轴向钢筋增强混凝土一维应力层裂实验研究

基于φ74 mmSHPB实验平台进行了混凝土及轴向钢筋增强混凝土（UDRC）杆的一维应力层裂实验，采用超高速相机拍摄实验中杆表面的实时变形情况，使用数字图像相关法（DIC）分析杆表面的位移场及应变场演化过程，探讨混凝土及增强混凝土在应力波加载过程中发生拉伸断裂（层裂）的规律，并进一步结合有限元分析了钢筋在层裂过程中的作用。结果表明:UDRC杆中应力波的传播满足一维应力假设；钢筋对UDRC发生拉伸层裂的影响可以忽略，而在混凝土基体断裂后将使结构保持完整；断裂试件中的裂纹在拉压应力波交替作用下反复张开闭合，随着应力波在杆中的衰减而趋于稳定；UDRC与混凝土的层裂强度基本相同，且具有相似的应变率增强效应；在实验加载范围内，光圆钢筋和螺纹钢筋的结构增强效果没有区别。

EXPERIMENTAL STUDY ON ONE-DIMENSIONAL STRESS SPALL OF UNIDIRECTIONAL REINFORCED CONCRETE

The one-dimensional stress spalling experiments were conducted on concrete and unidirectional reinforced concrete (UDRC) bars. The cylindrical bar specimenwith a large aspect ratio were loaded on a 74 mm diameter Hopkinson pressure bar loading platform. The displacement field and the strain field on the surface of the specimen were recorded by using an ultra-high speed video camera combined with a digital image correlation (DIC) system. The spall strength of both materials was measured, and the role of steel bar in the process of spalling was investigated. The results show that both the concrete and the reinforced concrete bar specimen stay in a one-dimensional stress state during loading, and therefore the one-dimensional stress wave propagation theory can be applied. The steel bar reinforcement in RC bar does not change the spall strength of the specimen, but maintain its structural integrity after matrix fracture. The spall strength of both concrete and reinforced concrete bars are basically identical, and have similar rate dependency.