周边约束状态下板式混凝土早期开裂及收缩应变的分布

改进型的板式试件法可用于实验室或施工现场快速测试混凝土的早期抗裂性能。大量实验的统计结果表明这种板式混凝土的早期收缩裂缝的分布主要集中在两个区域：每边中点处相连形成的“十”字形区域和4个边角区域附近。通过埋置光纤光栅传感器法对这种混凝土板在早期处于风吹加速干燥条件下内部收缩应变的分布进行测量，结果表明：混凝土收缩应变与离干燥表面的距离成指数函数关系；在距离模具边框越近的位置，混凝土表现出的收缩应变值越小。

DISTRIBUTION OF SHRINKAGE STRAIN AND INDUCED CRACKS OF A ROUND RESTRAINED CONCRETE PLATE AT EARLY AGE

An experimental method for modified concrete plate specimen was developed to determine shrinkage cracking of concrete under restrained conditions. This method can be expediently used to measure the early age cracking potential of concrete at laboratory or in-situ. The results show that most of cracks distribute in the nearby ragion of four rim angles and a crissi-cross region through connecting the midpoint of each border. The shrinkage strain distribution in inner of a plate specimen under a windy accelerated drying condition was determined by embedded optical fiber sensors. It is indicated that the shrinkage strain of concrete is approximately an exponential function of the distance from drying surface of the concrete specimen. In addition, the less the measured shrinkage strain, the shorter distance from the frame edge is.