• Title/Summary/Keyword: bridge columns

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An Experimental Study on Precast Bridge Piers Confined by FRP for Technical Development of Accelerated Construction (급속시공기술 개발을 위한 FRP로 보강된 프리캐스트 교각의 실험 연구)

  • Lee, Seung-Hye;Lee, Yeong-Ho;Hwang, Yoon-Koog;Song, Jae-Joon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.237-240
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    • 2008
  • Today, some bridges or highways are becoming superannuated in Korea. Also, in this section, rehabilitation, replacement and expansion are necessary to increasing traffic volumes these days. Bridge reconstruction is major problem because it has relation to civil application, economical loss and loss of vehicles made a detour while this work. Many precast components and methods of construction are developed for this issue. Many research of various precast components and new materials are being performed owing to apply to prefabrication bridges. The present paper represents experimental studies on the performance of precast CFFT pier model. Also, stay-in-place RC pier and stay-in-place CFFT pier are made an experiment on due to comparing test results. Hysteretic responses of all columns are obtained through the test. Compared with the displacement ductility factors, conclusions of seismic performances can be made.

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Determination of cyromazine in commercial insecticides using HPLC-DAD

  • Kim, Young-Wook;Han, Bok Hee;Kang, Young Eun;Rhee, Chae Hong;Seo, Sang-Ji;Kim, Soohee;Jeong, Wooseog;Her, Moon
    • Korean Journal of Veterinary Service
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    • v.43 no.4
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    • pp.261-265
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    • 2020
  • Each commercial cyromazine insecticide has different HPLC conditions. The aim of this study was to establish a standardized chromatographic method for the determination of cyromazine in commercial insecticides. The separation was achieved on two C18 columns - Waters® Bondapak C (4×300 nm i.d., 10 ㎛) and X bridge (4.6×250 nm i.d., 5 ㎛) using a mobile phase composed of water/methanol/ethanolamine (76:24:0.1, v/v), with UV detection at wavelengths 230 nm and 254 nm. A total of six commercial cyromazine insecticides were analyzed. In this study, the optimal high-performance liquid chromatography conditions for the analysis of cyromazine were as follows: a mobile phase of water/methanol/ethanolamine (76:24:0.1, v/v) at a flow rate of 1.0 mL/min and a detection wavelength of 230 nm using a X bridge C18 column (4.6×250 nm i.d., 5 ㎛) at a column temperature of 25℃. The calibration curve was linear in the concentration range of 5~50 ㎍/mL, with a correlation coefficient of 0.99995. The cyromazine detection limit was 0.2 ㎍/mL, and the limit of quantification was 0.59 ㎍/mL. The percentage recovery ranged from 99.8% to 101.0% for cyromazine, and the relative standard deviation was not over 2.0%. The cyromazine concentration ranged from 92.7% to 109.4% and was within the acceptable range (90~120%) for the percent of the labeled amount. This method was found to be suitable for determining cyromazine in commercial insecticides.

A Study on the Structural Behavior and the Strength of Circular Hollow Steel(CHS) Section Columns (원형강관 기둥의 구조적인 거동 및 강도에 관한 연구)

  • Kang, Doo Won;Kwon, Young Bong
    • Journal of Korean Society of Steel Construction
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    • v.21 no.5
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    • pp.505-514
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    • 2009
  • This paper describes the structural behavior and the ultimate strengths of circular hollow steel (CHS) sections based on a series of compression tests. The ultimate strengths of CHS section columns are mainly dependent on both diameter-thickness ratio and column slenderness ratio. For the CHS sections with a high diameter-thickness ratio, an elastic or an inelastic local buckling may occur prior to the overall buckling, and it may decrease the column strength. Test sections were fabricated from SM400 steel plate of 2.8 mm and 3.2 mm in thickness and were tested to failure. The diameter-thickness ratios of the test sections ranged from 45 to 170 to investigate the effect of local buckling on the column strength. The compression tests indicated that the CHS sections of lower diameter-thickness ratio than the yield limit in the current design specifications showed an inelastic local buckling and a significant post-buckling strength in the local mode. Their ultimate stresses were larger than the nominal yield stress. It was known that the allowable stresses of the sections predicted by the Korean Highway Bridge Design Specifications (2005) were too conservative in comparison with test results. The Direct Strength Method which was newly developed was calibrated for application to the CHS sections by the experimental and numerical results. The Direct Strength Method proposed can predict properly the ultimate strength of CHS section columns whether a local buckling and an overall buckling occur nearly simultaneously or not.

A Study Shear Behavior of Reinforced Concrete Beams Mixed Steel Fiber (강섬유(鋼纖維)를 혼입(混入)한 철근(鐵筋)콘크리트 보의 전단학동(剪斷學動)에 관(關)한 연구(硏究))

  • Kwak, Kae Hwan;Lee, Kwang Myong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.11 no.4
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    • pp.1-8
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    • 1991
  • Recently the use of steel fibers has been increased in flexural members and columns of concrete structures subjected to cyclic loadings; such as bridge decks, highway roads, runway of airport, buildings, etc.. However only a few experimental tests have been carried out under fatigue loading. In the present study, the reinforced concrete beams with 1% and 2% steel fiber volume fraction are investigated with and without stirrups. It has been found that in fatigue tests, the failure of the beam is usually due to breaking of fibers rather than fiber pull-out. A comparison of experiments and numerical analysis using the nonlinear F.E.M. program (ADINA) is also presented herein.

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Low Cycle Fatigue Behavior of Longitudinal Reinforcement (축방향철근의 저주파 피로 거동)

  • Lee, Jae-Hoon;Ko, Seong-Hyun
    • Journal of the Korea Concrete Institute
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    • v.22 no.2
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    • pp.263-271
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    • 2010
  • The purposes of this study is to verify the fracture characteristic of steel which is manufactured in Korea, subjected to cyclic loading. This investigation deals with the low cycle fatigue behavior of longitudinal reinforcement in reinforced concrete bridge substructure (piles and columns of piers). Eighty-one specimens of longitudinal reinforcement were tested under axial strain controlled reversed cyclic tests with strain amplitudes. The selected test variables are ratio of tension strain to compression strain, yield stress of longitudinal reinforcement, ratio of diameter of longitudinal steel to clear length of longitudinal steel, size of longitudinal steel and strain amplitudes. Low cycle fatigue behavior and low-cycle fatigue life are investigated and discussed in this paper.

Seismic Performance of Hollow Rectangular Precast Segmental Piers (프리캐스트 중공 사각형 철근콘크리트 교각의 내진성능)

  • Lee, Jae-Hoon;Park, Dong-Kyu;Choi, Jin-Ho;Shin, Sung-Jin
    • Journal of the Korea Concrete Institute
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    • v.24 no.6
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    • pp.705-714
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    • 2012
  • Precast reinforced concrete bridge columns with hollow rectangular section were tested under cyclic lateral load with constant axial force to investigate its seismic performance. After all the precast column segments were erected, longitudinal reinforcement was inserted in the sheath prefabricated in the segments, which were then mortar grouted. Main variables of the test series were column aspect ratio, longitudinal reinforcement ratio, amount of lateral reinforcement, and location of segment joints. The aspect ratios were 4.5 and 2.5, and the longitudinal steel ratios were 1.15% and 3.07%. The amount of lateral reinforcement were 95%, 55%, 50%, and 27% of the minimum amount for full ductility design requirements in the Korean Bridge Design Code. The locations of segment joints in plastic hinge region were 0.5 and 1.0 times of the section depth from the bottom column end. The test results of cracking and failure mode, axial-flexural strength, lateral load-displacement relationship, and displacement ductility are presented. Then, safety of the ductility demand based seismic design in the Korean Bridge Design Code is discussed. The column specimens showed larger ductility than expected, because buckling of longitudinal reinforcing bar was prevented due to confinement developed not only by transverse steel but also by sheath and infilling mortar.

Transverse Reinforcement for Circular Internally Confined Hollow RC column (원형 내부 구속 중공 RC 기둥의 심부 구속 횡방향 철근 연구)

  • Won, Deok Hee;Han, Taek Hee;Park, Woo Sun;Park, Jong Sub;Kang, Young Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.2
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    • pp.927-935
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    • 2013
  • Recently, bridge structures has progressed the researches about seismic performance by occurrence of earthquake increased compared with the past. In the substructure of bridge, confining transverse reinforcement has arranged in plastic hinge region to resist the lateral load which increased the lateral confining effect. Columns are increased the seismic performance through secure of the stiffness and ductility The design specification for arrangement of confining transverse reinforcement same specification of domestic and international that suggested to solid reinforced concrete column(RC). This design specification have limits for Internally Confined Hollow RC(ICH RC) column because of different the component and performance characteristics of column. In this paper suggested the modified equation for economics and rational design through investigation of displacement ductility when applied the existing specification at the steel composite hollow RC column.

Evaluation of P-M Interaction Curve for Circular Concrete-Filled Tube (CFT) Column (원형 콘크리트 충전 강관(CFT) 기둥의 P-M 상관 곡선 평가)

  • Moon, Jiho;Park, Keum-Sung;Lee, Hak-Eun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.2
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    • pp.355-365
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    • 2014
  • Concrete-filled tubes (CFTs) have been used in civil engineering practices as a column of buildings and a bridge pier. CFTs have several advantages over the conventional reinforced concrete columns, such as rapid construction, enhanced buckling resistance, and inherited confinement effect. However, CFT component have not been widely used in civil engineering practice, since the design provisions among codes significantly vary each other. It leads to conservative design of CFT component. In this study, the design provisions of AISC and EC4 for CFT component were examined, based on the extensive test results conducted by previous researchers and finite element analysis results obtained in this study. Especially, the focus was made on the validation of P-M interaction curves proposed by AISC and EC4. From the results, it was found that the current design codes considerably underestimated the strength of CFT component under general combined axial load and bending. Finally, the modified P-M interaction curve was proposed and successfully verified.

A Comparative Study of Ancient Palace Ponds of Korea, China and Japan - Focus on the Recent Excavated Palace Pond - (고대 한.중.일 원지의 비교연구 - 최근 발굴된 원지를 중심으로 -)

  • 박경자
    • Journal of the Korean Institute of Landscape Architecture
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    • v.30 no.4
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    • pp.1-8
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    • 2002
  • The place of South Weol Dynastys authorities exhumed in the region of KangChoWu, China lies adjacent to a stone ditch through which water streams crookedly, and a dark trough of stone pond in the north side. There is a sharply curved stone ditch and a crescent-shaped water entrance made by stones. The place was separated by using stone columns and stone walls. There is a beam of ditch, a crooked entrance, a flat bridge of slate, a stepping-stone, a sluice gate, and a crooked corridor. There are big and small artificial islands, and reinforcing stone drainage way in the palace pond recently exhumed at the building site for the pavilion of Hwang-Yong Temple in Kuhwang-Dong, Gyeongju city, Korea. There are four facilities assumed to be entrance and exits at four corners and an open space on which gravel was spread extensively. A narrow road and a middle road with indefinite curves at the south of Asukakyoseki exhumed by the first, second and third and two stone buckets which one is to fill with water and the other is to drain water off like fountain are there, and besides wave protecting dam and north pond and the part that water pass were excavated. Palace ponds that were extensively distributed at old residential cities are a general phenomenon of countries in eastern Asia. Anap pond of Silla and Gungnam pond of Baekje were in Kroea. We believe that Asutnkyoseki is on the extension. Although more investigations in the background of thought and the genealogical relation about the palace pond are required, it seems that an idea was surely received from China.

Characteristics of Stress-strain Relationship of Concrete Confined by Lateral Reinforcement (횡철근에 의해 횡구속된 콘크리트의 응력-변형률 특성)

  • Jeong, Hyeok-Chang;Kim, Ick-Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.3
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    • pp.67-80
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    • 2009
  • The basic concept of seismic design is to attain the ductility required in a design earthquake. This ductility can be obtained by providing sufficient lateral confinements to the plastic hinge regions of columns. The most cost-effective design might be derived by determining the proper amount of lateral confinement using a stress-strain relationship for confined concrete. Korean bridge design code requires the same amount of lateral confinement regardless of target ductility, but Japanese design code provides the stress-strain relationship of the confined concrete to determine the amount of lateral confinement accordingly. While design based on material characteristics tends to make the design process more involved, it makes it possible to achieve cost-effectiveness, which is also compatible with the concept of performance-based design. In this study, specimens with different numbers of lateral confinements have been tested to investigate the characteristics of the stress-strain relationship. Test results were evaluated, using several empirical equations to quantify the effects.