Ultimate Hull Girder Strength under Longitudinal Bending
Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants |
|Research Institution||Osaka University |
YAO Tetsuya Osaka University, Graduate School of Engineering Professor, 大学院・工学研究科, 教授 (20029284)
NIHO Osamu Mitsui Engineering and Shipbuilding Co. Ltd, Basic Design Department; Manager (Researcher), 船舶艦艇事業本部, 課長;研究職
FUJIKUBO Msahiko Hiroshima University, Faculty of Engineering; Professor, 大学院・工学研究科, 教授 (30156848)
HAYASHI Shigehiro Graduate School of Engineering; Associate Professor, 大学院・工学研究科, 助教授 (60263216)
|Project Period (FY)
2000 – 2002
Completed (Fiscal Year 2002)
|Budget Amount *help
¥11,800,000 (Direct Cost: ¥11,800,000)
Fiscal Year 2002: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2001: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2000: ¥5,100,000 (Direct Cost: ¥5,100,000)
|Keywords||Ultimate Longitudinal Strength / Buckling Strength / Ultimate Strength / Progressive Collapse Analysis / Idealized Structural Unit Method / Smith's Methods / Continuous Stiffened Plate / Strength Assessment / 座屈・塑性崩壊挙動 / 断面の反りの影響 / 解析的手法 / 船体ビルジ部 / 座屈・塑性崩壊 / 有限要素法 / 簡易解析法 / 断面の反り / 船体桁 / 溶接残留応力|
1. The best modelling method of stiffener in the stiffened plating under thrust was investigated. It was found that the stiffener web should be modelled by a plate whereas stiffener flange should be modelled by a beam-column to obtain accurate results efficiently when the collapse behaviour of cotinuous stiffened plating is analysed either by the analytical method or the FEM.
2. To investigate the collapse behaviour and strength of bottom structure, a simple but effective method was developed which enables to simulate the collapse behaviour of stiffened plating subjected to combined lateral pressure and thrust loads. The rationality of this method was confirmed by comparing the calculated results by this method with those by the FEM analysis. This method was implemented into the computer code to simulate progressive collpse behaviour of a ship hull girder subjected to longitudinal bending. It was confirmed that the influence of lateral pressure on ship bottom and side shell plating on t
he ultimate hull girder strength is rather small.
3. Performing a series of elastoplastic large deflection analysis by the FEM, progressive collapse behaviour of a bilge circle was simulated and investigated. On the basis of the calculated results, a simple dynamical model was developed to simulate collapse behaviour of bilge circle. This model was implemented into the computer code to simulate progressive collapse behaviour of a ship hull girder subjected to longitudinal bending. It was confirmed that the ultimate hull girder strength is almost the same but the capacity beyond the ultimate hull girder strength is a little different when the buckling effect of a bolge circle is accounted.
4. New method was developed to account for the influence of warping of the cross-section produced by shear force on the progressive collapse behaviour and the ultimate hull girder strength. It was found that the ultimate hull girder strength is reduced by 15% at maximum when the normal stress by warping becomes compressive at the compression side of the hull girder bending.
5. The plate ISUM (Idealised Structural Unit Method) element was newly developed which enables to perform collapse analysis of a ship hull girder subjected to longitudinal bending. In this research project, collapse analysis was not yet performed. However, this new element was combined with beam-column elements and the collapse behaviour of a stiffened plate in compression was accurately simulated. The application of this elements to hull girder collapse analysis remains as a future task.
6. Sensitivities of various design factors on the ultimate hull girder strength were evaluated. Using these sensitivities, reliability analysis was performed on four existing vessels. It was concluded that these vessels are safe enough against breaking of their hull girder.
7. It can be recommended that different method should be applied according to the stage of design to evaluate the ultimate hull girder strength. For the detailed analysis, the Smith's method using accuately derived average stress-average strain relationships of stiffened plate element was recommended as the best method to evaluate ultimate hull girder strength of a ship hull girder. Less
Report (4 results)
Research Products (55 results)