Basic research on dynamic safety of large offshore structure

本文对大型海洋结构物的动力安全性进行了初步研究。如何有效地、积极地推进我国海洋空间的开发利用成为一个十分重要的问题。本文通过循环水槽实验和计算机仿真分析，得到以下主要研究结果：1）各柱涡激振动受柱杆间距的影响。对于涡激振动响应，在单柱情况下，随着柱间距的减小，涡激振动响应有增大的趋势。此外，人们已经认识到，由于柱在前后方向上产生涡激振动的频率不同，会引起整个结构的扭转振动。2）如果将结构在波浪力和地震力单独作用下的反应进行比较， ...更多信息 由于这些外力作用的位置不同，然而，当结构放大时，与连接材料相结合的结构模型的响应却表现出相似的特性。3）采用波浪力和地震力的可靠度指标对设计水平响应进行了比较。在波浪力中，平均波高、平均波周期和持续时间是主要参数。此外，地震力的主要参数是加速度和表层的主频。可以看出，利用可靠性指标可以对动力特性差异很大的外力进行响应评估，并评估各种外力的影响。4）当结构恢复力特性为线性和非线性时，波浪力作用下海洋结构物的最大响应有很大的依赖性。特别是，波浪力的最大响应与长持续时间理解的非线性特性的影响是大的。因此，在设计水平响应的评估中，澄清影响是重要的。少

A fundamental examination concerning dynamic safety of large offshore structure with buoyancy members was done in this research. Advancing an effective, positive use development of an oceanic space in our country becomes a very important problem. The circulating water tank experiment and the simulation analysis by the computer are done in this research.The main result of obtaining for this research is summarized as follows.1) Vortex induced vibration in each column is influenced by the interval of column member. As for the response by vortex induced vibration, the increasing tendency was seen at the case of single column when the interval of column narrowed. Moreover, it has been understood to cause torsion vibration as the entire structure by the difference of frequency where the vortex induced vibration of column in the back and forth is generated.2) If the responses of the structure subjected to separately wave force and seismic force were compared, a big difference was shown in ben … More ding moment stress because the position where these external force acted was different. However, it has been understood to show-a similar response in the structural model which is united with connected material when the structure is enlarged.3) The comparison on the design level response is done by using the reliability index for the wave force and the seismic force. In wave force, mean wave height, mean wave period, and duration are the main parameters. Moreover, the main parameter of seismic force is dominant frequency of the acceleration and surface layer. It has been understood that it is useful to be able to do the response evaluation to external force with a quite different dynamic characteristic by using the reliability index, and to evaluate the influence of each external force.4) The maximum response of offshore structure subjected to wave force depends greatly when the restoring force characteristic of the structure becomes linear and nonlinear. Especially, the maximum response to wave force with long duration understands the influence of a nonlinear characteristic is large. Therefore, it is important to clarify the influence in the evaluation of the design level response. Less