Internal damage detection in reinforced concrete member using ultrasonic pulse velocity nondestructive testing

Damage detection in structurally reinforced concrete elements is a vital topic for structural health monitoring and for assessing the capacity of reinforced concrete members. In this regard, many destructive tests exist that allow technical experts to evaluate the damage to a structural member. Such techniques are often employed for damage assessment after a natural disaster or a man-made event to assess the structural integrity and prioritize the locations that require urgent repair work. The researcher was successful in developing a testing methodology using nondestructive testing to identify internal damage in reinforced concrete elements by linking the delay in ultrasonic wave propagation to the initiation, development, and progression of cracks in the concrete surrounding the steel reinforcement. It was observed during experimentation that using the proposed methodology of gradual loading and comparing the speed of travel of the ultrasonic pulse velocity to the undamaged elements, the researcher was successful in identifying and localizing the internal cracked portions in the structural concrete member. Twelve reinforced concrete elements with full-size tension, compression, and shear reinforcements were tested to validate the proposed nondestructive test methodology. Direct and indirect methods of investigation were employed for testing purposes. From the performed experiments on reinforced concrete members, it was concluded that the proposed nondestructive testing methodology can be successfully applied in structural capacity assessment. The data collected from on-site investigations can be used for minimizing repair and strengthening work. In-addition an in-depth sensitivity analysis was conducted using the Latin hypercube sampling method to understand the influence of each variable on the ultrasonic pulse velocity test results. A purely random combination of parameters was adopted for the sensitivity analysis. Through the analysis, it was concluded that concrete strength played the most influential role in the ultrasonic pulse velocity testing followed by concrete cover, bar diameter and wave path length.