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海洋平台结构抗震可靠性时程分析方法 总被引：3，自引：0，他引：3
将地震运动视为随机过程,建立海洋平台结构在地震作用任一时刻基于剪切变形控制的极限状态方程,应用JC法计算海洋平台结构在地震作用任一时刻的可靠度,得到海洋平台结构抗震可靠度的时程曲线。该方法可满足工程设计的要求,便于工程应用。 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
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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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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 platforms. It is modeled as a random process that decreases with time in the presence of corrosion and fatigue crack propagati... 相似文献
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A system reliability estimation method for spatial jacket platforms is developed in this paper,The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Fi-nite Element Method(FEM).The limit failure states correspond to collapse of a series of structural mem-bers which are identified by engineering design criteria.In this paper the following aspects are taken intoaccount:the punching shear and buckiing failures in member failure modes for the tubular joints and tubu-lar columns respectively;incremental loading approach for establishment of the safety margin equations ofsystem failure;the algorithm of enumerating significant failure modes for the structural systems and otherconcepts,such as the false failure mode and the virtual limit state.The final work is devoted to the reliabili-ty analysis for a practical jacket platform presently put into operation on the Bohai Sea.The computed re-sults shows that method suggested in this paper is feasible and effective for 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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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 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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Owing to the ageing of the existing structures worldwide and the lack of codes for the continued safely management of structures during their lifetime, it is very necessary to develop a tool to evaluate their system reliability over a time interval. In this paper, a method is proposed to analyze system reliability of existing jacket platforms. The influences of dint, crack and corrosion are considered. The mechanics characteristics of the existing jacket platforms to extreme loads are analyzed by use of the nonlinear mechanical analysis. The nonlinear interaction of pile-soil-structure is taken into consideration in the analysis. By use of FEM method and Monte Carlo simulation, the system reliability of the existing jacket platforul can be obtained. The method has been illustrated through application to BZ28-1 three jacket platforms which have operated for sixteen years. Advantages of the proposed method for analyzing the system reliability of the existing jacket platform is also highlighted. 相似文献
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Efficient Approximate Method of Global Reliability Analysis for Offshore Platforms in the Ice Zone 总被引：1，自引：0，他引：1
Ice load is the dominative load in the design of offshore platforms in the ice zone, and the extreme ice load is the key factor that affects the safety of platforms. The present paper studies the statistical properties of the global resistance and the extreme responses of the jacket platforms in Bahai Bay, considering the randomness of ice load, dead load, steel elastic modulus, yield strength and structural member dimensions. Then, based on the above results, an efficient approximate method of the global reliability analysis for the offshore platforms is proposed, which converts the implicit nonlinear performance function in the conventional reliability analysis to linear explicit one. Finally, numerical examples of JZ20-2 MSW, JZ20-2NW and JZ20-2 MUQ offshore jacket platforms in the Bahai Bay demonstrate the satisfying efficiency, accuracy and applicability of the proposed method. 相似文献
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海洋平台优化设计的研究进展 总被引：4，自引：0，他引：4
结构优化是结构设计理论的重要发展,随着“十五”渤海大油田勘探开发战略的实施,结构优化技术将在新型抗冰振平台设计中发挥重要作用。从静力优化设计、动力优化设计、基于可靠度优化设计、全寿命优化设计四个方面论述了海洋平台结构优化设计的研究现状,并展望了海洋平台优化设计的研究前景。 相似文献
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1 .IntroductionNowadays tremendous efforts have been devotedtothe analysis of randomseismic responses .Forexample ,American PetroleumInstitute (API) has declared that the analysis of randomseismic re-sponsesis a useful tool for safety inspection. Owing to the complexity of platformand randomness ofload,it is difficult to carry out the randomresponse analysis of a jacket platform. The conventionalrandomvibration methods ,such as square root of the sumof squares (SRSS) and complete quadratic… 相似文献
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This paper deals with the prediction of the dynamic response of steel offshore platforms to high energy impacts from typical supply vessels. The contribution of the high modes of a cantilever beam type structure with a concentrated top mass subjected to transverse impact from rigid and deformable strikers is analysed. A procedure to develop simplified equivalent systems for efficient structural response analysis is presented and its reliability tested by comparing the results from the explicit non-linear FE simulations. Effects such as the overall rotation of the installation, plastic deformations in the contact area, different impact locations and different hinge mechanisms are taken into account. It is shown that the use of the proposed equivalent systems with a reduced number of DOF's can provide accurate results at significantly less computational efforts as compared to the FE simulations. The derivation of some parameters of the equivalent dynamic elastic–plastic SDOF/2SDOF systems, however, needs to consider the complexity of the analysed steel frames and perform preliminary non-linear static analyses. Therefore, further studies of different impact scenarios on platforms with different configurations are recommended to augment the results presented here. 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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The extreme behavior of surface waves as they encounter and pass compliant deepwater platforms is an important class of problems for offshore engineers attempting to specify the platform deck elevation. In this study analytical expressions for the probability density and cumulative distribution functions that utilize empirical coefficients in an attempt to accurately model surface wave runup and airgap problems are presented. The analysis focuses upon interpreting the tails of the measured data histograms using two parameter Weibull distribution models. The appropriate empirical constants, assumed to be solely dependent upon the significant wave height, were evaluated and compared for all the test data. Based upon a small select set of data, for a mini-TLP and two Spar platforms, the airgap problem was found to be adequately modeled using a Rayleigh distribution. Further, for the seven seastates analyzed, the Weibull shape parameter was nearly constant and the data confirmed that the exclusive fit of the scale parameter assuming dependence only on the significant wave height was a reasonable approach for modeling the wave runup. Finally, by combining these models with a Poisson return model for each storm the associated reliability estimates for various deck heights were estimated. 相似文献
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无震脊或海山链俯冲对超俯冲带处的地质效应 总被引：3，自引：1，他引：2
全球海底分布着众多的无震脊或海山链,且在太平洋、印度洋及大西洋均存在靠近俯冲带的海岭。除小安德列斯弧外的巴拉克达脊和蒂勃朗脊起源自转换断层外,一般认为它们由与板块构造动力学迥异的地幔柱动力学所形成的。在板块汇聚边缘处,与扩张脊处所形成的正常洋壳一起,无震脊或海山链俯冲于陆缘弧或洋内弧之下,其对弧及弧后地区的地质效应(构造、地貌、地震以及岩浆作用等)有别于正常洋壳俯冲。无震脊或海山链的俯冲通常造成俯冲带地区的上驮板块的局部异常抬升、俯冲剥蚀作用效应的加强、海沟的向陆迁移以及地震强度的增加。同时,无震脊或海山链俯冲时,其携带的具富集地球化学特征的物质不仅影响着地幔地球化学,也对弧及弧后火山熔岩化学产生明显影响,并对超俯冲地区的热液矿床的形成产生重要影响。最后,本文指出了我国有关无震脊或海山链俯冲的可能的研究方向包括黄岩海山链俯冲对吕宋岛弧的可能影响、印度洋无震脊俯冲对青藏高原局部地区的影响,有我国学者参与的IODP344航次的研究对象——科科斯脊俯冲对哥斯达黎加地震成因的效应以及位于西太平洋地区靠近俯冲带的一些无震脊等。 相似文献
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A reliability based approach for analysis of offloading operations with two identical LNG carriers moored in a side-by-side configuration is suggested. The approach, although adopted for two tankers, is generally applicable to different types of LNG terminals. Different heading controls are conceivable for the discharging vessel in the case that the heading is not fixed: heading toward wind-sea, heading toward swell, heading toward wind and free weather vaning. The analyses show that heading toward the governing sea state is the most beneficial option for two identical LNG carriers moored in a side-by-side configuration. Strategies are discussed for estimation of limiting weather criteria that are consistent with prescribed target failure probabilities. 相似文献
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海工结构物浅基础稳定性的可靠度分析 总被引：5，自引：1，他引：5
应用可靠度理论对渤海某油田软粘土地基工作的沉垫式基础的稳定性进行了可靠度分析，阐述了各个设计指标的变化对分项系数及可靠度指标的影响规律，并将分析结果与该标准中规定的分项系数进行了比较。 相似文献