FRP加固钢筋混凝土柱偏心受压性能的尺寸效应研究

发布时间：2018-06-19 05:28

本文选题：CFRP + 钢筋混凝土矩形柱　；参考：《北京建筑大学》2017年硕士论文

【摘要】：现如今,在新建土木工程的同时,选择更为可靠的加固方法对既有混凝土结构进行加固与维护变得尤为重要。碳纤维增强塑料布(以下简称CFRP布)加固钢筋混凝土结构时能够充分利用CFRP布强度高、质量轻、延性好与耐久性好等特性,在国内外钢筋混凝土构件加固工程中受到越来越多的关注与应用。近年来,研究人员针对CFRP加固钢筋混凝土偏心受压柱力学性能的研究结论主要基于小尺寸构件的研究结果,在研究时很少考虑尺寸效应,然而在实际加固工程中,处于正常使用状态下的待加固钢筋混凝土柱尺寸均较大,而且大多数截面形状为矩形。本文针对CFRP加固钢筋混凝土柱偏心受压力学性能的尺寸效应进行了较为系统的试验研究与有限元分析。根据偏心距的不同,共设计了五组16根截面尺寸分别为200mm×200mm、400mm×400mm、600mm×600mm的小、中、大三种截面尺寸的钢筋混凝土柱,且小、中、大尺寸试件的加固层数与配筋率等均保证一定的几何相似比。采用单调偏心加载的方式,分析了截面尺寸的变化对CFRP加固矩形钢筋混凝土偏心受压柱的承载力、延性等力学性能的影响。并利用ANSYS有限元软件进行了数值分析,验证了有限元模型的正确性后,对CFRP加固矩形钢筋混凝土偏心受压柱进行了参数化分析,以混凝土强度等级、纵筋配筋率和CFRP布厚度为影响因素,研究了各种因素对其力学性能的影响。本文主要研究结果如下:1.小偏心受压试件,其极限承载力、名义强度等力学性能均存在明显的尺寸效应。小偏心受压构件的承载力安全储备系数随尺寸的增大而减小,CFRP布的应变随尺寸的增大而减小;柱中侧向挠度也存在尺寸效应,尺寸越大,其相对挠度越大,而且相对挠度并不按尺寸增大的比例增大;尺寸效应对极限荷载下的纵筋应变有一定影响,但影响不大。2.尺寸大小对CFRP布极限承载力随偏心距的变化趋势产生了影响,尺寸越大,变化趋势越平缓。尺寸大小对峰值状态下CFRP布的极限应变值随偏心距的变化趋势影响显著,然而对受压纵筋的极限应变值随偏心距的变化趋势影响不明显。尺寸大小对柱中相对侧向挠度随偏心距的变化也产生了影响,尺寸越大,其随偏心距变化的曲线越平缓。3.混凝土强度的提高能够削弱尺寸效应对试件力学性能的影响。配筋率的提高能够轻微改善尺寸效应对试件力学性能的影响,试件的极限强度随配筋率的增大而增大,提高配筋率还会提高试件的延性,其中大尺寸的极限强度提高幅度最大。对于尺寸相同的试件,随着CFRP布厚度的增加,试件的极限强度随之增大,但不是线性变化,而是随着厚度的增加,提高幅度逐渐降低。CFRP布的约束能够削弱尺寸效应对试件力学性能的影响,并且CFRP布厚度越厚,试件的尺寸效应越不明显。
[Abstract]:Nowadays, it is very important to choose more reliable reinforcement method to reinforce and maintain the existing concrete structure while building new civil engineering. Carbon fiber reinforced plastic sheets (CFRP sheets) can make full use of the high strength, light weight, good ductility and durability of CFRP sheets in strengthening reinforced concrete structures. More and more attention and application have been paid to reinforced concrete member reinforcement project at home and abroad. In recent years, the research results of CFRP reinforced concrete eccentrically compressed columns are mainly based on the research results of small size members, and the size effect is seldom taken into account in the research. However, in the actual reinforcement engineering, the size effect is seldom taken into account. The size of reinforced concrete columns under normal use is large and most of the sections are rectangular. In this paper, the size effect of eccentric compressive mechanical properties of reinforced concrete columns strengthened with CFRP is systematically studied and analyzed by finite element method. According to the difference of eccentricity, five groups of 16 reinforced concrete columns with 200mm 脳 200mm / 400mm 脳 400mm 脳 600mm 脳 600mm, medium and large size reinforced concrete columns are designed, and the number of reinforcement layers and the ratio of reinforcement to reinforcement ratio of small, medium and large specimens ensure certain geometric similarity ratio. By means of monotone eccentric loading, the influence of section size on the bearing capacity and ductility of rectangular reinforced concrete eccentrically compressed columns strengthened with CFRP is analyzed. After the validity of the finite element model is verified by ANSYS finite element software, a parameterized analysis of rectangular reinforced concrete eccentrically compressed columns strengthened with CFRP is carried out, and the concrete strength grade is given. The influence factors of longitudinal reinforcement ratio and CFRP cloth thickness on mechanical properties were studied. The main results of this paper are as follows: 1: 1. The ultimate bearing capacity, nominal strength and other mechanical properties of small eccentric compression specimens have obvious size effect. The safety reserve coefficient of bearing capacity of small eccentric compression member decreases with the increase of size, and the strain of CFRP cloth decreases with the increase of size, and the lateral deflection of column also exists size effect, the larger the size, the bigger the relative deflection of CFRP cloth. And the relative deflection does not increase in proportion to the size, and the size effect has a certain effect on the strain of longitudinal reinforcement under ultimate load, but the effect is not significant. The size of CFRP cloth has an effect on the change trend of ultimate bearing capacity with eccentricity, and the larger the size, the more gentle the change trend is. The size of CFRP fabric has a significant effect on the variation trend of the ultimate strain value with eccentricity at the peak value, but it has no obvious effect on the ultimate strain value of the compression longitudinal reinforcement with the eccentricity. The change of the relative lateral deflection with eccentricity is also affected by the size of the column. The larger the dimension, the more gentle the curve with the eccentricity. 3. The increase of concrete strength can weaken the effect of size effect on the mechanical properties of specimens. The increase of reinforcement ratio can slightly improve the effect of size effect on the mechanical properties of the specimen. The ultimate strength of the specimen increases with the increase of the reinforcement ratio, and the ductility of the specimen is also increased with the increase of the reinforcement ratio. For the specimens of the same size, the ultimate strength of the specimens increases with the increase of the thickness of CFRP cloth, but not linearly, but with the increase of the thickness. The effect of the size effect on the mechanical properties of the specimen can be weakened by decreasing the constraint of the CFRP cloth, and the thicker the thickness of the CFRP cloth, the less obvious the size effect of the specimen is.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.3

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