本文選題：混凝土箱梁 + 數(shù)值模擬　； 參考：《重慶交通大學》2014年碩士論文

【摘要】：近年來，隨著橋梁跨度的不斷增加，高大索塔、空心薄壁墩、薄壁箱梁等箱體結(jié)構(gòu)應用越來越廣泛。與此同時，混凝土箱體溫差應力與溫度裂縫問題日益突出，調(diào)查發(fā)現(xiàn)，國內(nèi)外由于溫度應力造成的橋梁結(jié)構(gòu)損壞已不占少數(shù)。另一方面，由于溫度應力帶來的結(jié)構(gòu)維修加固費用高達百萬元。在上述背景下，本文以混凝土箱梁橋為研究對象，針對箱梁在太陽輻射作用下的溫度場和溫度效應展開研究，主要研究內(nèi)容包括： ①混凝土箱體熱物理參計算模式研究 利用太陽與結(jié)構(gòu)表面的三角關(guān)系，構(gòu)建了結(jié)構(gòu)物表面地理位置、日期、時刻參數(shù)與太陽直接輻射能的關(guān)系。并以此為依據(jù)，推導出了天空輻射、太陽輻射與天空輻射反射、大氣逆輻射、構(gòu)件反射的計算模式。借助輻射氣溫的概念，將第二類邊界條件轉(zhuǎn)化為第三類邊界，以熱交換平衡為基礎(chǔ)，構(gòu)建了結(jié)構(gòu)表面輻射氣溫與大氣溫度、輻射能、構(gòu)件吸收系數(shù)等參數(shù)的關(guān)系。利用第三類邊界條件，求得了結(jié)構(gòu)表面溫度與輻射氣溫、熱流密度的關(guān)系。 ②混凝土箱體溫度場計算模式研究 以熱傳導基本方程Ti=f (x, y, z,t)為基礎(chǔ)，推導了邊界上溫度與時間、熱流密度與時間、熱流密度與溫差的關(guān)系。從計算精度、計算復雜程度等方面出發(fā)，對比了Fourier熱傳導方程、近似計算方法和半經(jīng)驗半理論公式各自的特點。運用ABAQUS數(shù)值模擬軟件，建立二維瞬態(tài)溫度場分析模型，并對其施加熱邊界條件，進行溫度場分析，得到任意時刻箱梁截面溫度分布，并與現(xiàn)場實測溫度進行對比，驗證了數(shù)值模擬的正確性。 ③混凝土溫度效應分析理論及方法的研究 對橋梁溫度分布沿縱向一致，混凝土材料特性各向同性，符合線彈性變形規(guī)律等方面做出了基本假定，以ε=α T為基礎(chǔ)，推導了混凝土箱梁自應力和次應力的計算公式，，并運用疊加原理，求得連續(xù)箱梁結(jié)構(gòu)總溫度應力的計算公式。以云南牛欄江特大橋為例，運用有限元分析軟件建立全橋模型，得到了全橋關(guān)鍵截面在溫度梯度荷載作用下的溫度效應情況。
[Abstract]:In recent years, with the continuous increase of bridge span, tall cable towers, hollow thin-walled piers, thin-walled box girder and other box structures are more and more widely used. At the same time, the problem of temperature difference stress and temperature crack in concrete box has become more and more serious. The investigation found that the damage of bridge structure caused by temperature stress at home and abroad has not been a minority. On the other hand, the cost of structural maintenance and reinforcement due to thermal stress is as high as one million yuan. Under the above background, the temperature field and temperature effect of box girder under solar radiation are studied in this paper. The main research contents are as follows: 1 study on the calculation model of thermal physical parameters of concrete box; based on the triangular relation between the sun and the surface of the structure, the geographical position and date of the surface of the structure are constructed. The relationship between the time parameters and the solar direct radiation energy. Based on this, the calculation models of sky radiation, solar radiation and sky radiation reflection, atmospheric counter radiation and component reflection are deduced. With the help of the concept of radiation temperature, the second kind of boundary condition is transformed into the third kind of boundary condition. Based on the heat exchange equilibrium, the relationship between the surface radiation temperature of the structure and the parameters such as atmospheric temperature, radiation energy, component absorption coefficient and so on is established. By using the third kind of boundary condition, the relationship between structure surface temperature, radiation temperature and heat flux density is obtained. (2) the calculation model of temperature field in concrete box is based on the basic equation of heat conduction, Tif (x, y, ZT. The relationship between temperature and time, heat flux and temperature difference on the boundary is deduced. Based on the calculation accuracy and complexity, the characteristics of Fourier heat conduction equation, approximate calculation method and semi-empirical semi-theoretical formula are compared. By using Abaqus numerical simulation software, the two-dimensional transient temperature field analysis model is established, and the temperature field is analyzed under the heating boundary condition. The temperature distribution of box girder section at any time is obtained and compared with the field measured temperature. The correctness of the numerical simulation is verified. (3) the theory and method of concrete temperature effect analysis are consistent with the longitudinal temperature distribution of the bridge, and the properties of concrete are isotropic. Based on 蔚 = 偽 T, the calculation formulas of self-stress and secondary stress of concrete box girder are derived, and the calculation formula of total temperature stress of continuous box girder structure is obtained by applying the superposition principle. Taking Niulanjiang Bridge in Yunnan Province as an example, the model of the bridge is established by using finite element analysis software, and the temperature effect of the key section of the bridge under the action of temperature gradient load is obtained.
【學位授予單位】：重慶交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U441.5

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