Structural system reliability analysis of SWATH ships

In this paper the structural system reliability method is applied to a built SWATH ship. Firstly, a typical transverse frame in the SWATH is idealized by a one-dimensional model through a series of finite element analyses. The safety margins are automatically generated by computer and the interaction of bending moment and axial force, including buckling effect, is taken into account. The significant failure modes of the structure are identified by an extended β-unzipping method, and the system reliability index is then evaluated by Ditlevsen's bounds. It is found that the most critical section is in the haunch area, and all the critical sections included in the significant failure paths are in the haunch area.     

Structural analysis methods for system reliability

The appropriateness of the use of traditional methods of structural analysis in reliability analyses is examined using two examples: partially restrained steel beams and the stability of earth slopes. It is found that new and innovative methods of structural analysis may cause simplifications in the system reliability analysis.     

一种有效的体系可靠度计算方法

以ANSYS大型有限元软件作为平台,运用其APDL语言实现了一种有效的体系可靠度计算方法,用成熟算例验证了混合分析法具有良好的计算稳定性,能有效解决非线性、多重要区域失效问题。     

Limitations of some of the approximate structural analysis methods that are used in structural system reliability

Structural system reliability often involves structures with non-linear behavior. In the reliability analysis, simplified structural models and simplified analysis procedures are used to model and analyze these structures. These simplified analysis procedures, for both frames and trusses, have their limitations. These limitations are illustrated in this paper through deterministic examples. It is recommended that further research be done on understanding the limitations of these methods and their effect on structural reliability analysis.     

隧道洞门结构可靠度分析

分析了可靠度的计算原理，介绍了用一次二阶矩阵法计算翼墙式隧道洞门的过程，提出了可靠度指标的满足条件，指出采用一次二阶矩阵法分析结构可靠度能够满足工程要求。     

结构体系可靠度分析的体系失效模式识别讨论

分别对极限状态体系和概率评估体系这两类体系失效模式判别方法进行了详细介绍,并对每种判别方法的特点进行总结,对该领域的研究成果进行了较系统的分类和阐述,以期指导体系失效模式的识别。     

Structural reliability and error control in reinforced concrete design and construction

Available statistical data suggest that human error in design and construction causes a significant proportion of performance failures; namely, structural failure, cost overruns and delays. A Human Reliability Analysis (HRA) model has been developed to simulate the effect of human error on the design and construction of a reinforced concrete beam. The proposed HRA model incorporates the effect of designer checking, independent design checking, engineering inspections of construction works, and interaction between the designer and contractor. Human performance models are described for all design and construction microtasks. It was found that human error leads to a significant loss of structural safety, but that error control measures (particularly design checking) significantly reduce this loss. It was also shown that construction errors are more detrimental to structural safety and are more difficult to detect and correct.     

Time-dependent system reliability analysis by adaptive importance sampling

A method for evaluating time-dependent reliability of a structural system subjected to stochastic loads is presented. Structural deterioration due to environmental stressors is also taken into account. An adaptive Monte Carlo simulation procedure combined with conditional expectation is proposed. The optimum common ratio of the standard deviation of an importance sampling variables to that of the corresponding original valuables is estimated iteratively as well as their mean values. Unlike systems evaluated by simple Monte Carlo simulations, the accuracy of the failure probability evaluated by adaptive importance sampling is relatively insensitive to the magnitude of the probability.     

基于系统可靠度的结构优化

针对系统可靠度的结构优化问题一直是个十分难以解决的问题。通过对结构系统基于可靠度优化模型的分析,确定了其优化准则,给出其基于可靠度下结构系统处于最优状态的条件;在此基础上,提出两阶段的直接迭代法进行求解,并给出算例。     

工程结构可靠度分析方法研究

基于可靠度理论，介绍了工程结构点和结构体系可靠度的各种分析方法，并探讨了各种方法的特点，指出结构体系可靠度的研究是今后可靠度发展的方向。     

某药厂15号楼可靠性鉴定与加固

通过现场检测实验和理论分析，对该楼房结构的可靠性做出了评价，并在此基础上，结合楼房未来的使用要求，对现有楼房存在的隐患提出了结构加固方案；同时对可靠性鉴定过程中遇到的一些问题进行探讨。     

基于可靠度的结构抗震优化设计

介绍了结构抗震设计的目的与目标,并对基于概率可靠度的结构抗震设计方法进行了阐述,根据“投资—效益”准则,提出了基于功能的结构体系目标可靠度优化决策的三种模型,从而为结构抗震优化设计的进一步研究奠定了理论基础。     

Systems reliability and structural design

It is demonstrated that current limit state structural design standards do not explicitly account for systems reliability. An improvement is suggested, using systems factors, which accounts for the different levels of damage implied by the various limit states.     

A first-order reliability method for certain system and load combination calculations

A first-order method is developed for calculating the probability of failure of certain types of structural systems subjected to load histories of the Ferry Borges-Castanheta type. For the method to be applicable, it must be possible to describe the failure of individual elements by non-time-dependent functions, as is the case with simple series systems or serviceability failures, for instance. The mathematical form of the failure functions must also conform to certain requirements. Within these limits the method gives a simple direct calculation, without the need for repeated conditioning, for example. The method is demonstrated with some simple examples and its usefulness is illustrated by an application to the fatigue reliability of offshore structures.     

Balancing weight, system reliability and redundancy in a multiobjective optimization framework

Redundancy is often desired in structural systems, although no redundancy definition has been widely accepted as an objective measurement. In this paper a probabilistic index is employed as a measure of structural redundancy. This index is compatible with structural system reliability analysis. The optimization problem is solved in a multiobjective framework in which the goal is to minimize and/or maximize several objectives simultaneously. Optimal structural designs are sought in the sense of least weight, highest system reliability and highest system redundancy. Numerical results show that optimal searchings balancing weight, system reliability and system redundancy produce more rational structural designs.     

结构安全性等级的实用计算

本文首先简要介绍了基于结构系统可靠性的结构安全性等级划分的基本思路,进而利用泰勒展开法推导了结构安全性等级的实用计算公式,通过算例验证了该方法的可行性。此外,将本文计算方法与现行鉴定标准中基于经验的方法进行了对照比较,证明定量与定性可以很好地结合。     

Generation of dominant modes and reliability analysis of frames

The paper presents a technique for reliability analysis of frames using the stiffness matrix method of linear elastic and piecewise linear elastic-plastic structural analysis and the first order second moment reliability method. It involves automatic generation of stochastically dominant mechanisms (modes) and their safety margin equations and calculation of bounds on the system reliability. Based on the computational experiments, logical strategies are proposed for selection of plastic hinges and branching of failure paths to identify stochastically dominant mechanisms. The proposed method is illustrated with numerical examples. The results show very good agreement with the results of other research workers. The proposed method of generating stochastically dominant modes is simple and fairly efficient and less computer-time consuming.     

System reliability considerations in probabilistic risk assesment of nuclear power plants

The frequencies and consequences of severe accidents at nuclear power plants are examined using a systematic procedure called probabilistic risk assessment (PRA). These accidents may be initiated by equipment malfunctions, operator errors or external initiators such as earthquakes, floods and tornadoes. It is in the case of the external events that the structural system reliability concepts are utilized. Taking the seismic risk analysis as an example, this paper discusses the different elements of the analysis — hazard analysis, fragility evaluation, systems analysis and risk quantification — and examines how the structural system reliability methods are applied. Areas requiring further investigation by the PRA analysts are indicated and the data and research needs are identified.     

工程结构可靠度认识

从结构安全性、耐久性、结构重要性系数以及结构分析方法等方面阐述了关于工程结构可靠度设计的内容,并提出了对目前可靠度理论发展的几点认识,以促进工程结构设计的发展,可供结构设计人员参考。