• Proceedings of the KSR Conference
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• 2005.05a
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• pp.562-567
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• 2005

F.C.M applied from Jin Jung Li to Yang Su Li(660m) in Puk Han River Bridge(1,414m) construction part is a construction method on the double-track construction which is the third section part of work, called Chung Ang Railroad Line(Deok-So${\sim}$Won-Ju). This method is the beginning application on Railroad Bridge. After completing upper slab structure, there are several following works such as setting up ballast, sleepers and laying long rails. So it is important to consider the properties of Railroad Bridge while designing the length of bridge and its single span. After the physical process study the shrinkage and creep of concrete, bending up by prestressing in general PSM bridge, relaxation of tendons as time goes by after post-tension, the conclusion of such a study is applied to the Puk-Han River Bridge in this construction field.

• Computers and Concrete
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• v.11 no.6
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• pp.515-529
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• 2013

The moment-curvature relation for simple bending is a well-studied subject and the classical moment-curvature diagram is commonly found in literature. The influence of axial forces has generally been considered as compression onto symmetrically reinforced cross-sections, thus strain at the reference fiber never has been an issue. However, when dealing with integral structures, which are usually statically indeterminate in different degrees, these concepts are not sufficient. Their horizontal elements are often completely restrained, which, under imposed deformations, leads to moderate compressive or tensile axial forces. The authors propose to analyze conventional beam cross-sections with moment-curvature diagrams considering asymmetrically reinforced cross-sections under combined influence of bending and moderate axial force. In addition a new diagram is introduced that expands the common moment-curvature relation onto the strain variation at the reference fiber. A parametric study presented in this article reveals the significant influence of selected cross-section parameters.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.109-112
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• 2004

It was found from the previous experimental studies that the long-term deformation of SRC columns was quite different from that of RC columns. A new approach method is needed to quantitatively predict the long-term deformation of SRC columns. In this study, the causes of the difference between the behaviors of RC and SRC columns are investigated and discussed. SRC columns exhibit a time-dependent relative humidity distribution in a cross section differently from that of RC columns due to the presence of a flange, which interferes with the moisture diffusion of concrete. This different relative humidity distribution may reduce the drying shrinkage and the drying creep in comparison with RC columns.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.173-180
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• 2011

Recently, many railway stations are built under the railway line in urban area. The passage of railway vehicles generates mechanical vibrations of a wide range of frequency. Thus, it is required to place structural vibration isolation systems to reduce vibration and noise originating from surrounding environments. This study is to investigate the maximum floating slab length based on track/floating slab interaction analyses. Actions to be taken into account include temperature, braking/acceleration, bending of the deck, and creep/shrinkage. The additional rail stress has been chosen for the criterion for the maximum slab length. In addition, further analyses are performed to include the stopper which restrict the in-plane movement of the floating slab track. Several alternatives for stopper positions were thoroughly studied in this study.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.534-537
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• 2006

The jacking of cantilever before key segment closure has been introduced to offset the long term forces caused by creep and shrinkage. In this paper, the behavior of structural system with the jacking force in approach bridge of Incheon Bridge was reviewed. The introduction of jacking force effectively offset the long term horizontal forces and allows economic substructure member design.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.723-730
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• 2011

It is very important to experimentally evaluate concrete behavior at elevated temperature because aggregates make up approximately 80 percent of volume in concrete. In this study, an experiment to evaluate mechanical properties of normal weight and light weight concrete of 60 MPa was conducted. Based on loading level of 0, 20 and 40 percent, the tests of 28 days compressive strength, elastic modulus, thermal strain, total strain, and transient creep using ${\phi}100{\times}200mm$ cylindrical specimens at elevated temperature were performed. Then, the results were compared with CEB (Committes Euro-international du Beton) model code. The results showed that thermal strain of light weight concrete was smaller than normal weight concrete. Also, the results showed that compressive strength of light concrete at $700^{\circ}C$ was higher than normal weight concrete and CEB code, similar to that obtained at ambient temperature. Transient creep developed from loading at a critical temperature of $500^{\circ}C$ caused the concrete strains to change from expansion to compression. The transient creep test result showed that internal force was high when the ratio of shrinkage between concrete and aggregate was more influential than thermal expansion.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.135-139
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• 1992

콘크리트가 구조용 재료로써 활용되기 시작한 이래 크리프와 건조수축의 특성규명을 위한 연구는 많은 연구자들에 의해 수행되어 왔다. 그러나 그 거동은 아직도 명확히 규명된 것은 아니며 이는 고강도 콘크리트의 경우 더욱 그러하다. 따라서 본 연구는 현재 국내에서 그 사용이 늘어나고 있는 고강도 콘크리트의 크리프 및 건조수축특성에 대한 기본적인 자료를 제공하기 위해 수행되었다. 본 연구의 주된 변수는 고강도 콘크리트, 배근유무, 철근비, 건조조건, 재하재령 등이며 이들의 영향에 대한 크리크 및 건조수축특성을 규명하였다. 이것은 앞으로 고강도콘크리트구조물 설계에 중요한 자료가 될 것으로 사료된다.

• 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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.24-25
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• 2016

In this study, the thermal strain of high strength concrete with the compressive strength of 80, 130, 180MPa were measured under 25% of compressive strength loading condition. As results, it is considered that decline of the elastic modulus and shrinkage strain of high strength concrete become grater at the elevated temperatures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.417-424
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• 2001

It is very important to know the magnitude of the restraint moment which is appeared at the inner-support of the continuous PSC girder. The Age-adjusted Effective Modulus Method(AEMM) is used to get the magnitude of the restraint moment for the purpose of the time-dependent analysis of the concrete. The important factors for computing the restraint moment, the creep coefficient and the shrinkage strain are computed by comparing Korean specification with AC1209. The restrain moment is created by the individual continuity load. The main purpose of this paper is ensuring the safety of structure by acquiring the time-dependent stress acting on the concrete because the process of construction is getting difficult due to the advance of technology. The negative moment at the inner-support is decreased about 55% by introducing the process of making the continuous bridge relatively early.