可靠度理论在结构设计中的若干应用研究

发布时间：2018-07-15 12:37

【摘要】：自上世纪80年代以来,可靠度理论在结构设计中得到了很大发展,很多国家的结构设计规范都采用了可靠度设计方法,如美国的建筑规范、桥梁规范,欧洲标准以及日本和我国的一些结构设计规范等。但是无论是国内还是国外,可靠度理论在很多方面的应用还不是很完善,需要继续深入研究。就我国而言,可靠度理论在建筑工程领域的应用比较早、发展相对较快,而在电力建设工程领域的应用比较晚、发展也相对较慢。本文结合3个科研项目,对可靠度理论在建筑、港工和电网输电线路设计中的有关问题进行了研究,主要包括以下几个方面： 1.针对按现行建筑结构设计规范的分项系数设计方法设计的结构的可靠指标在不同情况下相差较大的问题,提出了建筑结构基于可靠指标的设计方法,其中优化确定了荷载与抗力的灵敏度系数,将其表示为荷载效应比的线性函数,从而建立了分项系数与荷载效应比的简化关系式。计算表明,按本文方法设计的结构的可靠度与目标值具有较好的一致性。 2.针对现行建筑结构规范正常使用极限状态设计中的频遇值系数和准永久值系数是按经验确定的问题,根据收集的楼面活荷载与风荷载的统计资料,采用统计原理确定楼面活荷载与风荷载频遇值系数和准永久值系数；针对混凝土规范对正常使用极限状态裂缝宽度验算所采用的荷载组合的修订,分别按规范规定和本文确定的准永久值系数对钢筋混凝土受弯构件的最大裂缝宽度极限状态进行了可靠度分析。结果表明,规范修订后准永久组合下最大裂缝宽度极限状态的可靠度满足统一标准的要求。 3.根据海洋环境中钢筋混凝土结构的工作特点,建立了钢筋未锈蚀、钢筋已锈蚀但混凝土保护层未开裂和混凝土保护层已开裂3个阶段的钢筋锈蚀概率模型；采用Monte-Carlo方法对钢筋锈蚀率和3种锈蚀状态的发生概率进行了统计分析；采用建立的钢筋锈蚀率概率模型,对满足港工规范最低耐久性要求的钢筋混凝土受弯构件的时变可靠度进行了分析。结果表明,某时刻钢筋的锈蚀率服从正态-正态双峰分布；结构在海洋环境中暴露时间越长,钢筋未锈蚀和保护层未开裂的概率越小;锈蚀钢筋混凝土构件的可靠度随时间明显降低。 4.根据收集的有关荷载、抗力的统计数据和有关标准的验收规定,确定了一般输电线路永久荷载、风荷载、覆冰荷载及杆塔构件、绝缘子、金具和导线抗力的统计参数和概率模型,采用考虑随机变量概率分布类型的一次二阶矩方法对按现行输电线路规范设计的输电线路的相关组件进行了可靠度校准,为确定跨高铁输电线路杆塔构件、绝缘子、金具和导线的目标可靠指标提供了依据。 5.根据对一般输电线路的可靠度校准结果,提出了跨高铁输电线路杆塔构件、绝缘子、金具和导线的目标可靠指标；建立了杆塔构件重要性系数以及绝缘子、金具和导线的安全系数与可靠指标的关系,从而可直接通过重要性系数或安全系数对输电线路进行可靠度设计。
[Abstract]:Since the 80s of last century, reliability theory has been greatly developed in structural design. Reliability design methods have been adopted in many countries' structural design specifications, such as American building codes, bridge specifications, European standards, and some structural design norms in Japan and China. However, it is both domestic and foreign, reliability theory. In our country, the application of reliability theory in the field of construction engineering is relatively early and relatively fast, and the application in the field of electric power construction is relatively late, and the development is relatively slow. This paper combines 3 scientific research projects, the reliability theory in construction, port workers and The related problems in the design of power transmission lines are studied, including the following aspects:
1. in view of the problem that the reliability index of the structure designed according to the present structural design criterion of the current architectural structure is different in different circumstances, a design method based on the reliability index is proposed, in which the sensitivity coefficient of load and resistance is determined, and it is expressed as a linear function of the load effect ratio. The simplified relation between the partial coefficient and the load effect ratio is established. The calculation shows that the reliability of the structure designed by this method is in good agreement with the target value.
2. the frequency value coefficient and the quasi permanent value coefficient in the normal use limit state design of the current building structure specification are determined by the experience. According to the collected data of the live load and wind load, the statistical principle is used to determine the coefficient and the quasi permanent value coefficient of the floor live load and the wind load carrier frequency, and to the concrete gauge. The reliability analysis of the maximum crack width of the reinforced concrete flexural member is analyzed according to the standard and the quasi permanent coefficient determined in this paper. The results show that the maximum crack width limit of the standard permanent combination under the standard revision is shown. The reliability of the state meets the requirements of the unified standard.
3. according to the working characteristics of the reinforced concrete structure in the marine environment, the corrosion probability model of steel bar corrosion, which has not been corroded, the steel bar has been corroded but the concrete protection layer is not cracked and the concrete protective layer has cracked in 3 stages, and the probability of the corrosion rate of steel bar and the occurrence probability of 3 kinds of corrosion corrosion states is analyzed by the Monte-Carlo method. By using the established probability model of steel corrosion rate, the time dependent reliability of reinforced concrete flexural members satisfying the minimum durability requirements of the port workers is analyzed. The results show that the corrosion rate of steel bar at a certain time obeys the normal normal Shuangfeng distribution; the longer the exposed time of the structure is in the marine environment, the steel bar is not corroded and the protective layer is not open. The smaller the probability of cracking, the lower the reliability of corroded reinforced concrete members.
4. the statistical parameters and probability models of the general transmission lines, such as permanent load, wind load, ice load and tower components, insulators, gold and wire resistance, are determined according to the collected load, the statistical data of resistance and the relevant standards. The first two moment method, which considers the probability distribution types of random variables, is adopted. The reliability calibration of the related components of the transmission line, which is designed for the line of line transmission lines, provides the basis for determining the target reliability index of the tower members, insulators, fittings and wires on the transmission lines of the transmission lines.
5. according to the reliability calibration results of the general transmission lines, the target reliability indexes of tower members, insulators, fittings and wires are proposed for transmission lines across the high speed rail transmission lines, and the relationship between the importance coefficient of the tower members and the safety factor of insulators, fittings and wires and the reliability index is established, which can be directly passed through the importance coefficient or safety. The reliability of the transmission line is designed by the coefficient.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU318

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