• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.449-454
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• 2002

For finite analysis of concrete columns strengthened with glass fiber sheets, an effective concrete model which considers the confining effects by lateral reinforcement and glass fiber sheets is necessary. In this paper, the so-called elasto-plasticity and continuum fracture model (EPF model) is modified to consider high confining effects of strengthened reinforced concrete columns by introducing a simple correction factor ($\alpha$) which relates maximum lateral confining stress of the column to the evolution of deviatoric plasticity. Then, a finite element analysis is carried out for the strengthened reinforced concrete columns using the modified EPF model and equally spaced truss elements. It is shown that the, analysis predicts well the failure behavior of reinforced concrete columns strengthened with glass fiber sheets.

• Earthquakes and Structures
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• v.15 no.5
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• pp.463-471
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• 2018

The virtual forces of the original local flexibility method are restricted to inducing stress on the local parts of a structure. To circumvent this restriction, we developed a pseudo local flexibility (PLFM) method that can successfully detect damage to hyperstatic beam structures using fewer modes. For this study, we further developed the PLFM so that it could detect damage in plate structures. We also devised the theoretical background for the PLFM with non-local virtual forces for plate structures, and both the lateral and rotary degree of freedom (DOF) measurements were considered separately. This study investigates the effects of the number of modes, the actual location that sustained damage, multiple damage locations, and noise in modal parameters for the damage detection results obtained from damaged numerical plates. The results revealed that the PLFM can be used for damage detection, localization, and quantification for plate structures, regardless of the use of the lateral DOF and/or rotary DOF.

• Structural Engineering and Mechanics
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• v.34 no.3
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• pp.301-317
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• 2010

This paper studies the reliability of an analytical tool for predicting the lateral load-deformation response of RC columns while subjected to lateral cyclic displacements and axial load. The analytical tool in this study is based on a fiber element model implemented into the program DRAIN-2DX (fiber element). The response of RC column under cyclic displacement is defined by the behavior of concrete, and reinforcing steel under general reversed-cyclic loading. A tri-linear stress-strain relationship for the cyclic behavior of steel is proposed and the improvement in the analytical results is studied. This study only considers the behavior of columns with flexural dominant mode of failure. It is concluded that with the implementation of appropriate constitutive material models, the described analytical tools can predict the response of the columns with reasonable accuracy when compared to experimental data.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.442-447
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• 2003

The actual behavior of the railroad track structure is suspected to be a complex interaction between the vertical, lateral, longitudinal, and torsional behaviors. A FE program are developed in the present study to be used for extensive nonlinear analysis of the track structures subjected to thermal load. Using the rigorous study on the deformed shape of the rail and tie, and stress resultants, characteristics of the three dimensional behavior are investigated. It is found that the flexural rigidity of the tie and the rotational stiffness of pad-fastener can be affect the behavior of the track structure and the postbuckling behavior in each rail, except lateral behavior, is not same.

• International Journal of High-Rise Buildings
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• v.1 no.1
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• pp.21-28
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• 2012

Diagrid system has been in the spotlight for its superiority in terms of the resistance to lateral force when applied to skyscrapers. In diagrid system, most of columns can be eliminated because vertical loads (gravity loads) and horizontal loads (lateral loads) are delivered simultaneously thanks to the triangular shape of diagrid. However, lack of studies on connection shape and node connection details makes it hard to employ the system to the buildings. In this study, the structural safety of the node connections in circular steel tube diagrid system which has been considered in the Cyclone Tower in Korea (Seven stories below and fifty-one above the ground) was evaluated using the 4 full-scale specimens. The parameters are the extended length (20 mm, 40 mm & 60 mm), thickness (40 mm & 50 mm).

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.430-433
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• 2006

The reinforced concrete column confined by square steel tubes(RCST) is a reinforced column (RC) confined by thin steel tubes which cover over the full length of the column but terminates 15mm from the column's ends. The steel tube is in uniaxial tension stress state and won't buckle when the column sustains axial load. This will highly increase the bearing capacity and ductility of the columns. The hysteretic behavior of four square RCST columns and one square RC column were experimentally studied under constant axial load and lateral cyclic load. The wide-to-thickness (D/t) ratio of RCST columns employed in this research is 75. The main variables of the experiment were axial load ratio and compressive strength of the concrete. Based on the findings in this research, RCST columns exhibits high lateral strength, ductility, and energy dissipation ability.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.112-115
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• 2004

An analytical study is conducted using the Galerkin technique to determine the behaviour of thin fibre-reinforced composite pipes under soil pressure. Geometric nonlinearity and material linearity are assumed. It is assumed that the vertical and lateral soil pressures are proportional to the depth and the lateral displacement of the pipe respectively. It is also assumed that the radial shear stress is negligible because the ratio of the thickness to the radius of the pipe is very small. The calculation results are compared with the finite element analysis result.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.213-224
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• 2005

The safety factor of a tunnel considering the failure of supports is important because the failure of supports might cause the collapse of the tunnel. In the previous studies, shotcrete was modelled as beam elements and the failure of the shotcrete was checked according to the allowable working stress concept. In this study, shotcrete was modelled by both beam elements and continuum (elasto-plastic) elements. Safety factors of tunnels were estimated by two dimensional numerical analysis with varying rock mass class, coefficient of lateral pressure, thickness of shotcrete, rock bolt reinforcement and excavation method. Also the study suggested not only a proper amount of supports but also modelling method.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.91-99
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• 2017

Special consideration should be given to differential column shortening during the design and construction of a tall building to mitigate the adverse effects caused by such shortening. The effects of the outrigger - which is conventionally used to increase the lateral stiffness of a tall building - on the differential shortening are investigated in this study. Three analysis models, a constant-section, constant-stress, and general model, are prepared, and the differential shortenings of these models with and without the outrigger are compared. The effects of connection time, sectional area, and location of the outrigger on the differential shortening are studied. The sectional area of the outrigger shows a non-linear relation in reducing the maximum differential shortening. The optimum locations of the single and dual outriggers are investigated by an exhaustive search method, and it is confirmed that a global optimum location exists. This study shows that the outrigger can be utilized to reduce the differential shortening between the interior core wall and the perimeter columns as well as to reduce the lateral displacements due to wind or earthquake loads.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.480-486
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• 1993

We propose and demanstrate a fiber laser as a sensor, whose output is the frequency of beat signals between eigenpolarization modes of the fiber laser. For the measurement of lateral stress, proportional constant of 4.8 kHz/gram is obtained with a good linearity. For the measurements of temperature and longitudinal strain applied to the polarization maintaining fiber laser, proportional constants of 30 kHz/$^{\circ}C$ -cm, and 43 kHz/${\mu}m$, respectively, are obtained.