Impact loads widely exist in practical engineering and often cause cumulative damage and cracks or even fracture failure of concrete structures with their repeated long-term action. This experimental research is conducted on the damage evolution characteristics of concrete under impact loads by regarding C50 nonreinforced concrete as the research object and using a self-developed drop-weight device with electromechanical impedance measurement technology. Results show the following. (1) Under low-energy impact, concrete damage has long continuous development process and remarkable cumulative effects. An apparently sudden break characteristic appears before failure. Under high-energy impact, concrete damage accumulates rapidly, and piezoceramic patch signals grow linearly. (2) The root mean square deviation (RMSD) of the concrete increases exponentially with impact times. Particularly, when the RMSD exceeds 0.075, the concrete damage process enters the rapid development stage and approaches the critical failure state. (3) Under the experimental conditions in this study, the relationship between the ultimate impact times (damage life) and impact heights of the concrete samples shows the development trend of the power function. The above results can provide reference for the research on service life prediction methods of concrete structures under impact loads.

中文翻译：

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冲击载荷下C50混凝土损伤演化特性的试验研究。

冲击载荷在实际工程中广泛存在，并且由于其反复长期作用，通常会引起混凝土结构的累积损坏和裂缝甚至断裂破坏。以C50非钢筋混凝土为研究对象，并采用自行研制的具有机电阻抗测量技术的落锤装置，对冲击荷载作用下混凝土的损伤演化特性进行了实验研究。结果显示如下。（1）在低能冲击下，混凝土损伤的持续发展过程长，累积效应显着。在故障之前出现明显的突然断裂特征。在高能冲击下，混凝土破坏迅速累积，压电陶瓷贴片信号呈线性增长。（2）混凝土的均方根偏差（RMSD）随冲击时间呈指数增长。特别是，当RMSD超过0.075时，混凝土破坏过程进入快速发展阶段并接近临界破坏状态。（3）在本研究的实验条件下，最终冲击时间（损伤寿命）与混凝土样品冲击高度的关系表明了幂函数的发展趋势。以上结果可为冲击荷载下混凝土结构使用寿命预测方法的研究提供参考。最终冲击时间（损伤寿命）与混凝土样品冲击高度之间的关系表明了幂函数的发展趋势。以上结果可为冲击荷载下混凝土结构使用寿命预测方法的研究提供参考。最终冲击时间（损伤寿命）与混凝土样品冲击高度之间的关系表明了幂函数的发展趋势。以上结果可为冲击荷载下混凝土结构使用寿命预测方法的研究提供参考。