素混凝土和RC圆柱体收缩徐变特性及计算方法研究

发布时间：2018-04-11 08:23

本文选题：混凝土 + 收缩徐变　；参考：《湖南科技大学》2014年硕士论文

【摘要】：混凝土的收缩徐变机理比较复杂，不确定影响因素较多，是引起预应力混凝土梁桥跨中下挠过大主要原因之一。为了提高收缩徐变对混凝土梁桥结构行为影响的认识，本文通过大量混凝土圆柱体和钢筋混凝土圆柱体的长期试验研究，总结出混凝土和钢筋混凝土长期收缩徐变规律，并提出混凝土和钢筋混凝土构件收缩徐变计算模型，提高了对混凝土和钢筋混凝土构件收缩徐变预测精度。主要内容如下：（1）通过对混凝土圆柱试件收缩应变的长期测试和不同加载龄期的混凝土圆柱体进行长期徐变试验，得到混凝土收缩徐变长期变化规律，，在用B3变异系数和B3方差对国内外的收缩徐变预测模型进行对比研究的基础上，提出新的混凝土收缩应变预测模型，同时对CEB-FIP（1990）徐变模型进行了修正。（2）通过6根素混凝土（钢筋混凝土）柱徐变对比试验，研究了钢筋混凝土圆柱徐变特性，结合CEB-FIP（1990）和中国建科院模型对实测数据进行拟合回归分析，计算出不同加载龄期作用下钢筋对混凝土徐变的影响系数，并与时变函数采用CEB-FIP（1990）模型和中国建科院模型的Dischinger方法进行了对比。试验结果表明：（1）相同加载龄期的钢筋混凝土柱徐变系数较素混凝土偏小，加载龄期对钢筋混凝土后期徐变系数影响较少；（2）国内外徐变预测模型对短期加载龄期（9d）的徐变系数预测精度较高，对长期加载龄期(39d)的徐变系数预测精度较差，特别是对后期徐变系数预测普遍不足，GZ（1993）（1990）模型整体预测效果较好；（3）Dischinger方法中钢筋对混凝土徐变影响系数考虑偏低，对不同加载龄期下钢筋混凝土徐变变形差值预测偏低。
[Abstract]:The shrinkage and creep mechanism of concrete is more complicated and the uncertain factors are many, which is one of the main causes of overdeflection in prestressed concrete bridge span.In order to improve the understanding of the influence of shrinkage and creep on the structural behavior of concrete beam bridges, this paper summarizes the long-term shrinkage and creep laws of concrete and reinforced concrete through a large number of long-term experimental studies on concrete columns and reinforced concrete cylinders.The calculation model of shrinkage and creep of concrete and reinforced concrete members is put forward, which improves the precision of predicting shrinkage and creep of concrete and reinforced concrete members.The main contents are as follows:1) through the long-term test of shrinkage strain of concrete cylinder specimen and the long-term creep test of concrete cylinder with different loading age, the long-term variation law of concrete shrinkage and creep is obtained.Based on the comparative study of the shrinkage and creep prediction models at home and abroad by using the B3 coefficient of variation and the B3 variance, a new concrete shrinkage strain prediction model is proposed, and the CEB-FIP1990) creep model is modified.(2) the creep characteristics of reinforced concrete columns are studied through a comparative test of creep of six plain concrete (reinforced concrete) columns. Combined with CEB-FIP 1990), the measured data are analyzed by fitting regression analysis with the model of China Institute of Science and Technology.The influence coefficient of reinforcement on concrete creep under different loading ages is calculated and compared with the Dischinger method of time-varying function using CEB-FIP1990) model and the model of China Institute of Science and Technology.The test results show that the creep coefficient of reinforced concrete columns with the same loading age is smaller than that of plain concrete.The effect of loading age on creep coefficient in later stage of reinforced concrete is less. 2) the prediction accuracy of creep coefficient of domestic and foreign creep prediction models is high for short-term loading age of 9 days, and poor for long term loading age of 39 days.Especially, the prediction of creep coefficient in later stage is generally insufficient. The overall prediction effect of GZ / 1993 / 1990) model is better. The influence coefficient of steel bar on creep of concrete is considered low in the method of reinforcing steel and the difference of creep deformation of reinforced concrete under different loading age is lower.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.33

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