• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.647-657
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• 2006

Probabilistic Risk Assessment considering statistically random variables is performed for the preliminary design of a Cable Stayed Bridge, which is Prestressed Concrete Bridge consisted of cable and plate girders, based on the method of Working Stress Design and Strength Design. Component reliabilities of cables and girders have been evaluated using the response surface of the design variables at the selected critical sections based on the maximum shear, positive and negative moment locations. Response Surface Method (RSM) is successfully applied for reliability analyses for this relatively small probability of failure of the complex structure, which is hard to obtain through Monte-Carlo Simulations. or through First Order Second Moment Method that can not easily calculate the derivative terms of implicit limit state functions. For the analysis of system reliability, parallel resistance system consisting of cables and plate girder is changed into series connection system and the result of system reliability of total structure is presented. As a system reliability, the upper and lower probabilities of failure for the structural system have been evaluated and compared with the suggested prediction method for the combination of failure modes. The suggested prediction method for the combination of failure modes reveals the unexpected combinations of element failures in significantly reduced time and efforts compared with the previous permutation method or system reliability analysis method, which calculates upper and lower bound failure probabilities.

• Journal of the KSME
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• v.33 no.7
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• pp.614-627
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• 1993

좌굴하기 쉬운 구조물을 설계할 때는 반드시 좌굴특성에 대한 어떤 직관을 가져야 한다. 이글의 목적은 셸 구조물이 비선형붕괴(nonlinear collapse), 분기좌굴(bifurcation buckling) 또는 이들 모드의 조합에 의해서 어떻게 좌굴될 것인가에 대한 감각을 전하는데 있다. 이 불안정에 대한 직관적 이해는 보강되고 여러 요소들로 조립되며 분지셸(branched shell)을 갖거나 복잡한 벽구 조를 갖는 실제 셸 구조물 등의 많은 예에 의해서 얻어질 수 있다. 이 글에서는 수식의 개발이 아니라 불안정의 예측에 주안점을 두고 있으며, 큰 처짐과 소성의 조합에 의해 발생되는 비선 형좌굴과 결함민감도가 특히 강조된다. 또한 최적화된 구조물의 국부 및 전체 불안정, 좌굴모드의 상호작용, 그리고 결함민감도(imperfection sensitivity) 등이 예시된다.