大跨度钢斜拉桥施工及运营过程系统可靠度研究

发布时间：2018-06-19 18:42

  本文选题：大跨度钢斜拉桥 + 系统可靠性　； 参考：《西南交通大学》2015年博士论文

【摘要】：随着近年来斜拉桥不断向大跨度方向蓬勃发展,其结构形式日趋表现出大型化、复杂化以及纤柔化的特点。大跨度钢斜拉桥在规模尺度上的超越对结构的整体安全性能提出了更大的挑战,其施工及运营期的系统可靠性问题也更为突出。本文针对既有系统可靠度研究在理论方法以及实践分析等方面的固有困难,从系统极限状态曲面概念出发,将支持向量分类算法(SVC)和LHS抽样迁移策略等方法引入了系统可靠度理论的研究,并针对既有可靠度指标算法缺陷进行了改进与修正,进一步完善了系统可靠度的理论方法。在此基础上,基于所获取的变量统计概率模型,对大跨度钢斜拉桥施工及运营期的系统可靠性演化规律及特点进行了深入研究和探讨。所完成的研究工作主要包括以下五个方面：1.结构可靠度指标计算方法的进一步研究。针对传统结构可靠度指标算法在收敛性以及计算效率上的固有缺陷,从理论原理和工程应用角度出发,在厘清问题本质来源的基础上,首先基于方向修正原理提出了计算结构一次二阶矩可靠度指标的方向修正算法。然后通过理论推导和几何分析,对线抽样Monte Carlo法进行了修正改进,使其适用性得到拓展提高。最后通过数值抽样以及回归分析方法对改进的功能函数二阶展开形式进行了系统研究,建立了基于非线性回归分析预测算法的二次二阶矩可靠度指标计算方法。并基于代表性数值算例验证了所提出方法的有效性和优越性。2.基于SVC抽样迁移的系统可靠度理论算法研究。针对传统系统可靠度理论算法中存在的约界困难、精度有限以及工作量大等固有缺陷,从系统层面出发,引入了结构系统极限状态曲面的概念。在此基础上,利用支持向量分类算法对该极限状态曲面进行了直接重构。以此为依据并结合LHS抽样迁移策略,建立了计算结构系统可靠度的SVC抽样迁移计算方法。两典型标准算例验证结果表明,所提出算法具有较高的计算精度、抽样效率以及求解稳定性,可有效避免现有算法中的固有弊端,更适用于实际结构可靠度问题的分析求解。3.大跨度钢斜拉桥荷载及抗力统计概率模型研究。在广泛调研和数据收集的基础上,通过梁段称重结果以及其他既有统计分析,对大跨度钢斜拉桥永久作用的统计概率模型进行了深入研究。然后针对桥梁施工及运营特点,并结合既有研究成果,获取了结构施工及运营阶段中各类可变作用的统计概率模型。最后通过广泛的文献调研总结,较为完整地确定了适用于大跨度钢斜拉桥系统可靠度分析的塔、梁抗力统计概率模型,为后续系统可靠度的计算研究奠定了基础。4.平行钢丝斜拉索极限抗力概率模型研究。针对平行钢丝斜拉索构造组成以及受力特点,利用概率统计理论并结合钢丝试验结果,对索中钢丝的抗力概率模型进行了深入研究。在此基础上,根据钢丝串并联组成关系(Daniels概率强度模型)并结合Monte Carlo数值模拟方法,提出了计算平行钢丝斜拉索抗力的数值抽样算法。联合应用这一算法以及构件可靠度分析理论,对大跨度钢斜拉桥斜拉索的构件可靠性开展了研究。5.大跨度钢斜拉桥施工及运营期系统可靠度研究。基于所建立的荷载及抗力统计概率模型,以典型特大跨度钢斜拉桥——苏通长江大桥为研究对象,采用所提出的SVC抽样迁移计算方法,分别对结构施工及运营过程中8种关键工况的系统可靠度问题进行了深入探讨。系统研究了各工况结构首要失效模式灾变机理以及系统可靠度指标的变化情况,从而较为全面地获得了苏通长江大桥及类似桥梁施工及运营过程中各关键工况的系统可靠性演化规律。
[Abstract]:With the rapid development of the cable-stayed bridge to the large span in recent years, its structural forms are becoming more and more large-scale, complicated and flexible. The surpassing of large span steel cable-stayed bridges on scale scale poses a greater challenge to the overall safety performance of the structure, and the problem of system reliability in the construction and operation period is also more prominent. In this paper, in view of the inherent difficulties in the theoretical and practical analysis of the existing system reliability, from the concept of the system limit state surface, the support vector classification algorithm (SVC) and the LHS sampling migration strategy are introduced into the research of the system reliability theory, and the defects of the existing reliability index algorithms are improved. With the correction, the theoretical method of system reliability is further perfected. On this basis, based on the obtained statistical probability model, the system reliability evolution law and characteristics of the large span steel cable-stayed bridge during the construction and operation period are deeply studied and discussed. The completed research work mainly includes the following five aspects: 1. structure can be done In view of the inherent defects in the convergence and calculation efficiency of the traditional structure reliability index algorithm, based on the theoretical principle and engineering application, the first two order moment reliability index of the calculation structure is proposed based on the direction correction principle, based on the theory and engineering application. Through theoretical deduction and geometric analysis, the Monte Carlo method of line sampling is modified to improve its applicability. Finally, the two order expansion of the improved functional function is studied by numerical sampling and regression analysis, and the prediction calculation based on nonlinear regression analysis is established. The two times two order moment reliability index calculation method. Based on the representative numerical example, the validity and superiority of the proposed method.2. based on the system reliability theory algorithm based on SVC sampling migration is studied. From the system level, the concept of the limit state surface of the structural system is introduced. On this basis, the support vector classification algorithm is used to reconstruct the limit state surface directly. Based on the LHS sampling migration strategy, a SVC sampling transfer calculation method for calculating the reliability of the structural system is established. Two typical standard calculation examples are given. The results show that the proposed algorithm has high calculation precision, sampling efficiency and solution stability. It can effectively avoid the inherent disadvantages of existing algorithms. It is more suitable for the analysis of actual structural reliability problems to solve the statistical probability model of load and resistance of.3. long-span steel cable-stayed bridges. The statistical probability model of permanent action of long span steel cable-stayed bridge is studied through the weighing result of beam section and other statistical analysis, and then the statistical probability model of various variable functions in the construction and operation stage is obtained by combining the characteristics of the bridge construction and operation and combining with the existing research results. Finally, the statistical probability model is obtained. A comprehensive study on the reliability analysis of the long-span steel cable-stayed bridge system is made by extensive literature investigation and summary, and the statistical probability model of the beam resistance is established, which lays a foundation for the study of the probability model for the ultimate resistance of the.4. parallel wire cable-stayed cable for the calculation and study of the reliability of the subsequent system. By using the probability statistics theory and the result of steel wire test, the resistance probability model of wire in cable is deeply studied. On this basis, a numerical sampling algorithm for calculating the resistance of parallel wire cable-stayed cables is proposed based on the Daniels probability intensity model and the Monte Carlo numerical simulation method. With the application of this algorithm and the theory of component reliability analysis, the reliability of the construction and operation period of.5. long-span steel cable-stayed bridge is studied. Based on the statistical probability model of load and resistance, the typical large span steel cable-stayed bridge, Sutong Yangtze River bridge is used as a typical special long span steel cable-stayed bridge. By using the proposed SVC sampling migration calculation method, the system reliability of the 8 key working conditions in the construction and operation process is discussed. The catastrophe mechanism of the primary failure modes and the changes of the reliability index of the system are systematically studied. The evolution of system reliability under various critical conditions during construction and operation of similar bridges in Yangtze River bridge.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U445;U448.27
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本文编号：2040887