Ultimate Hull Girder Strength under Longitudinal Bending

1.考虑加筋板与板之间的相互作用，推导了连续加筋板在双向推力作用下局部屈曲强度的解析表达式。推导了连续加筋板在推力作用下的极限强度解析表达式.阐明了横向推力和侧压力对有、无加劲肋连续板屈曲强度和极限强度的影响，推导了计算屈曲/极限强度的公式。并将其应用到基于Smith方法的连续倒塌分析方法中.在局部板的情况下，伴随着饥饿马模式的初始挠度，挠度和塑性变形局限于板的某一部分，而弹性卸载发生在板的其余部分。建立了理想结构单元法中的板单元，可以准确模拟这种行为.不 ...更多信息 将ISUM单元与一个能模拟双轴弯扭屈曲行为的薄壁梁柱单元相结合，应用于双轴推力作用下连续加筋板的倒塌分析。计算结果表明，该单元对船体梁在横向弯曲作用下的倒塌分析是有效的.制作了1/10焊接钢缩比的芯片载体模型，并对这些模型进行了下垂条件下的倒塌试验。研究发现，甲板和舷侧外板上部的屈曲破坏成为船体梁整体破坏的触发器.对180块不同长宽比、板厚、加劲肋类型和尺寸组合的加筋板进行了基准计算。两种情况下被认为是有和没有焊接残余应力。10种不同的方法。得出的结论是，根据各个计算方法中的条件和假设，计算结果会发生分散。采用8种不同的方法对4艘现役舰船和1/3比例的钢质焊接护卫舰模型进行了基准计算，以评估其极限总纵强度。研究结果表明，本文提出的计算方法能较好地模拟实际结构的倒塌特性，并能考虑结构的局部变形、塑性变形以及加劲肋的脱出.本文推荐了Smith方法，该方法采用精确推导的加筋板单元的平均应力-平均应变关系，是计算船体梁总纵极限强度的最佳方法。少

1. Analytical formulation is derived to evaluate local buckling strength of continuous stiffened plate subjected to bi-axial thrust considering the interactions between panel and stiffener. Analytical formulation is also derived to evaluate the ultimate strength of continuous stiffened plate under thrust.2. The influences of transverse thrust and lateral pressure on buckling strength and ultimate strength of continuous plate with and without stiffeners are clarified, and the formulas to evaluate buckling/ultimate strength are derived. These are implemented into the method of progressive collapse analysis based on the Smith's method.3. In case of local panel accompanied by initial deflection of a hungry-horse mode, deflection and plastic deformation are localised at a certain part of the plate while elastic unloading takes place in the remaining part of the plate. A plate element of the Idealized Structural Unit Method (ISUM) is developed which can simulate such behavior accurately.4. T … More his ISUM element is combined with a thin-walled beam-column element which can simulate bi-axial flexural-torsional buckling behaviour, and is applied for the collapse analysis of a continuous stiffened plate subjected to bi-axial thrust. It is demonstrated that this element shall be effective for the collapse analysis of a hull girder under loingitudinal bending.5. 1/10-th welded steel scale models of a Chip Carrier are fabricated and the collapse tests are conducted on these models under the sagging condition. It is found that the buckling collapse of the deck and the upper part of the side shell plating become the trigger of the overall collapse of the hull girder.6. Benchmark calculation is performed on 180 stiffened plates with different combination of panel aspect ratio, panel thickness, type of stiffener and size of stiffeners. Two cases are considered with and without welding residual stress. 10 different methods are applied. It has been concluded that scatter takes place in the calculated results depending on the conditions and assumptions in the individual calculation methods.7. Benchmark calculation is performed on 4 existing vessels and a 1/3-scale welded steel frigate model to evaluate ultimate longitudinal strength applying 8 different methods. It has been concluded that the calculation method which can simulate the actual collapse behavior accompanied by localisation of deflection and plastic deformation as well as tripping of stiffeners.8. The Smith's method using accuately derived average stress-average strain relationships of stiffened plate element is recommended as the best method to evaluate ultimate longitudinal strength of a ship hull girder. Less