KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
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Target Reliability Index and Load-resistance Factors for the Gravitational Loads-governed Limit States for a Reliability-based Bridge Design Code

신뢰도기반 교량설계기준의 중력방향하중 지배 한계상태에 대한 목표신뢰도지수 및 하중-저항계수

  • 김정곤 (서울대학교 건설환경공학부) ;
  • 김호경 (서울대학교 건설환경공학부, 건설환경종합연구소) ;
  • 이해성 (서울대학교 건설환경공학부)
  • Received : 2021.12.06
  • Accepted : 2022.03.03
  • Published : 2022.06.01
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Abstract

This paper presents a new class of the vehicular live load factor for a reliability-based bridge design code. The significance of the current vehicular live load factor of 1.8 is investigated based on the return period of the vehicular live load and the design life of a bridge. It is shown that the current vehicular live load factor corresponds to a return period of 6.7 million years for a 100-year design life, which seems to be unrealistic in an engineering sense, and that the target reliability of 3.72 is set to too high without any reasoning for the gravitational load-governed limit state compared with that of the other limit states. In case the same return period as the design wind velocity or the ground acceleration is employed for the vehicular live load, the corresponding vehicular live load factor becomes around 1.15, and the target reliability index for the return period may be selected as 2.0 or 2.5 depending on the governing load effect. The complete sets of the load-resistance factors for the proposed target reliability indices are evaluated through optimization.

신뢰도기반 교량설계기준에서 적용할 수 있는 새로운 종류의 차량활하중계수를 제시한다. 현재 사용하고 있는 차량활하중계수 1.8에 대한 적절성을 차량활하중의 재현주기와 교량설계수명에 기초하여 분석하였다. 중력방향하중 지배 한계상태에 대한 목표신뢰도지수 3.72는 적절한 논거 없이 너무 높게 설정된 값이며, 이에 상응하는 하중계수 1.8은 100년 설계수명 교량에서 재현주기 약 670만년 정도에 해당하는 활하중 파괴점을 나타내는 무의미한 값이라는 것을 보였다. 설계 풍속이나 지반가속도와 동일한 재현주기를 차량활하중에도 적용하면 차량활하중계수는 1.15 정도가 되고 목표신뢰도지수는 한계상태를 지배하는 하중에 따라서 2.0 혹은 2.5에 해당하게 된다. 제안한 목표신뢰도지수에 대한 전체 하중-저항계수 조합은 최적화에 의하여 산정하였다.

Keywords

Acknowledgement

이 연구는 국토교통부 건설기술연구사업(21SCIP-B119963-06)에 의하여 수행되었습니다. 연구 지원에 감사드립니다.

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