一种非对称无横撑半潜式平台的整体强度评估

Global Strength Analysis of a Novel Semi-Submersible Platform

本文基于设计波法对某新型半潜式平台的整体强度进行了研究分析。不同于传统半潜式平台结构形式,该新型半潜式平台的浮筒一大一小,对应的两组立柱也是一大一小,因此结构关于中纵剖面是非对称的;此外该半潜式平台没有横撑结构。本文首先确定了作业吃水和自存吃水情况下新型半潜式平台四种典型危险工况对应的设计波参数,然后研究分析了不同危险工况下半潜式平台的整体强度,并对新型半潜式平台与传统半潜式平台在整体强度方面的差异进行了比较。研究结果表明,该新型平台的最大应力最易出现在大立柱内侧与甲板连接拐角区域,而传统有横撑半潜式平台的最大应力多发生在横撑与立柱连接区域。此外,浮筒与甲板之间的大倒角设计有助于提高新型半潜式平台的整体强度。

Based on the design wave method,the global strength analysis of a novel accommodation/crane semi-submersible（SEMI）is conducted in this paper.The semi-submersible platform adopted in the paper is different from the conventional semi-submersible platform in geometrical characteristic and hydrodynamic performance.The novel semi-submersible platform,with two non-symmetrical pontoons and with two groups of non-symmetrical columns connected with the pontoons and deck,is not symmetrical about its middle longitudinal section.In addition,the shape of the pontoons at the bow and stern are not same with each other,and the horizontal connections braces of the novel semi-submersible platform is not taken into consideration at the design process to improve the towing speed.The unique geometrical characteristics of this novel SEMI makes its stress distribution distinguish from that of traditional semi-submersible,which makes it＇s necessary to study the global strength of the novel semi-submersible.In this paper,the wave parameter of the four kinds of typical conditions are first screened out based on the design wave method.Further,a fine meshed finite element model of the novel semi-submersible is established,and the global strength analysis are conducted under the typical design conditions to obtain the stress distribution of the novel platform via the quasi static analysis recommend by the design code.Finally,another novel semi-submersible platform with horizontal connection braces are demonstrated in the example,and the discrepancy of the stress distribution arising from the horizontal connection braces are investigated by comparing the stress result associated with the novel semi-submersible platform with and without horizontal braces.The numerical results indicate that the maximum Von Mises stress of the novel semi-submersible platform without horizontal connection braces occurs at the inner part of large columns and deck connection areas which may resulted from the discontinuity of the material.While the maximum Von Mises stress of the structure with horizontal connection braces mainly appears at the connection between the columns and the braces.In addition,it has found that the large fillet radius shape for the joint area,where columns and deck connect with each other,is an effective design to reduce the novel semi-submersible＇s global strength.This study can provide a significance reference and guidance for the design of future new concept semi-submersible platform.