碳纤维加固钢筋混凝土结构可靠性分析

发布时间：2018-09-03 18:39

【摘要】：由于我国大部分建筑物投入使用时间的增加、环境对建筑结构的腐蚀、施工质量低劣和自然灾害等原因,导致了结构的承载力和安全性能达不到预定的要求,所以必须对这些建筑进行修复与加固。碳纤维增强复合材料(CFRP)以其优良的物理和力学性能,已经被广泛的应用于建筑结构的加固工程中。为了对建筑结构加固的安全性进行准确的计算分析,研究结构可靠度指标变化规律和影响因素显得尤为重要,本文主要研究内容和成果如下:(1)介绍几种常用的可靠度计算方法:中心点法、设计验算点法、JC法和映射变换法等,对比分析各种方法的优缺点和适用范围,在后文研究中主要采用JC法来计算分析结构可靠度指标。(2)对一锈蚀的钢筋混凝土梁进行受弯和受剪承载力可靠度指标变化规律分析,研究荷载效应比和碳纤维加固量对可靠度指标的影响。选取五组不同的荷载效应比,采用JC法进行计算。结果表明:加固前与加固后,随着荷载效应比的增大,受弯和受剪承载力可靠度指标逐渐减小,且减小趋势越来越缓慢;在适用条件下,每增加一层碳纤维布,梁的受弯承载力可靠度指标提升4%左右,受剪可靠度指标提升9%-14.6%。(3)对一轴心受压柱进行设计与加固,研究荷载效应比、钢筋锈蚀率和碳纤维加固量对柱轴压承载力可靠度指标的影响。结果表明:加固前与加固后,轴心受压柱的可靠度指标随着荷载效应比的增大逐渐减小,且减小趋势越来越缓慢;每增加一层碳纤维布,轴心受压柱的可靠度指标提升3.7%-5.8%。(4)大偏心受压柱的压弯可靠度指标应同时考虑受压和受弯可靠度指标的影响。采用碳纤维对锈蚀的大偏心受压柱进行加固,研究荷载效应比和初始偏心矩对其可靠度指标的影响,结果表明:锈蚀前与锈蚀后,大偏心受压柱受压、受弯和压弯承载力可靠度指标均随着初始偏心距和荷载效应比的增大而减小,减小趋势逐渐减缓;加固前后受压承载力可靠度指标受初始偏心距的影响很小。锈蚀大偏心受压柱在经过一层碳纤维布加固后,受压承载力可靠度指标较加固前提高4.7%-10.5%,受弯承载力可靠度指标提高11.2%-39.7%,压弯承载力可靠度指标提高10.8%-39.5%,所以选取适量的碳纤维布对柱进行加固可以很好的提高其承载力和安全性。
[Abstract]:Due to the increasing time of putting into use of most buildings in our country, the corrosion of the environment to the building structure, the poor quality of construction and natural disasters, the carrying capacity and safety performance of the structure can not meet the scheduled requirements. Therefore, these buildings must be repaired and reinforced. Carbon fiber reinforced composite (CFRP) has been widely used in the reinforcement of building structures due to its excellent physical and mechanical properties. In order to accurately calculate and analyze the safety of building structure strengthening, it is very important to study the variation law of structural reliability index and the influencing factors. The main contents and achievements of this paper are as follows: (1) introduce several commonly used reliability calculation methods: central point method, design checking point method, JC method and mapping transformation method, and compare and analyze the advantages and disadvantages and applicable scope of various methods. In the later research, JC method is used to calculate and analyze the reliability index of the structure. (2) the variation law of the reliability index of a corroded reinforced concrete beam under bending and shear load is analyzed. The effect of load effect ratio and carbon fiber reinforcement on reliability index is studied. Five groups of different load effect ratios were selected and calculated by JC method. The results show that the reliability index of flexural and shear capacity decreases gradually with the increase of load-effect ratio before and after reinforcement, and the decreasing trend is more and more slow. The reliability index of flexural bearing capacity of beam is increased by about 4%, and the index of shear reliability is increased by 9- 14.6. (3) A column under axial compression is designed and strengthened to study the load-effect ratio. The effect of corrosion rate of steel bar and the amount of carbon fiber reinforcement on the reliability index of axial compression capacity of column. The results show that the reliability index of axial compression column decreases gradually with the increase of load effect ratio before and after reinforcement, and the decreasing trend is more and more slow. The reliability index of axial compression column is 3.7- 5.8. (4) the influence of compression and bending reliability index should be taken into account at the same time. Carbon fiber was used to reinforce the corroded columns with large eccentricity. The effects of load effect ratio and initial eccentric moment on the reliability of columns were studied. The results show that: before and after corrosion, large eccentricity columns are subjected to compression. The reliability index of flexural and compressive bearing capacity decreases with the increase of initial eccentricity and load effect ratio, and decreases gradually, while the reliability index of compressive bearing capacity before and after reinforcement is little affected by initial eccentricity. The corroded eccentric columns are strengthened with a layer of carbon fiber sheets. The reliability index of compressive bearing capacity is increased by 4.7-10.5, the reliability index of flexural bearing capacity is increased by 11.2-39.7. the reliability index of compression bearing capacity is increased by 10.8- 39.5. therefore, the strength and safety of columns can be improved very well by selecting appropriate amount of carbon fiber cloth for strengthening columns.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375

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