活性粉末混凝土(RPC)的断裂力学性能

在试验及观察的基础上,对活性粉末混凝土的断裂过程进行定性分析,给出活性粉末混凝土的裂纹发展原理及钢纤维的增韧机理,并分析其不同于普通混凝土的两个基本断裂特征。介绍了利用缺口梁三点弯曲试验确定混凝土拉伸软化本构方程的方法。基于Hillerborg模型,提出活性粉末混凝土的拉伸软化模型,根据三点弯曲断裂试验结果,确定出活性粉末混凝土的双线性拉伸软化曲线中的具体参数。据该软化曲线公式,计算出的活性粉末混凝土断裂能同试验得出的值相比,误差仅为0.9%。笔者得出的双线性软化曲线能较精确地反映活性粉末混凝土材料的断裂特性,可为今后进行RPC裂缝的分析和预测提供定量计算的依据,对于研究活性粉末混凝土的断裂能、尺寸效应等问题也很具意义。

Fracture Mechanics of Reactive Powder Concrete

According to the existing test results, the qualitative analy sis of fracture process and fracture characteristic of reactive powder concrete were given. The crack extension of reactive powder concrete and enhancement of fiber were a l l discussed. Two fracture characteristics of RPC differed from plain c oncrete were presented. A determination method of tensile softening constitutive equation of concrete by means of three-point bend tests on notched beams was in tr oduced. Based on the Hillerborg model, the tension-softening curve of reactive p owder concrete was presented. The bilinear softening curve was obtained based on t he result of three-point bending fracture test. The fracture energy ac quired from the softening curve was approximate to the test value. with an error of 0.9%. The results indicate that the bilinear softening curve can describe the fr acture characteristic of reactive powder concrete precisely. It is useful for th e analysis and prediction of fracture of reactive powder concrete in the future. It is also important in the study of fracture energy and size effect.