Elastic Response Analysis of Very Large Floating Structures in Waves Using Spectrum Finite Element Method

波浪中超大型漂浮结构的弹性响应分析采用谱有限元法

基本信息

批准号：
08651102
负责人：
FUJIKUBO Masahiko
金额：
$ 1.47万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08651102/
关键词：
Very Large Floating Structure Finite element method Elatic response Beam model Response in Waves Bending response Torsional response 超大型浮体式海洋構造物曲げ振り応答超大型浮体式構造物メガフロート梁

项目摘要

The objective of the present project is to develop a simplified method of elastic response analysis of a Very Large Floating Structure (VLFS) in waves to evaluate the relationship between elastic response and structural parameters, such as mass and stiffness distributions, in the initial design stage. For this purpose, one-dimensional spectrum finite element using the dynamic shape function of bending and flexural-torsional deformation of a beam placed on an elastic foundation was derived. In the proposed approach, the exact solution of dynamic equilibrium equation of a beam under given extrernal loads can be obtained by small number of elements. The change in mass and stiffness can be easily considered by using standard finite element procedures.A series of structural response analysis of pontoon-type and semi-submersible type VLFSs was performed, and the influences of mass and stiffness distributions on structural responses were investigated. It has been found that :(1) The reduction of mass of the end part of structures is an effective way to avoid resonance in waves for pontoon-type very large floating structures.(2) The increase of bending stiffness is effective to reduce the bending response of a VLFS,including deflection and bending stress. The same holds for flexural-torsional responses.(3) The influence of vertical shear stiffness on the bending response of VLFS is only negligible.(4) For the VLFS with a large width to length ratio, the deformation as a plate takes place in width direction in reality. Accordingly, a beam model tends to overestimate the stiffness of structures.Some limitation must be therefore imposed on the application of a beam model to the response analyzes of a VLFS.

本项目的目的是开发一种简化的方法，对波浪中非常大的浮动结构（VLF）进行弹性响应分析，以评估弹性响应与结构参数之间的关系，例如质量和刚度分布，在初始设计阶段。为此，得出了弯曲的动态形状函数的一维光谱有限元，并得出了放置在弹性基础上的光束的弯曲扭转变形。在提出的方法中，可以通过少量元素获得梁下梁的动态平衡方程的精确解。使用标准有限元程序可以轻松考虑质量和刚度的变化。进行了浮桥型和半熟悉类型VLFS的一系列结构响应分析，并研究了质量和刚度分布对结构响应的影响。已经发现：（1）结构末端部分的减少是避免浮动型非常大的浮动结构的波的有效方法。（2）弯曲刚度的增加有效地减少VLF的弯曲响应，包括偏转应力和弯曲应力。（3）垂直剪切刚度对VLFS弯曲响应的影响仅可忽略不计。（4）对于宽度较大的VLFS，宽度比的比例很大，变形作为板的变形在现实中宽度为宽度。因此，光束模型倾向于高估结构的刚度。因此，必须对梁模型应用于VLFS的响应分析进行某些限制。