Strain, natural frequency, damping coefficient and elastic modulus of mortar beams determined by fiber Bragg grating (FBG) sensors

Gustavo Macioski,Valmir De Oliveira,Marcelo Henrique Farias De Medeiros

doi:10.1590/s1983-41952021000300012

Abstract

Abstract Structural health monitoring can detect anomalies in time, allowing the implementation of more efficient maintenance and repair actions in special engineering structures. An alternative in the monitoring and evaluation of structures in civil engineering is the use of optical fibers inscribed with Bragg gratings (FBG or Fiber Bragg Grating). This paper aims to compare available techniques to estimate the elastic module of cementitious composites, as well as contribute to the application of optical fiber sensors in the monitoring of strain, natural vibration frequency, damping coefficient and elastic modulus of mortar beams. The FBG sensors manufactured and calibrated by the authors presented a good precision for measuring those parameters in mortar samples. The results show that FBG sensors and strain gauge sensors present a similar result for strain and estimation of the elastic module (static and dynamic), therefore, bare FBGs could be further investigated for non-destructive testing.

Highlights

Young's modulus, elastic modulus or modulus of elasticity is a mechanical parameter that represents the stiffness of a solid material that can be affected by the material chemical composition, microstructure, and defects [1]–[5]
Determining this parameter is essential for the calculation of the serviceability requirements of structures defined by American Concrete Institute (ACI) 318 Building Code for concrete structure design [7] and other international structural standards
During the fiber Bragg grating (FBG) calibration, the optical fiber was pulled on a metal apparatus and the strain was monitored by a dial indicator

Summary

Introduction

Young's modulus, elastic modulus or modulus of elasticity is a mechanical parameter that represents the stiffness of a solid material that can be affected by the material chemical composition, microstructure, and defects [1]–[5]. It can be obtained by the ratio of the requested normal stress to the specific deformation suffered by the material [6]. All structural analysis depends directly on the elastic modulus of materials. This parameter can be estimated from the compressive strength, the elastic modulus can be obtained experimentally by quasi-static or dynamic tests

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