工程结构可靠度分析的若干方法研究

发布时间：2018-03-05 01:36

本文选题：可靠度　切入点：决策理论　出处：《西安建筑科技大学》2017年博士论文　论文类型：学位论文

【摘要】：土木工程结构由于其独特的实用价值和良好的力学性能,一直被人们应用于各行各业的基础设施建设中,但由于存在诸多不确定因素,结构总有失效的可能性,绝对安全的结构是没有的。单纯的力学计算不能解决实际问题,为了保证结构在规定的时间内,在规定的条件下正常工作,对其进行可靠性分析变得尤为重要。可靠度作为一种评判结构可靠性的数量化指标,对结构可靠性进行定量描述,并能对各种不确定性分别加以某种形式的定量考虑。一般直接求解结构失效概率的多重积分不是一件容易的事情,需要利用与之对应的近似方法计算结构可靠度。结构可靠度分析方法关键在于如何进行不确定因素的分析和结构功能函数的构建,既而寻找与之对应的可靠度求解方法。当计算结果不符合标准时,则需要对结构重新进行设计分析以及风险评估。对此,本文在总结国内外已有相关研究文献的基础上,基于最优化理论思想,利用约束条件的非线性优化和模型拟合求解等方法深入研究了工程结构可靠度分析方法,作为常规分析方法的补充,对该领域的发展起着至关重要的作用。在显式结构功能函数条件下,针对可行域过大的不足之处,在原有研究的基础上,提出了基于非精确搜索的结构可靠度一维分析方法。根据可靠指标的几何含义,提出了基于自适应迭代方向修正的HL-RF可靠度分析方法,从合理选择迭代方向的角度,加快了迭代速度,避免了算法不收敛的问题。分别利用数值算例比较验证了迭代算法的正确性和有效性。通过分析决策理论,在最优化理论的指导下,通过效用函数和模糊偏好关系,提出了基于效用决策优化模型的结构可靠度分析方法,针对具有非线性显式结构功能函数的构件进行了可靠度计算,并利用算例分析验证了方法的有效性和正确性。在隐式结构功能函数条件下,基于支持向量机和粗糙集理论,通过最优化理论,提出了RST-SVM结构可靠度分析方法,并在此基础上利用粗糙集理论对不确定性进行了分析,通过工程算例求解以及实验验证了本方法的合理性。利用粗糙集理论建立了结构相关属性的量化形式和探讨了对于结构可靠性的影响程度,有利于后续结构的进一步设计和优化。在结构动态可靠性研究的基础上,对结构施工期间大量的随时间变化的宏观测量信息进行详细的分析,引入威布尔理论模型,建立了结构可靠度动态分析的威布尔预测模型,根据变形-时间所反映的情况作出判断和反馈,探讨了险情出现的原因,分析了结构可靠性。通过工程实例,分析了边坡变形破坏模式的可靠性,验证了分析模型的实用性。并与数值分析结果对比,展示了本文方法的合理性与工程参考价值。
[Abstract]:Because of its unique practical value and good mechanical properties, civil engineering structure has always been applied in the infrastructure construction of various industries. However, due to many uncertain factors, the structure always has the possibility of failure. There is no absolutely safe structure. Simple mechanical calculations cannot solve practical problems. In order to ensure that the structure works normally within a specified time and under specified conditions, Reliability analysis becomes particularly important. As a quantitative index to evaluate the reliability of structures, the reliability of structures is described quantitatively. In general, it is not easy to solve the multiple integrals of structural failure probability directly. It is necessary to use the corresponding approximate method to calculate the structural reliability. The key of the structural reliability analysis method lies in the analysis of uncertain factors and the construction of structural function functions. When the calculation results are not up to the standard, it is necessary to redesign and analyze the structure and evaluate the risk. In this paper, based on the summary of the relevant research literature at home and abroad, Based on the theory of optimization, the reliability analysis method of engineering structure is deeply studied by nonlinear optimization of constraint conditions and model fitting solution, which is used as a supplement to conventional analysis methods. It plays an important role in the development of this field. Under the condition of explicit structure-function function, aiming at the deficiency of oversize feasible region, based on the original research, A one-dimensional method of structural reliability analysis based on inexact search is proposed. According to the geometric meaning of reliability index, a HL-RF reliability analysis method based on adaptive iterative direction correction is proposed. The iteration speed is accelerated and the problem of non-convergence of the algorithm is avoided. The correctness and validity of the iterative algorithm are verified by numerical examples, respectively. Under the guidance of the optimization theory, the validity of the iterative algorithm is verified by analyzing the decision theory. Based on utility function and fuzzy preference relationship, a structural reliability analysis method based on utility decision optimization model is proposed. The reliability of components with nonlinear explicit structural function is calculated. The validity and correctness of the method are verified by an example. Based on the support vector machine and rough set theory, the reliability analysis method of RST-SVM structure is proposed based on the support vector machine and rough set theory. On this basis, the uncertainty is analyzed by rough set theory. The rationality of the method is verified by engineering examples and experiments. The quantitative form of structure related attributes is established by rough set theory and the degree of influence on structural reliability is discussed. Based on the study of structural dynamic reliability, a large amount of macroscopical measurement information varying with time during construction is analyzed in detail, and the Weibull theory model is introduced. A Weibull prediction model for dynamic analysis of structural reliability is established. According to the situation reflected by deformation-time, the causes of danger are discussed, and the structural reliability is analyzed. The reliability of the slope deformation and failure mode is analyzed and the practicability of the analysis model is verified. The rationality and engineering reference value of this method are shown by comparing with the numerical analysis results.
【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU311.2

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