【作者】 史永涛；

【导师】 管品武；

【作者基本信息】 郑州大学 ， 结构工程， 2009， 硕士

【摘要】 在我省西部黄土沟壑地区,高墩连续梁是较经济的桥型。收缩和徐变是混凝土材料本身固有的时变特性,当相邻薄壁空心高墩墩顶竖向位移差别较大时,会引起连续梁较大的内力。正确估计和预测收缩徐变对高墩的影响,对工程设计与施工监控有重要意义。由于施工工艺的要求,采用现场预拌混凝土,混凝土要求流动性大,水泥和细骨料比例偏大、粗骨料比例偏小,使得商品混凝土收缩偏大,容易出现裂缝。为保证结构的安全和耐久性,对混凝土收缩应力进行研究具有重要意义。本文研究主要成果有:(1)根据收集到的国内外混凝土收缩徐变研究成果,详细讨论了混凝土收缩徐变机理和影响因素,为混凝土收缩徐变预测模型研究作了理论准备。(2)对国外几种典型混凝土收缩徐变预测模型对比研究发现,国外预测模型中,GL 2000模型整体上与试验数据符合最好,在需要引用国外模型进行收缩徐变计算时,推荐采用GL 2000模型或参考我国86模型的改进公式。(3)以西张村大桥为工程背景,以配制低收缩徐变混凝土为目的,进行了配比试验研究,成果已运用到实际工程中;针对现场实际使用的混凝土,设计了收缩试验,并计算出现场环境中混凝土徐变系数与混凝土应变,计算结果与实测结果符合较好。(4)通过理论计算得出了混凝土收缩应力和钢筋对收缩、徐变的影响系数,为有限元计算中考虑钢筋影响提供了参数。(5)以西张村大桥空心薄壁高墩为工程背景,利用有限元分析软件MIDAS建立了计算机模型,采用收缩徐变试验、施工进度等实际参数,进行了模拟分阶段施工过程仿真分析计算,计算结果直接应用于西张村大桥的高墩施工监控中,并为该地区同类型高墩设计与施工提供了直接的参考依据。更多还原

【Abstract】 In the western loess gully region of Henan province , the high-pier continuous girder bridge is the more economical type. The shrinkage and creep are the inherent time-dependent characteristics of concrete material. When the vertical displacement of adjacent high-rise pier of thin-wall and hollow section top has larger difference , continuous beams would have given rise to internal forces. It is important to accurately estimate and predicate the effect on high-rise pier of thin-wall and hollow section which arise from shrinkage and creep for design and construction control. Due to the requirements of the construction process, the use of ready-mixed concrete at the scene is necessary. However, owing to the larger liquidity, the larger ratio of cement and fine aggregate in mixing proportion and the smaller ratio of coarse aggregate, merchandise concrete has larger shrinkage and emerges cracks easily.Through the forgoing research work,the major findings are as follows:(1)Based on the past research findings, this paper explains detailedly the mechanism of concrete shrinkage and creep, the effect factors, the calculation theories and methods. On the solid theoretical foundation, the author do the work of the selection of the prediction model of concrete shrinkage and creep.(2)Comparison research indicates the GL 2000 model performs best for predicting shrinkage and creep, among the four neoteric prediction models. So the GL2000 model and the improved fomula which considering the 1986 model are firstly recommended in case of lack of test data and the foreign models have to be chosen.(3)With Xizhangcun Bridge for engineering background, study batching technology of low-shrinkage and low-creep for concrete. The result has been applied to practical engineering. This paper designs an experiment of shrinkage of C40 concrete, calculats the shrinkage and creep coefficient in accordance with the conditions at the scene and the calculation result fit well with the measured result.(4)Through theoretical calculation, obtain the stress which caused by the shrinkage of concrete and influence coefficients computation of the impact on shrinkage and creep of concrete which caused by reinforced. We can take into the parameters to consider the effect of the reinforced with the finite element method.(5) With Xizhangcun Bridge for engineering background, this paper establishs the MIDAS module of construction supervision, does the simulation and analysis with actual parameters of the construction processes. The result is directly applied to the monitoring of the construction of the high-pier, and provids the data for the design and construction of high-rise pier of thin-wall and hollow section with the same type in this region.更多还原