本文選題：橋梁工程 + 溫度場�。� 參考：《長沙理工大學(xué)》2015年碩士論文

【摘要】：混凝土箱梁因太陽輻射而產(chǎn)生非線性梯度溫度,當(dāng)這種梯度溫度引起的變形被結(jié)構(gòu)內(nèi)、外約束阻礙時(shí),會產(chǎn)生相當(dāng)大的溫度應(yīng)力。國內(nèi)外學(xué)者研究了普通箱形斷面日照溫度場及溫度應(yīng)力,尚無針對PK形式斷面的研究。我國現(xiàn)行規(guī)范中并無無鋪裝層混凝土梁梯度溫度的取值,也未給出混凝土梁橫向溫度應(yīng)力的計(jì)算方法。本文以馬鞍山長江公路大橋右汊斜拉橋?yàn)楣こ瘫尘?對該橋PK形式主梁施工階段及運(yùn)營階段的日照溫度場進(jìn)行了現(xiàn)場實(shí)測和有限元建模分析,分別計(jì)算了其橫、縱向溫度應(yīng)力。本文的主要研究內(nèi)容和成果如下:(1)介紹了混凝土導(dǎo)熱微分方程的一般形式和邊界條件,以及將混合邊界條件簡化為第三類邊界條件的計(jì)算原理和過程。論述了太陽輻射強(qiáng)度、換熱系數(shù)、太陽輻射吸收率等參數(shù)的計(jì)算過程。(2)對PK斷面混凝土梁施工階段和運(yùn)營階段的日照溫度場進(jìn)行了觀測和分析,得到了其頂板、腹板、底板豎向梯度溫度及箱內(nèi)外大氣溫度的變化規(guī)律,分析了橋面鋪裝層對混凝土梁日照溫度場的影響,本橋12cm瀝青混凝土鋪裝層對混凝土梁日照溫度場有明顯的削弱作用。(3)應(yīng)用ANSYS分別建立了PK斷面混凝土梁的二維和三維溫度場計(jì)算模型,計(jì)算結(jié)果與實(shí)測值吻合,二維模型與三維模型溫度場計(jì)算結(jié)果基本一致。計(jì)算得到了用指數(shù)函數(shù)表示的施工和運(yùn)營階段的豎向梯度溫度,并與各國規(guī)范取值進(jìn)行了對比分析。(4)參數(shù)敏感性分析表明,吸收率及風(fēng)速對日照溫度場影響較大,瀝青混凝土鋪裝層厚度對混凝土梁豎向梯度溫度也會產(chǎn)生較大影響。(5)分別應(yīng)用ANSYS二維模型和三維模型計(jì)算了主梁施工階段的橫向溫度應(yīng)力,三維模型的計(jì)算結(jié)果比二維模型大22%左右。對比分析表明施工階段的最大橫向拉、壓應(yīng)力均高于運(yùn)營階段。(6)應(yīng)用FBR.CAL計(jì)算了主梁施工階段和運(yùn)營階段的縱向溫度應(yīng)力,施工階段的最大縱向拉、壓溫度應(yīng)力均高于運(yùn)營階段。本文計(jì)算結(jié)果與按規(guī)范取值的計(jì)算結(jié)果存在較大差異,建議完善規(guī)范中關(guān)于無鋪裝層混凝土梁梯度溫度取值的規(guī)定。
[Abstract]:The nonlinear gradient temperature of concrete box girder is caused by solar radiation. When the deformation caused by this gradient temperature is obstructed by the internal and external constraints of the structure, it will produce considerable thermal stress. Domestic and foreign scholars have studied the sunshine temperature field and temperature stress of the common box section, but there is no research on the competition section. There is no gradient temperature value of concrete beam without pavement in the current code of our country, and the calculation method of transverse temperature stress of concrete beam is not given. Taking the right branch cable-stayed bridge of Ma'anshan Yangtze River Highway Bridge as the engineering background, the field measurement and finite element modeling analysis of the sunshine temperature field of the main girder in the construction and operation stages of the bridge are carried out, and the transverse and longitudinal temperature stresses are calculated respectively. The main contents and achievements of this paper are as follows: (1) the general form and boundary conditions of concrete thermal conductivity differential equation are introduced, and the calculation principle and process of simplifying the mixed boundary condition to the third kind of boundary condition are introduced. The calculation process of solar radiation intensity, heat transfer coefficient, solar radiation absorptivity and other parameters are discussed. (2) the temperature field of sunlight during construction and operation of concrete beams with competitive section is observed and analyzed, and the roof and web are obtained. The variation law of vertical gradient temperature of bottom plate and atmospheric temperature inside and outside the box is analyzed, and the influence of bridge deck pavement on sunshine temperature field of concrete beam is analyzed. 12cm asphalt concrete pavement of this bridge has obvious weakening effect on sunlight temperature field of concrete beam. (3) Two-dimensional and three-dimensional temperature field calculation models of competing section concrete beam are established by using 12cm, and the calculated results are in good agreement with the measured values. The results of two-dimensional model and three-dimensional model are in good agreement with each other. The vertical gradient temperature in construction and operation stages expressed by exponential function is calculated and compared with the values taken in various countries. (4) the sensitivity analysis of parameters shows that the absorptivity and wind speed have great influence on the sunshine temperature field. The thickness of asphalt concrete pavement also has a great influence on the vertical gradient temperature of concrete beam. (5) the transverse temperature stress of the main beam in construction stage is calculated by using ANSYS two-dimensional model and three-dimensional model, respectively. The results of 3D model are about 22% larger than that of 2D model. The comparative analysis shows that the maximum transverse tensile stress and compressive stress in construction stage are higher than those in operation stage. (6) the longitudinal temperature stress of main girder in construction and operation stage is calculated by using FBR.CAL. The maximum longitudinal tensile stress and compressive temperature stress in construction stage are all higher than that in operation stage. There is a great difference between the calculated results and the calculated values according to the code. It is suggested that the regulation of gradient temperature of unpaved concrete beams should be perfected in the code.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441.5

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