Distributed sensing, fiber bragg gratings and strain gauges for strain monitoring of RC tensile element

Abstract

Strain Monitoring of rebars embedded inside Reinforced Concrete (RC) structures can be used to study their serviceability performance and issues such as crack monitoring (position and strains in the crack), bond, tension-stiffening etc. Thus, the structural assessment for structural integrity and soundness both for present and future utility can be performed. Focusing on the Structural Health Monitoring (SHM), the mechanism of the array of sensors along the rebar were used which can efficiently exhibit a damage-sensitive feature of RC specimen, through its measurement. The present paper is finalized to studying different monitoring techniques for the steel rebar's strain profile whenever the latter is embedded inside RC tensile elements. A double pull-out test was selected and performed on several RC prisms of short length and similar cross sections thanks to its realistic load transfer mechanism. Three possible steel strain monitoring approaches were adopted, involving strain gauge sensors, Fiber Bragg Gratings (FBG) sensors & Distributed Optical Fiber Sensors (DOFS). The aim of this study is to concurrently check the performance capabilities of these three techniques, to determine both the pros and cons of each along with determining the most performant one. This study represents a step forward in the understanding of the tools aimed at achieving a more and more accurate measurement of reinforcement strain data and into future research into the fundamentals of RC. A successful and accurate monitoring can accomplish the twofold concern of a resilient structure, strength and security.