半潜式海洋平台结构的疲劳失效概率计算研究

本文根据Ｍｉｎｅｒ线性累积损伤原理，引入随机变量，客观地分析了半潜式平台结构因疲劳引起损伤的情况，提出了平台结构在设计寿命期间的疲劳可靠性分析方法，通过算例，验证了方法的可靠性，并得出有意义的结论。     

深海平台系泊系统在灾害性海洋环境下可靠性评估

基于深海平台系统的耦合时域分析技术和结构可靠性理论,分析深水系泊系统在灾害性极限海况下的失效模式。根据系泊链的结构形式特点,建立破断强度的概率模型;并根据系泊链动力响应时间历程,采用广义极值理论,通过对非线性随机动力响应的数值拟合,提出建立载荷概率模型的方法。并以某半潜平台系泊系统为研究对象,通过不同极限环境条件下的分析对比,研究载荷方向对可靠性指标的影响。根据分析结果可知,在200年一遇海况下,当环境载荷方向是135°时,系统可靠性指标,已低于目标可靠性指标要求,该系泊系统处于不安全状态。     

基于谱分析LNG船典型热点疲劳可靠性分析

研究LNG船在疲劳载荷作用下应力热点的疲劳可靠性。通过整船有限元分析得到不同浪向角规则波中各热点的应力频响函数,用谱分析法确定各热应力点在各短期海况下的应力范围模型,进而通过长期预报,用Weibull分布对各热点应力范围分布模型进行拟合并探讨热点型式和受载特性对参数变化的影响。基于线性累积损伤理论,利用S-N曲线计算各热点的疲劳累积损伤值并建立极限状态方程,评估LNG船舯部典型热点的疲劳可靠性和结构的疲劳安全性。针对不同热点讨论了应力范围长期分布函数—Weibull分布参数的取值对典型热点可靠性指标的影响,并给出典型热点目标可靠性指标和长期应力范围极值之间的关系以用于指导设计和安全性评价。     

基于可靠性的鱼雷装备抽样检验方案研究

研究了抽样检验的基本理论,分析了鱼雷装备的可靠性指标构成和在抽样检验中量化指标的选取。运用概率论和数理统计方法,提出了基于可靠性的抽样检验方案;综合分析 OC 特性曲线,通过使用超几何分布计算接收概率,建立了特殊武器装备可靠性抽样检验的模型。通过具体算例,方案可操作性得到了实际检验,为装备试验、生产、维修中的装备验收工作提供了科学决策的理论依据。     

便携式AUV通用质量特性参数指标分析

根据便携式 AUV 的功能特点和典型任务剖面，依据国军标要求，分析了便携式 AUV 通用质量特性定量要求涉及的综合性、可靠性、维修性、测试性、保障性、安全性及环境适应性等参数指标，给出了可靠性、维修性等关键指标的计算方法，并针对某具体型号进行了计算分析。     

张力腿平台关键部位疲劳可靠性分析

为确保深海中张力腿(TLP)平台的安全可靠运行,研究了TLP平台关键部位的疲劳可靠性。首先建立了TLP平台的整体模型,结合中国南海海况,计算了波浪荷载。然后分析了用于平台疲劳可靠性研究的S-N曲线法和断裂力学方法,计算了不同工况下TLP平台的应力响应,确定了疲劳关键部位,建立了关键部位的中间局部模型和精细子模型。最后采用子模型技术,应用S-N曲线法和断裂力学方法对平台关键部位的疲劳可靠性指标进行了计算和分析。结果表明:平台立柱和浮箱连接部位上部角点的疲劳可靠性指标低于下部角点,但可以满足设计要求;应用断裂力学方法计算得到的疲劳可靠性指标与应用S-N曲线法计算得到的疲劳可靠性指标接近,且疲劳可靠性指标的最小值出现在相同的部位,表明分析结果合理,可以为TLP平台的安全评估提供参考。     

珊瑚砂地质条件下钢板桩结构可靠性分析

在热带地区开展水运工程设计施工项目，经常会遇到珊瑚砂地质，其力学特性较为特别，强度低、易碎、黏性低，力学指标变异性较大，国内现有设计规范对珊瑚砂地质条件特殊性考虑不足，设计人员在相关设计参数选取时经常忽略采用可靠度理论进行结构安全复核。以马尔代夫机场扩建项目为案例，运用可靠度理论分析了珊瑚砂力学指标的高变异性对钢板桩结构稳定可靠度的影响。根据分析，在珊瑚砂地质条件下，按照《码头结构设计规范》（JTS167-2018）进行稳定性计算，得出的结果偏于危险，应引起结构设计人员的重视。在进行结构设计时，应同时按照《港口工程结构可靠性设计统一标准》（GB50158-2010）复核板桩结构可靠度。同时，珊瑚砂较小的黏性，在进行结构可靠度计算时可以忽略。     

SCA6—1型声学水位计可靠性设计与预计

本文就ＳＣＡ６－１型声学水位计的可靠性设计与预测做了研究和计算,得出了可靠性指标和可靠性保障技术。这是对产品质量要求必不可少的。本文所使用的方法可为其它产品所借鉴     

港口工程结构可靠度研究进展

本文系统地总结了结构可靠度理论在港口工程领域的研究和应用,对国内外工程结构可靠性设计标准的发展历程进行了回顾,介绍了中国港口工程结构可靠度设计的基本原则和方法,并从四个方面总结了港口工程结构可靠度的研究发展和现状:(1)港口工程结构荷载与抗力的统计分析;(2)防波堤的可靠度计算与可靠性设计;(3)重力式、板桩、高桩和开敞式码头的可靠性设计;(4)桩基基础和边坡稳定研究。目前,港工结构可靠性研究正在从近似概率设计向全概率设计转变。新方法和新技术的发展和应用将推动港口工程可靠性设计理论和实践的变革。     

QSF3—1型声学应答释放器的可靠性分析

本文就海洋监测系统中用到的一种仪器－ＱＳＦ３－１型声学应答释放器进行了可靠性分析。采用了迄今为止，在国外被公认的对复杂系统进行可靠性分析的最好方法－失效树分析法。详细地介绍了建树过程及各基本事件概率的计算方法，给出了ＱＳＦ３－１型声学应答释放器的可靠性指标。最后对提高释放器的可靠性途径进行了讨论。     

Genetic Algorithms of Structural Fuzzy Reliability Index

In this paper the simple generation algorithms are improved.According to the geometricmeaning of the structural reliability index,a method is proposed to deal with the variables in the standardnormal space.With consideration of variable distribution,the correlation coefficient of the variables andits fuzzy reliability index,the feasibility and the reliability of the algorithms are proved with an example ofstructural reliability analysis and optimization.     

基于遗传算法的简易海洋平台的疲劳可靠性优化设计

本文提出了利用损伤力学的非线性疲劳损伤模型，在随机海浪交变荷载作用下，简易海洋平台疲劳可靠性优化设计的遗传算法。计算结果表明了计算模型的可靠性与遗传算法解决结构物疲劳可靠性优化设计的有效性     

Asymptotic Analysis Methods for Structural Reliability

- Applying Laplace asymptotic approximation of integral, asymptotic analysis methods of structural reliability are proposed in generalized and orthogonal random space. Analytic results show that the proposed methods are simple in calculation and accurate enough for problems of continuous random variables.     

Probabilistic Durability Assessment of Concrete Structures in Marine Environments: Reliability and Sensitivity Analysis

A probabilistic framework for durability assessment of concrete structures in marine environments was proposed in terms of reliability and sensitivity analysis, which takes into account the uncertainties under the environmental, material, structural and executional conditions. A time-dependent probabilistic model of chloride ingress was established first to consider the variations in various governing parameters, such as the chloride concentration, chloride diffusion coefficient, and age factor. Then the Nataf transformation was adopted to transform the non-normal random variables from the original physical space into the independent standard Normal space. After that the durability limit state function and its gradient vector with respect to the original physical parameters were derived analytically, based on which the first-order reliability method was adopted to analyze the time-dependent reliability and parametric sensitivity of concrete structures in marine environments. The accuracy of the proposed method was verified by comparing with the second-order reliability method and the Monte Carlo simulation. Finally, the influences of environmental conditions, material properties, structural parameters and execution conditions on the time-dependent reliability of concrete structures in marine environments were also investigated. The proposed probabilistic framework can be implemented in the decision-making algorithm for the maintenance and repair of deteriorating concrete structures in marine environments.     

The influence of wave-current sea states on the reliability estimates of offshore towers

Since offshore towers are high-cost, high-risk structures, reliability analysis is of great importance in their design. This paper presents a possible practical approach to certify a design through selective critical member reliability estimates. After a brief review of current research in this field, the authors outline a procedure for reliability estimation of structural members in extreme stress and fatigue limit states. A spectral approach for the extreme response statistics with stochastic loading is described. The reliabilities are computed by the Level II first-order second moment (advanced) method. The fatigue reliability is estimated with a narrow-banded stress assumption with discrete, but significant sea states within the life of the structure. Two numerical examples, a three shallow water model and a two-dimensional deep water model are presented along with the influences of stochastic variables (sea state, current, tubular member diameter) on reliabilities (extreme stress and fatigue damage).     

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.     

Risk Assessment of Vertical Breakwaters -A Case Study in Turkey

In the reliability-risk assessment, the second order reliability index (βⅡ ) method and the Conditional Expectation Monte Carlo (CEMC) simulation are interrelated as a new Level Ⅲ approach for the analysis of the safety level of the Dalaman yacht harbor vertical wall breakwater in Turkey. The missing wave data of the Dalaman measurement station are hindcasted by use of multi-layer feed-forward neural networks with the steepest descent and conjugate gradient algorithms. The structural failure probabilities of sliding and overturning failure modes are forecasted by approximation of the failure sur-face with a second-degree polynomial of an equal curvature at the design point. in the new approach, for each randomly generated load and tide combination, the joint failure probability reflects both the occurrence probability of loading condition and the structural failure risk at the limit state. The approach can be applied to risk assessment of vertical breakwaters in short CPU durations of portable comput     

A Global Refiability Assessment Method on Aging Offshore Platforms with Corrosion and Cracks

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.     

我国东海和南海沿岸的历史风暴潮探讨

根据我国丰富的地方史志资料分析,证实在我国频临东海,南海沿岸的历史风暴潮是由台风引起的,这与冬半年出现在我国北方沿岸的风暴潮不同。列出了历朝风暴潮按月的统计和重大历史风暴潮灾害表。对史志的记载进行了探讨,指出时间记载的可靠性,古地名的变迁:随同风暴潮记载的海象、气象、天象和物象的记述;以及由风暴潮引起的次生灾害。