• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.179-186
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• 2001

It has been known that lap splicing in the longitudinal reinforcement of bridge columns is not desirable for seismic performance, but it is sometimes unavoidable. Lap splices were usually be located in the plastic hinge region of most bridge columns that were constructed before the adoption of the seismic design provision of Korea Bridge Design Specification on 1992. This research is to evacuate the seismic performance of reinforced concrete bridge piers with lap splicing of longitudinal reinforcement in the plastic hinge region, and to develop the enhancement scheme of their seismic capacity by retrofitting with glassfiber sheets and to develop appropriate limited ductility design concept in low or moderate seismicity region. Nine test specimens in the aspect ratio of 4.0 were made with three confinement ratios and three types of lap splicing. Quasi-static tests under three different axial load levees were conducted. It has been observed that displacement ductility ratios of test columns with lap splicing were significantly reduced.

• Journal of the Earthquake Engineering Society of Korea
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• 제17권3호
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• pp.107-115
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• 2013

The purpose of this study was to investigate the performance of hollow reinforced concrete bridge column sections with reinforcement details for material quantity reduction. The proposed reinforcement details has have economic feasibility and rationality and makes construction periods shorter. A model of column sections with reinforcement details for material quantity reduction was tested under quasistatic monotonic loading. As a result, the proposed reinforcement details for material quantity reduction was were equal to existing reinforcement details in terms of the required performance. In the a subsequent paper, the an experimental and analytical study will be performed for the performance assessment of hollow reinforced concrete bridge column sections with reinforcement details for material quantity reduction will be performed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.271-279
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• 2003

The objective of this study is to evaluate the damage of the reinforced concrete bridge piers. For the purpose of this research, twelve reinforced concrete specimens were fabricated and experimented with quasi-static test method. The selected test parameters are lap splice, axial load ratio, confinement steel ratio and number of loading cycle. The method of evaluate of damage index is the model proposed by Park and Ang. In accordance with this research, the most effective test parameter is lap splice of longitudinal steel. Therefore, the retrofit scheme of reinforced concrete bridge piers with lap splice of longitudinal steel, which was constructed before 1992, must be settled without delay. Otherwise, the effect of axial force is trivial. The more confinement steel is less damage index and more loading cycle lead to raise damage. The damage statement proposed Park and Ang is the same with experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• 제19권6호
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• pp.1-9
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• 2015

Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct. Details of reinforcement for rectangular section require a lot of rectangular hoops and cross-ties. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of the flared column. It can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency. The final objectives of this study are to suggest appropriate oblong hoop details and to provide quantitative reference data and tendency for seismic performance or damage assessment based on the drift levels such as residual deformation, elastic strain energy. This paper describes factors of seismic performance such as ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio and effective stiffness.

• Journal of the Korean Society for Advanced Composite Structures
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• 제1권3호
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• pp.10-16
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• 2010

In construction industries, new construction materials are needed to overcome some problems associated with the use of conventional construction materials due to the change of environmental and social requirements. Accordingly, the requirements to be satisfied in the design of civil engineering structures are diversified. As a new construction material in the civil engineering industries, fiber reinforced polymeric plastic (FRP) has a superior corrosion resistance, high specific strength/stiffness, etc. Therefore, such properties can be used to mitigate the problems associated with the use of conventional construction materials. Nowadays, new types of bridge piers and marine piles are being studied for new construction. They are usually made of concrete filled fiber reinforced polymeric plastic tubes (CFFT). In this paper, a new type of FRP-concrete composite pile which is composed of reinforced concrete filled FRP tube (RCFFT) is proposed to improve compressive strength as well as flexural strength. The load carrying capacity of proposed RCFFT compression member is discussed based on the result of experimental and analytical investigations.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제28권4A호
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• pp.611-622
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• 2008

Nonlinear analyses have been carried out for both bridge piers and a bridge structure being repaired using a repair element in order to assess the post-repair seismic response of such structures. For this purpose, a simplified CFRP stress-strain model has been proposed. The analytical predictions incorporating the current developments correlate reasonably well with experimental results in terms of strength and stiffness. In addition, nonlinear dynamaic analyses have also been conducted for a bridge structure in terms of the created multiple earthquake sets to evaluate the effect of pier repair on the response of a whole bridge structure. In these analyses, potential plastic hinge zones of piers are virtually repaired by CFRP and steel jacketing. Comparative results prove the virtual necessity of performing nonlinear post-repair analyses under multiple earthquakes, particularly when the post-repair response features are required. In all, the present approaches are expected to provide salient information regarding a healthy seismic repair intervention of a damaged strcuture.

• Journal of Korean Society of Steel Construction
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• 제15권1호
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• pp.1-8
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• 2003

In locations where the cost of concrete is relatively high or in situations where the weight of concrete members has to be kept to a minimum, it may be more economical to use hollow reinforced concrete vertic al members. Hollow reinforced concrete colun-ms with a low axial load, a moderate longitudinal steel percentage and a reasonably thick wall were found to perform in a ductile manner at the flexural strength, similar to solid columns. Hollow reinforced concrete columns with a high axial load, a high longitudinal steel percentage, and a thin wall were found, however, to behave in a brittle manner at the flexural strength, since the neutral axis is forced to occur away from the inside face of the tube towards the section centroid and, as a result, crushing of concrete occurs near the unconfined inside face of the section. If, however, a steel tube is placed near the inside face of a circular hollow column, the column can be expected not to fail in a brittle manner through the disintegration of the concrete in the compression zone. A design recommendation and example through the moment-curvature analysis program for curvature ductility are herein presented. A theoretical moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted, providing that the stress-strain relation for the concrete and steel are known. In this paper, a unified stress-stain model for confined concrete by Mander is developed foi members with circular sections.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.873-878
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• 2002

This study is performed to investigate the behavior of multi-column piers and to evaluate the seismic performance. In this study, 3 types of scale model piers with 2-column are designed and tested by quasi-static load in both longitudinal and transverse directions. Each type of model consisting of 2 specimens has different reinforcement details in the lap splice of longitudinal bars and amount of transverse reinforcements. This paper reports that relatively large amount of ductility can be achieved by providing sufficient lap-splice length and transverse reinforcements with end hook even if longitudinal bars are lap spliced in the base of pier. But because multi-column piers have small longitudinal stiffness, careful consideration is needed in case of multi-span continuous bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.363-368
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• 2000

The Korean Bridge Design Standard Specifications adopted the seismic design requirements in 1992. However, The current seismic design requirements for bridges are based on the USA seismic codes for sever earthquake. This provides the basic factors that affects the performance of spiral reinforced concrete piers for seismic loading, and The specimen tests are performed based on load-displacement, effective stiffness and displacement ductility, etc. The quasi-static test was adopted in order to investigate seismic performance of the spiral reinforced concrete pier specimens which had different transverse steel amount, spacing and longitudinal steel ratio under different axial load levels. This study is concluded that seismic design for transverse reinforcement content of spiral reinforced concrete column has influenced on axial load and effective stiffness etc.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.37-40
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• 2004

An experimental study was conducted to investigate the stress-strain behavior of confined concrete columns according to transverse reinforcement volumetric ratio. Uniaxial loading tests of eleven column specimens$(250\times100\times500mm)$ with rectangular section were conducted to study effect of confinement. The main variables in this test are transverse reinforcement volumetric ratio and cross tie arrangement. the results indicate that the strength and the ductility of confined concrete columns are subjected to transverse reinforcement volumetric ration and cross tie arrangement.