4. Study on the Risk-Based Methodology for Ship Structural Design

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3. Case <strong>Study</strong>• Step <strong>4.</strong> Structural Reliability Analysis‣ By MC simulation & AFOSM (Advanced First Order Second Moment)Heading Angle(degree)Probability of FailureFull LoadingP f-full, angleNormal BallastP f-ballast, angleP r Pfull, 0 8.79 x 10 -12 2.82 x 10 -16f full angle f330 1.01 x 10 -11 2.66 x 10 -1630 9.26 x 10 -12 2.85 x 10 -17angle60 6.25 x 10 -12 6.04 x 10 -2090 1.22 x 10 -12 2.93 x 10 -21120 5.65 x 10 -12 9.58 x 10 -19P150 9.07 x 10 -12 2.46 x 10 -16f onewave rfullPf full180 8.42 x 10 -12 2.59 x 10 -16210 1.03 x 10 -11 3.15 x 10 -17240 7.69 x 10 -12 7.56 x 10 -20270 1.77 x 10 -12 <strong>4.</strong>26 x 10 -21 Therefore,300 6.79 x 10 -12 1.14 x 10 -18 P f onewave 3.19910Pf ballast ranglePfballast,angleangleangle• r angle: it is assumed to be 0.083 (equally). rballastf ballast• r full = 0.45 (ratio of full loading cond.)• r ballast = 0.40 (ratio of normal ballast cond.)12PThe 6 th ASEF- 23 -
3. Case <strong>Study</strong>• Step 5. Design Safety Level‣ Design safety level (P Safe-Design ) was estimated• on the basis of HPP (Homogeneous Poisson Process)n( T)TP( n)T totalnumber of waves e for n 0, 1, 2, n!• It means, within the time interval (T), a specific event having the intensity of λ could occurn-times independently with the probability of P(n).8 0( P88f onewave10) P 1010(0)f onewave PfonewavePSafeDesign P8 e eT 10 0!• Structural failure when the vessel experiences one wave is defined as the event• T is defined as 10 8 , based on the assumption that one wave approaches the vessel every 10 seconds• P Safe-Design means the probability of no event occurrence throughout the design life of 25 years n = 0 & λ = P f-one wave• Therefore,PSafeDesign P(0)T 128(3.19910) 108 e100.9997The 6 th ASEF- 24 -
Page 2 and 3: Contents1. Safety Level Based Hull
Page 4 and 5: 1. Safety Level Based Assessment•
Page 10 and 11: 2.Safety Level of LSM(Local Support
Page 12 and 13: 2. Safety Level of LSM• Considera
Page 14 and 15: 2. Safety Level of LSM• Calculati
Page 16 and 17: 3. Case Study• S
Page 28 and 29: 4. Conclusion• I
Page 30: The 6 th ASEF- 29 -

4. Study on the Risk-Based Methodology for Ship Structural Design

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