Browsing by Author "Lee, Chien-Liang"

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A study on AGV-induced floor micro-vibration in TFT-LCD high-technology fabs
(2012-04-01)
Lee, Chien-Liang
;
Wang, Yen-Po
;
Su, Ray Kai Leung
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土木工程學系
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Department of Civil Engineering
This study explores vertical floor micro-vibration induced by the automated guided vehicles (AGVs) in thin-film-transistor liquid-crystal-display (TFT-LCD) fabs. The state-space procedure is adopted to compute the AGV-induced floor vibration as it preserves the desired numerical stability and accuracy in high-frequency responses. The dynamic analysis of an AGV moving on an equivalent three-span beam model of a TFT-LCD building is simulated by taking into account various AGV speeds and engine forces. Numerical simulations demonstrate that if proper engine forces and excitation frequency contents of the AGV moving loads are used, the peak AGV-induced floor micro-vibration level can be predicted by the proposed method. Moreover, the effectiveness of vibration control by span-reduction as well as energy-dissipation by viscoelastic dampers is also examined. In comparison with span-reduction, application of energy-dissipation devices is more effective in vibration suppression as they enhance the damping characteristics of the multi-span floor system whose natural frequencies are potentially in resonance with the excitation frequencies of the AGV moving loads ranging in a broad bandwidth. Copyright (C) 2011 John Wiley & Sons, Ltd.
An Experimental Study of DLV Method in Damage Detection of Frame Structures
(2010)
Wang, Yen-Po
;
Chen, Yi-Hsuan
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Lee, Chien-Liang
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土木工程學系
;
Department of Civil Engineering
A structural damage detection method integrating the damage locating vector (DLV) method and ARX model for system identification of frame structures from seismic acceleration responses has been explored in this paper. The concept of the DLV method is to identify the members with zero stress under some specific loading patterns derived from the changes in flexibility matrix of the structure before and after the damage state. Success of the DLV method requires clear identification of the flexibility matrix for at least the first few dominant modes. In this study, a five-storey steel frame with diagonal bracings is considered as the objective building. The damage condition of the structure is simulated by partially removing some of the diagonals. With the flexibility matrices of both the intact and damaged structure identified from seismic structural responses via shaking table tests, results indicate that the damaged locations can be successfully identified by the DLV method if sufficient modes of vibration are taken into account in the realization of the flexibility matrices. The feasibility of using DLV method for damage detection of frame structures using seismic response data is confirmed.
An experimental study of in-plane arch-shaped dampers
(2018-10-01)
Lee, Chien-Liang
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Wang, Yen-Po
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Cai, Meng-Yan
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土木工程學系
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Department of Civil Engineering
As an effort to minimize material utilization, seismic steel dampers designed to deform inelastically in an in-plane flexural mode have attracted serious attention recently. This paper presents a new type of metallic yielding damper referred to as the in-plane arch-shaped damper modified from its portal frame-shaped counterpart by replacing the straight beam with a circular arch to minimize the effects of stress concentration and warping, and therefore to avoid premature failure. Component tests of both the portal frame-shaped and arch-shaped in-plane dampers were conducted for comparison. Hysteresis loops obtained from the component tests under cyclic loads indicate substantial improvement on the energy-dissipative characteristics of the proposed damper. Moreover, seismic performance assessment of the proposed damper was carried out further via shaking table tests of a five-story model frame. Encouraging results have been achieved in terms of acceleration reduction, damping enhancement and peak suppression of the frequency response functions, suggesting the potential of the proposed device to be used in earthquake-resisting systems.
Assessment of vibrations induced in factories by automated guided vehicles
(2013-04-01)
Lee, Chien-Liang
;
Wang, Yen-Po
;
Su, Ray Kai Leung
;
土木工程學系
;
Department of Civil Engineering
This study proposes a simplified sub-structural model to explore the floor micro-vibration induced by automated guided vehicles in thin-film transistor liquid crystal display factories. Time history analyses of a sequence of automated guided vehicles moving loads considering various car spacings on an equivalent three-span continuous beam model of a thin-film transitor liquid crystal display factory were simulated. The effectiveness of vibration control using viscoelastic dampers was also examined. Numerical simulations demonstrate that the simplified method can predict the measured floor vibration spectra with satisfactory accuracy and that the automated guided vehicles induced floor vibrations without control exceed the acceptable VC-B level required for the installation of specific precision process tools. The application of energy dissipation devices has shown to be effective in vibration mitigations as they enhance the damping characteristics of a multi-span floor system. The maximum response of the whole continuous beam induced by a group of automated guided vehicles can be effectively suppressed to a desired VC-B level if multiple viscoelastic dampers are implemented along the automated guided vehicles moving bay and the spacing between each automated guided vehicle is properly adjusted. The simplified analytical method can help engineers quickly assess the level of automated guided vehicles-induced floor vibration and assist in the design of low-vibration floor systems in high-technology factories.
Wind-induced interaction of a non-uniform tuned liquid column damper and a structure in pitching motion
(2008-12-01)
Wu, Jong-Cheng
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Wang, Yen-Po
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Lee, Chien-Liang
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Liao, Pei-Hsuan
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Chen, Yi-Hsuan
Wind-induced interaction between a tuned liquid column damper (TLCD) and a structure (bridge deck) in pitching motion is investigated both theoretically and experimentally. Non-uniform cross-sections in TLCDs are considered in general. Theoretically, the interacted equations of motion under wind excitation were derived for a single-degree-of-freedom rotational structure equipped with a TLCD based on energy principles. An addition term, which had never been revealed in existing literature, was discovered. The second part in this study was to demonstrate the existence of this additional term through experimental verification. This task was carried out by conducting large scale tests on the system of a TLCD on a rotational structure (which is a spring-constrained steel beam pivoted at mid-span) and by making comparisons between the experimental and analytical responses of the interacted structure subjected to harmonic loading. To obtain all necessary parameters for computing the analytical responses in the interaction, the individual identification of the properties of the TLCD and structure using free vibration and forced vibration techniques was also performed. Comparison results show that analytical responses with the additional term included can represent the actual interaction more closely than those without the additional term. Therefore, the inclusion of the additional term in pitching interaction equations is essential. (C) 2008 Elsevier Ltd. All rights reserved.