• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.293-298
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• 1995

The strength of shear connectors embedded in lightweight concrete slab with deck plate is influenced by various factors of deck plate, shear conncetor and concrete. Generally, it is reported that the strength of shear connector in lightweight concrete decreases in comparison with that in normal concrete. So this paper is to use compressive strength of lilghtweight concrete, width-height ratio of deck plate, and cross sectional area of shear conncetor as variables, to evaluate the strength of shear conncetors in composite beam of steel and lilghtweight concrete slabs with deck plate, and then to suggest the reasonable strength equation by comparing the push-out test results with establixhed strength formula. As the result of 24 specimens test, in case of lightweight concrete slab with deck plate, it has showed that in the same strength, the strength of shear connector decreased about 10~20% in comparison with that in normal concrete. In spite of lightweight concrete, the test results were closely approached the established strength formula of shear connector using Fisher's reduction coefficient.

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.651-661
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• 2017

This paper presents an experimental study of bond-slip behavior of reinforced lightweight aggregate concrete (LC) and normal weight concrete (NC) with embedded steel bar. Tests were conducted on tension-pull specimens that had cross-sectional dimension with a reinforcing bar embedded in the center section. The experimental variables include concrete strength (20, 40, and 60 MPa) and coarse aggregate type (normal-weight aggregate and reservoir sludge lightweight aggregate). The test results show that as concrete compressive strength increased, the magnitudes of the slip of the LC specimens were greater than those of the NC specimens. Moreover, the bond strength and stiffness approaches zero at the loaded end, or close to the central anchored point of the specimen. In addition, the proposed bond stress-slip equation can effectively estimate the behavior of bond stress and steel bar slipping.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.78-85
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• 1999

In this study, I-type girders used as main members of a two span continuous steel bridge, are optimally designed by a Load and Resistance Factor Design method(LRFD) using an numerical optimization method. The width, height web thickness and flange thickness of the main girder are set as design variables, and light weight design is attempted by choosing the cross-sectional area as an object function. The main program is coded with C++ and connected with optimization modul ADS, which is coded with FORTRAN. The results of the program show that the stress constraints of noncomposite section during the initial construction stage become active in the positive moment area and the service limit state constaints become active in the negative moment area.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.129-136
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• 2012

On this study, $CO_2$ gas, net of Ar gas, and mixed gas in solid wire(AWS ER 70S-6) and flux cored wire(AWS E71T-1) were used to weld on Mild steel(SS400). After the progress, the status changes of the welds in Mild steel(SS400) were investigated with compositional changes. For stable experiments, welding was conducted using the automatic feeder. Radiation testing, hardness testing, chemical composition analysis and penetrated cross-section were measured. Through these experiments, shapes of penetrated cross-section, chemical composition changes, and weld defects according to the variation of welding gas were known. Weld defects and weld cross-sectional shapes by the variation of the welding voltage were also detected.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.463-468
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• 2003

A finite element formulation to predict the flexural behavior of composite girder is presented in which the early-age properties of concrete are specified including maturing of elastic modulus, creep and shrinkage. The time dependent constitutive relation accounting for the early-age concrete properties is derived in an incremental format by expanding the total form of stress-strain relation by the first order Taylor series with respect to the reference time. The total potential energy of the flexural composite member is minimized to derive the time dependent finite element equilibrium equation. Numerical applications are made for the 3-span double composite steel box girders which is a composite bridge girder filled with concrete at the bottom of the steel box in the negative moment region. The numerical analysis with considering the variation of concrete elastic modulus are performed to investigate the effect of it on the early-age behavior of composite structures. The one dimensional finite element analysis results are compared with the analytical method based on the sectional analysis. Close agreement is observed among the two methods.

• Steel and Composite Structures
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• v.19 no.6
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• pp.1483-1499
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• 2015

With the improvement of the quality of construction materials and the development of construction technologies, large-scale long-span steel frame buildings have been built recently. The P.E.B system using tapered members is being employed as an economically-efficient long-span structure owing to its advantage of being able to distribute stress appropriately depending on the size of sectional areas of members. However, in December 2005 and in February 2014, P.E.B buildings collapsed due to sudden loads such as snow loads and wind gusts. In this study, the design and construction of the P.E.B system in Korea were analyzed and its structural safety was evaluated using the finite element analysis program to suggest how to improve the P.E.B system in order to promote the efficient and rational application of the system.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.423-426
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• 2005

Steel reinforced concrete (SRC) columns, which are widely employed in high-rise buildings, exhibit particular time-dependent behavior due to creep and shrinkage of the concrete, and this behavior may cause problems related to serviceability and structural stability. SRC columns also exhibit a time-dependent, cross-sectional relative humidity distribution that differs from reinforced concrete (RC) columns, due to the presence of an inner steel plate, which interferes with the moisture diffusion of concrete. This differential moisture distribution of SRC columns may reduce the drying shrinkage and the drying creep as contrasted with RC columns. Therefore, we propose that the differential moisture distribution be taken into account to accurately predict SRC column shortening.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.419-422
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• 2005

Prestressed composite girder bridges with concrete infilled steel tube at negative flexural moment region takes the advantages provided due to the interactive reaction in the steel tube and concrete interface layer, enhancing local buckling resistance and the concrete strength provided by the lateral confining effect of concrete. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to negative flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.

• Earthquakes and Structures
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• v.7 no.5
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• pp.753-777
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• 2014

This study investigates the behavior of precast concrete cantilever wall systems with new vertical connections under cyclic loading. C-type steel connections for PC wall systems are proposed for the transfer of bending moments between walls in the vertical direction, whereas a shear key in the center of the wall is prepared to transfer shear forces by bearing pressure. The proposed connections are assembled easily because the directions of the slots are different at the edges of the walls. Structural performance characteristics such as the strength, ductility, and failure modes of test specimens were investigated. The longitudinal reinforcing steel bars, which are connected to the C-type connections, yielded first. Ultimate deformation was terminated owing to premature failure of the connections. The strength and deformation obtained from the cross-sectional analysis were generally similar to experimental data.

• Structural Engineering and Mechanics
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• v.48 no.3
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• pp.383-394
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• 2013

Cold-formed profiles have been largely used in the building industry because they can be easily produced and because they allow for a wide range of sections and thus can be utilized to meet different project requirements. Attainment of maximum performance by structural elements with low use of material is a challenge for engineering projects. This paper presents a numerical study aimed at minimizing the weight of lipped and unlipped cold-formed channel columns, following the AISI 2007 specification. Flexural, torsional and torsional-flexural buckling of columns was considered as constraints. The simulated annealing method was used for optimization. Several numerical simulations are presented and discussed to validate the proposal, in addition to an experimental example that qualifies its implementation. The ratios between lips, web width, and flange width are analyzed. Finally, it may be concluded that the optimization process yields excellent results in terms of cross-sectional area reduction.