• Journal of Korean Society of Steel Construction
• /
• v.21 no.2
• /
• pp.175-181
• /
• 2009

An intelligent control technique using a neural network is proposed for offshore structures exposed to sea-bed earthquakes. Fluid-structure interaction effect was considered in developing controller and a training algorithm for the neural network is presented. In the numerical example, the performance of the proposed neural network controller was compared with that of a passive controller and uncontrolled structures. Based on the example, it can be concluded that the proposed neuro-control scheme can be used for offshore structures with nonlinear characteristics due to its interaction with fluid.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.189-194
• /
• 2007

An experimental real-time hybrid method, which implements the wind response control of a building structure with only a two-way TLMD, is proposed and verified through a shaking table test. The building structure is divided into the upper experimental TLMD and the lower numerical structural part. The shaking table vibrates the TLMD with the response calculated from the numerical substructure, which is subjected to the excitations of the measured interface control force at its top story and an wind-load input at its base. The results show that the conventional method can be replaced by the proposed methodology with a simple installation and accuracy for evaluating the control performance of a TLMD.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.210-215
• /
• 2007

In this paper, excitation systems using an active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.

• Journal of the Korean Society of Safety
• /
• v.32 no.6
• /
• pp.89-97
• /
• 2017

The tuned mass damper (TMD) system was first proposed as an efficient vibration control method for high-rise buildings, and multiple TMD (MTMD) system was then proposed for the purpose of improving the robust performance. Thereafter, the active TMD (ATMD) is proposed to improve the vibration control performance over the TMD and MTMD systems. However, this system may experience an system-instability problem in case of the actuator malfunction. In order to overcome such limitations of actuator malfunction causing the instability of the structural system, in this study, we investigate the feasibility of the multiple ATMD (MATMD) system that facilitates both advantages of the MTMD and ATMD. Numerical example demonstrates that, when the proposed system is designed to have the same capacity as the ATMD, it shows a similar control performance to the ATMD, but also has very good adaptive control performance against the emergency situations such as actuator failures.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.7
• /
• pp.667-672
• /
• 2009

This paper is concerned with the development of linear magnetic actuator for active vibration control. The newly developed linear magnetic actuator consists of permanent magnets and copper coils. On the contrary to the voice-coil type actuator, the linear magnetic actuator utilizes magnetic flux to generate the shaft movement. In this study, experiments on the prototype linear magnetic actuator were carried out to investigate its dynamic characteristics. Block and inertia forces generated by the actuator were measured. The experimental results show that the actuator can be used as both actuator and active tuned-mass damper. The linear magnetic actuator was attached to a cantilever as the active-tuned mass damper and active vibration control experiment was carried out. The experimental results show that the newly developed linear magnetic actuator can be effectively used for the active vibration control of structures.

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

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.5
• /
• pp.485-495
• /
• 2008

An experimental real-time hybrid method, which implements the vibration control of a building structure with only a two-way TLMD, is proposed and verified through a shaking table test. The building structure is divided into the upper experimental TLMD and the lower numerical structural part. The shaking table vibrates the TLMD with the response calculated from the numerical substructure, which is subjected to the excitations of the measured interface control force at its top story and sinusoidal waves input at its base. The results show that the conventional method can be replaced by the proposed methodology with a simple installation and accuracy for evaluating the control performance of a TLMD.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.432-441
• /
• 2008

In this study, the control performance of a Tuned Liquid Mass Damper(TLMD) manufactured to reduce the orthogonal bi-directional responses of building structures was experimentally evaluated. the TLMD using only one control device reduce bi-directional responses of building structures by making the TLMD behave as TMD and TLCD to the strong and weak axial direction of building structures. first, the control performance was evaluated by forcing sinusoidal waves to a test model that the TLMD is installed on the scale-downed building structure. Second, the real-time hybrid shaking table test was performed to evaluate the performance of the vibration control system made up of numerical part as a scale-downed building structural model and a physical experimental part as a TLMD. the superiority of bi-directional vibration control performance of the manufactured TLMD was verified by comparing the uncontrolled and controlled results of these tests.

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

• Journal of the Korea Institute of Building Construction
• /
• v.7 no.3
• /
• pp.75-82
• /
• 2007

A vibration in the building occurs by influences of the facility equipment and the structural system. As the building recently becomes higher and bigger, the vibration in the floor slab is issued. Specially, the vibration with $4{\sim}8Hz$ frequency is harder to control than any other range of frequency. This vibration easily affects human sensibility and often makes the resonance phenomenon by corresponding with the floor slab's natural frequency when people and heavy equipments move. Moreover, the permission regulations for the vibration of the building are established by building's purposes. However, it is not subdivided in detail and sometimes ambiguous to each client. Even though the vibration could cause negative influences in a research building, there is not the vibration criterion for a research building. Therefore, it is necessary to set up its own vibration criterion with the client before building and to keep checking this vibration criterion under the construction. This study proposes the reasonable control methods and the vibration criterion for floor slab's vibration which are adapted to the R4-project. The R4-project is a research building and a high-rise building also. Accordingly, this study could help to the next similar project in the design and the construction phase.