半潜式平台极限强度.doc
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半潜式平台极限强度,摘 要半潜式平台长期在深海作业，不可避免地会遭遇恶劣海况，由风、浪和流引起的极值环境载荷可腀@教ń峁棺畲蟪性啬芰Γ佣斐扇嗽薄⑵教ê秃Ｑ蠡肪车难现厮鹗В逼教ɑ肪吃睾珊统性啬芰哂忻飨缘乃婊裕虼似拦腊肭笔狡教ń峁拱踩杂谄教耷慷龋捎每煽啃苑椒ń醒芯俊１疚囊怨ば挪渴晃甯呒际醮翱蒲邢钅课尘埃...
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摘 要
半潜式平台长期在深海作业，不可避免地会遭遇恶劣海况，由风、浪和流引起的极值环境载荷可腀@教ń峁棺畲蟪性啬芰Γ佣斐扇嗽薄⑵教ê秃Ｑ蠡肪车难现厮鹗В逼教ɑ肪吃睾珊统性啬芰哂忻飨缘乃婊裕虼似拦腊肭笔狡教ń峁拱踩杂谄教耷慷龋捎每煽啃苑椒ń醒芯俊１疚囊怨ば挪渴晃甯呒际醮翱蒲邢钅课尘埃捎弥鸩狡苹捣ㄑ芯堪肭笔狡教耷慷龋⒔岷辖峁箍煽啃约扑愕氖的Ｄ夥ǎ肭笔狡教ㄕ寮耷慷瓤煽啃约扑隳Ｐ停肭笔狡教ń峁股杓坪桶踩云拦捞峁┮谰荨�
本文首先详细分析了加筋板格屈曲失效模式，采用梁-柱理论、理性弹塑性假设和塑性铰理论研究了加筋板单元的应力-应变关系，并给出不同阶段加筋板单元应力-应变计算公式。
其次，采用简化方法研究了船体和平台结构逐步破坏过程，编写了船体和平台结构极限强度计算程序，与箱型梁模型试验和实船事故比较分析结果表明本文的计算程序是正确可靠的，采用该程序研究了目标平台结构整体极限强度，详细地分析不同因素对平台结构极限强度的影响。
最后，采用拉丁超立方抽样方法结合条件期望和对偶变数方差减缩技术，给出结构可靠性计算的数值模拟法，建立半潜式平台整体极限强度可靠性计算模型，在目标平台结构可靠性分析的基础上给出平台结构目标可靠度的建议值。
关键词：半潜式平台；屈曲模式；极限强度；简化方法；结构可靠性；方差减缩技术
Abstract
Heavy sea state inevitably occurs during long working period of semi-submersible platforms at deep sea. Extreme environmental loads due to wind, wave and current, may exceed maximum load carrying capacity of platform structures which lead to huge loss of persons, platforms and environment. On account of obvious randomness of environmental loads and load carrying capacity of platforms, safety assessment of platform structures should be conducted by reliability method based on ultimate strength of platforms. This thesis is based on 11th five years research projects of high technology ships of industry and information department. The purpose of this thesis is to study ultimate strength of semi-submersible platforms using progressive collapse method, to establish calculation model of overall ultimate strength reliability of semi-submersible platforms using numerical simulation method of structural reliability calculation method, and to provide an important basis of design and safety assessment of semi-submersible platforms.
Firstly, buckling mode of stiffened plate is analyzed in detail. Stress-strain relationship of stiffened plate elements is studied using beam-column theory, idealized elastic-plastic assumptions and plastic joint theory. Calculation formulas of stress-strain relationship of stiffened plate elements at different stages are also given.
Secondly, progressive collapse course of ship and platform structures is studied using simplified method. Calculation program of ultimate strength of ship and platform structures is compiled and comparative analysis results of box girder model test and ship accident show this program is true and reliable. Overall ultimate strength of target platform is studied using this program and effect of different factors to ultimate strength of platform structures is also analyzed.
Finally, numerical simulation method of structural reliability calculation is given using Latin hypercube sampling with variance reduction techniques of conditional expectation and antithetic variates. Calculation model of overall ultimate strength reliability of semi-submersible platforms is established and target reliability index is suggested based on structural reliability analysis of target platform.
Key words: semi-submersible platform; buckling mode; ultimate strength; simplified method; structural reliability; variance reduction techniques
目录
摘要 I
Abstract III
第1章 绪论 1
1.1 论文研究的目的和意义 1
1.2 国内外研究现状 2
1.2.1 平台环境载荷研究 2
1.2.2 平台结构极限强度研究 3
1.2.3 平台结构可靠性研究 4
1.3本文研究内容和创新点 6
第2章 半潜平台加筋板单元应力-应变关系研究 9
2.1引言 9
2.2 半潜平台加筋板单元屈曲失效模式 9
2.2.1 加强筋翼缘失效 9
2.2.2 带板破坏 11
2.2.3 加强筋和板的组合失效 12
2.3 半潜平台加筋板单元应力-应变关系 14
2.3.1 角单元和受拉单元 15
2.3.2 受压单元 15
2.4 算例分析 17
2.4.1 单元划分 17
2.4.2 单元应力-应变关系 18
2.5 小结 21
第3章 半潜平台整体极限强度研究 23
3.1 引言 23
3.2半潜平台整体弯矩曲率的增量计算方法 23
3.3 模型试验和实船强度比较分析 24
3.3.1 Reckling模型 24
3.3.2 Dowling模型 27
3.3.3 VLCC 29
3.4 半潜平台整体极限强度算例分析 32
3.4.1平台单元划分 33
3.4.2目标平台弯矩－曲率关系 33
3.5半潜式平台结构强度影响参数分析 34
3.5.1材料对弯矩的影响 34
3.5.2焊接残余应力的影响 39
3.5.3横向压力的影响 40
3.5.4加筋板单元载荷—缩短行为的影响 40
3.5.5腐蚀的影响 43
3.6小结 45
第4章 半潜式平台整体可靠性研究 47
4.1引言 47
4.2结构可靠性计算方法 47
4.2.1 直接积分法 47
4.2.2改进的一阶二次矩 49
4.2.3 数值模拟法 50
4.3平台整体可靠性计算 60
4.3.1平台载荷的统计特征 60
4.3.2 结构能力的统计特征 62
4.4.3可靠性计算 63
..
半潜式平台长期在深海作业，不可避免地会遭遇恶劣海况，由风、浪和流引起的极值环境载荷可腀@教ń峁棺畲蟪性啬芰Γ佣斐扇嗽薄⑵教ê秃Ｑ蠡肪车难现厮鹗В逼教ɑ肪吃睾珊统性啬芰哂忻飨缘乃婊裕虼似拦腊肭笔狡教ń峁拱踩杂谄教耷慷龋捎每煽啃苑椒ń醒芯俊１疚囊怨ば挪渴晃甯呒际醮翱蒲邢钅课尘埃捎弥鸩狡苹捣ㄑ芯堪肭笔狡教耷慷龋⒔岷辖峁箍煽啃约扑愕氖的Ｄ夥ǎ肭笔狡教ㄕ寮耷慷瓤煽啃约扑隳Ｐ停肭笔狡教ń峁股杓坪桶踩云拦捞峁┮谰荨�
本文首先详细分析了加筋板格屈曲失效模式，采用梁-柱理论、理性弹塑性假设和塑性铰理论研究了加筋板单元的应力-应变关系，并给出不同阶段加筋板单元应力-应变计算公式。
其次，采用简化方法研究了船体和平台结构逐步破坏过程，编写了船体和平台结构极限强度计算程序，与箱型梁模型试验和实船事故比较分析结果表明本文的计算程序是正确可靠的，采用该程序研究了目标平台结构整体极限强度，详细地分析不同因素对平台结构极限强度的影响。
最后，采用拉丁超立方抽样方法结合条件期望和对偶变数方差减缩技术，给出结构可靠性计算的数值模拟法，建立半潜式平台整体极限强度可靠性计算模型，在目标平台结构可靠性分析的基础上给出平台结构目标可靠度的建议值。
关键词：半潜式平台；屈曲模式；极限强度；简化方法；结构可靠性；方差减缩技术
Abstract
Heavy sea state inevitably occurs during long working period of semi-submersible platforms at deep sea. Extreme environmental loads due to wind, wave and current, may exceed maximum load carrying capacity of platform structures which lead to huge loss of persons, platforms and environment. On account of obvious randomness of environmental loads and load carrying capacity of platforms, safety assessment of platform structures should be conducted by reliability method based on ultimate strength of platforms. This thesis is based on 11th five years research projects of high technology ships of industry and information department. The purpose of this thesis is to study ultimate strength of semi-submersible platforms using progressive collapse method, to establish calculation model of overall ultimate strength reliability of semi-submersible platforms using numerical simulation method of structural reliability calculation method, and to provide an important basis of design and safety assessment of semi-submersible platforms.
Firstly, buckling mode of stiffened plate is analyzed in detail. Stress-strain relationship of stiffened plate elements is studied using beam-column theory, idealized elastic-plastic assumptions and plastic joint theory. Calculation formulas of stress-strain relationship of stiffened plate elements at different stages are also given.
Secondly, progressive collapse course of ship and platform structures is studied using simplified method. Calculation program of ultimate strength of ship and platform structures is compiled and comparative analysis results of box girder model test and ship accident show this program is true and reliable. Overall ultimate strength of target platform is studied using this program and effect of different factors to ultimate strength of platform structures is also analyzed.
Finally, numerical simulation method of structural reliability calculation is given using Latin hypercube sampling with variance reduction techniques of conditional expectation and antithetic variates. Calculation model of overall ultimate strength reliability of semi-submersible platforms is established and target reliability index is suggested based on structural reliability analysis of target platform.
Key words: semi-submersible platform; buckling mode; ultimate strength; simplified method; structural reliability; variance reduction techniques
目录
摘要 I
Abstract III
第1章 绪论 1
1.1 论文研究的目的和意义 1
1.2 国内外研究现状 2
1.2.1 平台环境载荷研究 2
1.2.2 平台结构极限强度研究 3
1.2.3 平台结构可靠性研究 4
1.3本文研究内容和创新点 6
第2章 半潜平台加筋板单元应力-应变关系研究 9
2.1引言 9
2.2 半潜平台加筋板单元屈曲失效模式 9
2.2.1 加强筋翼缘失效 9
2.2.2 带板破坏 11
2.2.3 加强筋和板的组合失效 12
2.3 半潜平台加筋板单元应力-应变关系 14
2.3.1 角单元和受拉单元 15
2.3.2 受压单元 15
2.4 算例分析 17
2.4.1 单元划分 17
2.4.2 单元应力-应变关系 18
2.5 小结 21
第3章 半潜平台整体极限强度研究 23
3.1 引言 23
3.2半潜平台整体弯矩曲率的增量计算方法 23
3.3 模型试验和实船强度比较分析 24
3.3.1 Reckling模型 24
3.3.2 Dowling模型 27
3.3.3 VLCC 29
3.4 半潜平台整体极限强度算例分析 32
3.4.1平台单元划分 33
3.4.2目标平台弯矩－曲率关系 33
3.5半潜式平台结构强度影响参数分析 34
3.5.1材料对弯矩的影响 34
3.5.2焊接残余应力的影响 39
3.5.3横向压力的影响 40
3.5.4加筋板单元载荷—缩短行为的影响 40
3.5.5腐蚀的影响 43
3.6小结 45
第4章 半潜式平台整体可靠性研究 47
4.1引言 47
4.2结构可靠性计算方法 47
4.2.1 直接积分法 47
4.2.2改进的一阶二次矩 49
4.2.3 数值模拟法 50
4.3平台整体可靠性计算 60
4.3.1平台载荷的统计特征 60
4.3.2 结构能力的统计特征 62
4.4.3可靠性计算 63
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