数值模拟中混凝土类材料应变率效应曲线的惯性效应修正

数值模拟是研究混凝土类材料在动载下响应的有效方法，准确输入材料真实的应变率效应曲线对预测结构在动载下的响应有重要作用。收集了1990年以来针对混凝土类材料的动态抗压实验数据，并将惯性效应对材料动态强度的影响进行剥离，得到真实的材料应变率效应引起的抗压动态强度放大因子（DIF_ε）与应变率对数的关系曲线。分析数据发现：实验得到的抗压动态强度放大因子（DIF_s）和惯性效应引起的抗压动态强度放大因子（DIF_i）都随试件尺寸的增大而增大；随着材料准静态强度增大，混凝土类材料DIF_i随应变率增长的增长幅度减小。对比拟合曲线与其他曲线可知，在高应变率下，新的应变率效应拟合曲线比已有半经验公式能更好地反映实验数据的DIF_ε；模拟时分别输入新的应变率效应曲线和CEB推荐公式，将输出结果与DIF_s对比，验证了新的应变率效应曲线的优越性。

MODIFICATION OF DIF-STRAIN RATE CURVE OF CONCRETE-LIKE MATERIALS IN NUMERICAL SIMULATION OF SHPB EXPERIMENTS

Numerical simulation is an effective technique to study the response of concrete-like materials to dynamic loads. For predicting the concrete-like materials structure response to dynamic loads, it's important to input the DIF-strain rate curve exactly in numerical simulation. The data in dynamic compressive experiments of concrete-like materials since 1990 was collected, and the inertia-induced effect on dynamic strength of material was stripped out to obtain DIF_ε-logε curve. It is discovered that DIF_s and DIF_i increase with specimen size. At the same time, DIF_i of concrete-like materials increase less with the strain rate when the quasi-static strength of the materials increases. New curve and semi-empirical formula curve were compared, which show that the new curve was coincided with DIF_ε of experiments better than the semi-empirical formula at high strain rate. Furthermore, the superiorities of new curve are validated by comparing the DIF recommended by CEB with the new curve as the numerical inputs.