發(fā)布時間：2018-07-09 14:23

  本文選題：混凝土箱梁 + 太陽輻射　； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：混凝土橋梁在外界環(huán)境尤其是太陽輻射的作用下會產(chǎn)生非線性溫度分布，，由此引起的橋梁上部結(jié)構(gòu)的應(yīng)力與外荷載引起的效應(yīng)相當，溫度應(yīng)力成為混凝土箱梁開裂的重要原因之一。但是由于問題的復(fù)雜性，在目前的橋梁設(shè)計中通常采用相對簡化的理論和模型來計算溫度效應(yīng)，但簡化的模型和計算方法有時會使計算結(jié)果與實際情況存在較大誤差。本文針對太陽輻射作用下混凝土箱梁的溫度場和溫度應(yīng)力計算方法展開了以下幾方面的研究： 1.根據(jù)天文學(xué)以及傳熱學(xué)相關(guān)理論知識建立了混凝土箱梁日照溫度場分析模型，并在應(yīng)用一種實用太陽輻射強度計算方法的基礎(chǔ)上系統(tǒng)地建立了熱傳遞模型及其對應(yīng)的邊界條件。據(jù)此編制了可以針對箱梁日照條件下溫度場進行分析的有限元計算接口程序，通過計算結(jié)果闡明了混凝土箱梁溫度分布的特點。 2.為了研究各種環(huán)境因素對箱梁溫度場的影響，并找出關(guān)鍵影響因素，本文通過改變程序中各參數(shù)的取值對箱梁日照溫度場分布的影響因素進行了詳細的分析，如太陽輻射強度、外界氣溫、橋梁走向、結(jié)構(gòu)尺寸及材料參數(shù)等。經(jīng)研究發(fā)現(xiàn)，太陽輻射強度是最關(guān)鍵影響因素，其他因素次之。 3.混凝土箱梁橋的溫度應(yīng)力由溫度自應(yīng)力和溫度次應(yīng)力組成。本文基于一個數(shù)學(xué)積分性質(zhì)采用一種考慮泊松效應(yīng)的方法來計算溫度自應(yīng)力，溫度次應(yīng)力則通過結(jié)構(gòu)力學(xué)方法獲得。公式推導(dǎo)過程和計算結(jié)果都表明：考慮泊松效應(yīng)會對溫度自應(yīng)力計算結(jié)果有較大影響，傳統(tǒng)的計算方法有時是偏不安全的。 本文應(yīng)用有限元方法實現(xiàn)了太陽輻射作用下的混凝土箱梁溫度場的計算，并分析了其關(guān)鍵影響因素，又應(yīng)用一種考慮泊松效應(yīng)的溫度應(yīng)力計算法對箱梁溫度應(yīng)力的大小和特點進行了研究，實現(xiàn)了混凝土箱梁溫度效應(yīng)的分析。本文研究內(nèi)容與結(jié)論可為橋梁設(shè)計中溫度效應(yīng)的計算提供一定的參考。
[Abstract]:Concrete bridge will produce nonlinear temperature distribution under the action of external environment, especially solar radiation, and the stress of the superstructure caused by this will be equivalent to the effect caused by external load. Thermal stress has become one of the important reasons for cracking of concrete box girder. However, due to the complexity of the problem, the relatively simplified theory and model are usually used to calculate the temperature effect in the current bridge design. In this paper, the calculation methods of temperature field and temperature stress of concrete box girder under solar radiation are studied as follows: 1. Based on the theoretical knowledge of astronomy and heat transfer, the analytical model of sunshine temperature field of concrete box girder is established, and the heat transfer model and its corresponding boundary conditions are established systematically on the basis of a practical solar radiation intensity calculation method. Based on this, a finite element calculation interface program for temperature field analysis of box girder under sunshine condition is developed. The characteristics of temperature distribution of concrete box girder are clarified by the result of calculation. 2. In order to study the influence of various environmental factors on the temperature field of box girder and find out the key factors, this paper analyzes in detail the factors affecting the distribution of temperature field of box girder by changing the values of each parameter in the program, such as the intensity of solar radiation. Outside temperature, bridge direction, structure size and material parameters. The results show that solar radiation intensity is the most important factor, followed by other factors. 3. 3. The temperature stress of concrete box girder bridge consists of self-stress and sub-stress. In this paper, based on a mathematical integral property, a method considering Poisson effect is used to calculate the temperature self-stress, and the temperature secondary stress is obtained by the structural mechanics method. Both the formula derivation process and the calculation results show that considering Poisson effect will have a great influence on the calculation results of temperature self-stress, and the traditional calculation method is sometimes unsafe. In this paper, the finite element method is used to calculate the temperature field of concrete box girder under solar radiation, and the key influencing factors are analyzed. A temperature stress calculation method considering Poisson effect is applied to study the size and characteristics of the temperature stress of the box girder, and the analysis of the temperature effect of concrete box girder is realized. The contents and conclusions of this paper can provide some references for the calculation of temperature effect in bridge design.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U441.5;U448.213

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