地震组合时结构的可靠度分析与设计方法

发布时间：2018-02-22 10:39

本文关键词： 地震组合随机过程可靠度分析可靠度设计灵敏度系数优化　出处：《西安建筑科技大学》2013年硕士论文　论文类型：学位论文

【摘要】：地震是世界三大科学难题之一，近年来地震灾害频发，而中国是一个多地震的国家。结构设计环节需要在安全性和经济性之间找到一个平衡点，而当前是以概率为依据的。以分项系数表达的近似概率极限状态设计方法是当前国内外结构设计的主要方法，在应用过程中已暴露出灵活性不足的缺陷，而地震组合时的承载力设计表达式同样以此种形式表达。当前对地震组合时的承载力设计表达式进行可靠度分析，由于组合中涉及可变作用准永久值，，而作用随机变量组合方法存在理论缺陷，同时，设计使用年限不同于设计基准期时，确定地震作用在设计使用年限内极大值的分布尚缺乏理论依据。本文以作用概率组合方法为侧重点，建立更合理的可靠度分析模型，通过校核现行设计表达式，找出可靠度控制粗略的缺陷，结合设计值法，建立用于地震组合时的灵活、实用、控制精度高的承载力设计表达式。主要研究内容如下： 1）针对目前地震组合时的分项系数设计法，分析了有准永久值参与组合时当前的可靠度分析方法。指出在设计使用年限异于设计基准期情况下地震作用分布确定环节理论不足的现状。 2）建立基于作用随机过程组合的结构功能函数。借助可变作用随机过程概率模型、可变作用在设计基准期内极大值的分布，结合序位值分布的理论知识，推导体现超越概率的准永久序位值的分布；建立地震作用的随机过程概率模型，结合概率地震危险性分析成果及设计基准期内地震作用极大值分布推导任意设计使用年限内地震作用极大值的分布。为地震组合时结构的可靠度分析与设计方法提供理论知识。 3）选择钢筋混凝土单筋梁对地震组合时的承载力设计表达式进行基于作用随机过程组合的可靠度分析。因为多数作用效应比例下可靠指标绝对值较小，建议用失效概率均值反求目标可靠指标；因为可靠指标有负值的情况，这样就出现一个不恰当现象，作用效应不确定系数起的却是抗力不确定系数作用，建议此种情况结构功能函数不考虑作用效应不确定系数；因为设计基准期内不同作用效应比例下可靠指标稳定性差，说明现行设计方法可靠度控制粗略的缺陷；因为单一结构承载力设计表达式隐含的可靠指标随设计使用年限增加而显著降低，说明作用取值要重视设计使用年限的影响。 4）将作用随机过程组合方法与基于概率的设计值法结合，将设计值表达成分项系数和标准值乘积的形式，增加实用性，提出快捷有效的标准灵敏度系数优化方法。最后建立灵活、实用、可靠度控制精度高的用于地震组合时的承载力设计表达式。基本变量的变异性和作用效应比例是标准灵敏度系数取值的主控因素，按设计使用年限50年和一个合理的目标可靠指标优化出的结果用于不同设计使用年限和不同目标可靠指标的情况，误差在允许范围内。作用效应不确定性系数考虑与否对标准灵敏度系数的取值产生较大影响，但对最终抗力值的影响很小。
[Abstract]:The earthquake is one of the world's three major scientific problems, frequent earthquake disasters in recent years, and Chinese is an earthquake prone country. Structural design links need to find a balance between security and economy, and is currently based on probability. To approximate expression of partial coefficient probability limit state design method is the main method of the structural design of the domestic, in the application process has exposed the defects of lack of flexibility, and the bearing capacity of the same combination of seismic design expressions of this form of expression. The combination of seismic bearing capacity for reliability analysis design, due to the variable function combination of quasi permanent value, and the role of random variable combination method has theoretical defect, at the same time, the design service life is different from the design reference period, determine the distribution of earthquake in the design service life within the maximum value of the lack of theory On the basis of probability combination method. In this paper the role of focus, establish the reliability analysis model is more reasonable, by checking the current design expression, find out the reliability control rough defects, combining the design value method is established for seismic combination of flexible, practical, bearing capacity design formula of high control precision. The main research contents are as follows:
1) according to the partial coefficient design method of seismic combination, the current reliability analysis method is analyzed when quasi permanent value is involved in combination. It is pointed out that the design of service life is different from that of design reference period, and the theory of earthquake action distribution confirmation is insufficient.
2) establish the function of structure function based on the combination of random process. With the probabilistic model of variable action stochastic process, the distribution of variable role in the design reference period with the maximum value, order value theory of knowledge distribution, the distribution of quasi permanent order reflects the value of the derived probability; a stochastic process probability model of seismic action, combined with the earthquake the earthquake hazard analysis results and design reference period maximum value distribution is arbitrary distribution of earthquake action within the term of maximum use of the design. Provide theoretical knowledge for reliability analysis and design method of seismic combination structure.
3) selection of reinforced concrete beam with single reinforcement of bearing capacity design formula of seismic combination of reliability analysis of stochastic process based on the combination of the absolute value of reliability index. Because most of the effect of the proportion of small, suggested the failure probability of mean reverse target reliability index; reliability index for a negative situation, it will appear a an inappropriate phenomenon, the effect of uncertainty coefficient is the resistance of the uncertainty factor, the proposed structure function without considering the effect of uncertainty coefficient; because the reliability index for different effects in design reference period the proportion of poor stability, shows that the current design method of reliability control of rough defects; because the reliability index of design expression the implied capacity of single structure with design life decreased, indicating that the effect of value should pay attention to the design service life Influence.
4) the effect of stochastic process and probability combination method combined with the design value based on the value of the product form design expression value coefficient and standard components, increase the practicality, coefficient optimization method proposed standard sensitivity effective. Finally establish a flexible, practical, reliable control and high precision for bearing capacity design formula of earthquake when combined. The proportion and function variation of basic variables is the main effect of standard sensitivity coefficient of factors, according to the design life of 50 years and a reasonable target reliability index is the result of optimization design for different age and different target reliability index, the error is in the allowable range. The effect of uncertainty considering the influence coefficient and the sensitivity coefficient of the standard, but it has little effect on the ultimate resistance value.

【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU352.11;TU318

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