高应变率下建筑钢筋的本构模型

Constitutive Models for Reinforcing Steel Bars under High Strain Rates

采用静力和高应变率试验系统。研究了建筑钢筋HPB235，HRB335和HRB400在静栽以及应变率为2～80S^-1下的力学行为．试验结果表明。建筑钢筋的力学性能呈应变率相关性．随着应变率的增大。建筑钢筋的屈服强度和极限强度提高，相比之下，屈服强度的提高幅度大于极限强度；屈服强度较低的钢种比屈服强度较高的钢种呈现更明显的应变率敏感性．经回归分析，给出了以钢筋力学性能特征值为基础的建筑钢筋模型和John-son-Cook模型中的参数．通过算例和已有的模型进行了比较．结果表明：所提出的模型反映了建筑钢筋的动力反应本质。并且可以用来描述应变率小于2S^-1时的建筑钢筋力学行为．

Dynamic mechanical behaviors of reinforcing steel bars HPB235, HRB335 and HRB400 made in China were investigated with static and high strain rate test system over the range of strain rates from 2 s^-1 to about 80 s^-1. The test results show that the mechanical property of reinforcing steel bars is strain rate dependent. As the strain rate increases, the yield strength and the ultimate strength will increase. Compared with the ultimate strength, the yield strength exhibits more percentage increment. The reinforcing steel bar with lower yield strength is more strain rate sensitive. By means of regressive analysis the parameters in two dynamic constitutive models for reinforcing steel bars, i.e. model based on characteristic values and Johnson-Cook model, were derived. Numerical examples are presented to compare the model proposed in this paper with the models documented in the literature. The results show that the proposed model properly describes the dynamic response of the reinforcing steel bars and may be used for the range of strain rate less than 2 s^-1.