• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2334-2343
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• 2000

This paper proposes an efficient beam-shell modeling technique for the free vibration analysis of a T-joint thin-walled beam structure. Except a small portion of a T-joint which is modeled by shell elements, the structure is modeled by thin-walled beam elements that can describe warping and distortion. In order to match the shell and thin-walled beam elements at the interface of the dissimilar elements, a technique based on a pseudo inverse matrix is formulated. This paper also examines the role of the thin-walled element taking into account the distortion and warping deformation degrees of freedom in predicting accurately the dynamic characteristics of a T-joint thin-walled structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.698-701
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• 2005

We have investigated experimentally a nano patterning using electron beam lithography for the nickel stamper fabrication. Recently, DVD and Blu-ray disk(BD) have nano-scale patterns in order to increase the storage density. Specially, BD has 100nm-scale patterns which are generally fabricated by electron beam lithography. In this paper, we found optimum condition of electron-beam lithography for 100nm-scale patterning. We controlled various conditions of EHP(acceleration voltage), beam current, dose and aperture size in order to obtain optimum conditions. We used 100nm-thick PMMA layer on a silicon wafer as photoresist. We found that EHP was the most dominant factor in electron-beam lithography.

• Structural Engineering and Mechanics
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• v.32 no.3
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• pp.447-457
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• 2009

A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.1
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• pp.32-40
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• 2010

The purpose of this study was to evaluate structural safety and economic efficiency of prestressed hybrid beam using T-shape steel member which was developed to build large span educational facilities. Hybrid beam specimens were manufactured with 16.0m long and load was uniformly distributed by 12.0kN steel hexahedrons. In this study, honeycomb beam design process was introduced to T-shape section steel beam design. Vibration condition of specimens were analyzed by Korea Building Code 2009 and AISC Steel Design Guide Series-11. As a result, the prestressed hybrid beam with T-shape steel member has about 10.4% of cost reduction effect.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.425-430
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• 2002

This thesis is a study on behavior for anchorage zone in prestressed double T beam using strut-tie model. Stress conditions of Anchorage zone in prestressed double T beam are very disturbed because large concentrated forces act on relatively small areas. Hence, anchorage zone must be considered in Design of prestressed double T beam. If irrational design or irrational construction be conducted, that may lose stability in capacity as structure. In current design practice, certain parts of structure are designed with extreme accuracy, while anchorage zone in prestressed double T beam is designed using common sense, and experience. Therefore, it is generally very conservative. For that reason, logical, reasonable concept and accuracies are desired at design of anchorage zone in prestressed double T beam. Strut-tie method satisfies those desires. In this thesis, anchorage zone in prestressed double T beam is analyzed by considering prestressing forces. Strut-tie model is constructed based on principle stress trajectory obtained from 3D-finite element analysis in anchorage zone, and amounts of reinforcement be obtained. Results of analysis are compared with the way used in current design practice, and this thesis presents that strut-tie model can be an economical design than current design methods without losing the degree of safety.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.49-56
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• 2007

The existing Double T-Beams have been positively constructed in America and Europe due to their elegant appearance and simple section shapes. However, there are some problems; thery are relatively weak in the structural resistance, and need to use somewhat limited and complicated construction methods. In this paper, new composite beams made of concrete and steel are proposed, by taking adventage of their merits in an effort to solve thess controversial problems. In addition, feasibility is presented in developing composite Double T-Beams by introducing pre-stressing forces as well to enhance structural safety.

• Computers and Concrete
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• v.17 no.1
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• pp.67-86
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• 2016

Strengthening as well as correcting unsightly deflections of reinforced concrete (RC) beam may be accomplished by retrofitting. An innovative way to do this retrofitting that is proposed in this study utilizes turnbuckle to apply external post-tensioning. This Turnbuckle External Post-Tensioning (T-EPT) was experimentally proven to improve the serviceability and load carrying capacity of reinforced concrete beams. The T-EPT system comprises a braced steel frame and a turnbuckle mechanism to provide the prestressing force. To further develop the T-EPT, this research aims to develop a numerical scheme to analyze the structural performance of reinforced concrete beams with this kind of retrofitting. The fiber method analysis was used as the numerical scheme. The fiber method is a simplified finite element method that is used in this study to predict the elastic and inelastic behavior of a reinforced concrete beam. With this, parametric study was conducted so that the effective setup of doing the T-EPT retrofitting may be determined. Different T-EPT configurations were investigated and their effectiveness evaluated. Overall, the T-EPT was effective in improving the serviceability condition and load carrying capacity of reinforced concrete beam.

• Composites Research
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• v.30 no.5
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• pp.297-302
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• 2017

Finite element analysis of T-beam laminate structure under bending-torsional loading was conducted to prevent the delamination which is the major failure behavior on laminated composites. Three-dimensional preform, which is that fabric is braided through thickness direction, is suggested from the laminate analysis. The analysis aimed to optimize the fiber ratio in laminated composites. After it is suggested that guideline for design of T-beam structure using commercial software ANSYS Composites PrePost. The results show that strength of T-beam structure is increased 21.6% when the fiber density along with beam length direction is two times bigger than transverse direction. It is expected that development of high strength T-beam structure using designed three-dimensional preform.

• Steel and Composite Structures
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• v.21 no.6
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• pp.1251-1264
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• 2016

After observing relatively poor performance of bolted web-welded flange beam-to-column connections during 1994 Northridge earthquake, various types of connections based on two concepts of: (i) strengthening the connection; and (ii) weakening the beam ends were proposed. Among these modified or newly proposed connections, bolted T-stub connection follows the concept of strengthening. One of the connections with the idea of weakening the beam ends is reduced beam section (RBS). In this paper, finite element simulation is used to study the cyclic behavior of a new proposed connection developed by using a combination of both mentioned concepts. Investigated connections are exterior beam-to-column connections designed to comply with AISC provisions. The results show that moment capacity and dissipated energy of the new proposed connection is almost the same as those computed for a T-stub connection and higher than corresponding values for an RBS connection.

• Journal of Korean Society of Steel Construction
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• v.13 no.6
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• pp.715-723
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• 2001

This paper represents the behavior of CFT column to H-beam full-scale connection with external T-stiffener. 6 specimens whose T-stiffeners which are compounded of vertical element and horizontal element were made under the parameter of the strength ratio of each elements(vertical element and horizontal element in T-stiffener) to the beam full plastic moment. The analysis-parameters demonstrated in the base of the data that we get in experiment are strength stiffness, and plastic rotational capacity. All of specimen showed stable hysteretic behavior, and the horizontal element is more critical than vertical element in strength and stiffness. The mean beam plastic rotation of all specimen except the TS-2 specimen is 2.97% rad.