不同加载率对混凝土试件动力特性的影响研究

Dynamic property influences and studies of concrete cylinder at different loading rates

本文建立三维随机骨料数值模型,在ANSYS软件的基础上,运用等效粘弹性模型,对混凝土圆柱体试件进行了三种加载率冲击荷载的加载计算,模拟分析混凝土的动力特性,并统计出试件起裂点的位置和数目,以此来分析混凝土动强度比静强度增大的原因。结果表明:三种加载率作用下,起裂点的位置几乎不变,但起裂点的面积发生了变化,起裂点的数目不断的增大,并与CT试验中混凝土的破坏过程和起裂点数目两方面进行比较,发现数值试验的破坏过程与CT试验的结果具有相似性,得到混凝土静力加载时破坏面追随结构软弱面向前发展,动荷载作用下裂纹追随能量释放最快路径发展,使得强度得到充分发挥等结论,解释了混凝土强度增大的原因。

This paper develops a 3D random aggregate model of concrete based on the software ANSYS. A concrete cylinder under impact load is calculated by adopting the equivalent viscoelasticity model under the conditions of three different loading rates to simulate the dynamic properties of the concrete. The number and locaitons of cracking points on the cylinder are used to analyze and demonstrate the reason for the dynamic strength increasing relative to the static strength. The results show that, under the conditions of different loading rates, the locations of cracking points remain almost unchanged, but the area covered by the cracking points are different, and the number of cracking points increases. A comparison with CT experiments indicates the fracture process of numerical tests is similar to that of CT. Both suggest the same phenomena, i.e. under static load the development of failure surfaces follow the weakness of structure, while under dynamic load the crack development, follow the fastest path of energy releasing so that the strength is fully used. This may explain the reasons for dynamic strength increasing.