• Title/Summary/Keyword: Precom

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Experimental study on long-term behavior of prestressed steel I-beam-concrete composite beams

  • Sung, Deokyong;Hong, Seongwon
    • Steel and Composite Structures
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    • v.42 no.5
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    • pp.671-683
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    • 2022
  • To investigate and predict the long-term time-dependent behavior, such as creep, shrinkage, and relaxation of PS strands, and prestress loss in prestressed steel-concrete composite beams, named Precom, full-scale tests were conducted and the collected data were compared with those obtained from the two proposed analytical models. The combined effective modulus method (EMM)-empirical model proposed with a flowchart considered the creep effect to determine the prestress loss. Conversely, the age-adjusted effective modulus method (AEMM) with CEB-FIP equation was developed to account for the concrete aging. The results indicated that the AEMM with CEB-FIP model predicts the long-term behavior of Precom effectively.

Static Behavior of Prestressed Steel-Concrete Composite Girder (프리스트레스트 강합성 거더의 정적거동 평가)

  • Lee Pil-Goo;Kim Sung-Il;An Hae-Young;Moon Jong--Hoon
    • Proceedings of the KSR Conference
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    • 2005.11a
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    • pp.240-245
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    • 2005
  • There has been a strong demand on more economic and lower depth girder bridges for short and medium span range, PRECOM, which is a new type steel-concrete composite girder, has been developed to realize a more economic bridge system with a lower depth girder. In the PRECOM girder bridge, a steel plate girder is simply supported and then concrete form is hung to girder. Thus, the self-weight of the concrete is loaded to the steel girder. To increase the resistance of concrete in the lower casing against tensile stress, compressive force is introduced by prestressed tendon To evaluate the manufacturability and performances of the completed bridge, four 15-m girders and a bridge specimen with two 20m girders wvere constructed. The camber during the construction and introduction of an appropriate compressive force was evaluated. Dynamic data were obtained through the modal testing of the completed girders. Static loading test was also conducted to examine cracks and evaluate the decrease in stiffness and failure behavior under extreme conditions.

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Dynamic Performance Evaluation of New Type PSC Railroad Bridges (신형식 PSC 철도교량의 동적성능 평가)

  • Choi, Sanghyun
    • Journal of the Society of Disaster Information
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    • v.7 no.4
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    • pp.259-265
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    • 2011
  • After the commercial opening of the KTX in 2005, the high speed railroad has been rapidly emerged as the major transportation means due to its high energy efficiency. Recently, the government has announced its plan to build the future transportation system around the high speed railroad. Based on this policy, the existing lines as well as the lines under construction or design are planning to increase design speed. In this paper, the suitability of the mid-span PSC girder bridges for the high speed railroad is evaluated via dynamic analysis. IT, Precom, and WPC girder bridges are considered for the purpose of this study and, for comparison, the identical modeling method and the analysis technique are utilized. The performance indices used for dynamic performance evaluation are the natural frequency, the vertical displacement, the end axial displacement, track irregularity, etc. The KTX train is utilized as a dynamic load, and the dynamic analysis is performed up to the train speed of 420km/hr with the increment of 10km/hr.

Experimental Evaluation for Damping Ratio Limit of Railway Bridge according to Structure Types (철도교량 구조형식별 감쇠비 하한값 산정을 위한 시험적 연구)

  • Min, Rak-Ki;Sung, Deok-Yong;Park, Yong-Gul
    • Journal of the Korean Society for Railway
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    • v.15 no.2
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    • pp.154-161
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    • 2012
  • The damping ratio of railway bridge has become one of the most important issues in dynamic design and dynamic stability of railway bridge. In the present study, laboratory and field test were performed for railway bridges such as a twin I-shaped steel composite girder, PSC box, steel box, PSC, IPC, PRECOM, preflex. The damping ratio of railway bridge according to structure types was estimated by logarithmic decrement method. Therefore, magnitude, frequency and amplitude of load did not affect damping ratio of railway bridge. Also, damping ratio limit of steel composite and PSC bridges was evaluated in 1.0%.

Experimental Evaluation of Modal Properties for Estimation of the Railway Bridge Dynamic Performance (철도교량 동적성능 평가를 위한 동특성 추출 실험연구)

  • Kim Sung-Il;Kim Nam-Sik;Lee Jung-Whee;Lee Pil-Goo
    • Proceedings of the KSR Conference
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    • 2005.11a
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    • pp.211-216
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    • 2005
  • Resonance of railroad bridge can be broken out when natural frequency of the bridge coincides with exciting frequency of moving forces. In order to avoid aforementioned unpleasant response of the structure, exact determination of dynamic structural properties is important to understand dynamic behavior of the structure under moving train loads. In the present paper, a 25 meters long full scale IPC girder and 15m Precom girder models were fabricated as a test specimen and modal testing was carried out to evaluate modal parameters including natural frequencies and modal damping ratios. In the modal testing, a digitally controlled vibration exciter as well as an impact hammer is applied to obtain frequency response functions more exactly and the modal parameters are evaluated varying with structural status.

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