Scalar Damage Modeling of Reinforced Concrete Beam Under Polarized Monotonic Stress Field Using Ultrasonic Pulses

Abstract

The extensive use of concrete has increased the demand for reliable non-destructive evaluation (NDE) techniques to investigate aging structures thoroughly. Among these NDE techniques, the ultrasonic pulse velocity (UPV) test stands out because of its versatility in-field application and its relatively low cost. Unfortunately, despite the promising results of UPV and pulse attenuation, its dependency on the nature of the applied stress is continuously overlooked. This research pioneered an approach that focused on developing a scalar damage model that relates the damage variable to the nature and the intensity of the applied stresses, concrete strength, and steel ratio. The results showed that transducers placed at different locations exhibited different deterioration rates of which the higher the applied stress intensity, the higher the scalar damage's inclination angle. Transducers placed in concrete under compression stress deteriorate earlier as compared to concrete under tension. As the steel ratio and concrete strength increase, the inclination angle of the elastic data trend also decreases. It was established in this research that beams with ductile response to the applied load tend to have a larger inclination angle for the elastic data trend while its UPV readings at the data trend's transition are greater than 3000 m/s which is conventionally accepted as concrete within normal to good quality although the beam undergoes critical stress redistribution as it approaches plastic hinging. Ultimately, this study showed that the scalar damage model exhibited superiority in quantitatively monitoring early damage propagation, in contrast to UPV reading and pulse attenuation.

Measuring damage anisotropy in concrete from ultrasound velocity data

“…Detection of concrete damage in real scale or mock-up reinforced concrete structures introduces additional challenges compared to ultrasonic measurements on plain concrete specimens. References [22] and [23] consider the measurement in reinforced concrete slabs and beams, respectively. It has to be noted that in the previously cited references damaged concrete is always considered as isotropic, and hence the corresponding measurement methods enable the evaluation of damage level as a scalar property only.…”