Efficiency Of Tuned Mass Dampers Research Articles

Vibration Monitoring of Two Long-Span Floors Equipped with Tuned Mass Dampers

This paper presents the field tests and vibration performance assessment of two long-span floors with tuned mass dampers (TMDs). The floors considered are made of steel beams and concrete slabs, as part of a gymnasium with composite floors spanning 36 m in each direction and equipped with 30 TMDs. Operational modal analysis based on ambient acceleration measurements is performed to extract the modal parameters of the floors. Ambient vibration tests were conducted at three stages of construction for each floor, namely (i) after the concrete slab was completed, (ii) after one layer over the concrete slab was added, and (iii) after the flooring (surfacing) was fully finished. The effects of the layers making up the flooring system and of the TMDs on the dynamic properties of the floors are studied. The finite element models of the floors are validated using the identified modal parameters. The effects of natural frequency of TMDs on the dynamic properties of the floors are investigated using the validated model. Finally, the effects of flooring on the vibration serviceability of the two floors are studied with TMDs in operation, when the floors were subjected to crowd-induced rhythmic loading, from which the efficiency of TMDs is assessed numerically. The results show that the coupled vibrations of the two floors with TMDs turned off occur in the first two modes, while the natural frequencies of the floors decrease with the addition of layers. The TMDs in operation break the first mode of the floor into two modes with similar mode shapes, resulting in smaller vibration response and larger damping ratios, which vary with the natural frequency of TMDs. Also, the wood flooring significantly increases the human-induced vibration of the floor, while the plastic flooring shows basically no effect.

Effect of Soil and Structure Nonlinear Interaction on the Efficiency of Tuned Mass Damper

In this paper, three 10, 15, and 20-story two-dimensional concrete structures have been used with a moment frame bearing system as models under analysis. First, using various time history analyses by the OpenSees software, the optimal parameters of the tuned mass damper (TMD), including frequency and mass, were obtained. Structures controlled with and without TMD were modelled on three soft, moderate, and hard soil types classified according to Code 2800. The models were analyzed in terms of time history by 7 ground motions. In order to take into account the nonlinear interaction of soil and structure, the model of the beam on nonlinear Winkler foundation has been used. The results show that nonlinear interaction in most cases reduces the efficiency of TMD. Moreover, as the soil becomes softer, the efficiency reduction of the mass damper increases.

Dynamic response of footbridges with tuned mass dampers

The increase of vibration problems in modern footbridges shows that footbridges should no longer be designed for static loads only. Not only natural frequencies but also damping properties and pedestrian loading determine the dynamic response of footbridges and design tools should consider all of these factors. Footbridge vibrations don’t cause usually structural problems, but if the vibration behaviour does not satisfy the comfort criteria, changes in the design or damping devices could be considered. The most popular external damping devices are viscous dampers and tuned mass dampers (TMD). The paper presents the basic principles of optimal TMD configuration and design procedure. The efficiency of TMD is demonstrated on the example of a footbridge prone to vibrations induced by pedestrians. It is shown that if the TMD is tuned quite precisely the reduction of accelerations can be very significant.

Pedestrian load models of footbridges

The increase of vibration problems in modern footbridges shows that footbridges should no longer be designed for static loads only. Not only natural frequencies but also damping properties and pedestrian loading determine the dynamic response of footbridges and design tools should consider all of these factors. In this paper the pedestrian load models for serviceability verification of footbridges, which are missing in the current European codes, are presented. For simplicity reasons the proposed pedestrian load models are based on stationary pulsating loads instead of moving pulsating loads. It is shown that simplified procedure can be used in verification of the serviceability limit state related to vibration due to pedestrians. Footbridge vibrations don’t cause usually structural problems, but if the vibration behaviour does not satisfy the comfort criteria, changes in the design or damping devices could be considered. The most popular external damping devices are viscous dampers and tuned mass dampers (TMD). The efficiency of TMD is demonstrated on the example of a footbridge prone to vibrations induced by pedestrians. It is shown that if the TMD is tuned quite precisely the reduction of accelerations can be very significant.

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.

Control of human-induced vibration of an innovative CSBS–CSCFS

The large interior space requirement of public buildings leads to the development of an innovative Cable Supported Beam Structure–Concrete Slab Composite Floor System (CSBS–CSCFS). Field tests indicate that human activities can induce significant vibration of CSBS–CSCFS in some extreme cases, implying that to attenuate the dynamic response of the structure is better if the structure is expected to achieve optimum dynamic behavior. Therefore, a passive dynamic control system comprising tuned mass dampers (TMDs) is designed and installed in the structure. This paper discusses the dynamic performance of CSBS–CSCFS under human-induced loads after the installation of TMDs and the efficiency of the dynamic control system through field tests and human perception to vibration. The tests are divided into two phases, namely, free and human-induced vibration tests. Results show that the dynamic control system significantly improves the dynamic performance of the structure and human comfort. Furthermore, the efficiency of TMDs is mainly determined by the activation of TMDs, which is influenced by the coincidence of dynamic response of structure and property of dynamic control system. Generally, the human-induced vibration of CSBS–CSCFS can be well controlled by the economic and convenient methods of installing passive dynamic control devices.

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.

Study on Seismic Response Control of Self-Anchored Suspension Bridge with TMD

Large span self-anchored suspension bridges which are located in the strong earthquake zone often have no sufficient anti-seismic capacity, especially the bridge pylon. Therefore, seismic response control is necessary. This paper studies the lateral damping control effects of one large-span self-anchored suspension bridge with tuned mass damper (TMD). Using a spatial dynamic analysis finite element mode, the seismic responses are calculated out. Seismic response analysis results show that a large lateral displacement appeared at the pylon top under the lateral seismic action and the moment peak at the pylon bottom is nearly reaching its equivalent yield moment gotten by moment-curvature curve, which would be resulted in a high risk of collapse of self-anchored suspension bridge under lateral earthquake action. Therefore, one TMD is considered to be applied on the pylon top of the self-anchored suspension bridge to reduce the seismic response. The simulation result shows that the TMD can provide remarkable effect on seismic response control of the pylon. The control efficiency of TMD can be up to 23.4%. The moment at the pylon bottom and the displacement at the pylon top both decrease obviously. The parameter analyses of TMD are also performed to get the best design parameter. The research results can be used as the reference of seismic response control or anti-seismic design for the same type of bridge.

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.