Debond identification in GFRP strengthened RC beam using surface guided wave mode generated by angle beam transducer

Abstract

Abstract Debonding failure is one of the most common failure modes for FRP-strengthened RC structures. Thus, the strengthened structure requires regular inspections using an efficient and field-friendly technique. This paper proposes the use of angle beam (wedge) transducers to identify the debonded zone in a GFRP-strengthened RC beam. An experimental study is conducted to investigate the capability of wedge transducers to generate and receive the intended mode in the specimen. The inspection is carried out in longitudinal and transverse directions, both using the wedge and normal contact transducers. The normalised signal amplitude versus the sensor position plot is compared for ‘with wedge’ and ‘without wedge’ cases. It is found that the use of a wedge transducer significantly reduces the signal noise, thus improving the debond detection ability compared to the usage of normal transducers. Further, a three-dimensional finite element model is developed to understand the characteristics of wave propagation in the same beam specimen. The modal characteristics and normalised amplitude of signals captured in the numerical model is found in good agreement with the experimental results. The successful numerical validation paves the way for further parametric studies using the model in future work. As this technique does not involve the permanent installation of sensors, it can prove to be a competent technique for rapid in-situ nondestructive evaluation of FRP-strengthened RC structures.