A Novel Structural Assessment Technique to Prevent Damaged FRP- Wrapped Concrete Bridge Piers from Collapse

Repairing deteriorated concrete bridge piers using externally wrapped FRP (fiber reinforced polymer) composites has been proven as an effective approach. This technique has also been applied to low-rise building structures. Failures in FRP-wrapped concrete structures may occur by flexural failures of critical sections or by debonding of FRP plate from the concrete substrate. Debonding in the FRP/adhesive/concrete interface region may cause a significant decrease in member capacity leading to a premature failure of the system. In this paper, a novel structural assessment technique aiming at inspecting the near-surface FRP debonding and concrete cracking of damaged FRP-wrapped concrete bridge piers to prevent the structures from collapse is presented. In the first part of this paper, failure mechanisms of FRP-wrapped concrete systems are briefly discussed. The second part of this paper introduces a novel structural assessment technique in which farfield airborne radar is applied. In this development, emphasis is placed on inspection of debonding in glass FRP (GFRP)-wrapped concrete cylinders, while the technique is also applicable to beams and slabs with bonded GFRP composites. Physical radar measurements on laboratory specimens with structural damages were conducted and used for validating the technique. Processed experimental measurements have shown promising results for the future application of the technique. Finally, research findings and issues are summarized.