基于抗力时变特性的内河框架码头可靠度分析

发布时间：2018-04-01 14:02

本文选题：框架码头　切入点：结构全寿命　出处：《重庆交通大学》2014年硕士论文

【摘要】：码头结构在长期使用过程中，受自然环境、使用条件和内部材料等因素的影响，钢筋混凝土构件易产生钢筋锈蚀、混凝土碳化以及钢筋与混凝土间粘结力降低等现象，导致其抗力随时间不断的降低。本文应用可靠度理论，提出考虑钢筋混凝土构件时变特性的内河框架码头全寿命分析方法，并通过算例说明如何运用该方法计算随时间变化的结构物可靠度。论文的主要工作和结论包括以下内容：（1）基于混凝土锈胀开裂过程的随机性，考虑内河环境中混凝土碳化引起的钢筋锈蚀作为混凝土结构劣化的主要环境作用因素，提出了一种预测钢筋锈蚀程度的概率模型。基于该模型，采用蒙特卡罗法模拟码头横梁性能退化过程，得到钢筋锈蚀率在不同时段的概率分布，实现了混凝土构件“混凝土碳化-钢筋锈蚀-混凝土开裂-钢筋锈蚀加剧-构件承载能力下降”的性能劣化全过程数值模拟。模拟结果表明钢筋锈蚀率的分布特征随时间变化。（2）本研究将钢筋混凝土构件的抗力和作用荷载均视为随机过程，将其离散为设计使用期内不同时间段相应极值的随机变量，同时假设以最危险构件的可靠度代表整个结构系统的可靠度，，采用JC法计算结构物的时变可靠指标，建立了基于抗力随时间变化的内河框架码头可靠度计算模型。（3）以某内河钢筋混凝土框架码头为背景，基于本文的研究方法，采用MATLAB编程计算码头构件时变可靠指标。在此基础上分析码头主要构件因钢筋锈蚀和混凝土劣化造成的可靠指标退化过程，从结构可靠性理论方面对结构的剩余寿命进行定量的评估。结果表明钢筋开始锈蚀时间是结构抗力退化的一个重要时间节点，在码头设计时推迟钢筋开始锈蚀时间对码头结构的安全性和耐久性有重要的意义。
[Abstract]:During the long-term use of wharf structure, due to the influence of natural environment, usage conditions and internal materials, reinforced concrete members are prone to corrosion, carbonization of concrete and reduction of bond force between reinforcement and concrete, etc.It causes its resistance to decrease over time.Based on the reliability theory, this paper puts forward a method to analyze the whole life of the inland river frame wharf considering the time-varying characteristics of reinforced concrete members, and illustrates how to use this method to calculate the reliability of structures varying with time.The main work and conclusions of the thesis include the following:1) based on the randomness of the process of concrete corrosion cracking, a probabilistic model for predicting the degree of reinforcement corrosion is proposed, considering the corrosion of steel bar caused by concrete carbonization in the inland river environment as the main environmental factor of the deterioration of concrete structure.Based on the model, Monte Carlo method is used to simulate the degradation process of wharf beam performance, and the probability distribution of the corrosion rate of reinforcement in different periods is obtained.Numerical simulation of the whole process of performance deterioration of concrete members "concrete carbonization-reinforcement corrosion-concrete cracking-reinforcement corrosion aggravation-member bearing capacity decline" has been realized.The simulation results show that the distribution of corrosion rate of steel bars varies with time.2) in this study, the resistance and the action load of reinforced concrete members are regarded as random processes, which are discretized into random variables corresponding to extreme values in different time periods of design life.At the same time, assuming that the reliability of the most dangerous component represents the reliability of the whole structure system, the time-varying reliability index of the structure is calculated by using JC method, and the reliability calculation model of the inland river frame wharf based on the variation of resistance with time is established.Taking the reinforced concrete frame wharf of a inland river as the background and based on the research method in this paper, the time-varying reliability index of wharf members is calculated by MATLAB programming.On this basis, the process of reliability index degradation caused by the corrosion of reinforcement and deterioration of concrete is analyzed, and the residual life of the structure is quantitatively evaluated from the aspect of structural reliability theory.The results show that the corrosion time of steel bar is an important time node of structural resistance degradation. It is important for the safety and durability of wharf structure to delay the start corrosion time of steel bar in the design of wharf.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U656.1

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