海洋平台结构形状与拓扑优化设计

以实际环境荷载作用下的实际海洋导管架平台结构为对象，研究了海洋平台结构在风，流，海冰等多荷载模式和多荷载工况下的优化设计的理论方法和应用技术，建立了结构尺寸优化，形状优化和拓扑优化问题的统一模型。计算结果反映出形状优化比尺寸优化所得设计更优，而拓扑优化的设计效果最好。不同的荷载工况对应的最优拓扑形式不同，因此在实际设计中应考虑实际的荷载工况，选取不同的拓扑形式。     

Reliability-Based Full-Life Cycle Optimum Design of Offshore Jacket Platform

Based on the consideration of operation environment and structural property, an optimnm design model of offshore jacket platform is developed in this paper, namely, the reliability-based full-life cycle optimum design model. In this model, the time-dependent reliability assessment method for structural members is established by combination of the decrease, of sectional size and performance deterioration of material. The initial investment, maintenance cost and failure loss cost are assembled into the model. The total cost of the platform structure system in its full service period is chosen as the objective function, and the initial reliabilities of the layer elements partitioned in advance are taken as the design variables. Different models are obtained, depending on whether the system reliability eonstraint is considered or not. This optimum design model can result in the lowest full-life cost and the optimal initial layer reliability of an offshore jacket platform in the design of marine structures. The feasibility of this model is illustrated with an actual jacket platform in the Liaodong Gulf as an example.     

基于拓扑优化与多目标优化的集装箱相似畸变模型设计

使用相似原理构建缩尺模型是探究大型结构性能的最基本和最优途径。基于PATRAN软件的PCL语言与ISIGHT软件,提出一种联合静动力学、拓扑优化与多目标优化的集装箱相似畸变模型构建方法。利用拓扑优化的SIMP法(Solid Isotropic Material with Penalization)得到缩尺集装箱墙壁结构的最优材料分布,既保证了结构性能又降低了缩尺模型的重量;基于全局多目标算法建立优化模型,采用有限元方法对集装箱性能进行分析,以结构刚度和一阶模态频率为目标函数进行寻优,得到相似模型的最优设计参数。最终利用有限元分析验证该模型的合理性。结果表明:该方法具有一定的通用性,能为其它类似结构的相似模型构建提供参考。     

Structural Model Updating of Jacket Platform by Control Theory Using Vibration Measurement Approach

The identification of variations in the dynamic behavior of structures is an important subject in structural integrity assessment.Improvement and servicing of offshore platforms in the marine environment with constant changing,requires understanding the real behavior of these structures to prevent possible failure.In this work,empirical and numerical models of jacket structure are investigated.A test on experimental modal analysis is accomplished to acquire the response of structure and a mathematical model of the jacket structure is also performed.Then,based on the control theory using developed reduction system,the matrices of the platform model is calibrated and updated.The current methodology can be applied to prepare the finite element model to be more adaptable to the empirical model.Calibrated results with the proposed approach in this paper are very close to those of the actual model and also this technique leads to a reduction in the amount of calculations and expenses.The research clearly confirms that the dynamic behavior of fixed marine structures should be designed and assessed considering the calibrated analytical models for the safety of these structures.     

Optimum Design of Jacket Platforms Considering Structure-Pile-Soil Interaction

This paper proposes an optimum design medel for the offshore jacket platform considering multi-design criteria,multi-design constraints and the structure-pile-soil interaction,and gives an optimum designprocedure in which the proposed optimum design model is used together with structural analysis softwareSAP91 and optimum algorithm software OPBI.The Chengbei ~#11 offshore platform,which lies in theShengli oil field,is designed by use of the above optimum design model.The results show that the optimumdesign model is stable,and it depends on neither the optimization algorithm nor initial values of design vari-ables.All values of the objective function converge to the same minimum value,and the speed of conver-gence is high,showing that the proposed optimum design model is reasonable.     

渤海导管架平台的冰激振动响应分析

为研究渤海海域海冰撞击导管架海洋平台的冰振响应,基于锥体冰力函数,本文建立了渤海海域的冰力作用模型。采用ANSYS有限元软件对导管架平台与海冰的相互作用进行数值模拟,开展了海冰作用下抗冰平台的静力分析及平台动力响应分析。通过与静力分析结果对比,验证了动冰力对结构响应的动力放大效应。在此基础上通过改变冰厚、冰速等海冰参数,研究了不同冰力作用周期下导管架平台的冰振响应。研究表明,海冰厚度及海冰流动速度是影响平台动力响应的主要因素,为导管架平台结构的动力优化设计提供了研究基础。     

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…     

基于拓扑优化方法的船体支柱布局优化设计

船体支柱的布局影响到船舶功能性舱室的布置及相应的结构设计,而目前支柱布局多依赖母型船或者工程师设计经验,缺少基于数学优化的技术支撑。变密度的拓扑优化方法可将属于离散变量优化的支柱布局问题转化为连续变量优化问题。通过悬臂梁—支柱结构的算例,验证了该方法用于解决支柱布局优化问题的可行性。针对某型VLCC的支柱—大跨度甲板结构的支柱布局优化问题,根据布置限制条件设定了支柱优化设计域,选择了两种不同的优化目标函数进行支柱的布局优化设计,最后对优化结果进行了对比分析。结果表明,本方法具有较好的可行性,无需过多设计经验即可优化得到结构性能较好的支柱布局方案,可为此类的支柱布局优化设计提供技术支撑。     

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。     

A new method for platform design based on parametric technology

A new method for platform design, named parametric platform design method (PPDM), is presented in this paper in order to improve the mobile platform design efficiency. In this method, an integrated parametric system that fully considers the characteristics of the platform is developed, which significantly optimizes the design process with the top–bottom design concept. In the parametric system, the main geometric dimensions are taken as parameters, while the topology between the structure members, the function requirements and the safety requirements are converted into geometric constraints. By geometric constraint solving (GCS), a set of parameters that satisfy all the given constraints are determined, and then the design scheme is obtained by several core algorithms, such as parametric tank subdivision, 3D stability calculation, parametric structure design, FEM preprocessing, etc. The parametric method greatly increases the changeability and the reusability of the platform model, and concurrent design is well supported. As the model is driven by parameters, PPDM is an excellent method for optimization design. As a result, PPDM has incomparable advantages on the design efficiency over traditional methods.     

浅海导管架平台结构损伤诊断试验研究

基于模型试验研究了浅海导管架平台的结构损伤诊断,采用标量型ARMA模型识别出结构的三阶模态参数,分别采用遗传算法和模态应变能法对试验模型不同模拟损伤工况进行了损伤诊断。基于遗传算法,提出了采用不同自由度一阶模态参数的损伤诊断方法。研究表明,由于海洋平台的前三阶模态分别为不同自由度的一阶模态,采用两阶或三阶模态识别损伤时,损伤杆件影响较小的自由度方向的模态参数对结构的损伤诊断将产生不利的影响,成为识别噪声。因此,可分别采用不同自由度的一阶模态进行结构损伤诊断。     

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.     

柔性气囊助浮法拆除导管架技术研究

文中研究采用柔性气囊助浮法起升导管架的拆除技术。浅水海域浮吊进入困难并且拆除导管架的施工费用昂贵。考虑气囊产生的浮力巨大、价格便宜及连接结构方便的特点,针对即将拆除的QK18-2平台,设计气囊助浮起升导管架的技术方案。考虑水深确定导管架吃水,设计气囊与导管架的连接方式。针对导管架在位起浮状态,计算带有气囊的导管架系统幅频响应RAOs,考虑不同的海洋环境参数,计算分析风浪流作用下导管架系统6个自由度的时域运动响应,文中提出了多点系泊控制导管架运动的合理系泊方式。研究结果表明,气囊助浮法拆除导管架技术具有较高的工程实用价值,针对目标导管架平台设计的气囊助浮拆除技术方案,具有费用低、风险小及不需使用浮吊的技术优势,该项技术可以在导管架平台拆除中推广应用。     

海洋平台现场动态应力测试

迄今为至胜利浅海油田已相继建成大小平台几十座,平台结构型式是导管架式,志管架平台的结构计算理论已基本成熟,现场应力测试是对平台结构设计的验证、补充和发展,但是有关平台的现场应力测试在海洋工程界则是一个空白。本文主要介绍埕北２５Ａ井组平台现场应力测试的方法、结果以及与理论计算的对比。     

Using incomplete modal data for damage detection in offshore jacket structures

The development of robust techniques for early damage detection for offshore structures is crucial to avoid the possible catastrophe caused by structural failures. This article applies the cross-model cross-mode (CMCM) method for damage detection that is capable of identifying the damage to individual members of offshore jacket platforms, when limited, spatially incomplete modal data is available. Basically, the CMCM method is classified as a direct, physical property adjustment model updating method. Implementing this method requires only a few modes measured from the damaged structure. In dealing with spatial incompleteness, this paper investigates both model reduction and modal expansion techniques. Specifically, either Guyan (static condensation) or SEREP (system equivalent reduction expansion process) transformation matrix, between the master and slave degrees-of-freedom, is employed in the model reduction or modal expansion process. One theoretical development is an iterative procedure to compute the transformation matrix associated with the (unknown) damaged structure. Numerical studies are conducted for a jacket platform with multiple damaged members based on synthetic data generated from finite-element models. The results suggest that (i) Guyan scheme always outperforms SEREP, (ii) model reduction is always better than modal expansion, and (iii) the CMCM method in conjunction with iterative Guyan reduction approach yields the best damage location and severity estimate.     

海洋平台结构风险评估

作为结构系统可靠性方法与结构损伤冗余设计的一个合理延伸与综合，结构风险评估与决策技术是近年来得到迅速发展的新方法。本文讨论了海洋平台结构风险评估的理论框架，涉及了结构风险评估的几个基本方面，为进一步进行详细研究确立了一条主线。本文还对导管架式平台的结构风险评估进行了简要讨论。     

Structural monitoring of offshore platforms using impulse and relaxation response

Monitoring offshore platforms, long span bridges, high rise buildings, TV towers and other similar structures is essential for ensuring their safety in service. Continuous monitoring assumes even greater significance in the case of offshore platforms, which are highly susceptible to damage due to the corrosive environment and the continuous action of waves. Also, since a major part of the structure is under water and covered by marine growth, even a trained diver cannot easily detect damage in the structure. In the present work, vibration criterion is adopted for structural monitoring of jacket platforms. Artificial excitation of these structures is not always practicable and ambient excitation due to wind and waves may not be sufficient for collecting the required vibration data. Alternate methods can be adopted for the same purpose, for example, the application of an impact or a sudden relaxation of an applied force for exciting the structure. For jacket platforms, impact can be applied by gently pushing the structure at the fender while relaxation can be accomplished by pulling the structure and then suddenly releasing it using a tug or a supply vessel in both cases. The present study is an experimental investigation on a laboratory model of a jacket platform, for exploring the feasibility of adapting vibration responses due to impulse and relaxation, for structural monitoring. Effects of damage in six members of the platform as well as changes in deck masses were studied. A finite element model of the structure was used to analyze all the cases for comparison of the results as well as system identification. A data acquisition and analysis procedure for obtaining the response signatures of the platform due to the impulse and relaxation procedure was also developed for possible adoption in on-line monitoring of offshore platforms. From the study, it has been concluded that both impulse and relaxation responses are useful tools for monitoring offshore jacket platforms. The present work forms the basis for the development of an automated, on-line monitoring system for offshore platforms, using neural networks.     

海洋工程结构的多目标模糊优化设计

本文从模糊综合评判的角度出发，研究了海洋工程结构的多目标优化设计方法。运用模糊层次分析法来确定各追逐目标的重要性因子；通过模糊变换求得方案的模糊评判；并用理想评判集的模糊识别法确定设计方案的优劣。从而进行结构的优化设计。文章还给出了海洋平台桩腿结构的模糊优化设计实例。     

大型导管架吊点分步离散优化设计

导管架吊点的设计是关系导管架起吊安全的重要环节.针对大型导管架吊点结构特点,利用有限元法和优化技术,提出了分步离散优化设计方法.在建立吊点有限元模型和给定边界条件的基础上,按线性静力分析,将吊点设计分为选型和板厚优化两个步骤.在吊点选型过程中,以最少板数为优化目标;在吊点板厚优化过程中,以综合最小板厚为优化目标.该方法不仅是大型导管架吊点优化设计的通用有效方法,而且同样适用于其它类似的工程问题.