基于数字图像相关技术的混杂纤维混凝土动态抗拉性能试验研究

Experimental Study on Dynamic Tensile Properties of Hybrid Fiber Reinforced Concrete Based on Digital Image Correlation Technology

为研究不同纤维混杂比例下的钢-聚丙烯纤维混凝土(SPFRC)的动态抗拉性能,对六组不同纤维混杂比例的混凝土试件进行动态巴西劈裂试验,借助高速摄像仪和数字图像相关技术(DIC)对各组试样动态拉伸断裂过程进行记录和分析。研究表明:试件的应力时程曲线可以划分为缓速增长、快速增长、稳定、衰减和二次增长五个阶段,相较于素水泥砂浆试件,纤维混凝土试件在应力率二次增长后出现显著的稳定波动平台,纤维混凝土试件的动态拉伸破坏过程具有显著的延性特征;在总纤维掺量保持2%不变的条件下,混杂1%钢纤维与1%聚丙烯纤维的试件具有较优的动态抗拉强度和耗能能力;添加纤维可以减弱试件中心处的拉应变集中现象,混杂1.5%聚丙烯纤维和0.5%钢纤维的试件具有较优的开裂控制能力,平均开裂应变较素水泥砂浆试件提高了2.94倍。

In order to study the dynamic tensile properties of steel polypropylene fiber concrete(SPFRC)with different fiber hybrid ratio,six groups of concrete specimens with different fiber hybrid ratio were subjected to dynamic Brazilian splitting test.The dynamic tensile fracture process of each group of specimens was recorded and analyzed by means of high-speed camera and digital image correlation technology(DIC).The results show that the stress time history curve of the specimen can be divided into five stages:slow growth,rapid growth,stability,attenuation and se-condary growth.Compared with the plain cement mortar specimen,the fiber reinforced concrete specimen has a significant stable fluctuation platform after the secondary growth of the stress rate,and the failure process has significant ductility characteristics.When the total fiber content remains unchanged at 2%,the specimens mixed with 1%steel fiber and 1%polypropylene fiber have relatively better dynamic tensile strength and energy dissipation capacity.Adding fiber can weaken the tensile strain concentration at the center of the specimen.The specimen mixed with 1.5%polypropylene fiber and 0.5%steel fiber has better cracking control ability,and the average cracking strain is 2.94 times higher than that of plain cement mortar.