Structural Collapse Behavior of Very Large Floating Structures in Waves

点击翻译按钮获取中文摘要

A method of global collapse analysis of a pontoon type Very Large Floating Structure (VLFS) in waves was developed and applied to the structural safety assessment of a VLFS in extreme waves. The results can be summarized as follows1. As a fundamental tool of the collapse analysis of a VLFS, a computer code for the buckling/plastic collapse analysis of stiffened plates using Idealized Structural Unit Method (ISUM) was developed. The degrees of freedom (d.o.f.s) required in ISUM is much smaller than in Finite Element Analysis (FEA). ISUM results were verified through a comparison with FEA results.2. A computer code for the progressive collapse analysis of a VLFS was developed applying ISUM stiffened plate model. A concept of ISUM super element that can further reduce d.o.f.s to be solved were introduced to enable a global collapse analysis of a VLFS having planar dimensions of thousands of meters.3. In order to examine the fundamental features of dynamic collapse behaviour of a VLFS in waves, a simplified dynamic collapse analysis of a VLFS was performed assuming the deflection expressed by the sum of elastic eigen modes. A tank test for a small-scale model was performed to examine the accuracy of hydroelastic response analysis employed in the project4. A system of global collapse analysis of a pontoon type VLFS in waves was developed combining ISUM and elastic response analysis. The external loads including radiation forces, obtained by the hydroelastic response analysis, are applied quasi statically to ISUM VLFS model mounted on an elastic foundation.5. Applying the developed system, the structural safety of a floating airport model in ultimate strength limit state was assessed. It was found the VLFS under consideration has enough strength reserve beyond the design loads. The structural reliability analysis of a pontoon-type VLFS considering damage to the breakwater was performed also.