大跨混凝土箱梁桥日照最不利温度场及温度应力研究

发布时间：2018-01-07 10:41

本文关键词：大跨混凝土箱梁桥日照最不利温度场及温度应力研究　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：桥梁是长期暴露在自然环境下的结构物,在桥梁的全寿命周期内必然会受到太阳辐射、气温变化等温度作用的影响,而温度作用是导致混凝土箱梁桥产生裂缝的主要因素之一。目前,各国规范对混凝土箱梁桥的温度分布模式并没有统一的规定,同时由于地区气候条件的不同温度分布模式具有明显的区域化特点。海洋环境下混凝土箱梁桥的温度场分布不同于其他地区,温度裂缝对混凝土箱梁的安全性、适用性、耐久性的影响更大。因此,开展海洋环境下混凝土箱梁桥的最不利温度场及温度应力的研究,确定符合跨海预应力混凝土连续梁桥实际情况的温差分布模式对指导后续类似桥梁设计具有重要意义。选择夏季太阳辐射强烈与冬季寒流入侵的典型天候在施工阶段对曹妃甸区纳潮河2#大桥关键截面分别进行了 10天最不利正温度场与3天负温度场的现场实测。系统地分析了混凝土箱梁顶板、底板及腹板的温度场及温度应力的分布规律,并对实测数据进行曲线拟合,得到跨海连续箱梁桥施工阶段的最不利竖向、横向温度梯度。结合太阳物理学、气象学、传热学的相关理论,建立了箱梁日照温度场分析的边界条件。同时,考虑箱梁长翼缘对腹板的阴影遮蔽作用,建立了混凝土箱梁日照最不利温度场及温度应力仿真分析的有限元计算模型。以曹妃甸区纳潮河2#大桥为工程算例,采用有限元分析软件ANSYS对箱梁瞬态温度场进行仿真分析,得出最不利正温度梯度发生当天测试截面各时刻的温度分布云图,将各测点温度时程曲线、箱梁最不利正温度梯度的计算曲线与实测曲线进行对比,验证环境与热工参数选取合理,采用有限元软件ANSYS对温度场进行数值模拟具有较高精度。根据热传导有限单元法原理,使用ANSYS建立平面模型进行热-应力耦合分析,采用APDL编制宏文件,将瞬态热分析得到的节点温度作为载荷施加在后续应力分析中,探讨混凝土箱梁桥的温度效应,主要分析最不利正温度梯度作用下关键截面的纵、横向温度自应力的分布规律。
[Abstract]:Bridge is a structure exposed to the natural environment for a long time. During the whole life cycle of the bridge, it is bound to be affected by the effect of temperature, such as solar radiation, temperature change and so on. Temperature is one of the main factors leading to cracks in concrete box girder bridges. At present, there is no uniform regulation on the temperature distribution mode of concrete box girder bridges in various countries. At the same time, the temperature distribution of concrete box girder bridges in marine environment is different from that of other regions, and the temperature cracks are safe to concrete box girder because of the obvious regionalization characteristics of different temperature distribution patterns of regional climate conditions. Applicability and durability are more important. Therefore, the most unfavorable temperature field and temperature stress of concrete box girder bridge under marine environment are studied. It is of great significance to determine the temperature distribution model of prestressed concrete continuous beam bridge in accordance with the actual situation of sea crossing prestressed concrete continuous beam bridge. The selection of typical weather conditions of strong solar radiation in summer and cold current invasion in winter is of great significance in guiding the design of similar bridges in the future. The key sections of Nachao2# Bridge in Caofeidian District were carried out respectively at the stage. The worst positive temperature field in 10 days and negative temperature field in 3 days are measured. The concrete box girder roof is systematically analyzed. The distribution law of temperature field and temperature stress of bottom plate and web plate, and the curve fitting of the measured data, the most unfavorable vertical and transverse temperature gradient in the construction stage of continuous box girder bridge across the sea is obtained, combined with solar physics. Based on the theory of meteorology and heat transfer, the boundary conditions for the analysis of the temperature field of the box girder are established, and the shading effect of the long flange of the box girder on the web is considered. The finite element calculation model of the most unfavorable temperature field and thermal stress of concrete box girder is established. The example of Naichao2# Bridge in Caofeidian District is given. The finite element analysis software ANSYS is used to simulate the transient temperature field of box girder. The temperature distribution cloud diagram of the most unfavorable positive temperature gradient is obtained at each time of the test section on the same day, and the temperature history curve of each measuring point is obtained. The calculation curve of the most unfavorable positive temperature gradient of box girder is compared with the measured curve to verify the reasonable selection of environment and thermal parameters. The finite element software ANSYS is used to simulate the temperature field with high accuracy. According to the principle of heat conduction finite element method, ANSYS is used to establish a plane model for thermal-stress coupling analysis. The macro document is compiled by APDL and the temperature of the node obtained by transient thermal analysis is applied as the load in the subsequent stress analysis to discuss the temperature effect of concrete box girder bridge. The distribution of temperature self stress in the key sections under the action of the most unfavorable positive temperature gradient is analyzed.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441.5

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