Prediction of Stress Level in Concrete Using Acoustoelastic Effect

Abstract

The primary objective of this research is to establish an improved method for analyzing changes in the propagation properties of ultrasonic waves through concrete under stress, particularly in determining acoustoelastic coefficients that influence these changes. Fundamental relationships governing the acoustoelastic effect are linearized at first order, considering the effects of initial strains, residual stresses, stress-induced isotropy, and nonlinearity in concrete. Beyond stress-induced velocity variations, the effect of stress on ultrasonic wave amplitude was also studied. The linearized equation for velocity was newlinemodified for amplitude, further, the coefficients of acoustoelasticity for velocity and amplitude were determined experimentally. It was found that while velocity exhibited an average change of about 4%, with a maximum of 8% at 60% of ultimate stress, whereas, the amplitude varied significantly, with an average change of over 100% and a peak of 160%. As compared to pulse velocity the variation in amplitude holds much more information about the stress state of concrete. therefore, it is recommended that for accurate determination of stress state and condition assessment of concrete element velocity and amplitude can be used simultaneously.