本文選題：再生混凝土 + 碳纖維布�。� 參考：《西華大學(xué)》2016年碩士論文

【摘要】：目前我國混凝土的用量不斷增長,在崇尚保護(hù)環(huán)境和科學(xué)發(fā)展的今天,過量開采天然骨料用于制備混凝土,將對環(huán)境造成不可彌補(bǔ)的破壞,因此對再生混凝土的研究應(yīng)用有著重要意義。由于再生混凝土的來源和制備工藝比較特殊,因此使其具有孔隙率、吸水率等較大,而強(qiáng)度、彈性模量等較低,抗?jié)B性、抗凍性、收縮、徐變等較差的特點(diǎn),制約了再生混凝土的發(fā)展。本文將6根不同再生骨料取代率、不同受力主筋直徑的混凝土梁分成兩組,每組試驗(yàn)梁受力主筋直徑相同,并包含1根普通混凝土梁、1根再生混凝土梁、1根CFRP布加固后的再生混凝土梁,研究其抗彎性能。并進(jìn)一步采用軟件進(jìn)行數(shù)值模擬分析。其中主要研究工作和成果如下:1、對CFRP布材料性能和加固方法進(jìn)行研究,討論了混凝土、鋼筋、CFRP布本構(gòu)方程,并進(jìn)行CFRP布加固再生混凝土正截面破壞試驗(yàn),考察CFRP布對再生混凝土梁的承載力、撓度、裂縫開展等內(nèi)容的影響程度。經(jīng)過碳纖維布加固后的試驗(yàn)梁,其抗彎承載力得到提高,并且延緩裂縫的出現(xiàn)。裂縫發(fā)展速度較緩慢,在極限荷載的25%~85%左右剪彎段斜裂縫發(fā)展迅速。2、CFRP布可以有效抑制混凝土梁表面的裂縫出現(xiàn)與開展,加固后的再生混凝土梁開裂后撓度以較慢的速度增長。隨著主筋直徑的增大,CFRP布與鋼筋共同承擔(dān)梁底部拉應(yīng)力的效果更好,CFRP布的利用率有所提高,梁體剛度損失減小。梁開裂后,彎矩產(chǎn)生的拉應(yīng)力大部分由CFRP布來抵抗,受主筋直徑的影響較小。3、利用有限元分析理論,針對試驗(yàn)數(shù)據(jù)建立有限元數(shù)值分析模型,討論模擬再生混凝土梁所用的有限元單元類型和破壞準(zhǔn)則,得到與試驗(yàn)結(jié)果較吻合的數(shù)值模型。對數(shù)值模擬結(jié)果與試驗(yàn)結(jié)果比對,驗(yàn)證數(shù)值分析結(jié)果的準(zhǔn)確性,分別研究鋼筋、碳纖維布應(yīng)力應(yīng)變云圖,得到CFRP布加固再生混凝土梁各材料的整體受力狀態(tài)。(1)在極限荷載的60%左右,鋼筋的應(yīng)變達(dá)到極限應(yīng)變,此時(shí)鋼筋屈服,此后拉應(yīng)力將全部由CFRP布承擔(dān)。(2)碳纖維布加固后的試驗(yàn)梁,受拉鋼筋的應(yīng)變滯后于碳纖維布應(yīng)變,隨著配筋率的增加,滯后程度減弱。碳纖維布在較大配筋率下更能發(fā)揮其抗拉性能,減小梁體剛度損失。(3)混凝土開裂時(shí)刻的第一主應(yīng)力最大值發(fā)生在加載點(diǎn)對齊位置附近,混凝土梁破壞時(shí)刻的第一主應(yīng)力最大值發(fā)生在梁剪彎段中間位置。因此混凝土開裂過程表現(xiàn)為跨中裂痕首先發(fā)展,當(dāng)加載到極限荷載的1/4時(shí),彎剪段裂痕迅速發(fā)展,最終因CFRP布斷裂而發(fā)生彎曲破壞。4、對有限元模型的縱向受力鋼筋的參數(shù)進(jìn)行更改,得出不同配筋率的極限承載力。根據(jù)CFRP加固混凝土結(jié)構(gòu)受彎承載力計(jì)算公式對CFRP加固再生混凝土受壓區(qū)高度按公式進(jìn)行修正。
[Abstract]:At present, the amount of concrete is increasing in our country. In today's advocation of environmental protection and scientific development, excessive exploitation of natural aggregate for concrete preparation will cause irreparable damage to the environment. Therefore, it is of great significance to the research and application of recycled concrete. The source and preparation process of recycled concrete are very special, so the production of recycled concrete is very special. It has the characteristics of low porosity, water absorption, low strength, modulus of elasticity, impermeability, frost resistance, shrinkage, creep and other poor characteristics, which restrict the development of recycled concrete. In this paper, 6 concrete beams with different recycled aggregate replacement rates and different strength main tendons are divided into two groups. Each test beam is subjected to the same diameter of the main reinforcement. With 1 ordinary concrete beams, 1 recycled concrete beams and 1 regenerated concrete beams strengthened with CFRP cloth, the flexural performance of the reinforced concrete beams is studied. The software is used to carry out numerical simulation analysis. The main research work and results are as follows: 1, the properties and reinforcement methods of CFRP materials are studied, and the constitutive equation of concrete, steel and CFRP is discussed. The influence degree of CFRP cloth on the bearing capacity, deflection and crack development of recycled concrete beams was investigated by CFRP reinforced concrete reinforced recycled concrete cross section failure test. The bending bearing capacity of the reinforced concrete beams strengthened by CFRP was improved, and the crack development was delayed. The crack development speed was slow, 25% of the limit load. The slanting cracks in the left and right shear and bending sections develop rapidly in.2, and CFRP cloth can effectively restrain the appearance and development of cracks on the surface of concrete beams. After the reinforcement of the reinforced concrete beams, the deflection of the reinforced concrete beams increases at a slower speed. With the increase of the diameter of the main reinforcement, the effect of the tensile stress at the bottom of the beam is better and the utilization ratio of the CFRP cloth is raised with the increase of the diameter of the main reinforcement. After the beam cracking, the tensile stress produced by the bending moment is mostly resisted by the CFRP cloth, and the influence of the diameter of the main tendons is less.3. The finite element numerical analysis model is set up by the finite element analysis theory, and the finite element model and failure criterion used in the simulated regenerated concrete beam are discussed, and the test is obtained and tested. The numerical simulation results are compared with the experimental results, and the accuracy of the numerical analysis results is verified. The stress and strain nephogram of the reinforced steel and carbon fiber cloth is studied, and the overall stress state of the materials of the regenerated concrete beams strengthened by CFRP cloth is obtained. (1) the strain of the steel bar reaches the limit strain at the limit load of about 60%. When the reinforcing bar yields, the tensile stress will be all made by the CFRP cloth. (2) the strain of the tensile steel is lagged behind the strain of carbon fiber cloth after the reinforcement of carbon fiber cloth. With the increase of the reinforcement ratio, the lag degree weakens. The stiffness loss of the beam is reduced by the larger reinforcement ratio. (3) the cracking time of the concrete is reduced. The maximum value of the first principal stress occurs near the alignment position of the loading point. The maximum value of the first principal stress of the concrete beam at the moment of failure occurs at the middle position of the beam shear bending section. Therefore, the cracking process of the concrete is first developed in the middle span crack. When the load to the limit load of 1/4, the cracks in the shear section rapidly develop and finally break with the CFRP cloth. The bending failure.4 is taken, the parameters of the longitudinal reinforced bar in the finite element model are changed, and the ultimate bearing capacity of the different reinforcement ratio is obtained. According to the formula of the flexural bearing capacity of the reinforced concrete structure reinforced by CFRP, the height of the compression zone of the regenerated concrete reinforced by CFRP is amended according to the formula.
【學(xué)位授予單位】：西華大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TU37

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 孟慶伶;混凝土梁常見的質(zhì)量問題及其產(chǎn)生原因[J];鐵道建筑;2002年07期

2 周煥文;;掽筋混凝土梁的動(dòng)力沖擊系數(shù)公式的探，

本文編號：1949247