严寒地区混凝土箱梁的温度梯度观测与分析

发布时间：2018-06-20 01:47

本文选题：混凝土箱梁 + 温度梯度　；参考：《长安大学》2015年硕士论文

【摘要】：随着桥梁温度应力在桥梁设计和建设上引起的问题日渐被人所知,国内外的学者和科研人员开始对温度应力进行深入的研究。国内外的很多实际工程和研究成果表明,日照温度分布对混凝土箱梁的温度应力有很大的影响,采用不同的日照温度梯度模式计算出来的温度应力相差很大。目前不同国家、不同地区对混凝土箱梁桥的日照温度梯度模式都有不一样的认识,例如美国规范将美国划分为了四个气候区,每个气候区都有各自不同的温度梯度模式来指导设计和施工。中国疆域辽阔,气候千差万别,但是桥梁规范上只沿用了美国二区的温度梯度模式,规定了一组温度梯度模式,今后仍然有较大的改进空间。因此有必要通过实验研究和理论分析,探索和研究适合我国不同地区的预应力混凝土桥梁日照温度分布规律以及温度梯度模式,以便于指导工程设计和施工。本文主要对鄂尔多斯地区的温度梯度模式进行探索和研究,基于内蒙古鄂尔多斯地区的一座连续刚构桥的施工监控工作,同时在国内外混凝土温度场分布和温度梯度已有研究成果的基础上,深入了解了混凝土箱梁日照温度分布和温度梯度模式,明确混凝土箱梁日照温度分布和温度梯度研究的现状以及存在的一些问题,从而确定现场温度测点的位置,实测了箱梁截面在日照作用下的温度分布,并总结出箱梁截面的温度分布规律,得出一天中最不利时刻的温度场,由此作为拟合箱梁最不利温度梯度模式的基础。基于实桥的温度实验分析,通过对箱梁截面内预埋温度传感器对箱梁温度场进行连续的观测和记录,得到有关箱梁温度场的数据。在分析箱梁截面不同位置的温度实测数据的基础上,根据当地实际的气象条件、混凝土材料的热工性质、箱梁截面的形状等一系列参数数值,通过采用热传导的形式结合有限元程序计算出箱梁截面在当地的太阳辐射强度条件下的温度场,得出箱梁的日照温度场分布并与现场实测值进行对比分析,验证了通用有限元程序对箱梁温度分布分析的正确性。通过理论数据与实测数据的结合可以更加明确箱梁日照温度场的温度分布规律。在实测温度场和计算温度场的条件下,参照不同国家桥梁规范上规定的温度梯度模式,结合混凝土箱梁日照温度场影响因素及混凝土箱梁温度效应的研究结论,考虑桥梁所处地理纬度的不同、太阳辐射的强弱、大气温度的影响,通过实际情况拟合出适合于当地的大跨混凝土箱梁截面的竖向温度梯度。中国规范规定的温度梯度模式其实是沿用了美国规范的一种模式,但是美国规范在美国划分4个不同区域来指导桥梁建设与施工。中国气候与美国不尽相同,而且全国只用了一种温度梯度模式,所以今后仍然有很大的改进空间。本文提供鄂尔多斯地区的温度梯度模式,通过对比,对此地区进行温度梯度的拟合与分析。
[Abstract]:With the problems caused by the bridge thermal stress in the design and construction of the bridge, scholars and researchers at home and abroad began to do in-depth research on the temperature stress. Many practical engineering and research results at home and abroad show that the temperature distribution of sunshine has a great influence on the temperature stress of concrete box girder, and the temperature stress calculated by different sunshine temperature gradient model is very different. At present, different countries and different regions have different views on the temperature gradient model of sunlight for concrete box girder bridges. For example, the US standard divides the United States into four climate zones. Each climate zone has its own temperature gradient model to guide design and construction. China has a vast territory and varied climates. However, the bridge code only adopts the temperature gradient model of the second region of the United States, and defines a set of temperature gradient models, and there is still much room for improvement in the future. Therefore, it is necessary to explore and study the sunshine temperature distribution law and temperature gradient model of prestressed concrete bridges suitable for different areas in China through experimental research and theoretical analysis, in order to guide the design and construction of the project. In this paper, the temperature gradient model in Ordos region is explored and studied. Based on the construction monitoring work of a continuous rigid frame bridge in Ordos region, Inner Mongolia, At the same time, based on the existing research results of temperature field distribution and temperature gradient of concrete at home and abroad, the sunshine temperature distribution and temperature gradient model of concrete box girder are deeply understood. The present situation and some problems in the study of sunshine temperature distribution and temperature gradient of concrete box girder are made clear, so as to determine the location of the spot temperature measurement points, and the temperature distribution of the box girder section under the action of sunlight is measured. The temperature distribution of box girder section is summarized, and the temperature field at the most unfavorable time of day is obtained, which is the basis of fitting the most unfavorable temperature gradient model of box girder. Based on the experimental analysis of the temperature of the real bridge, the temperature field of the box girder is continuously observed and recorded by the embedded temperature sensor in the section of the box girder, and the data of the temperature field of the box girder are obtained. Based on the analysis of the measured temperature data at different positions of the box girder section, a series of parameters such as the local meteorological conditions, the thermal properties of the concrete materials, the shape of the box girder section, etc. The temperature field of box girder section under the condition of local solar radiation intensity is calculated by means of heat conduction and finite element program, and the distribution of sunshine temperature field of box girder is obtained and compared with the field measured value. The correctness of the finite element program for the temperature distribution analysis of the box girder is verified. Through the combination of theoretical data and measured data, the temperature distribution of sunshine temperature field of box girder can be more clearly defined. Under the condition of measured temperature field and calculated temperature field, according to the temperature gradient model stipulated in different national bridge codes, combined with the influence factors of sunshine temperature field of concrete box girder and the research conclusion of temperature effect of concrete box girder, Considering the different geographical latitude of the bridge, the intensity of solar radiation and the influence of atmospheric temperature, the vertical temperature gradient suitable for the local section of long-span concrete box girder is fitted through the actual situation. The temperature gradient model stipulated by Chinese code is actually a model of American code, but American code divides four different areas in the United States to guide bridge construction and construction. The climate in China is different from that in the United States, and only one temperature gradient model is used in the country, so there is still much room for improvement in the future. In this paper, the temperature gradient model in Ordos area is provided, and the fitting and analysis of the temperature gradient in this area are carried out by comparison.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

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