【作者】 庞彪；

【导师】 张敬珍；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 由于混凝土材料导热性能差,在各种温度变化作用下,预应力混凝土桥梁结构内部会产生相当大的应力、变形、甚至出现温度裂缝,而近年来交通运输业发展迅速,混凝土的强度越来越高,采用悬臂逐段现浇施工方法修建的预应力混凝土连续刚构桥梁的跨径越来越大,桥墩附近箱梁节段浇筑的体积也越来越大,此时混凝土水化热引起的温度效应非常显著。因此,在体积较大的0、1号梁段箱梁浇筑过程中,必须关注水化热引起的温度问题并采取措施加以解决,减少混凝土因水化热温升引起的开裂及后期强度损失。本文在参阅了大量专业书籍和学术论文的基础上,以一座主跨为185m的四跨连续刚构箱梁桥为背景,运用现场实测与有限元分析相结合的方法,研究分析了箱梁现浇体积较大的0、1号梁段浇筑时温度场和应力场的特点。具体工作和研究成果如下:(1)通过现场温度监测和大量数据观察,对箱梁0、1号梁段水化热温度场分布情况和随时间变化的规律进行研究分析。(2)参考传热学的相关知识,结合有限元分析理论,应用有限元分析软件MIDAS,建立箱梁0、1号梁段有限元实体模型,模拟混凝土浇筑后水泥水化作用,通过计算得出各个时间段箱梁温度场分布,总结了混凝土水化热影响下施工过程中0、1号梁段箱梁结构的温度发展历程以及温度场分布的规律,结合实测的温度监测数据进行对比分析,研究该分析方法的准确性与可行性,并提出相应的温度控制原则及措施,直接应用于工程实际。(3)采用有限元分析软件MIDAS计算箱梁温度应力,得到预应力混凝土连续刚构桥箱梁0、1号梁段应力场分布,分析、探求预应力混凝土连续刚构桥箱梁结构对温度作用的反应,提出混凝土箱梁裂缝控制措施,为同类桥型的施工提供借鉴和参考。更多还原

【Abstract】 Because of the bad heat conduction of the concrete material, prestressed concrete bridges are subject to varied temperature actions, which can make notable influence on the transformation and stress of bridge structures, sometimes even engender cracks. With the rapid development of transportation, the strength of concrete becomes higher and higher, the span of the prestressed concrete continuous rigid frame bridges constructed by cantilever method becomes larger and larger. At the same time, the volume of the box girders near piers are much bigger than before, and the temperature actions which were aroused by heat of cement hydration are extremely notable. Thus, it is important to make attention to the temperature problem caused by heat of cement hydration and to solve the problem in order to reduce the cracks brought by temperature in cement during the placement of the large volume of box girders—the zero-block and first-block.After consulting lots of professional theories and academic articles, the temperature field and stress field during the placement of the zero-block and first-block is this paper. All the following analysis is on the basis of a four-span continuous rigid frame bridge whose main span is 185m. The paper’s work and research results are as follows:(1) Through on-site temperature monitoring and observation of large amounts of data, it researches and analyzes the hydration heat temperature field and the rule with time varying of the zero-block and first-block.(2) According to the thermal conduction theory and finite element method, the model of zero-block and first-block is built to simulate the cement hydration, then, sums up its temperature development process and the distribution. Then, compare with the temperature monitoring data and the result of compute, it studies the method of analysis of the accuracy and feasibility. At last, it puts forward the corresponding temperature control principles and applies to engineering practice.(3) Use of finite element analysis software MIDAS to calculate box girder temperature stress and get the stress distribution of zero-block and first-block. Then, it analyzes and seeks the action of the response to temperature about prestressed concrete continuous rigid frame bridges. At last, it puts forward the measures to control the cracks of concrete box-girder, and provides reference information to similar bridges.更多还原