混凝土箱体结构温度场及温度效应分析

发布时间：2018-06-27 02:42

本文选题：混凝土箱梁 + 数值模拟　；参考：《重庆交通大学》2014年硕士论文

【摘要】：近年来，随着桥梁跨度的不断增加，高大索塔、空心薄壁墩、薄壁箱梁等箱体结构应用越来越广泛。与此同时，混凝土箱体温差应力与温度裂缝问题日益突出，调查发现，国内外由于温度应力造成的桥梁结构损坏已不占少数。另一方面，由于温度应力带来的结构维修加固费用高达百万元。在上述背景下，本文以混凝土箱梁桥为研究对象，针对箱梁在太阳辐射作用下的温度场和温度效应展开研究，主要研究内容包括： ①混凝土箱体热物理参计算模式研究利用太阳与结构表面的三角关系，构建了结构物表面地理位置、日期、时刻参数与太阳直接辐射能的关系。并以此为依据，推导出了天空辐射、太阳辐射与天空辐射反射、大气逆辐射、构件反射的计算模式。借助辐射气温的概念，将第二类边界条件转化为第三类边界，以热交换平衡为基础，构建了结构表面辐射气温与大气温度、辐射能、构件吸收系数等参数的关系。利用第三类边界条件，求得了结构表面温度与辐射气温、热流密度的关系。 ②混凝土箱体温度场计算模式研究以热传导基本方程Ti=f (x, y, z,t)为基础，推导了边界上温度与时间、热流密度与时间、热流密度与温差的关系。从计算精度、计算复杂程度等方面出发，对比了Fourier热传导方程、近似计算方法和半经验半理论公式各自的特点。运用ABAQUS数值模拟软件，建立二维瞬态温度场分析模型，并对其施加热边界条件，进行温度场分析，得到任意时刻箱梁截面温度分布，并与现场实测温度进行对比，验证了数值模拟的正确性。 ③混凝土温度效应分析理论及方法的研究对桥梁温度分布沿纵向一致，混凝土材料特性各向同性，符合线弹性变形规律等方面做出了基本假定，以ε=α T为基础，推导了混凝土箱梁自应力和次应力的计算公式，，并运用叠加原理，求得连续箱梁结构总温度应力的计算公式。以云南牛栏江特大桥为例，运用有限元分析软件建立全桥模型，得到了全桥关键截面在温度梯度荷载作用下的温度效应情况。
[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 = 伪 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.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.5

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