A Wireless Passive Sensing System for Displacement/Strain Measurement in Reinforced Concrete Members.

Hilmi Demir,Ayhan Altintas,Vakur Erturk,Ozgur Kurc,Burak Ozbey

doi:10.3390/s16040496

Hilmi Demir, Ayhan Altintas + Show 3 more

Open Access

https://doi.org/10.3390/s16040496

Copy DOI

Abstract

In this study, we show a wireless passive sensing system embedded in a reinforced concrete member successfully being employed for the measurement of relative displacement and strain in a simply supported beam experiment. The system utilizes electromagnetic coupling between the transceiver antenna located outside the beam, and the sensing probes placed on the reinforcing bar (rebar) surface inside the beam. The probes were designed in the form of a nested split-ring resonator, a metamaterial-based structure chosen for its compact size and high sensitivity/resolution, which is at µm/microstrains level. Experiments were performed in both the elastic and plastic deformation cases of steel rebars, and the sensing system was demonstrated to acquire telemetric data in both cases. The wireless measurement results from multiple probes are compared with the data obtained from the strain gages, and an excellent agreement is observed. A discrete time measurement where the system records data at different force levels is also shown. Practical issues regarding the placement of the sensors and accurate recording of data are discussed. The proposed sensing technology is demonstrated to be a good candidate for wireless structural health monitoring (SHM) of reinforced concrete members by its high sensitivity and wide dynamic range.

Highlights

Readily-employed technologies to monitor relative displacement and strain in a reinforced concrete member with sensors such as strain gages are generally wired
Several load-and-release experiments were performed within the elastic deformation region of the steel rebars
The system utilizes the electromagnetic coupling between a transceiver antenna and several nested split-ring resonator (NSRR) probes, which are metamaterial-inspired, high-sensitivity structures

Summary

Introduction

Readily-employed technologies to monitor relative displacement and strain in a reinforced concrete member with sensors such as strain gages are generally wired. The sensor must be connected to a data acquisition system at all times This requirement makes them unpractical to be used in an actual structure and limits their usage in structural health monitoring (SHM) [1]. It is, important that the utilized measurement system enables wireless exchange of data, and the sensing device embedded inside the concrete does not need electrical energy to function (passive structure). A wireless, passive displacement/strain measurement system for reinforced concrete members enables the monitoring of deformation of such members in a much practical manner. Passive RFID is an emerging technique where a passive tag transfers

Methods

Results

Conclusion