本文選題：CFRP + 鋼筋混凝土矩形柱�。� 參考：《北京建筑大學》2017年碩士論文

【摘要】：現(xiàn)如今,在新建土木工程的同時,選擇更為可靠的加固方法對既有混凝土結(jié)構(gòu)進行加固與維護變得尤為重要。碳纖維增強塑料布(以下簡稱CFRP布)加固鋼筋混凝土結(jié)構(gòu)時能夠充分利用CFRP布強度高、質(zhì)量輕、延性好與耐久性好等特性,在國內(nèi)外鋼筋混凝土構(gòu)件加固工程中受到越來越多的關注與應用。近年來,研究人員針對CFRP加固鋼筋混凝土偏心受壓柱力學性能的研究結(jié)論主要基于小尺寸構(gòu)件的研究結(jié)果,在研究時很少考慮尺寸效應,然而在實際加固工程中,處于正常使用狀態(tài)下的待加固鋼筋混凝土柱尺寸均較大,而且大多數(shù)截面形狀為矩形。本文針對CFRP加固鋼筋混凝土柱偏心受壓力學性能的尺寸效應進行了較為系統(tǒng)的試驗研究與有限元分析。根據(jù)偏心距的不同,共設計了五組16根截面尺寸分別為200mm×200mm、400mm×400mm、600mm×600mm的小、中、大三種截面尺寸的鋼筋混凝土柱,且小、中、大尺寸試件的加固層數(shù)與配筋率等均保證一定的幾何相似比。采用單調(diào)偏心加載的方式,分析了截面尺寸的變化對CFRP加固矩形鋼筋混凝土偏心受壓柱的承載力、延性等力學性能的影響。并利用ANSYS有限元軟件進行了數(shù)值分析,驗證了有限元模型的正確性后,對CFRP加固矩形鋼筋混凝土偏心受壓柱進行了參數(shù)化分析,以混凝土強度等級、縱筋配筋率和CFRP布厚度為影響因素,研究了各種因素對其力學性能的影響。本文主要研究結(jié)果如下:1.小偏心受壓試件,其極限承載力、名義強度等力學性能均存在明顯的尺寸效應。小偏心受壓構(gòu)件的承載力安全儲備系數(shù)隨尺寸的增大而減小,CFRP布的應變隨尺寸的增大而減小;柱中側(cè)向撓度也存在尺寸效應,尺寸越大,其相對撓度越大,而且相對撓度并不按尺寸增大的比例增大;尺寸效應對極限荷載下的縱筋應變有一定影響,但影響不大。2.尺寸大小對CFRP布極限承載力隨偏心距的變化趨勢產(chǎn)生了影響,尺寸越大,變化趨勢越平緩。尺寸大小對峰值狀態(tài)下CFRP布的極限應變值隨偏心距的變化趨勢影響顯著,然而對受壓縱筋的極限應變值隨偏心距的變化趨勢影響不明顯。尺寸大小對柱中相對側(cè)向撓度隨偏心距的變化也產(chǎn)生了影響,尺寸越大,其隨偏心距變化的曲線越平緩。3.混凝土強度的提高能夠削弱尺寸效應對試件力學性能的影響。配筋率的提高能夠輕微改善尺寸效應對試件力學性能的影響,試件的極限強度隨配筋率的增大而增大,提高配筋率還會提高試件的延性,其中大尺寸的極限強度提高幅度最大。對于尺寸相同的試件,隨著CFRP布厚度的增加,試件的極限強度隨之增大,但不是線性變化,而是隨著厚度的增加,提高幅度逐漸降低。CFRP布的約束能夠削弱尺寸效應對試件力學性能的影響,并且CFRP布厚度越厚,試件的尺寸效應越不明顯。
[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.
【學位授予單位】：北京建筑大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU375.3

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