PK断面混凝土梁日照温度场及温度应力分析

发布时间：2018-07-10 05:11

本文选题：桥梁工程 + 温度场　；参考：《长沙理工大学》2015年硕士论文

【摘要】：混凝土箱梁因太阳辐射而产生非线性梯度温度,当这种梯度温度引起的变形被结构内、外约束阻碍时,会产生相当大的温度应力。国内外学者研究了普通箱形断面日照温度场及温度应力,尚无针对PK形式断面的研究。我国现行规范中并无无铺装层混凝土梁梯度温度的取值,也未给出混凝土梁横向温度应力的计算方法。本文以马鞍山长江公路大桥右汊斜拉桥为工程背景,对该桥PK形式主梁施工阶段及运营阶段的日照温度场进行了现场实测和有限元建模分析,分别计算了其横、纵向温度应力。本文的主要研究内容和成果如下:(1)介绍了混凝土导热微分方程的一般形式和边界条件,以及将混合边界条件简化为第三类边界条件的计算原理和过程。论述了太阳辐射强度、换热系数、太阳辐射吸收率等参数的计算过程。(2)对PK断面混凝土梁施工阶段和运营阶段的日照温度场进行了观测和分析,得到了其顶板、腹板、底板竖向梯度温度及箱内外大气温度的变化规律,分析了桥面铺装层对混凝土梁日照温度场的影响,本桥12cm沥青混凝土铺装层对混凝土梁日照温度场有明显的削弱作用。(3)应用ANSYS分别建立了PK断面混凝土梁的二维和三维温度场计算模型,计算结果与实测值吻合,二维模型与三维模型温度场计算结果基本一致。计算得到了用指数函数表示的施工和运营阶段的竖向梯度温度,并与各国规范取值进行了对比分析。(4)参数敏感性分析表明,吸收率及风速对日照温度场影响较大,沥青混凝土铺装层厚度对混凝土梁竖向梯度温度也会产生较大影响。(5)分别应用ANSYS二维模型和三维模型计算了主梁施工阶段的横向温度应力,三维模型的计算结果比二维模型大22%左右。对比分析表明施工阶段的最大横向拉、压应力均高于运营阶段。(6)应用FBR.CAL计算了主梁施工阶段和运营阶段的纵向温度应力,施工阶段的最大纵向拉、压温度应力均高于运营阶段。本文计算结果与按规范取值的计算结果存在较大差异,建议完善规范中关于无铺装层混凝土梁梯度温度取值的规定。
[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.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.5

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