Stress Evaluation for Rocks and Structural Concrete Members through Ultrasonic Wave Analysis: Review

The preferable way to monitor structural behavior is to measure the actual stress in the structural members. Unfortunately, stress relieving by cutting holes or slots has been the only method applicable to date for measuring the in situ stress in concrete members. Other methods such as strain gauges can only measure the change of stresses and are time consuming. Investigations have been made to find nondestructive methods for stress measurement in concrete. The progress made on stress evaluation through acoustic-wave analyses is reviewed in this paper. While the traditional elastic-acoustic waves are able to detect stress changes in concrete, it is only applicable in the elastic range and is not suitable to most field conditions. Alternatively, the coda-wave interferometry and nonlinear acoustic waves are sensitive to the microstructural changes in concrete and provide potential field applicability for in situ measurements. These coda-wave and nonlinear parameters may be used as a qualitative/quantitative indicator to microscale-damage diagnostics and stress changes. (C) 2017 American Society of Civil Engineers.