Performance Of Tuned Mass Damper Research Articles

Effects of geometrical nonlinearity on the performance of bidirectional tuned mass dampers

AbstractThis research work focuses on the presentation of a novel model for considering the effects of geometrical nonlinearity in the response of bidirectional tuned mass dampers (TMDs). A new form of nonlinear equations of motion is derived. Unlike the conventional linear model, herein, the equations of motion are coupled in two orthogonal directions. The response of the novel nonlinear equations is obtained and compared to the typical linear equations and it is shown that the linear ones are not accurate enough to model the response of the multidirectional TMDs. Perturbation analysis is done to assess the response of TMD system under two internal resonance cases. In the proposed model, phenomena such as jump and energy transfer can take place. The effects of excitation amplitude, damping ratios, and frequency detuning parameters are investigated on the jump and energy transfer phenomena. According to the proposed nonlinear equations, the performance of the bidirectional TMDs depends on the excitation amplitude. Moreover, in some cases, by considering the nonlinear terms in the bidirectional motion equations of TMDs, their performance is improved. However, the nonlinear terms may affect the performance of TMDs negatively, which leads to a very high amplitude of the responses in the main controlled structure under seismic and harmonic excitations.

The effect of the TMD on the vibration of an offshore wind turbine considering three soil-pile-interaction models

In this paper we propose the use of the power series method and the Newmark-Beta algorithm to study the mitigation by the tuned mass damper (TMD) of an offshore wind turbine(OWT). The monopile of the OWT is taken as slender beam buried in a homogeneous soil while the tower is considered as tapered slender beam. Mathematically, both monopile and tower are modeled as elastic Euler-Bernoulli beams, with a point mass at the tower top representing the rotor nacelle assembly (RNA). First of all, the power series method is utilized to calculate the first natural frequencies of AF and CS models. The obtained results are compared with the first natural frequency of DS model obtained from FEM-Abaqus with good satisfaction. Next, the obtained mode shapes are used to establish the system of ordinary differential equations (ODE) governing the dynamic of OWT subjected to a TMD. Afterwards, the Newmark-Beta algorithm is employed to solve the ODE. Accuracy of the introduced approach is verified by setting a comparison between our results with those obtained using FEM-Abaqus. Finally, the influence of several parameters on the performance of TMD is shown in some plots.

Effect of Frequency Characteristics of Ground Motion on Response of Tuned Mass Damper Controlled Inelastic Concrete Frame

This paper investigates the performance of tuned mass damper (TMD) and dynamic behavior of TMD-controlled concrete structure considering the ground motion (GM) characteristics based on frequency content. The effectiveness of TMD in reducing the structural response and probability of collapse of the building frames are affected by the frequency characteristics of GMs. To attenuate the seismic vibration of the buildings, the TMD controlled building has been designed based on the modal analysis (modal frequencies and modal mass participation ratio). In this study, to investigate the performance of TMD, four different heights (i.e., 3, 5, 10, 20 stories) inelastic concrete moment-resisting frames equipped with TMDs are developed using an open-source finite element software. A series of numerical analyses have been conducted using sixty earthquakes classified into three categories corresponding to low, medium, and high-frequency characteristics of GMs. To evaluate the proposed strategy, peak lateral displacements, inter-story drift, and the probability of collapse using fragility analysis have been investigated through the structures equipped with and without TMD. The results appraise the effect of TMD and compare the seismic responses of earthquake frequency contents and the vibration control system of the inelastic building frames.

Passive control of jacket–type offshore wind turbine vibrations by single and multiple tuned mass dampers

Vibration control is gaining focuses in the field of offshore wind turbines (OWTs) in recent years as the turbine tower becomes taller and more slender. Although a number of research works have been carried out to control the OWT vibrations, using tuned mass damper (TMD) and multiple tuned mass dampers (MTMDs) to control the jacket–type OWT vibrations is rarely reported, especially for the MTMDs, of which the application in the field of OWTs is still in the initial stage. This study focuses on the performance of TMD and MTMDs in controlling the tower vibrations of the jacket–type OWT subjected to the combined wind, wave and current loads, which are the most common external vibration resources for OWTs. The control effectiveness is numerically investigated and evaluated by the reductions of the standard deviation displacement (σ(d)) and the standard deviation acceleration (σ(a)) of the tower top. After the installation of TMD, σ(d) and σ(a) are reduced by 32% and 29% respectively. Larger TMD mass ratios lead to better control effectiveness, but the improvement becomes less obvious as the mass ratios constantly increase. The control effectiveness of the MTMD system is slightly decreased compared with a single large TMD. However, the robustness of MTMDs is superior since the OWT vibrations can still be controlled effectively even if some TMDs do not function. The control effectiveness of the MTMD system can also be affected by the change in the positions of malfunctioned TMDs.

Performance of a TMD to Mitigate Wind-Induced Interference Effects between Two Industrial Chimneys

The present paper studies the performance of a tuned mass damper (TMD) installed in a 183 m tall chimney located at the edge of the wake shed by another chimney. Numerical and experimental results are available. For the simulations, wind action is considered by solving several 2D flow problems on a selected number of horizontal planes, in the transverse direction to the stacks. On such planes, Navier-Stokes equations are solved to estimate the fluid action at different positions of the chimneys and standard interpolation techniques are applied in the vertical direction. An Arbitrary Lagrangian-Eulerian (ALE) approach is used to consider the moving domain, and a fractional-step scheme is used to solve the fluid field. For the structural modelling, chimneys are meshed using 3D beam finite elements. The time integration procedure used for the structural dynamics is based on the standard second order Bossak method. For each period of time, the fluid problem is solved, the aeroelastic analysis is carried out and the geometry of the fluid mesh of each plane is updated according to the structural movements. With this procedure and model updating techniques, the response of the leeward chimney is evaluated for different scenarios, revealing an interesting dependence of the TMD performance on the wind speed and direction.

Numerical performance assessment of Tuned Mass Dampers tomitigate traffic-induced vibrations of a steel box-girder bridge

In this paper, the effects of Tuned Mass dampers (TMDs) on the reduction of the vertical vibrations of a real horizontally curved steel box-girder bridge due to different traffic loads are numerically investigated. The performance of TMDs to reduce the bridge vibrations can be affected by the parameters such as dynamic characteristics of TMDs, the location of TMDs, the speed and weight of vehicles. In the first part of this study, the effects of mass ratio, damping percentage, frequency ratio, and location of TMDs on the performance of TMDs to decrease vertical vibrations of different sections of bridge deck are evaluated. In the second part, the performance of TMD is investigated for different speeds and weights of traffic loads. Results show that the mass ratio of TMDs is the more effective parameter in reducing imposed vertical vibration in comparison with the damping ratio. Furthermore, it is found that TMD is very sensitive to its tuned frequency, i.e., with a little deviation from a suitable frequency, the expected performance of TMD significantly decreased. TMDs have a positive and considerable performance at certain vehicle speeds and this performance declines when the weight of traffic loads is increased. Besides, the results reveal that the highest impact of TMD on the reduction of the vertical vibrations is when free vibrations occur for the bridge deck. In that case, maximum reductions of 24% and 59% are reported in the vertical acceleration of the bridge deck for the forced and free vibration amplitudes, respectively. The maximum reduction of 13% is also obtained for the maximum displacement of the bridge deck. The results are mainly related to the resonance condition.

초정밀 장비의 진동 저감을 위한 능동형 동조질량감쇠기

In an environment where ultra-high-precision equipment is used, vibration inevitably occurs due to various factors. These vibrations generate fatal effects, such as defect generation and reduced production yield, on ultra-high-precision production equipment. Among the multiple methods for solving vibration problems, a Tuned Mass Damper (TMD) is a useful technique that reduces vibration without changing the existing structure by attaching a passive dynamic system consisting of additional mass, spring, and damper. However, it is difficult to realize fine-tuning of the system parameters for optimal performance because the passive elements have structural limitations. An active TMD, which has a form wherein sensors, actuators, and a control device are added to the passive TMD structure, was introduced. It has higher performance than passive TMD because dynamic characteristics can be induced to stable and highly damped by a well-designed control algorithm realized by software in the control device. In this study, an active TMD was developed utilizing passive TMD with a voice coil actuator and attached to the center of both end fixed beam that assumed a single-degree-of-freedom structure. A dual-loop control algorithm using a non-minimum phase system was designed for a high-damped response while retaining stability. The modal test was performed for experimental evaluation and excellent performance of active TMD was verified.

Performance Evaluation of Tall Buildings using Optimized Tuned Mass Damper

This study investigates the performance of tall buildings using tuned mass damper (TMD) under dynamic loads such as harmonic loads, and the Loma Prieta Earthquake 1989 data. The numerical investigations are performed by considering a sixteen-storied dynamical system. To do this end, the aforementioned system is considered to be uncontrolled (meaning no damper is used) and a controlled case is assumed where a TMD is placed on the top floor. TMD performance mainly relies on the set of parameters (mass ratio, damping ratio, and stiffness). In reality, the tuning process of those parameters take serious effort and gets worse with the complicacy of the structure. Hence to obtain better performance of the TMD the damping ratio and the frequency of the TMD are optimized by using unconstrained derivative-free method. Finally, the uncontrolled and controlled performance of the sixteen-storied structure has been evaluated and compared. The results show that the dynamical response of the studied problem can be reduced significantly via the use of optimized parameters.

Parent Nested Optimizing Structure for Vibration Reduction in Floating Wind Turbine Structures

A tuned mass damper (TMD) is a system that effectively reduces the vibrations of floating offshore wind turbines (FOWTs). To maximize the performance of TMDs, it is necessary to optimize their design parameters (i.e., stiffness, damping, and installation location). However, this optimization process is challenging because of the existence of multiple local minima. Although various methods have been proposed to determine the global minimum (e.g., exhaustive search, genetic algorithms, and artificial fish swarm algorithms), they are computationally intensive. To address this issue, a novel optimization approach based on a parent nested optimizing structure and approximative search is proposed in this paper. The approximative search determines an initial parameter set (close to the optimal set) with fewer calculations. Then, the global minimum can be rapidly determined using the nested and parent optimizers. The effectiveness of this approach was verified with an FOWT exposed to stochastic winds. The results show that this approach is 30–55 times faster than a conventional global optimization method.

Time-cost ‘‘trade-off’’ analysis for wind-induced inhabitability of tall buildings equipped with tuned mass dampers

One of the major concerns for tall buildings is the extreme accelerations induced by wind loads and perceived by their occupants. Normally, tuned-mass dampers (TMD) are installed on tall buildings to suppress vibration. However, an established procedure to evaluate the impact of the TMD system from the standpoint of financial profit/deficit is not readily available. This study proposes a framework that integrates local wind climate, wind-induced vibration and TMD performance analysis in terms of monetary outcomes. The proposed framework is composed of three parts: 1) evaluation of wind speed probability distribution at the building site; 2) calculation of wind-induced structural acceleration and its mitigation by TMD with variable mass ratio; 3) lifetime ‘‘net profit’’ assessment, based on the annual normalized inhabitable floor area. A feasibility study suggests that, for super-tall buildings, the TMD is financially effective in reducing wind-induced vibration and inhabitable floor area. Furthermore, large TMD is unnecessary and can lead to a financial deficit. Finally, a simulated mid-rise building does not require a TMD since the financial benefit is marginal.

Optimal Design of Tuned Mass Damper for Base-Excited Structures

The tuned mass damper (TMD) is a well-established vibration control device that has been implemented in several structures worldwide. The performance of passive TMD is greatly dependent on its design parameters. A key issue for the design of the optimal TMD is the identification of the parameters of the structure to which the TMD is to be attached. Here, it is important also to consider the perturbations that may arise in the structural frequency due to different practical issues. The present work focusses on this and aims to obtain the optimum TMD parameters in a Genetic Algorithm (GA) framework. The results of the proposed optimal strategy, in terms of optimal tuning ratio and optimal damping ratio, for a given value of the mass ratio, are compared with some of the existing optimal solutions for linear TMD under base excitation. The effectiveness of all these optimally designed TMDs in reducing the structural response is further demonstrated when the structure-TMD system is subjected to recorded earthquake ground motions. It is seen that in the tuned condition, the control performance obtained by the different designs of the TMD are similar to each other, although having some minor differences in the values of the optimum parameters. Also, the effectiveness of the different TMD designs in the detuned condition is investigated, in which the present design technique is found to be the most effective.

Shaking table test and numerical simulation of the vibration control performance of a tuned mass damper on a transmission tower

In this study, shaking table tests were performed on a 1/8-scaled test model equipped with and without a tuned mass damper (TMD) to validate the effectiveness of TMD on a transmission tower under seismic excitations and to investigate its damping mechanism. Based on the experimental results, the vibration control performance of TMD and the effects of earthquake characteristics were analysed. The results showed that TMD had efficient control effects on the transmission tower responses, but the control performance varied. Moreover, the vibration control performance was related to the earthquake types and decreased with the increase in excitation intensity. The vibration control performance along the height was also analysed comprehensively. Finally, the dynamic responses of the transmission tower model with TMD were simulated using the finite element software, ANSYS, which agreed well with the shaking table test results. Based on the finite element model, the effect of the damping ratio of TMD on the vibration control performance was determined through a parametric study, indicating that adding the damping ratio can improve the vibration control performance within a specific range. The experimental results and the numerical simulation method reported in this paper are applicable in transformation towers located in active seismic areas.

Seismic effectiveness of hysteretic tuned mass dampers for inelastic structures

The problem of reducing the damage due to seismic loads in engineering structures by means of tuned mass dampers (TMDs) is addressed. Differently from previous studies focused on linear or geometrically nonlinear TMDs, the present work is concerned with a device that exhibits a hysteretic restoring force with pinching. A numerical TMD optimization is carried out so as to ensure optimal energy transfer from the main structure to the TMD for various seismic ground motion severities. The effectiveness of the vibration protection strategy is discussed for two different structural systems, i.e. a multi-story steel building with a purely elastoplastic behavior and a masonry building that exhibits stiffness and strength degradation.Numerical simulations demonstrate that the hysteretic TMD can achieve a meaningful average reduction of the root mean square (RMS) displacement of the steel structure between 40% (for 1% mass ratio) and 60% (for 5% mass ratio). Various seismic records related to soil types and seismic intensity levels different from those considered at the design stage, or unpredictable variations of the main system stiffness up to 10%, are shown to have rather limited influence on the TMD performance. It is shown that a classical linear TMD can attain a protection level comparable to that of the hysteretic TMD only at the expense of much higher mass ratios. Compared to the multi-story structure, the performance of the hysteretic TMD in a masonry building is still satisfactory although degraded, i.e. by about 15% in terms of RMS displacement. The performance is better than that of a classical linear absorber for very small mass ratios, especially for mid- or high-intensity seismic ground motions. The greater robustness of the hysteretic TMD performance for a wide range of seismic ground motions is due to its softening-type backbone, which can be optimized to accommodate the frequency changes that engineering structures typically undergo under seismic excitation. The role of the pinching in the performance of the hysteretic TMD is clarified.

Wind-induced vibration control of a constructing bridge tower with MRE variable stiffness tuned mass damper

With the rapidly increasing number of long span bridges being built all over the world, the wind-induced vibrations of their constructing high bridge towers are becoming a serious issue. These vibrations will discomfort workers, affect construction accuracy, lead to construction period delay, and sometimes even cause accidents. Tuned mass dampers (TMDs) are well accepted to have a good performance in wind-induced vibration control under the condition that their natural frequencies are tuned to the natural frequencies of the main structures. However, as the natural frequencies of the bridge towers keep varying during its construction, their wind-induced vibrations can hardly be controlled by conventional TMDs. To improve the control efficiency, a novel magnetorheological elastomer variable stiffness tuned mass damper (MRE VSTMD) was proposed to retune the system. To verify the efficiency of the proposed system, a constructing bridge tower was modeled analytically and the corresponding MRE VSTMD was designed. Simulations were carried out and evaluations were made among the uncontrolled, passive controlled and semi-active controlled structures. It is proved that the proposed MRE VSTMD can improve the performance of passive TMDs by up to 40%. It is also observed that the softening behavior can double the stiffness variable range of MRE layers, indicating MRE VSTMD’s potential to further improve its performance with time varying excitation powers.

Parameters optimization of tuned mass damper using fast multi swarm optimization

Tuned mass damper (TMD) has been used for the vibration controller of building, especially for high rise buildings. TMD is one of the passive devices for reducing the response of the structure subjected to dynamic external disturbance such as wind, or earthquake load. TMD used its weight for reducing the vibration, TMD’s frequency is set to the structure’s frequency so that the frequency should be in resonance to each other for reducing the response of the structure during the dynamic load. Therefore, three variables have a significant effect for TMD performance, which are the mass ratio of TMD, the frequency ratio of TMD, and the damping ratio of TMD, which lead to two important variables of TMD properties, stiffness, and damping of TMD. This paper developed an empirical equation for obtaining the optimum parameters of tuned mass damper based on the H2 norm control system and fast multi swarm optimization (FMSO). The objective function was to minimize the acceleration and displacement response of the structure. The result shows a strong correlation both the mass ratio of TMD to the frequency ratio of TMD and the mass ratio of TMD to the damping ratio of TMD.

Using tuned mass damper inerter to mitigate vortex-induced vibration of long-span bridges: Analytical study

The undesirable vortex-induced vibration (VIV) may seriously influence the fatigue life and serviceability of bridge structures. It is important to take countermeasures to suppress the adverse VIV of long-span bridges. In the present study, a novel inerter-based system, namely the tuned mass damper inerter (TMDI), is proposed to control the VIV of the main deck of long-span bridges. In this system, an inerter device, which is able to transform the linear motion into the high-speed rotational motion and thus significantly amplifies the physical mass of the system, is incorporated into the conventional tuned mass damper (TMD) system to further improve the performance of TMD. An applicable layout of the TMDI inside the bridge deck is introduced and the governing equations of the structure-TMDI system subjected to VIV are established. The optimization of the TMDI parameters with the consideration of nonlinear aeroelastic effect is derived. The control performance and robustness of the proposed system are investigated through an analytical case study in both the time and frequency domains. It is observed that the TMDI system can obviously reduce the VIV responses of the bridge deck. Moreover, compared to the conventional TMD system, the static stretching of the spring due to gravity and the oscillation amplitude of the mass block in the TMDI system are significantly reduced. These properties make the proposed TMDI system an attractive alternative for the VIV control of long-span bridges.

Effects of hysteretic damping on the seismic performance of tuned mass dampers

SummaryA tuned mass damper (TMD) as a convenient passive device in average to tall buildings has limitations specifically against broad band seismic excitations. According to evidences from the literature, this drawback can be dominated by using nonlinear stiffness in TMDs; however, past studies did not explore this issue, and observations are not sufficient to reach a conclusion about seismic performance of nonlinear TMDs. This paper considers seismic performance of a nonlinear TMD developed by adding a martensitic shape memory alloy spring with significant stable features to conventional TMDs. To this end, single degree of freedom structures (from short to large periods) equipped with the nonlinear TMD are investigated subjected to set of ground motions, and through numerical analyses, effects of hysteretic damping and energy absorption capacity of the nonlinear TMD are examined. In addition, features of the proposed TMD configuration and effects of the excitation properties have been scrutinized through graphing frequency response curves by the arc length continuation method. Results indicate that the proposed configuration can make the nonlinear TMD robust against variations of the loading properties. Moreover, due to significant hysteretic damping of the shape memory alloy, spring seismic performance of the nonlinear TMD is better than conventional TMDs.

Reliability-Based Design of Tuned Mass Damper Using Monte Carlo Simulation Under Artificial Earthquake Records

Displacement- and reliability-based designs of tuned mass damper (TMD) for a shear building are studied herein. Different sources of uncertainties such as earthquake records and their peak ground accelerations (PGA), masses of floors, cross-sectional dimensions of structural members, damping of the structure and modulus of elasticity are considered. Monte Carlo simulation (MCS) is used for evaluating the performance of the designed TMD. A method for generating artificial earthquake record by using wavelet packet transform (WPT) and particle swarm optimization (PSO) is proposed to generate artificial records for areas without sufficient strong ground motion records. An illustrative example is used to study the displacement- and reliability-based designs of TMD, which are related to minimizing the structural displacement and maximizing the performance of TMD, respectively. In addition, the performance of TMD on mitigating the response of structure and its reliability under uncertain parameters of loading and structural properties are investigated. The results show that a displacement-based designed TMD could reduce the lateral displacement of a structure. Furthermore, it illustrates that the reliability-based designed TMD has a better performance in real condition of loading and structural parameters.

Analytical Prediction of Stability Lobes for Passively Damped Boring Bars

AbstractThe present article proposes the closed-form solution for analytical prediction of stability lobes in internal turning process. The passively damped boring bar is modeled as a cantilevered Euler-Bernoulli beam with constant cross sectional properties in which a Tuned Mass Damper (TMD) is embedded for the purpose of chatter suppression. The non-dimensional equations of motion are derived, assuming that the boring bar dynamics is well-represented by the fundamental mode of vibration. The stability of equivalent two-DOF dynamic model, i.e. boring bar with TMD, is analyzed in frequency domain. The closed- form expressions for critical depth of cut and spindle speed are presented in terms of boring bar and TMD characteristics. The proposed solution considers the effects of boring bar's structural damping and cutting geometry of insert on the stability behavior of passively damped cutting tool. An unconstrained optimization method is utilized to compute the most optimal set of tuning parameters for anti-chatter TMD. In order to improve the boundary of stability in a global sense, maximization of minimum critical depth of cut is selected as the objective of optimization. The superior performance of anti-chatter TMD is compared to H∞and H2TMDs for a wide range of applications. Moreover, the achieved results show a remarkable improvement of stability boundary compared to recent research works.

Tuned Mass Damper Positioning Effects on the Seismic Response of a Soil-MDOF-Structure System

Tuned mass dampers (TMDs) are effective structural vibration control devices. However, very little research is available on the experimental investigation of TMDs and their performance in systems undergoing dynamic soil-structure interaction. Geotechnical centrifuge tests are conducted to investigate story positioning effects of single and multiple TMDs in a soil-MDOF-structure system. The criteria for optimal story positioning will be established, and it is shown that story positioning influences TMD performance more than the number of TMDs used. Non-optimal story positioning was found to have the potential of reducing damping efficiency, amplifying peak structural response, and inducing lengthier high-intensity motion.