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42 results on '"Cho, Bong-Ho"'

22. Mitigation of wind-induced vibration of a tall residential building using liquid column vibration absorber

Author

Cho, Bong-Ho, Yu, Eunjong, Kim, Hongjin, Cho, Bong-Ho, Yu, Eunjong, and Kim, Hongjin

Abstract

The most important thing in applying mass type dampers including Liquid Column Vibration Absorber (LCVA) is tuning its natural frequency to an optimum value which is a function of the natural frequency of the building and the mass ratio of damper to the building. However, exact prediction of the natural frequency of the building at design stage is very difficult especially for concrete buildings. Thus, continuous updating of the target frequency and correction of the design of the damper based on field measurement is necessary. In this paper, application of LCVAs to mitigate the wind-induced vibration of 64-story residential buildings is presented. The LCVA were designed to have adjustable dimension for vertical column to take the advantage of ease tuning and wide frequency range. For updating of initial design, the tuning and performance assessment of LCVA several tests and measurement were carried out. The ambient vibration measurement of a partially completed building and a completed building without water in LCVA was performed and final values of the width of vertical column and the height of water were determined from the system identification results based on the collected acceleration data. In addition, ambient vibration measurement of buildings with LCVA water was performed and the system identification results indicated that the apparent damping ratio due to LCVA was increased about 3.13 to 3.89 times.

Published
2016

25. Seismic evaluation of asymmetric wall systems using a modified three-dimensional capacity spectrum method

Author

Cho, Bong-Ho, Hong, Sung-Gul, Ha, Tae-Hyu, Kim, Dae-Jin, Cho, Bong-Ho, Hong, Sung-Gul, Ha, Tae-Hyu, and Kim, Dae-Jin

Abstract

This paper proposes a modified three-dimensional capacity spectrum method to efficiently evaluate the seismic behavior of a building structure with asymmetric walls, where twisting is induced due to lateral loading. This method utilizes the demand surfaces and capacity curves that are created based on the inelastic earthquake response and seismic capacity of the asymmetric wall system, respectively. These two parameters are calculated from the displacement, torsional rotation angle and force coordinates of the structure under seismic loading. The seismic retrofit strategy of existing structures can be effectively determined by applying the proposed three-dimensional capacity spectrum method. In this procedure, a new performance point indicating the enhanced performance of the structure can be easily found by the modification of demand surfaces or capacity curves. The seismic evaluation and retrofitting strategies based on this approach are also discussed.

Published
2015

42. Dynamic Parameter Identification of Secondary Mass Dampers Based on Full-Scale Tests.

Author

Cho, Bong-Ho, Jo, Ji-Seong, Joo, Seok-Jun, and Kim, Hongjin

Subjects
*DAMPERS (Mechanical devices), *PRECAST concrete construction, *MATHEMATICAL decoupling, *SYSTEM identification, *EQUATIONS of motion
Abstract

For a secondary mass damper such as tuned liquid damper (TLD) or tuned liquid column damper (TLCD), whose moving mass is liquid, it is impossible to prefabricate the damper in a factory for the identification of dynamic properties. Also, it is not easy to prefabricate a concrete tuned mass damper (TMD), whose moving mass is made of concrete, in a factory. In this article, an identification method for finding dynamic properties of secondary mass dampers based on the full-scale field test is presented. Decoupled equations of motion are derived from a coupled equation of motion of building and damper. The decoupled equations of motion are then used for system identification using the response of the damper as an input and the response of the building as an output. The proposed method is applied to numerical examples and an actual TMD and TLCD installed in buildings. [ABSTRACT FROM AUTHOR]

Published
2012
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