發(fā)布時間：2018-04-14 16:26

  本文選題：碳化 + 銹脹力��； 參考：《西北農(nóng)林科技大學(xué)》2017年碩士論文

【摘要】：對西北地區(qū)渡槽工程進行質(zhì)量檢測發(fā)現(xiàn)大部分工程混凝土碳化現(xiàn)象嚴重,鋼筋銹脹導(dǎo)致混凝土開裂,影響到結(jié)構(gòu)承載力,降低了結(jié)構(gòu)的安全性。針對裂縫問題,各國學(xué)者相繼提出了控制裂縫的要求,裂縫寬度計算至今仍是研究的重點,但由于影響混凝土開裂的原因復(fù)雜,普遍適用的裂縫寬度計算公式仍然在研究中。隨著計算機技術(shù)的飛速發(fā)展,有限元軟件逐漸被學(xué)者們所接受。ANSYS有限元中SOLID65單元特有的屬性為模擬混凝土開裂提供了便利。本文應(yīng)用有限元軟件ANSYS建立了單根鋼筋均勻銹蝕導(dǎo)致混凝土開裂的數(shù)值模型,并通過熱-結(jié)構(gòu)耦合作用,模擬了混凝土碳化后鋼筋銹脹導(dǎo)致混凝土開裂的銹脹力,并將碳化深度模擬值與試驗值進行對比。通過給模型施加不同的荷載,計算了裂縫寬度模擬值,并與經(jīng)典公式以及實際工程測量值對比,研究了混凝土碳化深度對裂縫寬度的影響規(guī)律。結(jié)果如下:(1)本文根據(jù)熱傳導(dǎo)原理數(shù)值模擬混凝土碳化作用的可行性,通過應(yīng)用大型通用有限元軟件ANSYS較好的模擬了單根鋼筋均勻銹蝕導(dǎo)致混凝土開裂的鋼筋銹脹力,與理論值對比表明誤差在允許范圍內(nèi)。通過給模型施加碳化場,模擬了混凝土碳化后單根鋼筋均勻銹蝕導(dǎo)致混凝土開裂的銹脹力,分析了碳化對混凝土開裂的影響規(guī)律,發(fā)現(xiàn)增加碳化因素后,混凝土開裂所需的鋼筋銹脹力減小。(2)本文模擬了混凝土的碳化深度值,并與相同條件下的試驗值對比發(fā)現(xiàn)結(jié)果相近。建立了鋼筋銹脹力與混凝土碳化深度的線性回歸方程,且相關(guān)性較好。利用ANSYS強大的耦合功能,將碳化場與應(yīng)力場耦合,模擬結(jié)果更接近工程實際,為后期模擬混凝土碳化后的開裂變形及計算裂縫寬度提供了理論依據(jù)。(3)在熱-結(jié)構(gòu)耦合模型的基礎(chǔ)上,通過給模型施加不同的荷載,觀察鋼筋混凝土的裂縫擴展情況,發(fā)現(xiàn)荷載在某一范圍內(nèi),荷載越大,裂縫寬度越大,裂縫條數(shù)也增多。施加相同的荷載,模擬不同碳化深度下混凝土的開裂情況,發(fā)現(xiàn)碳化深度較小時,對裂縫寬度的影響不明顯,當(dāng)碳化深度超過某一范圍時,對裂縫寬度的影響明顯。(4)將裂縫寬度模擬值與理論值對比,發(fā)現(xiàn)數(shù)值模擬得到的裂縫寬度精度滿足要求;將模擬值與實際測量值對比,結(jié)果表明混凝土碳化深度與裂縫寬度的關(guān)系曲線近似相同;根據(jù)實際測量值,本文建立了裂縫寬度和碳化深度的關(guān)系曲線,近似成二次函數(shù)關(guān)系;根據(jù)數(shù)值模擬值,應(yīng)用MATLAB軟件擬合了裂縫寬度和碳化深度以及荷載的二元一次函數(shù)關(guān)系式,為日后對工程進行耐久性評價奠定了基礎(chǔ)。
[Abstract]:The quality test of aqueduct projects in Northwest China shows that the carbonation phenomenon of concrete is serious in most of the projects, and the corrosion expansion of steel bar leads to the cracking of concrete, which affects the bearing capacity of the structure and reduces the safety of the structure.To solve the problem of crack, scholars from all over the world have put forward the requirement of crack control. The calculation of crack width is still the focus of the research. However, due to the complexity of the reasons that affect the crack of concrete, the widely applicable formula for calculating the width of crack is still under study.With the rapid development of computer technology, finite element software has been gradually accepted by scholars. The unique properties of SOLID65 element in the finite element of. ANSYS provide convenience for the simulation of concrete cracking.In this paper, a numerical model of concrete cracking caused by uniform corrosion of a single reinforcing bar is established by using finite element software ANSYS, and the corrosion expansion force of concrete after carbonization is simulated by thermal-structural coupling.The carbonation depth simulation value is compared with the experimental value.By applying different loads to the model, the simulated values of crack width are calculated, and compared with the classical formula and the actual engineering measurements, the influence of carbonation depth of concrete on the crack width is studied.The results are as follows: (1) according to the feasibility of numerical simulation of concrete carbonation based on the heat conduction principle, the corrosion expansion force of concrete cracking caused by uniform corrosion of a single reinforcing bar is well simulated by using a large universal finite element software ANSYS.The comparison with the theoretical values shows that the error is within the allowable range.By applying carbonation field to the model, the corrosion expansion force of concrete cracking caused by uniform corrosion of a single reinforced bar after carbonization is simulated, and the influence of carbonation on concrete cracking is analyzed.In this paper, the carbonation depth of concrete is simulated, and the results are similar to the experimental results under the same conditions.The linear regression equation between the corrosion expansion force and the carbonation depth of concrete is established, and the correlation is good.With the powerful coupling function of ANSYS, the carbonation field and the stress field are coupled. The simulation results are closer to the engineering practice.This paper provides a theoretical basis for simulating cracking and deformation of concrete after carbonization and calculating crack width. On the basis of thermal-structural coupling model, the crack propagation of reinforced concrete is observed by applying different loads to the model.It is found that the larger the load, the wider the crack width and the more the number of cracks.Under the same load, the cracking of concrete under different carbonation depth is simulated. It is found that the crack width is not affected obviously when the carbonation depth is small, and when the carbonization depth exceeds a certain range,The effect on crack width is obvious. (4) comparing the simulated value of fracture width with the theoretical value, it is found that the accuracy of the crack width obtained by numerical simulation meets the requirement, and the simulated value is compared with the actual measured value.The results show that the relationship curve between the carbonation depth and the crack width is approximately the same, the curve of the relationship between the crack width and the carbonation depth is established according to the actual measured value, and the relation between the crack width and the carbonation depth is approximate to the quadratic function, and according to the numerical simulation value,The relationship between crack width, carbonation depth and load is fitted by MATLAB software, which lays a foundation for the durability evaluation of engineering in the future.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV332

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