• Steel and Composite Structures
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• v.1 no.3
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• pp.313-328
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• 2001

This paper presents a three-dimensional finite element analysis methodology for a quantitative evaluation of confinement in concrete-filled box-shaped unstiffened steel columns. The confinement effects of concrete in non-circular sections can be assessed in terms of maximum average lateral pressure. A brief review of a previous method adopted for the same purpose is also presented. The previous method is based on a two-dimensional finite element analysis method involving a concrete-steel interaction model. In both the present and previous methods, average lateral pressure on concrete is computed by means of the interaction forces present at the concrete-steel interface. Subsequently, the strength enhancement of confined concrete is empirically related to the maximum average lateral pressure. The results of the former and latter methods are then compared. It is found that the results of both methods are compatible in terms of confined concrete strengths, although the interaction model yields a somewhat overestimated estimation of confinement than those of the present method when relatively high strength concrete is used. Furthermore, the confinement in rectangular-shaped sections is investigated and the reliability of previously adopted simplifications in such cases is discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.351-354
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• 2003

Triaxial behavior of concrete cylinders wrapped with FRP material has been investigated for the increase of concrete strength by lateral confinement. Using the model by Richart et al., a modified empirical equation was proposed to estimate the strength of concrete cylinders with FRP confinement based on the linear relationship between the concrete strength and lateral confining pressure. From the experimental stress-strain result of the cylinder specimens having similar confining pressure, less ductility was observed for higher strength concrete. But the compressive strength of the specimen was linearly increased by lateral confinement. The confinement effectiveness coefficient for the strength enhancement of the cylinders by FRP wrap was obtained as 2.27 from the regression analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.42-47
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• 1996

Due to high increase of labor charge and necessarity of better quality control on concrete, various studies have been carried out to improve a flowability of concrete without the use of mechanical vibrator. As a result of enthusiastic study, one can closely access to the development of high flowable concrete in a laboratorial view. Application to practical field, however, is still far as long as a regulation for construction is not properly specified. Based on the idea that lateral pressure measured from high flowable concrete will be larger than those from general typed concrete, we read a series of lateral pressure from mechanical pressure plate and compared those with the values calculated form specified formula.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.295-300
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• 1996

The design of formwork system for vertical form faces is controlled by pressures predicted to act against the formwork by fresh concrete. An overestimation of pressure results in heavy, and ex-pensive formwork. An underestimation results in malformed structure, of in some cases, it causes the failure of the formwork. This study is a preliminary step in determination lateral pressures with High folwable concrete. To estimate lateral formwork pressures, we measured tensile strain of formtie in the movable part of the form. From the experimental results maximum lateral pressure and the location at which maximum pressures occurs, were determined. The experimental results are compared with the results predicted by the Gardner & Qureshi's proposed equation and the accepted Korean Standard Specification for concrete and ACI equation.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.609-614
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• 1998

Lateral pressure by tied reinforcement greatly enhances the maximum strength and ductility of columns under concentric loading. The lateral confinement effects will be improves ductility of high-strength concrete. The major purpose of this paper is to study on the improvements of maximum strength and strain at the point of tied high-strength concrete columns subject to axial loads. For this purpose, this study collected the other analytical results and the experimental data that has been performed by a lot of worldwide researchers and also analyzed it statistically. As the result, the theoretical equation for predict maximum strength and strain at the point was proposed. It is based on calculation of lateral confinement pressure generate from tensile that develop in transverse reinforcement.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.142-145
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• 1998

The purpose of this study is to estimate lateral formwork pressure controlled by super-workable fresh concrete using prototype structrues such as, tall wall, retaining wall, and beam quantitativly. As a result of this experiment, a function which can be used to design a formwork system and to predict formwork pressure curve is formulated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.97-102
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• 2002

Two dimensional Analysis has been applied to most of tunnel lining design in these days. Two dimensional analysis uses beam or curved beam element for finite element method. But because the behaviors of tunnel concrete lining structure is near to shell, it is required to model the tunnel lining as shell structure for safety design of tunnel lining structure. In this paper, two dimensional analysis by beam element and the three dimensional analysis by shell element of tunnel concrete lining are studied, in which 3 type of tunnel lining and lateral pressure factors are considered. As results of the study, three dimensional analyses of the behavior of tunnel concrete lining structure considering lateral pressure factor shows that the moment of three dimensional analysis is greater than those of two dimensional analysis. The results shows that three dimensional analysis is necessary for safety design of tunnel lining.

• KIEAE Journal
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• v.9 no.1
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• pp.39-45
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• 2009

The lateral pressure that functions on the form of the rammed earth method occupies an important part in the construction of the form. The following research constructed testing forms of $800mm{\times}1200mm$, that have the wall thickness of 200mm, 300mm, 400mm and 500mm to measure the lateral pressures according to the wall thicknesses. Research showed that compared to the concrete construction lateral pressures, the form results measured 2.3-8.9 times higher, and rather than thickness of the form, the distance between the rammer and mold and assuring time had direct relation to the lateral pressure of the form.

• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.111-135
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• 2013

An experimental study has been carried out on square plain concrete (PC) and reinforced concrete (RC) columns strengthened with carbon fiber-reinforced polymer (CFRP) sheets. A total of 78 specimens were loaded to failure in axial compression and investigated in both axial and transverse directions. Slenderness of the columns, number of wrap layers and concrete strength were the test parameters. Compressive stress, axial and hoop strains were recorded to evaluate the stress-strain relationship, ultimate strength and ductility of the specimens. Results clearly demonstrate that composite wrapping can enhance the structural performance of square columns in terms of both maximum strength and ductility. On the basis of the effective lateral confining pressure of composite jacket and the effective FRP strain coefficient, new peak stress equations were proposed to predict the axial strength and corresponding strain of FRP-confined square concrete columns. This model incorporates the effect of the effective circumferential FRP failure strain and the effect of the effective lateral confining pressure. The results show that the predictions of the model agree well with the test data.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.8-9
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• 2021

FCP requires different curvatures and shapes according to the method of division, and it is necessary to manufacture a formwork accordingly. FCP production equipment consists of CNC equipment and side shape control equipment. This can be implemented in various shapes of upper, lower, and side surfaces. In the side shape control equipment, it is implemented as a variable side formwork. Among the required performance of the variable side formwork, there is stiffness against side pressure, which needs to be verified. Therefore, in this study, the FCP fabrication experiment is conducted with the developed variable side formwork. By analyzing the error in the shape of the fabricated FCP, the lateral pressure resistance capability of the side form is measured and verified.