﻿ 环境烈度因子在FPSO船体梁强度评估中的应用
 舰船科学技术  2017, Vol. 39 Issue (10): 34-39 PDF

1. 哈尔滨工程大学 船舶工程学院，黑龙江 哈尔滨 150001;
2. 中国船舶及海洋工程设计研究院，上海 200011

The application of environmental severity factor on hull girder strength evaluation of FPSO
TANG Yu1, REN Hui-long1, QIU Wei-qiang2, YANG Fan1, ZHANG Zhi-kang2
1. College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China;
2. Marine Design and Research Institute of China, Shanghai 200011, China
Abstract: The rule formulas which used to calculate the design loads of FPSO and navigating-free ships are different because of the different operating conditions between FPSO and common ships. It is a key point that how to apply current seagoing ships rules to designing and evaluating FPSO. Based on the current seagoing ships rules, the thesis adopted environment severe factors to modify the formulas which intended to calculate design loads of ships operating in unrestricted service conditions. The modified formulas were used to calculate the design loads for FPSO. Then the obtained formulas were utilized to calculate the design loads of a FPSO with 300 000 DWT which followed by a hull girder strength check based on thin-wall theory. The check results of ESF method were compared with those which weren't modified with ESF and the latter was greater than the former obviously. Meanwhile, it was a time-saving method to apply thin-walled theory to evaluating hull girder strength which avoided whole ship finite element model.
Key words: FPSO     environmental severity factor (ESF)     bending strength     shear strength
0 引　言

FPSO需要在目标海域长期作业，在服务期内，FPSO（特别是不具备自航功能的FPSO）很有可能遭遇极端的载荷情况。出于安全考虑，目前的规范都将FPSO的设计环境条件定为100年一遇，因此，如何准确地确定FPSO的设计载荷是FPSO设计评估中的重点。

1 环境烈度因子的定义

 $\beta = \frac{{{L_S}}}{{{L_U}}},$ (1)

2 环境烈度因子的确定

2.1 LS的计算设置

2.2 LU的计算设置

2.3 环境烈度因子计算

3 FPSO船体梁纵向强度校核

3.1 弯曲强度校核

 ${M_{ws}} = - {k_1}{\beta _{VBM}}{C_1}{L^2}B\left( {{C_b} + 0.7} \right) \times {10^{ - 3}}\text{,}\;\;\text{中垂,}$ (2)
 ${M_{wh}} = - {k_2}{\beta _{VBM}}{C_1}{L^2}B{C_b} \times {10^{ - 3}}\text{,}\;\;\;\;\;\text{中拱}\text{。}$ (3)

 图 1 中拱/中垂静水弯矩与波浪弯矩分布图 Fig. 1 The bonding moment of hogging and sagging

 $SM = {M_t}/{f_p}\text{。}$ (4)

3.2 剪切强度校核

 ${F_{wp}} = + k{\beta _{VSF}}{F_1}{C_1}LB\left( {{C_b} + 0.7} \right) \times {10^{ - 2}}\left( + \right),$ (5)
 ${F_{wn}} = - k{\beta _{VSF}}{F_2}{C_1}LB\left( {{C_b} + 0.7} \right) \times {10^{ - 2}}\left( - \right)\text{。}$ (6)

 图 2 中拱/中垂静水剪力与波浪弯矩分布图 Fig. 2 The shear force of hogging and sagging

 ${f_s} = 110\;000\;{\rm{kN/}}{{\rm{m}}^{\rm{2}}},$ (7)

 图 3 目标FPSO三舱段模型图 Fig. 3 The three cargo hold model

3.3 ESF修正与否强度校核对比

4 结　语

1) 船体梁弯曲强度校核，未经ESF修正的计算结果相对修正后计算所得的规范要求剖面模数偏大10.95%~18.91%；规范要求的最小剖面模数前者偏大17.6%左右；

2) 船体梁剪切强度校核时，未经ESF修正的计算结果相对修正后的计算结果偏大14.28%~28.91%；

3) 相对有限元计算，采用薄壁梁理论可以快速、有效计算船体梁闭型舱室的剪切强度。

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