导管架式海洋平台结构极限承载力分析的 整体推进法及其软件

根据非线性有限元逐步分析的思想,以已有的结构弹性分析软件为计算核心,提出了一种近似分析结构极限承载力的方法——整体推进法;采用整体推进法,以导管架式海洋平台结构线弹性分析软件ENSA为计算核心,考虑结构构件的损伤影响和维修加固效果,编制了导管架式海洋平台结构极限承载力近似分析软件UAP,为导管架式海洋平台结构的安全度评定提供了方法和手段;最后对渤海八号生产／储油平台在1993年的状态和JZ20-2MUQ平台的完好状态进行了极限承载力分析。     

现役导管架式海洋平台结构整体安全度评估

本文提出了一整套评估导管式海洋平台结构整体安全度的简化方法。主要工作包括：讨论了现役结构内力重分析的影响因素并提出了考虑原则和处理方法；将基本构件依受力特点和重要性程度予以分类、并通过划分层结构而将结构整体简化为层结构的串联体系；用强度储备比定义了基本构件的安全度指标、并延拓此定义于层结构和结构体系；结合专家经验并利用模糊数学原理综合结构的整体安全度指标。文章同时给出了工程应用实例     

极端荷载作用下海洋导管架平台体系可靠度分析

采用非线性倒塌分析方法，考虑桩－土－结构的非线性相互作用，研究了导管架平台在极端荷载作用下承载能力的计算模型，分析了平台结构体系在极端荷载作用下的全倒塌全过程，在此基础上，结合蒙特卡洛法，提出了海洋导管架平台结构的体系可靠度计算方法。最后对工程实例－涠11－4C海洋平台的结构进行了体系可靠性分析，并对比分析了不同的荷载效应计算公式对计算经的影响，研究表明计算经满足工程设计要求，便于工程应用。     

海洋导管架平台的极限强度分析

海洋导管架平台的极限分析是一项较新的研究课题，随着海上采油事业的飞速发展，它已越来越受到海洋工程设计及维修部门的重视。其研究成果不仅能用于设计结构的应力校核，尚可用于现有平台结构的整体安全估算。本文利用非线性模拟技术及线性分析程序的完美结合。成功地分析计算了受集中哉茶作用的空间框架结构，及受静载荷和环境载荷作用下的真实导管架平台极限强度。     

火灾作用下海洋平台结构响应分析

结合BZ28-1南井口平台导管架,建立了海洋平台结构有限元计算模型。采用弹塑性分析方法,并应用温度升高时钢材的非线性应力/应变关系,采用火灾的标准温度-时间曲线建立平台结构温度随时间的变化模型,基于能量守恒原理建立热传导微分方程,计算热传导和对流对结构温度的影响,分析得到受火区域构件的温度场。依据钢材性能随温度升高的变化,分析火灾荷载下平台结构的响应。火灾发生时,平台结构中的构件在火温的作用下,温度逐渐升高,虽然作用在结构上的荷载不变,但由于钢材的弹性模量和屈服强度都急剧下降,使平台结构的承载能力下降;当温度上升到600℃以上时,平台结构就形成足够数目的塑性铰,使结构达到极限破坏状态。通过计算分析表明,当火灾作用6 min后,着火房间构件发生严重屈曲,但平台结构整体性能保持良好;当火灾作用22 min后,受火区域构件都发生了较大的变形,引起平台结构的毁损和倾覆。     

海洋平台结构实时安全监测系统

阐述了海洋平台结构实时计算模型的建立和修正方法，确定了在海洋环境监测的基础上本系统实时环境荷载，提出了海洋平台结构实时安全评估的方法，采用Delphi开发工具，开发出了Windows应用程序“海洋平台结构实时安全监测系统”。该系统于1998－1999年和1999－2000年冬季两次在渤海JZ20－2MUQ平台上试运行，实时监测了JZ20－2MUQ平台两个冬季的安全状况。     

锥体导管架海洋平台冰激结构振动响应分析

渤海冰区油气开发中,在桩腿上安装抗冰锥体的导管架平台是最常见的结构形式.冰激结构振动不仅会造成平台结构的损伤,还将对平台上部管线和设备的安全运行构成极大的威胁,并影响平台作业人员的正常生活和生产操作.针对渤海冰区锥体平台结构冰激振动响应的三种计算方法进行了研究,即平台结构的有限元分析、简化的结构动力分析和冰振响应幅值统计分析.以辽东湾JZ20-2油气田的MUQ平台为例,对以上三种冰振响应计算方法进行对比,以讨论它们的一致性和各自的适用条件.结果表明,这三种分析方法的计算结果基本一致,但有些计算参数需要现场实测资料的确定.     

固定式海洋平台极限强度试验研究

根据墨西哥湾某海域一典型固定式海洋平台为原型,按照几何相似准则和刚度相似准则设计并制作海洋平台试验模型,开展极限强度模型试验研究,观察并记录其破坏过程。并采用非线性有限元方法(ANSYS)对试验模型进行极限强度数值计算,将计算结果与试验结果对比,结果表明计算结果与试验结果吻合较好,验证非线性有限元方法的有效性。     

单点系泊海洋导管架平台结构体系可靠性分析

采用非线性逐步倒塌分析方法,考虑桩-土-结构的非线性相互作用,研究了单点系泊海洋导管架平台在极端荷载作用下的承载能力计算模型,在此基础上结合蒙特卡洛随机抽样法,提出了单点系泊海洋导管架平台结构体系可靠度计算方法。最后对工程实例BZ28-1SPM单点系?白海洋导管架平台结构在20年设计基准期和50年重现期进行了体系可靠性分析：研究结果表明：用50年重现期的环境荷载参数来进行BZ28-1SPM单点系泊海洋导管架平台结构的设计是合理的;在环境荷载中起主导作用的是由波浪引起的系泊力;在海洋平台结构的设计及对已服役平台结构的评估中运用体系可靠度理论,可以为海洋平台结构的设计、维护和评估提供理论依据。     

海洋平台结构地震响应不确定性因素分析

本文将海洋平台结构的刚度、质量、阻尼以及动水阳力系数C_m,C_d模拟为随机变量,利用随机有限元法,分析了这些参数的变异性引起的海洋平台结构地震响应变异性问题。结果表明,海洋平台结构地震响应的变异性与输入结构参数本身的变异性具有同一量级,动水阻力参数变异性对平台反应的影响比结构参数变异性平台反应的影响稍小。     

Ultimate Strength Analysis of Offshore Jacket Platform

- The ultimate strength analysis of offshore jacket platforms is a research project which has been developed in recent years. With the rapid development of marine oil industry, the departments of design and IMR (Inspection, Maintenance and Repair) in the offshore engineering have attached great importance to this project. The research procedure applies to both the stress check of new design platforms and the whole safety assessment of existing platforms. In this paper, we combine the pseudo non-linear technique with the linear analysis program and successfully analyze the ultimate strength of the space frame structure subject to the concentrated load and a real jacket platform subject to the dead load and environmental load.     

Static Analysis of Collision Strength of Offshore Platform

In this paper a numerical analysis method combining FEM incemental technique with limit analysis concept is proposed for the study of the static strength of offshore platform in collision. Large deformation and plasticity are accounted for and the limit yield surface expressed by generalized stress for a tubular section is derived. The modified stiffness matrix of space beam element is formulated by Plastic Node Method. The buckling behavior of beam columns can also be taken into account. It can trace the generation of plastic hinges during loading and finally the ultimate strength of offshore platform against collision is obtained.     

Aseismic Reliability Analysis Approach for Offshore Jacket Platform Structures

—By means of nonlinear pushover collapse analysis approach,the aseismic reliability analysesof two offshore jacket platforms in the Bohai Gulf in China are studied according to their ocean locationand environmental loadings there.On the basis of those analyses,an aseismic reliability analysis approachis presented.The results show that the aseismic reliability of those platforms is high.Also it is proved thatthis aseismic reliability analysis approach is simple,practical and reliable.     

Nonlinear Analysis of Pile Foundation Jacket Platform

In this paper,the nonlinear collapse of the BOHAI-8 pile foundation jacket platform hasbeen analyzed.The ultimate load and collapse process of two computational models of the structure aregiven.One model is of fixed support whose length is eight times the pile leg diameter and the other consid-ers the nonlinearity of the soil-pile interaction.     

极端波浪对海洋导管架平台的作用及其模型试验研究

通过极端波浪对海洋导管架平台作用力的模型试验,对极端波浪的作用进行了探讨。首先在常规波浪力计算公式的基础上,提出了极端波浪作用下的简易计算方法,并结合国外相应研究成果,提出了三个简易计算表达式;在对模型试验数据的分析基础上,给出了上述三个简易计算公式中的系数,从而得到极端波浪作用下的波浪力计算表达式。     

Finite Element Analysis of Deformed Legs of Offshore Platform Structures

The element stiffness matrix of the equivalent beam or pipe element of the deformed leg of the platform is derived by the finite element method. The stresses and displacements of some damaged components are calculated, and the numeri-cal solutions agree well with those obtained by the fine mesh finite element method. Finally, as an application of this method, the stresses of some platform structures are calculated and analyzed.     

Adaptive Predictive Inverse Control of Offshore Jacket Platform Based on Rough Neural Network

The offshore jacket platform is a complex and time-varying nonlinear system,which can be excited of harmful vibration by external loads.It is difficult to obtain an ideal control performance for passive control methods or traditional active control methods based on accurate mathematic model.In this paper,an adaptive inverse control method is proposed on the basis of novel rough neural networks (RNN) to control the harmful vibration of the offshore jacket platform,and the offshore jacket platform model is established by dynamic stiffness matrix (DSM) method.Benefited from the nonlinear processing ability of the neural networks and data interpretation ability of the rough set theory,RNN is utilized to identify the predictive inverse model of the offshore jacket platform system.Then the identified model is used as the adaptive predictive inverse controller to control the harmful vibration caused by wave and wind loads,and to deal with the delay problem caused by signal transmission in the control process.The numerical results show that the constructed novel RNN has advantages such as clear structure,fast training speed and strong error-tolerance ability,and the proposed method based on RNN can effectively control the harmfid vibration of the offshore jacket platform.     

Calibration of LRFD Format for Steel Jacket Offshore Platform in China Offshore Area （2） ： Load, Resistance and Load Combination Factors

1.IntroductionLoad and Resistance Factor Design(LRFD)isthe commonly adoptedreliability-based designfor-mat for structural design(CNE,1990;AAHTO,1994;OMTC,1983;CMC,1984).Code calibra-tionforthe LRFDformat is a processto determinethetarget reliability by de…     

Torsionally Coupled Response Control of Offshore Platform Structures Using Circular Tuned Liquid Column Dampers

In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively, The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.