Qin Zhangchen, Zheng Dan, Li Xinxin, Wang Haicui
School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
Materials (Basel). 2022 Oct 18;15(20):7278. doi: 10.3390/ma15207278.
The rate sensitivity of concrete material is closely related to the inertia and viscous effects. However, the effect of inertia on the dynamic strength of concrete remains unclear. In this paper, digital image correlation technology was applied to study the strain variation of dry and saturated concrete with different loading rates. The test results indicated that the strain gradually decreased with the distance from the load end, and the strain gradient around the load region increased with the strain rate, especially for saturated concrete. Then, a single degree of freedom model was established to evaluate the dynamic compressive strength of elastic concrete. The calculated results indicated that the influence of inertia on the dynamic increase factor (DIF) was negligible for concrete within a low strain rate. When the strain rate is larger than 10/s, the inertial effect on the strength of concrete should be considered. After that, a quasi-static concrete damaged plasticity (CDP) model was employed to simulate the influence of inertia on the stress distribution and axial reaction force at the loaded end of concrete under different rates of compressive loading and verified with experimental results. The results obtained in this study indicated that the dynamic nominal strength of concrete obtained from the tests could not be directly used for structural analysis which may overestimate the effect of inertia on the dynamic response of the structure.
混凝土材料的率敏感性与惯性效应和粘性效应密切相关。然而，惯性对混凝土动态强度的影响仍不明确。本文采用数字图像相关技术研究了不同加载速率下干燥和饱和混凝土的应变变化。试验结果表明，应变随距加载端距离的增加而逐渐减小，加载区域周围的应变梯度随应变率的增加而增大，对于饱和混凝土尤为明显。然后，建立了单自由度模型来评估弹性混凝土的动态抗压强度。计算结果表明，在低应变率范围内，惯性对动态增强系数（DIF）的影响可忽略不计。当应变率大于10/s时，应考虑惯性对混凝土强度的影响。此后，采用准静态混凝土损伤塑性（CDP）模型模拟了不同压缩加载速率下惯性对混凝土加载端应力分布和轴向反力的影响，并与试验结果进行了验证。本研究结果表明，试验得到的混凝土动态名义强度不能直接用于结构分析，否则可能高估惯性对结构动态响应的影响。
