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The target reliability index has been effectively used as the best solution to deal with the relationship between the structural safety and the optimal economy in any structural design.However,the target reliability index for offshore jacket platforms based on different sea areas in China has never been calibrated.This paper presents an approach for its calibration,and suggests many kinds of associated load cases.The uncertainties of loads and structural resistance are mainly investigated.The target reliability index for structural components,tubular joints and piles of offshore jacket platforms are discussed respectively in detail.Finally,through the calibrated results from the offshore jacket platforms of QK18-1,JZ20-2,SZ36-1 and BZ28-1 in the Bohai Bay,it is proposed to adopt 2.8 as the target reliability index of offshore jacket platforms in the Bohai Bay for a 25-year design period.The results provide significant reference for the design of offshore jacket platforms. 相似文献
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The target reliability index has been effectively used as the best solution to deal with the relationship between the structural safety and the optimal economy in any structural design. However, the target reliability index for off-shore jacket platforms based on different sea areas in China has never been calibrated. This paper presents an approach for its calibration, and suggests many kinds of associated load cases. The uncertainties of loads and structural resistance are mainly investigated. The target reliability index for structural components, tubular joints and piles of offshore jacket platforms are discussed respectively in detail. Finally, through the calibrated results from the offshore jacket platforms of QK18-1, JZ20-2, SZ36-1 and BZ28-1 in the Bohai Bay, it is proposed to adopt 2.8 as the target reliability index of offshore jacket platforms in the Bohai Bay for a 25-year design period. The results provide significant reference for the design of offshore jacket platforms. 相似文献
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For the fulfillment of the probability-based structural design for the offshore jacket platforms in the Bohai Bay, the design factors of loads, resistance and load combinations are much necessary to be calibrated according to the proposed target reliability index. Firstly, the limit states function for the offshore jacket platforms is introduced. Then, four approaches to calibrate the factors of load and resistance are presented and compared. Afterwards, the methods to calibrate the load combination factors are developed. Finally, the factors of load, resistance and load combination for the offshore jacket platforms in the Bohai Bay are calibrated and the corresponding design formulae are recommended. The results are proved to be rational in practice, and also illustrate that the proposed target reliability index for offshore jacket platforms in the Bohai Bay is also appropriate. 相似文献
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For the fulfillment of the probability-based structural design for the offshore jacket platforms in the Bohai Bay, the design factors of loads, resistance and load combinations are much necessary to be calibrated according to the proposed target reliability index. Firstly, the limit states function for the offshore jacket platforms is introduced. Then, four approaches to calibrate the factors of load and resistance are presented and compared. Afterwards, the methods to calibrate the load combination factors... 相似文献
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锥体导管架海洋平台冰激振动的DEM-FEM耦合分析及高性能算法 总被引：1，自引：0，他引：1
在寒区海域,冰荷载是影响海洋平台安全运行的主要环境荷载之一,由其引起的冰激振动给平台结构及其上部设备带来了严重危害。为分析不同冰况下平台的振动响应,本文建立了导管架海洋平台冰激振动的离散元（DEM）-有限元（FEM）耦合模型。采用具有黏接-破碎性能的等粒径球体离散单元对海冰的破碎特性进行模拟,通过由梁单元构建的海洋平台有限元模型获得结构的振动响应。在离散元与有限元的接触区域中实现了两个模型间计算参数的传递。为提高该耦合模型的计算效率和规模,发展了基于动力子结构方法的DEM-FEM耦合模型。为验证该耦合模型的有效性和可行性,将不同冰况下得到的冰荷载与ISO19906和JTS 144-1-2010标准进行了对比。结果表明,计算得到的冰荷载与标准相近,且冰厚与冰荷载呈二次非线性关系。同时,从冰速和冰厚两方面对比了渤海四桩腿JZ20-2 MUQ锥体导管架平台冰激振动加速度的数值结果和现场实测数据,发现冰速与振动加速度呈线性关系,冰厚与振动加速度呈二次非线性关系,并且振动加速度与冰速和冰厚平方的乘积呈线性关系。 相似文献
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基于测量结构水下光纤应变获取冰力的方法首次应用于渤海JZ20-2NW加锥导管架平台,该方法方便进行零点标定,可获取结构总冰力的绝对信息(包括均值和波动值)。首先介绍了JZ20-2NW平台的现场监测系统,主要包括结构水下应变响应记录冰力信息,甲板上部视频记录同步冰情(冰厚、冰速和来冰方向)信息和拾振器记录结构冰振响应;重点分析了由测点应变向结构总冰力的转化方法,并对总冰力进行了初步分析。将无量纲化实测冰力与5种典型冰力计算模型进行了比较,分析结果表明,锥体宽度与海冰厚度比值(简称"宽厚比")对冰力大小及变化起决定作用。 相似文献
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1 .IntroductionThe structural design method has evolvedfromthe workingstress method,damage stage methodtolimit state method.The more recent probabilisticlimit state design method,whichis based onreliabili-tytheory,has beengenerallyacceptedinthe designcode… 相似文献
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《中国海洋工程》2020,(4)
This paper investigates the possibility of utilizing response from natural ice loading for modal parameter identification of real offshore platforms. The test platform is the JZ20-2 MUQ jacket platform located in the Liaodong Bay, China. A field experiment is carried out in winter season, as the platform is excited by floating ices. The feasibility is demonstrated by the acceleration response of two different segments. By the SSI-data method, the modal frequencies and damping ratios of four structural modes can be successfully identified from both segments.The estimated information from both segments is almost identical, which demonstrates that the modal identification is trustworthy. Furthermore, by taking the Jacket platform as a benchmark, the numerical performance of five popular time-domain EMA methods is systematically compared from different viewpoints. The comparisons are categorized as:(1) stochastic methods versus deterministic methods;(2) high-order methods versus low-order methods;(3) data-driven versus covariance-driven stochastic subspace identification methods. 相似文献
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极端荷载作用下海洋导管架平台体系可靠度分析 总被引：4，自引：1，他引：4
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。 相似文献
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Economy and ice-resistance are two factors that must be considered in the design of offshore oil platforms in the Bohai Gulf. This paper focuses on the optimal design of ice-resistant offshore jacket platforms in the Bohai Gulf in consideration of fatigue life of tubular joints, with the minimum initial weight and satisfying dynamic properties. An efficient fatigue analysis procedure based on spectral analysis is proposed, in which a hybrid finite element model is adopted to simulate the jacket platform and the tubular joints, and the pseudo-excitation method is used to calculate the power spectral density of the hot spot stress. Finally, a practical jacket platform with an ice-breaking cone in the Bohai Gulf is optimized, and the results demonstrate that the fatigue life of tubular joints could be improved and the weight of jackets decreased simultaneously. 相似文献
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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 总被引：9，自引：1，他引：8
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ＪＺ２０２ＭＵＱ平台的完好状态进行了极限承载力分析 相似文献
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Corrosion and fatigue cracks are major threats to the structural integrity of aging offshore platforms.For the rational estimation of the safety levels of aging platforms,a global reliability assessment approach for aging offshore platforms with corrosion and fatigue cracks is presented in this paper.The base shear capacity is taken as the global ultimate strength of the offshore plaffoms,it is modeled as a random process that decreases with time in the presence of corrosion and fatigue crack propagation.And the corrosion and fatigue crack growth rates in the main members and key joints are modeled as random variables.A simulation method of the extreme wave loads which are applied to the structures of offshore platforms is proposed too.Furthermore,the statistics of global base shear capacity and extreme wave loads are obtained by Monte Carlo simulation method.On the basis of the limit state equation of global failure mode,the instantaneous reliability and time dependent reliability assessment methods are both presented in this paper.Finally the instantaueous reliability index and time dependent failure probability of a jacket platform are estimated with different ages in the demonstration example. 相似文献
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The spectral methods and ice-induced fatigue analysis are discussed based on Miner's linear cumulative fatigue hypothesis and S-N curve data.According to the long-term data of full-scale tests on the platforms in the Bohai Sea,the ice force spectrum of conical structures and the fatigue environmental model are established.Moreover,the finite element model of JZ20-2MSW platform,an example of ice-induced fatigue analysis,is built with ANSYS software.The mode analysis and dynamic analysis in frequency domain under all kinds of ice fatigue work conditions are carried on,and the fatigue life of the structure is estimated in detail.The methods in this paper can be helpful in ice-induced fatigue analysis of ice-resistant platforms. 相似文献
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辽东湾JZ20—2海域海冰参数的概率分布 总被引：11，自引：1，他引：11
基于辽东湾JZ2 0 2海域 1996 2 0 0 0年 4个冬季的海冰定点观测资料和海冰数值模拟结果 ,对该海域的平整冰厚、冰速、冰向和压缩强度等海冰参数进行了概率分析 ,确定了各自的分布参数 ,并对冰速和冰向进行了联合概率分析。结果表明 :冰厚和冰速分别服从对数正态分布和瑞利分布 ,海冰压缩强度服从正态分布。计算结果可用于JZ2 0 2海域海洋结构可靠性设计和疲劳累积损伤分析的海冰参数 ,也可作为其邻近海域的参考资料 相似文献
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Offshore engineers and scientists face fascinating economical and technical challenges in designing offshore platforms for shallow water oil and gas fields in moderate ice conditions. Petroleum production systems in these ice-infested areas such as the Bohai Bay of China, Cook Inlet, Barent Sea, and Caspian Sea must be designed to accommodate the harsh environmental conditions, among which the first-year sea ice is one of the major design consideration. Extreme ice loads and ice-induced vibrations still remain an area of uncertainty in offshore platforms. This paper demonstrates the main technical aspects on the use of jackets in the Bohai Bay, with particular focus on ice loads and the failure modes of slender ice-resistant structures, which are the two key issues in design considerations. A design proposal and some considerations for economical ice-resistant structures for safe development in the cold region are also conceptually discussed. 相似文献
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单点系泊海洋导管架平台结构体系可靠性分析 总被引：4，自引：1，他引：3
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。 相似文献