An EMI-Based Clustering for Structural Health Monitoring of NSM FRP Strengthening Systems.

Ricardo Perera,Antonio Ruiz,Cristina Barris,Marta Baena,Lluis Torres

doi:10.3390/s19173775

Abstract

The use of fiber-reinforced polymers (FRP) in civil construction applications with the near-surface mounted (NSM) method has gained considerable popularity worldwide and can produce confident strengthening and repairing systems for existing concrete structures. By using this technique, the FRP reinforcement is installed into slits cut into the concrete cover using cement mortar or epoxy as bonding materials, yielding an attractive method to strengthen concrete structures as an advantageous alternative to the external bonding of FRP sheets. However, in addition to the two conventional failure modes of concrete beams, sudden and brittle debonding failures are still likely to happen. Due to this, a damage identification technology able to identify anomalies at early stages is needed. In this work, some relevant cluster-based methods and their adaptation to electromechanical impedance (EMI)-based damage detection in NSM-FRP strengthened structures are developed and validated with experimental tests. The performance of the proposed clustering approaches and their evaluation in comparison with the experimental observations have shown a strong potential of these techniques as damage identification methodology in an especially complex problem such as NSM-FRP strengthened concrete structures.

Highlights

In the last few decades, strong research efforts have been devoted to the continuous structural condition assessment for the civil engineering infrastructure [1]
As commented previously, according to the analytical estimations, the predicted failure mode for this specimen should be the debonding of the fiber-reinforced polymer (FRP) bar due to a loss of adherence
A high frequency range methodology, based on electromechanical impedance (EMI), able to track in a fast, intuitive, and reliable way the evolution of the damages in concrete structures strengthened with near-surface mounted (NSM)-FRP systems has been proposed

Summary

Introduction

In the last few decades, strong research efforts have been devoted to the continuous structural condition assessment for the civil engineering infrastructure [1]. Within the field of strengthening of reinforced concrete (RC) structures with fiber-reinforced polymer (FRP) composite materials, some previous studies have been devoted to the identification of damage at their earliest stages on externally bonded (EB) FRP reinforcement. For this purpose, different non-destructive testing (NDT) methodologies such as infrared thermography [3,4] and ultrasonic testing [5,6] have been proposed. Most of these techniques require of a priori knowledge, at least approximate, of the possible damage locations and, the part of the structure to be inspected should be accessible; these disadvantages make difficult their application to large and complex

Results

Discussion

Conclusion