Monitoring of concrete behavior is an important task to evaluate the safety of concrete structures. This paper proposes a new stretching factor accumulation method based on the stepwise coda wave interference (CWI) to accurately calculate the relative velocity change Δv/v. The Δv/v and residual decorrelation coefficient K_d are used to study the concrete behavior in step loading experiment and short-time fixed loading experiment. The results show that: (1) In the loading stage of step loading experiments, both Δv/v and K_d can be used to monitor the load and the microcrack development; (2) In the relaxation stage of step loading experiments, the slow dynamics effect of concrete specimens can be characterized by Δv/v and K_d; (3) In the short-time fixed loading experiments, both Δv/v and K_d increase with the time of fixed loading, and the increasing rate of Δv/v decreases with the increase of concrete strength. This work can be used to promote the development of ultrasonic testing techniques that aid in concrete behavior monitoring.

混凝土行为监测是评估混凝土结构安全性的一项重要任务。本文提出了一种基于逐步尾波干涉（CWI）的拉伸因子累加新方法，以精确计算相对速度变化Δ v/v 。 Δ v/v和剩余去相关系数K _d用于研究阶梯加载试验和短时固定加载试验中混凝土的行为。结果表明：（1）在阶梯加载实验的加载阶段，Δv /v和_Kd都可以用来监测载荷和微裂纹的发展； (2) 在阶梯加载实验的松弛阶段，混凝土试件的慢动力效应可用Δ v/v和K _d来表征； (3) 短时定载试验中，Δ v/v和K _d均随定载时间的延长而增大，且 Δ v/v的增大率随混凝土强度的增加而减小。这项工作可用于促进有助于具体行为监测的超声波测试技术的发展。