钢纤维混凝土周期荷载作用前后AE及损伤演化对比研究

Contrastive study of AE and damage evolution of steel fiber reinforced concrete before and after cyclic loading

对0.5%、1%、1.5%以及2%4种钢纤维掺量下的混凝土进行了周期循环荷载作用前后的单轴压缩声发射(AE)监测试验。研究结果表明:随着钢纤维含量的增加,混凝土的单轴抗压强度呈对数型增长,延性变形能力显著提高;未疲劳荷载时,声发射呈"活跃—平静—活跃—平静"阶段性的"S"型变化特征,周期疲劳荷载后,声发射呈"活跃—平静"的两阶段特征;均质性系数m随钢纤维含量的增加而逐渐减小,表明混凝土越不均质;基于Weibull分布理论,分析得到声发射参数与损伤之间的关系表明:未疲劳荷载前,损伤呈指数型函数增长,并存在明显的损伤阈值,经过周期疲劳荷载后,损伤值在加载前期增长较快,并呈三阶段变化特征。

Uniaxial compression acoustic emission tests were conducted on concrete subjected to cyclic fatigue loading at 0. 5%,1%,1. 5%,2%,and four kinds of steel fiber content. The results show that with the increase of steel fiber content,the uniaxial compressive strength of concrete is a logarithmic growth,the ductility increased significantly; without fatigue,acoustic emission is＂active calm-active calm＂ stage of the ＂S ＂ type change characteristics,cycle fatigue loading,acoustic emission is ＂two stage active calm ＂; the heterogeneity coefficient m decreases with increasing the content of steel fiber concrete is decreased gradually,that is not homogeneous;Weibull distribution based on the theory of the relationship between AE parameters and damage analysis showed that： fatigue load,damage type of exponential growth function,and there is obvious damage threshold after a period,the fatigue load and damage value in early loading grew rapidly,and in three stages.