• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.229-234
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• 2000

교량의 교각 및 교대에 대한 세굴의 영향은 많은 학자들의 관심이 되어왔다. 연구의 주된 관심은 세굴에 영향을 미치는 인자들의 역학적인 거동에 대한 것으로써 세굴인자들의 최대 영향 및 최대세굴심을 예측하는 적절한 방법들이 연구되었다. 특히, 교각에서 일어나는 세굴은 이동하는 유체의 역학적인 상호작용과 불균등하게 분포된 하상입자들을 포함하는 3차원적인 문제로서, 그 현상이 대단히 복잡하여 하천흐름과 하상재료의 특성 및 교각의 형상과 같은 여러 요소에 의해 지배를 받기 때문에 세굴에 대한 정확한 예측은 매우 어렵다. 따라서, 복잡한 세굴인자들로 인해 세굴에 관한 연구는 주로 실험에 의하여 이루어지고 있는 실정이다. (중략)

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1349-1356
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• 1994

The results of laboratory experiments on the clear-water scour of cohesionless bed sediment for three types of pier shape were presented. According to the experimental data, the local scouring around the pier was initiated at $V/V_c=0.4{\sim}0.5$ and $Fr_p{\fallingdotseq}0.2$, and the relative local scour depths linearly increased with respect to the velocity ratio and the pier Froude number. The relative scour depth had the linear relationship with ${\tau}_r$ for ${\tau}_r$ < $10^{-4}$, but it tends to become constant for ${\tau}_r$ > $10^{-4}$, irrespective of ${\tau}_r$. And also the relative scour depths showed the close relationship with both the geometric standard deviation and the pier shape.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.29-36
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• 2001

Same as-built drawings in national roadway bridges in Korea were examined. As a result, many bridge piers were found whose aspect ratios are in the vicinity of 2.5. These columns are expected to do shear-flexure behaviour, but the previous research works considered flexure behaviour columns only. In the study, therefore, a shear-flexure behaviour column was selected as the model pier, and quasi static test on the full and 1/2 scale models was carried out. From the test results, the scale effect on the seismic performance evaluation was analyzed, and the seismic performance of the model bridge pier without seismic details was evaluated by the capacity spectrum method.

• Water for future
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• v.26 no.4
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• pp.107-115
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• 1993

The results of laboratory experiments on the clear-water local scour of cohesionless bed sediment at three types of the pier shape are presented. Based on the experimental data, the relative equilibrium depth of local scour is related to the pier shape, the geometric standard deviation of the bed material, the velocity ratio and the pier Froude number. The relative local scour depths were smallest ant the round-nosed pier and remarkably reduced at the non-uniform bed sediment, comparing with those at the uniform bed material. The effect of sediment grading on the local scour reduction was discussed and compared with Raudkivi and Ettema's experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.129-130
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• 2010

Lap splice of longitudinal reinforcing steels was located in the plastic hinge region of most bridge piers that had been designed and constructed before the adoption of the 1992 seismic design provision of Korea Highway Design Specification. This research aims at improving the seismic performance of reinforced concrete bridge piers with lap-spliced longitudinal steels, of which the plastic hinge region was wrapped by the shape memory alloy (SMA) wires. Quasi-static test was used to investigate the seismic behaviours of RC test specimens.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.687-696
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• 2004

It has been known that practically unavoidable lap splices of longitudinal reinforcement in the plastic hinge region have a bad effect on the seismic performance of reinforced concrete bridge columns. Lap splices were usually located in the plastic hinge region of most bridge columns designed before the implementation of the new seismic design provisions of 1992 Korea Bridge Design specification. The objective of this research is to evaluate the seismic performance of full-sized reinforced concrete bridge piers with lap splice of longitudinal reinforcement in the plastic hinge region, and to develop an appropriate lateral confinement concept of RC bridge columns with lap-spliced longitudinal steels in low or moderate seismicity region. Eight test specimens in the aspect ratio of 4.0 were made with three types of lap splicing, two levels of confinement steel ratios and two types of tie configurations. It was confirmed from the Quasi-Static test that displacement ductility ratios were significantly reduced for nonseismic test columns with lap spliced longitudinal steels but were satisfied the seismic requirement for limited ductile design specimens. As a conclusion, pertinent lateral confinement content was proposed for the seismic. performance of RC bridge piers with $50\%$ lap-spliced longitudinal reinforcing steels in low or moderate seismicity region.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.1-12
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• 2004

Due to the 1989 Loma Prieta, 1995 Hyogoken Nambu earthquakes, etc, a number of bridge columns  were collapsed in flexure-shear failures as a consequence of the premature termination of the column longitudinal reinforcement. Nevertheless, previous researches for the performance of bridge columns were concentrated on the flexural failure mode. It is well understood that the seismic behaviour of RC bridge piers was dependent on the performance of the plastic hinge of RC bridge piers, the ductility of which was desirable to be computed on the basis of the curvature. Experimental investigation was made to evaluate the variation of the curvature of the plastic hinge  region for the seismic performance of earthquake-damaged RC columns in flexure-shear failure mode. Seven 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 that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading under a constant axial load, $P=0.1f_{ck}A_g$. Residual seismic capacity of damaged specimens was evaluated by analzying the moment-curvature hysteresis and the curvature ductility. Test results show that the biggest curvature was developed around 15cm above the footing, which induced the column failure. It was observed that RC bridge specimens with lap-spliced longitudinal steels appeared to fail at low curvature ductility but significant improvement was made in the curvature ductility of RC specimens with FRP straps wrapped around the plastic hinge region. Based on the experimental variation of the curvature of RC specimens, new equivalent length of the plastic hinge region was proposed by considering the lateral confinement in this study. The analytical and experimental relationship between the displacement and the curvature ductility were compared based on this proposal, which gave excellent result.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.144-149
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• 2011

합류부에서의 수공구조물의 설치는 수리학적으로는 매우 불리하며, 최근 심각해지고 있는 국지성 집중호우로 인한 과중한 유량이 합류부에 집적되어 홍수위를 상승시킴으로써 하천 범람 피해의 주원인이 된다. 본 연구에서는 1차원 HEC-RAS 및 2차원 수치모형 CCH2D을 이용하여 합류부에서의 교각설치에 따른 하천흐름 변화를 분석하고 각 모형의 성과를 비교 검토한다. 또한 2차원 모형인 CCHE2D 모형의 원형교각 배치에 대한 단점을 보완하고자 2차원 수리해석 모형인 FLUMEN모형과 함께 비교 분석하여 실제 교각의 배치, 형상 및 제원이 고려된 격자망을 이용하여 합류부 주변에 위치한 교량에 의한 흐름 유동특성을 평가한다.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.823-832
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• 2004

The purpose of this research is to investigate the flexure-shear behavior of bridge columns under seismic loads. Four full scale circular reinforced concrete columns were tested under cyclic lateral load with constant axial load. The selected test variables are aspect ratio(1.825, 2.5, 4.0), transverse steel configuration, and longitudinal steel ratio. Volumetric ratio of transverse hoop of all the columns is 0.0023 in the plastic hinge region. It corresponds to $24\%$ of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by limited ductility concept. The columns showed flexural failure or flexure-shear failure depending on the test variables. Failure behavior and seismic performance are investigated and discussed in this paper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.143-153
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• 2021

The corroded pier that has corrosion of the tranverse steel, main steel and lapsplice directly affects the seismic performance. The corrosion of the tranvese and main steel directly reduce the shear strength and bendig strength. If steel corrosion occurs in lap splice, the flexural strength and flexibility of existing corroded pier that are not seismic design are significantly reduced. In addition, as the axial force acting on the pier increase the shear strength. Considering these effects. In this stuydy, we cosidered steel corrosion, lap splice and axial force, for a reasonable evaluation of seismic-performance. It is confirmed that flexular failure occurs at pies where shear failure is expected to occur due to corrosion of reinforcement. These failure modes and their reason are analyzed, and necessary considerations are presented for seismic reinforcement.