The
appropriate bonding condition between substrate reinforced concrete (RC) beams
and carbon fiber-reinforced
polymer (CFRP) laminates is essential to guarantee
the performance of CFRP strips as retrofitting materials. In this study, a
theoretical approach and experimental results toward developing a CFRP debond
monitoring system are presented. The goal of this study is to understand
suitable guided waves propagation in the CFRP-RC structure and to develop a new
theoretical framework of nondestructive testing (NDT), in which
debonding can
be detected without using past baseline data. The concept of time reversal
acoustics (TRA), which has been generally applied to body waves, is extended to
complex guided waves in CFRP-RC interfacial regions. Several indices sensitive
to structural damage are extracted by comparing the known
input with the
time-reversed signal. Active sensing devices such as lead zirconate titanate
(PZT) wafers are used to generate known input waveforms and to measure the
time-reversed responses. Two large-scale CFRP-retrofit RC beams, one tested
monotonically and the other in a fatigue regime, are used to demonstrate the
potential of the proposed debonding monitoring system.