STUDIES ON THE EFFECTS OF ENVIRONMENTAL CONDITION ON LONG-TERM DEFORMATION AND CRACK WIDTH OF REINFORCED CONCRETE MEMBERS

环境条件对钢筋混凝土构件长期变形及裂缝宽度影响的研究

基本信息

批准号：
03650389
负责人：
SATO Ryoichi
金额：
$ 1.28万
依托单位：
UTSUNOMIYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Deformational and cracking behaviors of reinforced concrete beams subjected to sustained flexural load were experimentally investigated under four different environmental conditions, that is, (1) in the room with the temperature of 20(]SY.+-。[)1ﾟC and relative humidity of 60(]SY.+-。[)5%, (2) in that with 70(]SY.+-。[)5%, (3) in the laborato-ry and (4) in the feild. Furthermore, computations of time-dependent deformations and crack widths of reinforced concrete flexural member under alternating temperature and humidity were performed, using numerical method developed by authors. Main results were abtained as follows ;(1) Creep was promoted mainly by seasonal temperature rise and did not necessarily depend upon relative humidity. Drying shrinkage strain in the feild, which changed reversibly during exposure to water, resulted in nearly a half of that in the laboratory due to rainfall.(2) Both curvature and compressive strain depended closely on creep and drying shrinkage. Curvatures and compressive strains of beams with compressive reinforcement were underestimated especially in the field by analysis used effective elastic modulus method. A step-by-step method based on Whitney's rate of creep law was effective in improving the procedure in terms of accuracy to a certain extent.(3) Effective rate of drying shrinkage to increase of crack width under load in the field was larger than that in the laboratory. This means that cracks do not necessarily widen in proportion to the magnitude of drying shrinkage strain.

在四种不同的环境条件下，在室内进行了实验研究，即（（1）在房间中，温度为20（1），在20（1）中进行了20（1），在70（]SY。SY.+ - 。[）5％，（2）中，在70（40（] 30（4）中，（4）（4），（4），（4），（4）（4）（4），（4）（4）（4），（4）（4），（4）（4），（4）（4）（4），（4）（4）（4）（4），（4）（4）（4），（4）在40（]）中，（1）（4）（4）（4）（4），（4）在40（]）中，（4）（4）（4）（4）（4），（4）在40（]）中，则在四种不同的环境条件下进行了实验研究。费尔德。此外，使用作者开发的数值方法，在替代温度和湿度下进行了钢筋混凝土柔性成员的时间依赖性变形和裂纹宽度的计算。主要结果如下：（1）蠕变主要是通过季节性温度升高促进的，不一定取决于相对湿度。在暴露于水中，在岩石中干燥的收缩菌株可逆地变化，导致在实验室中造成的几乎一半。具有压缩加固的光束的曲率和压缩菌株被低估了，尤其是在分析中使用了有效的弹性模量法。基于惠特尼（Whitney）的蠕变法率的逐步方法在一定程度上有效地改善了该程序。（3）（3）干燥收缩率在现场负载下增加裂纹宽度的有效速率大于实验室中的裂纹宽度。这意味着裂缝不一定与干燥收缩株的大小成比例扩大。