連結浮体の運動と連結力に関する研究(1)

抄録

A complex offshore structure like a semi-submersible rig is disassembled into main floating bodies and simple component materials. The former usually are connected by the later. It is not always necessarily that the coupling materials rigid. In case of rigid connection, it is to consider the spring constant as approaching infinity. If we could know the behaviors of the multi-floating body system coupled with springs, the behaviors of it under every condition not only rigid but also soft connection could be known. When it is soft connection, each body moves relatively. There must be the unique condition like that whereas the main floating body does not move, small bodies around it move. It is important to know the unique condition for the main body, because not moving is better for her. It is interesting to make clear the mutual relation among the arrangement of floating bodies, dimensions of it, values of the spring constant and the sway motion. For predicting the variance of relative sway motion, it needs to know the sway frequency response function or floating bodies. The sway frequency response function can not be defined exactly in nonlinear system but under the restricted condition it could be defined, and it is useful. One interpretation of it is shown. The spectrum of the coupling forces among floating bodies is derived and the variance of the coupling stress is obtained to study the fatigue strength. The comparison results between experiments and calculations on sway motions, and coupling forces are shown.