混凝土箱梁温度场与温度效应有限元分析

发布时间：2018-05-25 10:23

本文选题：箱梁 + 有限单元法　；参考：《重庆大学》2014年硕士论文

【摘要】：梁桥是桥梁结构中的一种古老的结构体系，在已有的大跨预应力混凝土梁桥中，横截面大多采用了箱形截面。箱梁在日照升温和骤然降温作用下的变形受到约束时，就会产生相应的内外约束应力，即所谓的温差应力。当应力较大时，因其带来的变形与裂缝问题将对桥梁结构的安全构成威胁。本文以贵广线幸福源水库双线特大桥为工程背景，对其在日照升温、骤然降温（包括日落降温和寒潮降温）等因素综合作用下的温度场和温度效应进行了分析研究。论文的主要研究工作如下： ①对背景桥梁横截面的温度场进行了现场实测。介绍了箱梁温度场的测试方案；对箱梁在日照升温、日落降温以及寒潮降温作用下的实测数据进行了详细的分析；总结了箱梁在各因素下温度场随时间的变化规律；为温度场的有限元仿真分析提供了宝贵的实测数据。 ②介绍了计算温度场和温度应力的有限元理论。介绍了热传导的基本理论，，包括傅立叶热传导微分方程和求解方程的定解条件；在变分原理的基础上，介绍了计算不稳定温度场的有限单元法；通过空间温度应力问题的基本方程的建立，介绍了求解弹性温度应力问题的有限元法。为箱梁温度场和温度应力的分析奠定了理论基础。 ③利用ANSYS有限元软件进行了温度场和温度效应的数值模拟。根据第一类边界条件，利用实测数据建立了二维有限元模型，对箱梁在日照升温、日落降温以及寒潮降温作用下的温度场进行了数值模拟；编制了以第二类和第三类边界条件为基础的参数化批处理命令流，对比了数值分析结果与现场实测结果，验证了数值分析的准确性和可靠性；通过数据整理和线性回归，拟合出了箱梁截面沿梁高和梁宽的温差变化曲线；建立空间有限元模型，根据温度场计算结果与拟合曲线，对箱梁在日照作用下的横向温度应力和纵向温度应力进行了分析。 ④对箱梁在骤然降温作用下的温度效应进行了分析。通过引入寒潮强度，构造了四种不同寒潮强度的工况；按第三类边界条件建立参数化有限元模型，通过改变寒潮强度相关参数，对不同工况下的温度效应进行了定量对比分析。
[Abstract]:Beam bridge is an ancient structure system in bridge structure. In the existing long-span prestressed concrete beam bridge, the box section is mostly used in the cross section. When the deformation of box girder under the action of sunshine and sudden cooling is restrained, the corresponding internal and external restraint stress, that is, the so-called temperature difference stress, will be produced. When the stress is large, the problem of deformation and crack will threaten the safety of bridge structure. In this paper, the temperature field and temperature effect of the double-line bridge of Guangguangliang Xingyuan Reservoir are analyzed and studied under the combined action of sunshine heating, sudden cooling (including sunset cooling and cold wave cooling) and so on. The main research work of this thesis is as follows: 1. The temperature field of the cross section of the background bridge is measured. The measurement scheme of box girder temperature field is introduced, the measured data of box girder under the action of sunshine, sunset and cold wave cooling are analyzed in detail, and the variation law of box girder temperature field with time under various factors is summarized. It provides valuable measured data for finite element simulation analysis of temperature field. 2. The finite element theory of calculating temperature field and temperature stress is introduced. The basic theory of heat conduction is introduced, including Fourier heat conduction differential equation and definite solution condition of solving equation, based on variational principle, finite element method for calculating unstable temperature field is introduced. The finite element method for solving the elastic temperature stress problem is introduced through the establishment of the basic equation of the space temperature stress problem. It lays a theoretical foundation for the analysis of temperature field and thermal stress of box girder. 3 numerical simulation of temperature field and temperature effect is carried out by using ANSYS finite element software. According to the boundary conditions of the first kind, the two-dimensional finite element model is established by using the measured data, and the temperature field of box girder under the action of sunshine, sunset and cold wave is numerically simulated. The parameterized batch command flow based on the second and third boundary conditions is compiled, the accuracy and reliability of the numerical analysis are verified by comparing the numerical analysis results with the field measured results, and the data collation and linear regression are used to verify the accuracy and reliability of the numerical analysis. The temperature difference curve of box girder section along the beam height and width is fitted, and the spatial finite element model is established. According to the temperature field calculation result and fitting curve, the transverse temperature stress and longitudinal temperature stress of box girder under sunlight are analyzed. The temperature effect of box girder under sudden cooling is analyzed. Through the introduction of cold wave intensity, four different cold wave intensity conditions were constructed, and the parameterized finite element model was established according to the third kind of boundary condition, and the temperature effect under different working conditions was compared and analyzed quantitatively by changing the relevant parameters of cold wave intensity.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.5

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