• Title/Summary/Keyword: PPWS method

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Development of Sag and Tension Sensitivity Estimation Method for Configuration Control under PPWS Erection in a Suspension Bridge (현수교 PPWS 가설중 형상관리를 위한 PPWS 새그 및 장력민감도 산정법 개발)

  • Jeong, Woon;Seo, Ju Won;Lee, Won Pyo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.5A
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    • pp.255-266
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    • 2012
  • Main cable of a suspension bridge is the important member which shows the overall structure integrity at bridge completion. Configuration of main cable is a free hanging state at cable erection completion and is different from that at bridge completion supporting the dead loads such as hanger, girder, and so on. Accordingly, the configuration control under cable erection is considerably significant because the configuration at cable erection completion has direct influence on that at bridge completion. That is performed by sag adjustments at center, side span and tension adjustments at anchor span. The former needs the sag sensitivity which represents the control quantity of strand length corresponding to that of sag. The latter requires the tension sensitivity which shows the change of strand tension according to that of strand temperature. In this study, the fundamental equations of cable were derived with the assumption of either catenary or parabola shape, the differential-related equations using chain rule on horizontal tension were drawn from those and finally the estimation methods of the sag / tension sensitivity were proposed from both those. The nonlinear numerical analysis flow charts of sag sensitivity based on the catenary equations were proposed and the sag sensitivities grounded on the differential-related equations were compared with the results using them for various parameters of sag change. Also, considering the combinations of sag change parameters, the calculation method of the final variation for the cable sag was suggested. For the real suspension bridge under construction with PPWS method, the sag/tension sensitivity were estimated considering the construction conditions like the change of PPWS length, PPWS temperature, bridge span, etc.. We hope that this study will be a systematic guideline for the configuration control under main cable erection and improved highly by field verification in the real bridge site.

Effect of the Tapered Angle on the Ultimate Load Factors of PPWS Sockets in Main Cables of Suspension Bridges (현수교 PPWS용 소켓의 내벽 경사각이 소켓의 극한 하중계수에 미치는 영향)

  • Yoo, Hoon;Lee, Sung-Hyung;Seo, Ju-Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.1
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    • pp.47-59
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    • 2013
  • Ultimate load factors of PPWS(Prefabricated Parallel Wire Strand) sockets in main cables of suspension bridges are studied with respect to the tapered angles of the inner surface of sockets. After briefly reviewing the current design method, 15 numbers of finite element models of sockets are prepared by varying the number of wires in a strand and the tapered angles. The finite element models are updated by comparing experimental and numerical results, so that the models can reflect the real behavior of sockets. The stress distributions at the first yielding and ultimate states are analyzed by performing the incremental load analysis using ABAQUS. It is concluded that the optimized tapered angle of sockets should be determined at the specific angle between the results of verification equations of the required bonding length and stress resistance length.

Applicability Verification of High-strength Parallel Wire Strands by Tensile Tests (인장 실험을 통한 현수교 주케이블용 고강도 평행선스트랜드의 적용성 검토)

  • Yoo, Hoon;Seo, Ju-Won;Lee, Sung-Hyung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.6A
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    • pp.435-447
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    • 2011
  • This paper discusses the problems in application of a parallel wire strand with high performance steel wires, which have the tensile strength of 1960 MPa grade, as a major component of the main cables in suspension bridges. Construction methods of main cables in suspension bridges are briefly reviewed by comparing the pros and cons of available methods. Required items for performance and quality of parallel wire strands are described based on the established references. Ultimate tensile strength tests are carried out for seven specimens in order to analyze the behavior of high-performance parallel wire strands. The test results demonstrate that the properties of test specimens are satisfied with performance indexes specified in this paper. The high-performance parallel wire strands are acceptable for application in main cables of suspension bridges.