深水导管架上部模块浮托安装过程疲劳分析
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摘要
深水导管架在海上浮托施工设计中存在高撞击力,撞击力幅值过大会使某些关键杆件产生超应力,导致局部节点产生低周疲劳,给导管架的使用寿命带来不利影响。对此,介绍深水导管架浮托法安装过程中的疲劳损伤计算方法,涉及边界条件的处理和拖船、上部模块及导管架之间载荷传递的模拟,结构响应计算,节点疲劳估算等。应用不同的S-N曲线,分别考虑高周和低周疲劳,计算某导管架上部模块在安装组对阶段其桩腿与上部模块对接位置的疲劳损伤。对计算结果显示的薄弱位置进行加强,从而为浮托安装作业提供技术指导和安全保障。
High impact forces may occur during the float-over operation of deep-water jacket at sea, which will generate overstress in some key structural elements, leading to low cycle fatigue at the local nodes and producing negative effect on the service life of the jacket. This paper introduces a fatigue damage calculation method for the deep-water jacket under float-over installation, including treatment of boundary conditions; simulation of load transfer among the barge, the topside and the jacket; calculation of structural responses; estimation of node fatigue and so on. The high cycle and the low cycle fatigue are considered respectively with different S-N curves, so as to calculate the fatigue damage on the connection between the topside and the jacket leg. The weak positions shown in the calculation result are strengthened and thus to provide technical guidance and security for the float-over installation.
High impact forces may occur during the float-over operation of deep-water jacket at sea, which will generate overstress in some key structural elements, leading to low cycle fatigue at the local nodes and producing negative effect on the service life of the jacket. This paper introduces a fatigue damage calculation method for the deep-water jacket under float-over installation, including treatment of boundary conditions; simulation of load transfer among the barge, the topside and the jacket; calculation of structural responses; estimation of node fatigue and so on. The high cycle and the low cycle fatigue are considered respectively with different S-N curves, so as to calculate the fatigue damage on the connection between the topside and the jacket leg. The weak positions shown in the calculation result are strengthened and thus to provide technical guidance and security for the float-over installation.
引文
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[2]NORSOK.Assessment of structural integrity for existing offshore load-bearing structure:NORSOK-N006[S].2009.
[3]DNV.Determination of Structural Capacity by Non-linear FE Analysis Methods:DNV-RP-C208[S].2013.
[4]DNV.Det Norske Veritas.SESAM user manual SESTRA version 8.8[S].2013.
[5]Det Norske Veritas.SESAM user manual FRAMEWORK Version 3.8[S].2011.
[6]MARINTEK.SIMO user manual[S].2012.
[7]Det Norske Veritas.SESAM user manual WADAM version 8.3[S].2011.
[8]PINKSTER J A.Low-frequency phenomena associated with vessels moored at sea[J].Society of Petroleum Engineers Journal,1975,12:487-494.
[9]许鑫,杨建民,吕海宁.导管架平台浮托法安装的数值模拟和模型试验[J].上海交通大学学报,2011,45(4):439-445.