高桩码头结构时变可靠度分析方法研究

发布时间：2018-10-07 20:50

【摘要】：海洋环境下混凝土码头面临的耐久性问题十分严重。高桩码头是港口码头重要的结构形式之一,其腐蚀破坏较为严重,破坏部位主要发生在处于浪溅区的纵横、面板、桩以及桩帽,致使高桩码头承载能力明显降低。随着时间推移,锈蚀高桩码头的耐久性病害导致的结构失效问题将越来越普遍。高桩码头安全状态评估是保证港口设施正常安全运行的必要措施。目前,规范仍采用时不变可靠度方法对码头构件的安全性进行评价,不能考虑结构承载力的时变特性。因此,建立有效的高桩码头时变可靠度分析方法是十分必要的。针对以上问题,本文开展了以下研究工作:(1)第一章总结了国内外现有的时变可靠度计算方法研究进展以及所存在的问题。(2)第二章根据设计基准期区段化的思想,在借鉴前人研究成果的基础上,建立了考虑结构承载力随时间衰减的适于工程应用、简便易行的时变可靠度计算方法。相比于已有方法,本文建立的新方法不局限于最大可变荷载的分布类型必须是极值I型的条件;且新方法只需通过一次积分便可直接计算得出可靠概率,免去了已有方法先求等效抗力,进而采用JC法反复迭代的复杂过程。(3)第三章研究了高桩码头承载力的影响因素;根据影响因素是否导致承载力的衰减,将这些因素分为两个大类,即“承载力随机性影响因素”和“承载力衰减性影响因素”,并建立各类影响因素的概率模型;根据海洋环境下钢筋混凝土结构耐久性破坏机理,建立了承载力衰减性影响因素概率模型。(4)第四章在高桩码头承载力影响因素概率模型基础上,结合两类已有的抗力随机过程模型,建立了码头各类构件的承载力退化模型;该退化模型的表达式亦适用于描述整体码头的承载力。根据第二章所建立的时变可靠度计算方法,计算码头各个构件的时变可靠指标。(5)第五章在高桩码头承载力影响因素的概率模型基础上,采用大型通用有限元软件ANSYS作为辅助分析工具,通过蒙特卡洛模拟,建立了四种荷载工况下,考虑时间因素的高桩码头整体承载力随机过程模型;基于整体承载力随机过程模型,建立了高桩码头结构整体时变可靠度分析方法。(6)第六章将针对一个工程实例,采用本文建立的时变可靠度计算方法以及码头承载力随机过程模型,进行码头构件以及整体码头的时变可靠度分析,以全面综合地展示本文的研究内容。
[Abstract]:The durability of concrete wharf in marine environment is very serious. High pile wharf is one of the important structural forms of port wharf, and its corrosion damage is more serious. The damage site mainly occurs in the vertical and horizontal side, face slab, pile and pile cap in the splash area, which results in the obvious reduction of the bearing capacity of the high pile wharf. With the passage of time, structural failure caused by durability disease of corroded pile wharf will become more and more common. The safety assessment of high-pile wharf is an essential measure to ensure the normal and safe operation of port facilities. At present, the method of time-invariant reliability is still used to evaluate the safety of wharf members, and the time-varying characteristics of structural bearing capacity can not be considered. Therefore, it is necessary to establish an effective time-varying reliability analysis method for high pile wharf. In order to solve the above problems, this paper has carried out the following research work: (1) the first chapter summarizes the research progress and existing problems of time-varying reliability calculation methods at home and abroad. (2) the second chapter is based on the idea of segmenting the design base period. Based on the previous research results, a simple and convenient time-varying reliability calculation method considering the attenuation of structural bearing capacity with time is established. Compared with the existing methods, the new method established in this paper is not limited to the condition that the distribution type of the maximum variable load must be the extreme I type, and the new method can directly calculate the reliable probability by only one integral. The complex process of iterative iteration with JC method is avoided. (3) in chapter 3, the influence factors of bearing capacity of high pile wharf are studied, according to whether the influence factors lead to the attenuation of bearing capacity. These factors are divided into two categories, that is, "random bearing capacity influencing factors" and "bearing capacity attenuation influencing factors", and the probability models of these factors are established, according to the durability failure mechanism of reinforced concrete structures under marine environment, The probability model of bearing capacity attenuation factors is established. (4) based on the probabilistic model of bearing capacity of high pile wharf, combined with two kinds of stochastic process models of resistance, the degradation model of bearing capacity of various components of wharf is established. The expression of the degradation model can also be used to describe the bearing capacity of the whole wharf. According to the time-varying reliability calculation method established in the second chapter, the time-varying reliability index of each member of the wharf is calculated. (5) the fifth chapter is based on the probability model of the factors affecting the bearing capacity of the high-pile wharf. By Monte Carlo simulation, the stochastic process model of the whole bearing capacity of high pile wharf under four load conditions considering time factors is established by using ANSYS, a general finite element software, as an auxiliary analysis tool. Based on the stochastic process model of overall bearing capacity, a method of global time-varying reliability analysis of high pile wharf structure is established. (6) in chapter 6, an engineering example is presented. The time-varying reliability calculation method and the random process model of wharf bearing capacity are used to analyze the time-varying reliability of wharf members and the whole wharf in order to show the research contents of this paper comprehensively and synthetically.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U656.113

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