experimental study of the semi-active mass damper under impulse excitation.

Mass dampers usually aim to control the steady state vibration of harmonic excitation, but few efforts have focused on suppressing the transient vibration caused by impulse excitation. To obtain the optimum tuning parameters of the semi-active tuned mass damper (TMD) under impulse, optimization analysis of the transient vibration response is carried out. The analytical solutions of transient response are obtained. The transient response of the primary system is attenuated effectively by optimizing three parameters of the TMD, namely, the stiffness, initial displacement, and initial velocity. Three experimental setups are built to achieve different values of the parameters to verify the simulation results. The stiffness of the TMD is modeled analytically and experimentally, and the vibration magnitude denotes that there are several fluctuations when the stiffness of the TMD changes. The results also show that initial displacement and initial velocity of the TMD can lead to different transient vibration magnitudes for the primary system. The optimum parameters of the semi-active TMD can be obtained by the proposed method, and the transient response can be controlled by optimizing the stiffness, initial displacement, and initial velocity of the TMD.

Dynamic response assessment of an offshore jacket platform with semi-active fuzzy-based controller: A case study

The present study investigates the dynamic responses of offshore jacket platforms using a passive and semi-active tuned mass damper (TMD, SATMD), where the control action is achieved by a fuzzy logic controller (FLC) under environmental (i.e., wind, water waves, sea currents) and seismic loadings. Since the studied structure failed to meet recent codes requirements adequately, the suppressing effect of a SATMD is considered as a way to retrofit structural performances under hydrodynamic loadings. After extraction of the dynamic properties of the jacket-type structure, simulations of an installation system with and without a TMD have been performed, and the effectiveness of TMD is quantified.In order to exploit the potential of the structure to overcome all types of excitations, the SATMD comes complete with a fuzzy-algorithm-controller, acknowledging that the use of a passive TMD is only a preliminary attempt to reduce the structure's dynamic responses. Comparison of the results indicates a significant response value reduction in acceleration, base shear, overturning moment, velocity and lateral displacement of a case study of steel jacket platforms.