• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.51-62
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• 2010

The purpose of this study was to investigate the performance of hollow precast segmental PSC bridge columns. The proposed system can reduce work at a construction site and makes construction periods shorter. Shortened construction times, in turn, lead to important safety and economic advantages when traffic disruption or rerouting is necessary. Two hollow precast segmental PSC bridge columns were tested under a constant axial load and a quasistatic, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures, was used. The proposed numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.973-978
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• 2003

This paper describes the experimental study on seismic strengthening effect of circular bridge columns with poor lap-splice details using FRP(Fiber Reinforced Plastic) wrapping, The as-built column suffered brittle failure due to the deterioration of lap-spliced longitudinal reinforcement without developing its flexural capacity or any ductility, The strengthening columns using FRP wrapping showed significant improvement in seismic performance due to FRP's confinement effect.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.97-100
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• 2005

It has been known that lab splices of the longitudinal reinforcement steel in bridge columns are 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 evaluate 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 steel bands. It was observed that RC bridge specimens with lap-spliced longitudinal steels appeared to fail at low curvature and displacement ductility, but significant improvement was appeared in the ductility of RC specimens with steel bands retrofitted around the plastic hinge region.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.247-255
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• 1999

Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers circular hollow columns are widely used in Korean highway bridges Since the occurrence of 1995 Kobe earthquake there have been much concern about seismic design for various infrastructures inclusive of bridge structures. It is however understood that there are not much research works for nonlinear behavior circular hollow columns subjected to earthquake motions. The ultimate of this experimental research is to investigate nonlinear behavior of hollow reinforced concrete bridge piers under the quasi-static cyclic load test and than to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. It can be concluded from Quasi-static test for 7 bridge piers that approximate 4-5 ductility factor can be experimentally obtained for bridge piers nonseismically designed in conventional way which approximate 5-6 ductility factor for those seismically designed.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.931-936
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• 2003

Lap splices were located in the plastic hinge region of most bridge piers that were constructed before the adoption of the seismic design provision of Korea Highway Design Specification on 1992. Lap splicing is also permitted if hoops or spiral reinforcement are provided over the lap length in the current seismic design provision. But sudden brittle failure of lap splices may occur under inelastic cyclic loading. The purpose of this study is the analytical prediction of nonlinear hysteretic behavior and ductility capacity of reinforced concrete bridge piers with lap splices under cyclic loading. For this purpose, a nonlinear analysis program, RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) is used. Lap spliced bar element is developed to predict behaviors of lap spliced bar. Maximum bar stress and slip of lap spliced bar is considered.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.453-456
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• 2003

This research is to evaluate the seismic performance of reinforced concrete bridge piers with lap-spliced longitudinal reinforcement steels in the plastic hinge region, and to develop the enhancement scheme of their seismic capacity. Six circular columns of 0.6m diameter and 1.5m height were made with two confinement steel ratios. They were damaged under series of artificial earthquakes that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under an axial load, P=$0.1f_{ck}A_{g}$, and residual seismic performance of damaged columns was evaluated. Test results show that RC bridge piers with lap-spliced longitudinal steels behaved with minor damage even under artificial earthquakes with 0.22g PGA, but failed at low ductility subjected to the subsequent quasi-static load test. This failure was due to the debonding of the lap splice. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region showed significant improvement both in flexural strength and displacement ductility.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.125-133
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• 2010

Researches and studies which have been conducted so far on external confinement of long span concrete columns have mainly concentrated on concentric loading. But, long span bridge concrete columns over the sea are mainly subjected to concentrated axial load, and at the same time lange amount of moment by eccentric load. This paper experimentally investigates the performance of externally confined high-strength concrete columns subjected to loading mechanism and evaluates the effectiveness of two confinement materials carbon fibre and high performance glass fibre. Twelve short columns with the same dimensions were cast and tested Six columns were reinforced with hoop bars, the remaining six columns were reinforced with spiral bars and wrapped with three layers of carbon failure and high performance glass FRP sheets. Test variables considered were the shape of internal reinforcement and strengthening materials according to loading location. The experimental results showed that eccentric load could obviously lower down the maximum failure load of FRP-confined concrete columns, compared with the columns under concentric load. And compared with the carbon FRP-confined reinforced concrete columns, high performance glass FRP-confined columns displayed a higher load capacity and ductility, when tested both concentrically and eccentrically.

• Computational Structural Engineering
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• v.20 no.2 s.76
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• pp.69-79
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• 2007

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.502-505
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• 2006

The Purpose of this study is to offer an appropriate and reliable safety evaluation method the reinforced concrete members like as reinforced concrete deep beams and reinforced concrete columns, etc. A nonlinear finite element analysis program named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used to evaluate the ultimate strength analytically for the reinforced concrete members that have complicated mechanical behaviors. The nonlinear material model for the reinforced concrete is composed of models for characterizing the behavior of the concrete, in addition to a model for characterizing the reinforcing bars. The proposed numerical method for the safety evaluation of reinforced concrete bridge structures that is consisted of reinforced concrete member is verified by comparison with reliable experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.505-511
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• 2003

Experimental investigation was conducted into the flexure/shear-critical behavior of earthquake-damaged reinforced concrete columns with lap splicing of longitudinal reinforcement in the plastic hinge region. Six test specimens in the aspect ratio of 2,5 were made with test parameters: confinement ratios, lap splices, and retrofitting FRP materials. They were damaged under series of artificial earthquakes of which magnitude could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under a constant axial load, P=$0.1f_{ck}A_g. Residual seismic performance of damaged columns was evaluated and compared to that of the corresponding original columns. Test results show that RC bridge piers with lap-spliced longitudinal steels in the plastic hinge region appeared to fail at low ductility. This was due to the debonding of the lap splice, which resulted from insufficient development of the longitudinal steels. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region indicated significant improvement both in flexural strength and displacement ductility, and strain energy ductility.