Performance Of Tuned Mass Damper Research Articles

Application of eddy current damper technology for passive tuned mass damper systems within footbridges

Footbridges are prone to vibrations induced by pedestrians depending on the bridgès natural frequencies. Well-known measures to increase the structural damping of a footbridge and hence control the risk of vibrations are Tuned Mass Dampers (TMD). One of the main parameters defining the overall effectiveness of a TMD is its damping mechanism; for this purpose eddy current dampers are an innovative solution, which can improve TMD performance significantly.This paper describes the design of an eddy current damper as part of a passive tuned mass damper. First, the theoretical potential is analyzed analytically. A detailed discussion on the optimization of TMD parameters combined with the characteristics of eddy current dampers shows its advantages. In the second part a TMD construction using an eddy current damper is designed based on a case study of a footbridge.

Comparison of TMD designs for a footbridge subjected to human-induced vibrations accounting for structural and load uncertainties

A vibration serviceability assessment of footbridges is required in design stage to evaluate the response to human-induced excitation. If the calculated response does not meet the desired criteria for vibration comfort, a Tuned Mass Damper (TMD) can be installed as a vibration mitigation device. The TMD mass, stiffness and damping constant must be tuned to the modal parameters of the structure to obtain the desired response reduction.The response prediction and TMD design rely on a good knowledge of the modal parameters of the footbridge and usually assume that the response is governed by a perfect harmonic loading causing resonance. Differences between the predicted and actual modal parameters may lead to both an unreliable response prediction and a suboptimal TMD performance. Therefore, a robust design of the TMD is proposed accounting for uncertainties in the modal parameters. Realistic walking scenarios of continuous pedestrian traffic are simulated to obtain an effective response reduction by the TMD.In this contribution, the robust design of a TMD is demonstrated for a slender footbridge accounting for reasonable levels of uncertainties in the modal parameters. Numerical optimisation is therefore applied and vibration serviceability requirements are imposed as design constraints. The obtained TMD parameters are compared to those obtained from the formulae proposed by Asami, determining the stiffness and damping constant as a function of its mass. It is found that the TMD mass can be further reduced when the TMD parameters are tuned independently from each other compared to the classical design according to Asami but a higher computation cost is needed. Furthermore, an increasing degree of robustness against variations in the modal parameters is obtained by increasing the TMD mass and damping.

Comparing the Effectiveness of Friction Damper and Tuned Mass Damper Using Numerical Simulation

The purpose of this study is to evaluate and compare the effectiveness of friction dampers and tuned mass dampers (TMD) using numerical simulations. Wind and earthquake loads are simulated on a 15-story model building structure in which a friction damper and/or a TMD are installed. The idealized one-dimensional structure with a friction damper at each story and/or a TMD at the top of the building is subjected to a simulated load, and the displacement and acceleration responses of the structure are measured. The outcomes show that a TMD is more useful to control the vibration of the building from a wind load and a friction damper is more suitable for loads created by large accelerations such as those found during seismic events. This study provides verification on the performance of friction dampers and TMDs according to each of the two load types, wind and earthquake, through numerical simulations.

OPTIMAL TMDS FOR IMPROVING THE SEISMIC PERFORMANCE OF HISTORICAL BUILDINGS

In this paper, optimal design and assessment of the capability of tuned mass dampers (TMDs) in improving the seismic behavior of confined masonry walls as the main element of historical buildings has been studied. For this purpose, the design parameters of TMDs have been determined through the minimization of wall response using Genetic algorithms (GAs). For simulation the behavior of confined masonry wall under earthquake, the triple linear shear beam model has been used. For illustration, the method has been tested on confined masonry walls equipped with linear TMDs. To study the effects of frequency content and peak ground acceleration (PGA) of earthquake records on the performance of TMDs, the controlled walls have been subjected to different earthquake records. Results have shown that the proposed method has been effective in designing optimal TMDs regarding the convergence and simplicity behavior of GA in solving the optimization problem. It has also been shown that using TMD enhances the seismic behavior of confined masonry walls which its efficiency depends on the earthquake characteristics and the mass ratio. Finally, it can be concluded that the results of this research could be used as guides to design TMDs for historical and heritage buildings

Life-cycle cost assessment of inelastic buildings with tuned mass dampers in seismic areas

A methodology is presented for evaluating, in a life-cycle cost (LCC) perspective, the seismic effectiveness of passive tuned mass dampers (TMDs) on inelastic building structures. Traditional assessment criteria reveal that TMD performance largely depends on the extent of response non-linearity and therefore on the seismic intensity level, proving satisfactory under moderate earthquakes but negligible under strong ones. Yet those criteria cannot provide a concise measure of control advantages, since they cannot weigh, on a physically sound, economic basis, the relative impact of different hazard levels. Through estimating the occurrence probability and expected lifetime cost of future seismic damages and losses, a multi-hazard LCC approach is here proposed as an efficient alternative for TMD cost-effectiveness assessment. An illustrative example shows that retrofitting a TMD on typical low-rise steel office structures in high seismicity regions may significantly reduce the building lifetime cost despite the detrimental effect observed under collapse limit state.

Life-cycle cost assessment of inelastic buildings with tuned mass dampers in seismic areas

A methodology is presented for evaluating, in a life-cycle cost (LCC) perspective, the seismic effectiveness of passive tuned mass dampers (TMDs) on inelastic building structures. Traditional assessment criteria reveal that TMD performance largely depends on the extent of response non-linearity and therefore on the seismic intensity level, proving satisfactory under moderate earthquakes but negligible under strong ones. Yet those criteria cannot provide a concise measure of control advantages, since they cannot weigh, on a physically sound, economic basis, the relative impact of different hazard levels. Through estimating the occurrence probability and expected lifetime cost of future seismic damages and losses, a multi-hazard LCC approach is here proposed as an efficient alternative for TMD cost-effectiveness assessment. An illustrative example shows that retrofitting a TMD on typical low-rise steel office structures in high seismicity regions may significantly reduce the building lifetime cost despite the detrimental effect observed under collapse limit state.

Performance of TMDs on nonlinear structures subjected to near-fault earthquakes

Tuned mass dampers (TMD) are devices employed in vibration control since the beginning of the twentieth century. However, their implementation for controlling the seismic response in civil structures is more recent. While the efficiency of TMD on structures under far-field earthquakes has been demonstrated, the convenience of its employment against near-fault earthquakes is still under discussion. In this context, the study of this type of device is raised, not as an alternative to the seismic isolation, which is clearly a better choice for new buildings, but rather as an improvement in the structural safety of existing buildings. Seismic records with an impulsive character have been registered in the vicinity of faults that cause seismic events. In this paper, the ability of TMD to control the response of structures that experience inelastic deformations and eventually reach collapse subject to the action of such earthquakes is studied. The results of a series of nonlinear dynamic analyses are presented. These analyses are performed on a numerical model of a structure under the action of near-fault earthquakes. The structure analyzed in this study is a steel frame which behaves as a single degree of freedom (SDOF) system. TMD with different mass values are added on the numerical model of the structure, and the TMD performance is evaluated by comparing the response of the structure with and without the control device.

Performance of tuned mass damper against structural collapse due to near fault earthquakes

Tuned mass dampers (TMD) are devices capable of reducing structural vibration by means of transferring energy from the protected structure to the control device. This vibration control strategy has relatively recent use in civil structures, and was proven effective against wind and far-fault earthquakes. In this paper, the effect of near-fault seismic records on structures with TMDs is studied. This type of seismic records has a short significant duration, with few pulses of high amplitude and low frequency. These characteristics raise a question about TMD performance against this type of earthquakes because the device has a very limited time to transfer the energy from the main structure.In this paper, the efficiency of TMD in preventing the collapse of a structure subjected to a series of near-fault records is analyzed. The structure used is a 4-story steel frame on which TMDs with different values of mass are incorporated. From a series of nonlinear dynamic analyses, where the scale of seismic records is modified, the minimum amplitude of each record that produces the structural collapse is found. By comparing the results of the structure with and without the addition of the control device, conclusions about its performance and capability in the prevention of collapse are established.

Numerical modelling for evaluating the TMD performance in an industrial chimney

A numerical technique for fluid-structure interaction, which is based on the finite element method (FEM) and computational fluid dynamics (CFD), was developed for application to an industrial chimney equipped with a pendulum tuned mass damper (TMD). In order to solve the structural problem, a one-dimensional beam model (Navier-Bernoulli) was considered and, for the dynamical problem, the standard second-order Newmark method was used. Navier-Stokes equations for incompressible flow are solved in several horizontal planes to determine the pressure in the boundary of the corresponding cross-section of the chimney. Forces per unit length were obtained by integrating the pressure and are introduced in the structure using standard FEM interpolation techniques. For the fluid problem, a fractional step scheme based on a second order pressure splitting has been used. In each fluid plane, the displacements have been taken into account considering an Arbitrary Lagrangian Eulerian approach. The stabilization of convection and diffusion terms is achieved by means of quasi-static orthogonal subscales. For each period of time, the fluid problem was solved and the geometry of the mesh of each fluid plane is updated according to the structure displacements. Using this technique, along-wind and across-wind effects have been properly explained. The method was applied to an industrial chimney in three scenarios (with or without TMD and for different damping values) and for two wind speeds, showing different responses.

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

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

Passive control of bilinear hysteretic structures by tuned mass damper for narrow band seismic motions

Tuned mass damper (TMD) has been extensively used in vibration control of engineering structures. Numerous available results show that TMD can greatly reduce the response of elastic structures under wind, water waves, and earthquakes. The efficiency of TMDs, however, decreases when primary system experiences nonlinear behaviors. In order to make use of TMDs in such situations, this paper investigates the feasibility of adopting TMD in controlling of inelastic structures subjected to seismic motions. The focus is to explore the performance of TMD controlled buildings in areas subjected to long distance earthquakes, where structures usually have low nonlinearity. An optimization criterion is proposed to minimize the maximum nonlinear response within the concerned frequency band of excitations, instead of conventional approach whereby the linear response of the primary system is minimized. The limit on stroke is taken into consideration for practicality. Through numerical studies, it is shown that the primary structures achieve much better damage reduction by adopting the optimal TMD parameters based on the proposed criterion.

Evaluation and analytical approximation of Tuned Mass Damper performance in an earthquake environment

This paper aims at assessing the seismic performance of Tuned Mass Dampers (TMDs) based on sets of recorded ground motions. For the simplest configuration of a structure-TMD assembly, in a comprehensive study characteristic response quantities are derived and statistically evaluated. Optimal tuning of TMD parameters is discussed and evaluated. The response reduction by application of a TMD is quantified depending on the structural period, inherent damping of the stand-alone structure, and ratio of TMD mass to structural mass. The effect of detuning on the stroke of the TMD and on the structural response is assessed and quantified. It is verified that a TMD damping coefficient larger than the optimal one reduces the peak deflection of the TMD spring significantly, whereas the response reduction of the main structure remains almost unaffected. Analytical relations for quantifying the effect of a TMD are derived and subsequently evaluated. These relations allow the engineer in practice a fast and yet accurate assessment of the TMD performance.

비틀림 강성을 가지는 동조질량감쇠기를 이용한 편심건물의 제어

In this stury, control performance of tuned mass damper (TMD) with torsional rigidity for an eccentric structure showing torsional responses is investigated. To this end, an eccentric structure subjected to earthquake excitation is used to evaluate the control performance of torsional TMD by varying installed location and torsional rigidity of TMD, To reduce computational time required for repetitive time history analysis of an example structure having non-proportional damping system due to TMD, an equivalent analytical model is used in this study. Torsional properties of TMD usually neglected in typical TMD are verified to be effective in reduction of torsional responses of the eccentric structure. In the case of eccentric structures, it has been seen that the center of a plane of a structure may not be optimal location of TMD.

Performance of Base Isolators and Tuned Mass Dampers in Vibration Control of a Multistoried Building

Earthquakes create vibrations on the ground that are translated into dynamic loads which cause the ground and anything attached to it to vibrate in a complex manner and cause damage to buildings and other structures. Civil engineering is continuously improving ways to cope with this inherent phenomenon. Conventional strategies of strengthening the system consume more materials and energy. Moreover, higher masses lead to higher seismic forces. Alternative strategies such as passive control systems are found to be effective in reducing the seismic and other dynamic effects on civil engineering structures. The present paper focuses on the performance evaluation of a few passive control systems such as base isolation systems and tuned mass dampers in the vibration control of a linear multi storied structure under harmonic and earthquake base motions. Base isolators such as Lead Rubber Bearing (LRB) system and Friction Pendulum System (FPS); and, a tuned mass damper (TMD) are designed for a ten storied reinforced concrete building. The building is modelled as a 10 degrees of freedom shear building model and Bouc Wen model is used to describe the hysteretic behaviour of base isolators. The performance of LRB system, FPS and TMD are evaluated numerically and compared. The frequency response characteristics of the systems are also studied.

413 解体重機用多段マスダンパーの研究開発

In recent years, because of demand for rebuilt the building that were constructed in high economic growth period (1960s), demolition work is carried out energetically in many places in Japan. Heavy equipment such as excavators is commonly used to the demolition work. However, the excavators generate uncomfortable vibration to neighbors. Therefore, the purpose of this study is research and development of vibration control device for excavators. A Tuned Mass Damper (TMD) is most commonly used for vibration control. Usually the TMD is tuned by using optimal design formula depending on the weight and the stiffness of the control target. However the tuning violated if the parameters of the control target are changes. In order to solve this problem, a Multiple Tuned Mass Damper (MTMD) is proposed in this study. The MTMD consists of a primary mass and secondary mass. The secondary mass is placed on the primary mass in series. Applying the secondary mass can widen the effective target frequency range of vibration control. In this paper, compared the performance of MTMD and TMD in numerical simulation. Then, prototype MTMD was fabricated and its performance was verified experimentally. As a result, it is confirmed that the prototype MTMD has effect in vibration control for excavator.

523 回転慣性を利用したTMDに関する研究 : 基本特性に関する研究

Tuned Mass Damper (TMD) is one of vibration control devices to reduce vibration response of structure. But, the case, which TMD cannot be set in some structures is not rare because of heaviness and stroke limit of auxiliary mass. So, we propose new TMD using rotary inertia and aim development of TMD which can be set in much many structures than that in existence. New TMD we propose change linear motion of auxiliary mass to rotating motion of another mass (rotating mass), and produce linear equivalent mass. It's expected to lightweight auxiliary mass and reduce stroke of auxiliary mass by that. And to change parameters of rotating mass, it will be expected effect of changing natural frequency (tuning) of new TMD. This paper shows experiments and results to check performance of tuning and vibration control performance as basic characters of new TMD. Experiment apparatus is connected rotating mass to auxiliary mass of usual mass damper via ball screw. Ball screw changes linear motion of auxiliary mass to rotating motion of rotating mass. It can be attached tiny mass (tuning mass) to rotating mass, and expected to change natural frequency of new TMD by tuning mass. We conduct free vibration experiments to check performance of tuning and input vibration experiments to check vibration control performance. As a result, we verify performance of tuning by tuning mass and vibration control performance of new TMD.

Robust optimum design of tuned mass dampers for high‐rise buildings under moderate earthquakes

AbstractIn the present study the optimum design of tuned‐mass‐damper (TMD) devices used for the vibration control of high‐rise buildings subject to moderate earthquakes is developed. For these structures a large acceleration demand can produce damage in equipment and contents: therefore, the performance of TMD will be based on the capacity of reducing this structural response. In order to maximize the performance and the efficiency of the TMD strategy, the ratio between the absolute accelerations of the protected and of the unprotected systems is assumed as objective function in the optimum design.The method is carried out in a stochastic way and a stationary‐filtered stochastic process is assumed to model the seismic action. Since the main disadvantage of using a single TMD is the mistuning related to errors in the evaluation of the natural frequency of the main structure, an uncertainty is introduced for this structural parameter, which is modelled as a random variable. Uncertainties in other structural mechanical properties and in TMD are neglected. Copyright © 2008 John Wiley & Sons, Ltd.

Study on soil-pile-structure-TMD interaction system by shaking table model test

The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very soft soil, soil-structure interaction (SSI) could render a damper on the structure totally ineffective. In order to experimentally verify the SSI effect on the seismic performance of TMD, a series of shaking table model tests have been conducted and the results are presented in this paper. It has been shown that the TMD is not as effective in controlling the seismic responses of structures built on soft soil sites due to the SSI effect. Some test results also show that a TMD device might have a negative impact if the SSI effect is neglected and the structure is built on a soft soil site. For structures constructed on a soil foundation, this research verifies that the SSI effect must be carefully understood before a TMD control system is designed to determine if the control is necessary and if the SSI effect must be considered when choosing the optimal parameters of the TMD device.

Efficacy of Tuned Mass Dampers for Bridge Flutter Control

This paper examines efficacy of tuned mass dampers (TMD) in controlling self-excited motion resulting from negative damping. New optimal TMD parameters are suggested which provide better performance than those suggested in the literature. The dependence of TMD performance on structural damping is highlighted. The equations of motion of a combined system comprised of multiple TMDs attached to a bridge deck are presented where the bridge motion is described in terms of reduced-order modal coordinates. Details concerning the multimode coupled flutter of long-span bridges with auxiliary TMDs are provided. The effectiveness and limitations of TMDs for controlling multimode bridge flutter are examined, emphasizing the dependence of TMD performance on the bridge dynamic and aerodynamic characteristics. This study shows that the effectiveness of TMDs is rather limited in controlling a hard-type flutter characterized by negative aerodynamic damping that grows rapidly with increasing wind speed beyond the onset of flutter. However, it is relatively effective in controlling a soft-type flutter in which the negative damping builds up slowly with increasing wind speed. Robust TMD design issues are also discussed in light of their sensitivity to design parameters in the vicinity of optimal values.

Control of response of structures with passive and active tuned mass dampers

AbstractTuned mass dampers (TMDs) and active tuned mass dampers (ATMDs) are control devices added in tall buildings to suppress the response of buildings in irregular external excitations such as earthquakes and wind. The performance of both passive and active damper systems can be assessed by parametric studies. This paper presents a brief description of the theory of passive and active tuned mass dampers. In this work, the effect of TMDs has been studied by changing the frequency ratio of the damper to the first mode of the structure. It was observed that the extra damping provided by TMDs, called effective damping, can primarily be obtained from design charts developed for this purpose. A 25‐storey building is designed and analysed using these charts as an example. The behaviour of a structure with an active tuned mass damper is investigated. The related parameters and equations of the active mass damper for the building are solved and its behaviour arising from external loads is studied. The conventional studies, which are based on white‐noise excitations, usually overestimate the performance of TMDs and ATMDs. Hence, in order to study the behaviour of a building with a TMD and an ATMD in real excitations, El‐Centro and Tabas earthquakes are selected. The results show a significant increase in the effect of TMD performance in controlling the structural displacements by using additional control devices. Copyright © 2002 John Wiley & Sons, Ltd.