• Title, Summary, Keyword: concrete-filled steel pier

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Design of Pull Box Members on the Landing Pier Using Finite Element Analysis of a Steel Plate (강재 플레이트 유한요소해석을 이용한 잔교 상부의 풀 박스 부재의 선정)

  • Kim, Sungwon;Hong, Hyemin;Han, Taek Hee;Seo, Seung Nam
    • Journal of Coastal Disaster Prevention
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    • v.4 no.3
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    • pp.111-118
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    • 2017
  • In this study, pull box members were designed by finite element analysis of a steel plate covering a pull box to secure its safety on the landing pier dedicated to the large research survey ship. It was assumed that the maximum load is due to the 250 tonf class crane used for unloading work when the working environment in the upper part of the landing pier was considered. The safety of the pull box was evaluated by the comparison between the yield strength of the steel plate and the result of stress analysis on the steel plate due to the crane load. It was found that the stress at the plate from the crane load exceeded the yield strength of the steel(205MPa) when the upper part of the pull box was protected by a $1950{\times}1950mm$ steel plate cover. In order to compensate for this, a concrete filled steel tube(CFT) column with a diameter of 150 mm and a steel thickness of 10 mm was reinforced at the center of the plate, and the finite element analysis was carried out. However, the maximum stress at the steel plate was higher than the yield strength of the steel in some load cases so that it was tried to find appropriate thickness of the steel plate and diameter of the CFT columns. Finally, the analysis results showed that the safety of the pull box was secured when the thickness of the steel plate and the diameter of the CFT column were increased to 30mm and 180mm, respectively.

The Evaluation of Seismic Performance for Concrete-filled Steel Piers (콘크리트 충전 강교각의 내진 성능 평가)

  • 정지만;장승필;인성빈
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.5
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    • pp.53-58
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    • 2002
  • A recent development, a concrete-filled steel(CFS) pier is an alternative to a reinforced concrete bridge pier in an urban area, because of its fast construction and excellent ductility against earthquakes. The capacity of CFS piers has not been used to a practical design, because there is no guide of a seismic design for CFS piers. Therefore, the guide of a seismic design value is derived from tests of CFS piers in order to apply it to a practical seismic design. Steel piers and concrete-filled steel piers are tested with constant axial load using quasi-static cyclic lateral load to check ductile capacity and using the real Kobe ground motion of pseudo-dynamic test to verify seismic performance. The results prove that CFS piers have more satisfactory ductility and strength than steel piers and relatively large hysteretic damping in dynamic behaviors. The seismic performance of steel and CFS piers is quantified on the basis of the test results. These results are evaluated through comparison of both the response modification factor method by elastic response spectrum and the performance-based design method by capacity spectrum and demand spectrum using effective viscous damping. The response modification factor of CFS piers is presented to apply in seismic design on a basis of this evaluation for a seismic performance.

Evaluation of Structural Performance of Precast Modular Pier Cap (프리캐스트 모듈러 피어캡의 구조성능 평가)

  • Kim, Dong Wook;Shim, Chang Su
    • Journal of the Korea Concrete Institute
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    • v.27 no.1
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    • pp.55-63
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    • 2015
  • Prefabrication technologies are making bridge construction safer and less disruptive to the environment and traveling public, making bridge designs more constructible and, improving the quality and durability by shifting site work to a more controllable environment. Modular bridge substructures with concrete-filled steel tube (CFT) piers and composite pier caps were suggested to realize accelerated bridge construction. The precast segmental pier cap consists of a composite pier table and precast prestressed segments on the table. The pier table has embedded steel section to mitigate stress concentration at the connection by small tubes. Each bridge pier has four or six CFT columns which connect to the pier cap. Shear strength of the pier cap was obtained by extending vertical reinforcing bars from the table to the precast segment. Transverse prestressing was introduced to control tensile stresses by service loadings. Structural performance of the proposed modular system was evaluated by static tests. Design requirements of the composite pier cap were satisfied by continuous reinforcing bars and prestressing tendons. Standardized modular substructures can be effectively utilized for the fast replacement or construction of bridges.

Development of Connection between CFT Column and Pier Foundation for Top-Down Construction (Top-Down 공사용 원형충전강관기둥과 피어기초의 개발)

  • Jeong, Mee-Ra;Rhim, Hong-Chul;Kim, Seung-Weon;Kim, Dong-Gun;Kang, Seung-Ryong
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.29-32
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    • 2009
  • Building foundations for Top-Down construction require a special setting, because the foundations have to be placed way before excavation for the substructure of main building, Usually, the foundation goes into the layer of rock and it is often called rock-pier foundation, Currently, a cage of steel reinforcing bars is inserted to the pre-excavated hole in the rock layer, hanging down from the wide flange steel column above. This paper presents a new method for connecting the prefounded column and the steel cage with a coupler for better connection between the two, The use of a circular Concrete Filled Tube (CFT) as a prefounded column makes it possible to have this type of connection. The details of the connection and application to a Top-Down construction site is also included in this paper.

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Experimental Study and Confinement Analysis on RC Stub Columns Strengthened with Circular CFST Under Axial Load

  • Liang, Hongjun;Lu, Yiyan;Hu, Jiyue;Xue, Jifeng
    • International journal of steel structures
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    • v.18 no.5
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    • pp.1577-1588
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    • 2018
  • As the excellent mechanical performance and easy construction of concrete filled steel tubes (CFST) composite structure, it has the potential to be used to strengthen RC pier columns. Therefore, tests were conducted on 2 reinforcement concrete (RC) stub columns and 9 RC columns strengthened with circular CFST under axial loading. The test results show that the circular CFST strengthening method is effective since the mean bearing capacity of the RC columns is increased at least 3.69 times and the ductility index is significantly improved more than 30%. One of the reasons for enhancement is obvious confinement provided by steel tube besides the additional bearing capacity supplied by the strengthening materials. From the analysis of the enhancement ratio, the strengthening structure has at least an extra 20% amplification except for taking full advantage of the strength of the strengthening material. Through the analysis of confining stress provided by steel tube and the stress-strain relationship of confined concrete, it is found that the strength of the core concrete can be increased by 21-33% and the ultimate strain can be enhanced to beyond $15,000{\mu}{\varepsilon}$.

Design of Precast Circular Piers with Prestressing Bars (강봉으로 긴장한 프리캐스트 원형교각의 설계)

  • Shim, Chang-Su;Chung, Chul-Hun;Yoon, Jae-Young;Kim, Cheol-Hwan;Lee, Yong-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.121-124
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    • 2008
  • Fast construction of bridge substructures is a new trend of bridge design. A precast pier system with bonded prestressing bars was proposed. In this paper, quasi-static tests on precast prestressed piers were conducted to evaluate the seismic behavior of the precast piers with bonded prestressing bars. In order to strengthen the shear strength of the joints between column segments, steel tubes filled with mortar were used. Displacement ductility and energy dissipation capacity of the precast piers were evaluated. The suggested precast pier system showed better seismic performance than the required ductility. Based on the research results, an example bridge pier for light-railway lines was designed and design considerations were discussed.

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Seismic Performance of Column-Footing Connection of Modular Pier using CFT (CFT를 이용한 모듈러 교각 기둥-기초 연결부의 내진성능)

  • Kim, Ji Young;Kim, Ki Doo;Ma, Hyang Wook;Chung, Chul-Hun
    • Journal of The Korean Society of Civil Engineers
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    • v.34 no.1
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    • pp.73-85
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    • 2014
  • The CFT (Concrete Filled steel Tubes) column-footing connection is cast-in-place embedded type which provides simple construction procedure, low cost, and superior structural performance. In this study, CFT column-footing connection of modular pier is proposed and structural performance is evaluated by experimental tests. To evaluate structural performance of the CFT column-footing connection, a series of experimental tests were performed for the 4 specimens with different embedded depth. As a result of the quasi-static test, the specimen with 0.6D (0.6 times the outside diameter of steel tube) embedded depth showed relatively low ductility than other specimens with larger embedded depth due to cone failure of base concrete occurred during the lower loading step. On the contrary, cone failure of the base concrete was not observed in the specimens with larger embedded depth than 0.9D, but typical flexural failure in lower part of CFT column was observed. With the analyses of force-displacement curve, displacement ductility, and energy dissipation capacity, it is concluded that the rational range of embedded depth of the CFT column-footing connection is from 0.9D to 1.2D in view of good seismic performance.

Parametric Study on Seismic Performance of Internally Confined Hollow CFT Column (내부 구속 중공 CFT 교각의 내진성능에 대한 매개변수 연구)

  • Yeom, Eung-Jun;Kim, Hyun-Jong;Han, Taek-Hee;Kang, Young-Jong
    • Journal of Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.15-21
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    • 2008
  • The internally confined hollow-concrete filled tube (ICH-CFT) column has two tubes on the both sides (hollow part and outer part) of the concrete. The inner tube and the outer tube perform great seismic abilities, ductility and absorption of energy due to the steel tubes and the hollow part. So, the study of this column type for the practical use is needed. In this study, the qualitative analysis about seismic capacities depending on parameters is performed for the practical design of the ICH-CFT column. The parameters are diameter of column, hollow ratio and thickness of tubes with the same resistance of the moment. Also, the economical evaluation of ductility and comparison with CFT column make this study to be of practical use. Especially, a change of seismic performance depends on the hollow ratio and the thickness of the outer tube, and the economical hollow ratios according to the thickness of the outer tube in the ICH-CFT column are suggested.