• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.842-849
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• 2009

The objective of this study is to investigate design parameters of a tuned liquid column damper(TLCD), which is affected by various excitation amplitudes, through shaking table test. Design parameters of a TLCD are examined based on the equivalent tuned mass damper(TMD) model of a TLCD, in which the nonlinear damping of a TLCD is transposed to equivalent viscous damping. Shaking table test is carried out for a TLCD specimen subjected to harmonic waves with various amplitudes. Transfer functions are ratios of liquid displacement of TLCD and control force produced by a TLCD, respectively, with respect to the acceleration excited by a shaking table. They are derived based on the equivalent TMD model of a TLCD. Then, the variation of design parameters according to the excitation amplitude is examined by comparing analytical transfer functions with experimental ones. Finally, the dissipation energy due to the damping of a TLCD, which is experimentally observed from the shaking table test, is examined according to the excitation amplitude. Comparisons between test results and analytical transfer functions showed that natural frequencies of TLCD and the ratio of the liquid mass in a horizontal column to the total liquid mass does not depend on the excitation amplitude, while the damping ratio of a TLCD increases with larger excitation amplitudes.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.11
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• pp.1167-1176
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• 2009

The objective of this study is to investigate design parameters of a tuned liquid column damper(TLCD), which is affected by various excitation amplitude, through shaking table test. Design parameters of a TLCD are examined based on the equivalent tuned mass damper(TMD) model of a TLCD, in which the nonlinear damping of a TLCD is transposed to equivalent viscous damping. Shaking table test is carried out for a TLCD specimen subjected to harmonic waves with various amplitude. Transfer functions are ratios of liquid displacement of TLCD and control force produced by a TLCD, respectively, with respect to the acceleration excited by a shaking table. They are derived based on the equivalent TMD model of a TLCD. Then, the variation of design parameters according to the excitation amplitude is examined by comparing analytical transfer functions with experimental ones. Finally, the dissipation energy due to the damping of a TLCD, which is experimentally observed from the shaking table test, is examined according to the excitation amplitude. Comparisons between test results and analytical transfer functions showed that natural frequencies of TLCD and the ratio of the liquid mass in a horizontal column to the total liquid mass do not depend on the excitation amplitude, while the damping ratio of a TLCD increases with larger excitation amplitude.

• Journal of Korean Association for Spatial Structures
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• v.15 no.2
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• pp.105-112
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• 2015

A shared tuned mass damper (STMD) was proposed in previous research for reduction of dynamic responses of the adjacent buildings subjected to earthquake loads. A single STMD can provide similar control performance in comparison with two traditional TMDs. In previous research, a passive damper was used to connect the STMD with adjacent buildings. In this study, a smart magnetorheological (MR) damper was used instead of a passive damper to compose an adaptive smart STMD (ASTMD). Control performance of the ASTMD was investigated by numerical analyses. For this purpose, two 8-story buildings were used as example structures. Multi-input multi-output (MIMO) fuzzy logic controller (FLC) was used to control the command voltages sent to two MR dampers. The MIMO FLC was optimized by a multi-objective genetic algorithm. Numerical analyses showed that the ASTMD can effectively control dynamic responses of adjacent buildings subjected to earthquake excitations in comparison with a passive STMD.

• Structural Engineering and Mechanics
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• v.11 no.4
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• pp.341-356
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• 2001

A new class of semi-active tuned mass dampers, named as "Ground Hook Tuned Mass Damper" (GHTMD) is introduced. This TMD uses a continuously variable semi-active damper (so called 'Ground-Hook') in order to achieve more reduction in the vibration level. The ground-hook dampers have been used in the auto-industry as a means of reducing the vibration of primary suspension systems in vehicles. This paper investigates the application of this damper as an element of a tuned damper for the vibration reduction of force-excited single degree of freedom (SDOF) models that can be representative of many structural systems. The optimum design parameters of GHTMDs are obtained based on the minimization of the steady-state displacement response of the main mass. The optimum design parameters which are evaluated in terms of non-dimensional values of the GHTMD are obtained for different mass ratios and main mass damping ratios. Using the frequency responses of the resulting systems, performance of the GHTMD is compared to that of equivalent passive TMD, and it is found that GHTMDs are more efficient. A design methodology to obtain the tuning parameters of GHTMD using the relationships developed in this paper is presented.

• Earthquakes and Structures
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• v.16 no.3
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• pp.349-358
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• 2019

Long span cable-stayed bridges are extremely vulnerable to dynamic excitations such as which caused by traffic load, wind and earthquake. Studies on cable-stayed bridge vibration control have been keenly interested by researchers and engineers in design new bridges and assessing in-service bridges. In this paper, a novel Hybrid-Tuned Mass Damper (H-TMD) is proposed and a hybrid control model named Mixed Logic Dynamic (MLD) is employed to build the bridge-H-TMD system to mitigate the vibrations. Firstly, the fundamental theory and modeling process of MLD model is introduced. After that, a new state switching design of the H-TMD and state space equations for different states are proposed to control the bridge vibrations. As the state switching designation presented, the H-TMDs can applied active force to bridge only if the structural responses are beyond the limited thresholds, otherwise, the vibrations can be reduced by passive components of dampers without active control forces provided. A new MLD model including both passive and active control states is built based on the MLD model theory and the state switching design of H-TMD. Then, the case study is presented to demonstrate the proposed methodology. In the case study, the control scheme with H-TMDs is applied for a long span cable-stayed bridge, and the MLD model is established and simulated with earthquake excitation. The simulation results reveal that the suggested method has a well damping effect and the established system can be switched between different control states as design excellently. Finally, the energy consumptions of H-TMD schemes are compared with that of Active Tuned Mass Damper (ATMD) schemes under variable seismic wave excitations. The compared results show that the proposed H-TMD can save energy than ATMD.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.603-622
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• 2008

This work deals with the design optimization of tuned mass damper (TMD) devices used for mitigating vibrations in high-rise towers subjected to seismic accelerations. A stochastic approach is developed and the excitation is represented by a stationary filtered stochastic process. The effectiveness of the vibration control strategy is evaluated by expressing the objective function as the reduction factor of the structural response in terms of displacement and absolute acceleration. The mechanical characteristics of the tuned mass damper represent the design variables. Analyses of sensitivities are carried out by varying the input and structural parameters in order to assess the efficiency of the TMD strategy. Variations between two different criteria are also evaluated.

• Wind and Structures
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• v.30 no.4
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• pp.423-432
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• 2020

A steel high-rise building (HRB) with 15 stories was analyzed under the dynamic load of wind or four different earthquakes taking into consideration the effect of soil-structure interaction (SSI) and using tuned mass damper (TMD) devices to resist these types of dynamic loads. The behavior of the steel HRB as a lightweight structure subjected to dynamic loads is critical especially for wind load with effect maximum at the top of the building and reduced until the base of the building, while on the contrary for seismic load with effect maximum at the base and reduced until the top of the building. The TMDs as a successful passive resistance method against the effect of wind or earthquakes is used to mitigate their effects on the steel high-rise building. Lateral displacements, top accelerations and straining actions were computed to judge the effectiveness of the TMDs on the response of the steel HRB subjected to wind or earthquakes.

• Journal of Korean Association for Spatial Structures
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• v.14 no.3
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• pp.75-84
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• 2014

When adjacent tall buildings experience earthquake excitation, structural pounding may happen. In order to mitigate seismic pounding damage to adjacent structures, many studies have been done to date. Tuned mass dampers (TMD) are widely used for reduction of dynamic responses of building structures subjected to earthquake excitations. If a TMD is shared between adjacent buildings and it shows good control performance, it will be effective and economic means to reduce seismic responses of adjacent structures. In this study, control performance of a shared tuned mass damper (STMD) for seismic response reduction of adjacent buildings has been evaluated. For this purpose, two 8-story example buildings were used and multi-objective genetic algorithms has been employed for optimal design of the stiffness and damping parameters of the STMD. Based on numerical analyses, it has been shown that a STMD can effectively control dynamic responses and reduce the effect of pounding between adjacent buildings subjected to earthquake excitations in comparison with a traditional TMD.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.263-269
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• 2003

This paper describes the vibration control using a tuned mass damper(TMD) for the existing footbridge. The footbridge connecting driveway to the Stadium is the simple steel box-girder bridge with the main span length of 44.6m. This footbridge has light weight(=25.3kN/m) and pedestrians walking on the footbridge were found to induce resonance at the fundamental mode of the structure, resulting in unacceptable accelerations in it. Taking into account economical and constructional benefits, TMD was designed to damp the vibrations of the modes next to the natural frequency caused by a pedestrian, with a limitation criteria of vertical amplitude. A set of two 500kgf vertical TMDs was manufactured by KR and installed into the railings next to the central section of this footbridge. The installation of TMDs reduced the peak acceleration in the meeting box to less than 90%. It is hoped that the study will present bridge engineers with a measure of retrofitting footbridges to make them more friendly to users.

• Structural Engineering and Mechanics
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• v.77 no.6
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• pp.721-734
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• 2021

The seismic analysis of structures without applying the effects of soil can undermine functional objectives of structure so that it can affect all the desired purposes at the design and control stages of the structure. In this research, employing OpenSees and MATLAB software simultaneously and developing a definite three-dimensional finite element model of a high-rise concrete structure, designed using performance-based plastic design approach, the performance of Tuned Mass Damper (TMD) and Active Mass Damper (AMD) is both examined and compared. Moreover some less noted aspects such as nonlinear interaction of soil and structure, uplift, nonlinear behavior of structure and structural torsion have received more attention. For this purpose, the analysis of time history on the structural model has been performed under 22 far-field accelerogram records. Examining a full range of all structural seismic responses, including lateral displacement, acceleration, inter-story drift, lost plastic energy, number of plastic hinges, story shear force and uplift. The results indicate that TMD performs better than AMD except for lateral displacement and inter-story drift to control other structural responses. Because on the one hand, nonlinear structural parameters and soil-structure interaction have been added and on the other hand, the restriction on the control force applied that leads up to saturation phenomenon in the active control system affect the performance of AMD. Moreover, the control force applied by structural control system has created undesirable acceleration and shear force in the structure.