Temperature Measurement and Damage Detection in Concrete Beams Exposed to Fire using PPP-BOTDA Based Fiber Optic Sensors


In this study, Brillouin scattering-based distributed fiber optic sensor is implemented to measure temperature distributions and detect cracks in concrete structures subjected to fire for the first time. A telecommunication-grade optical fiber is characterized as a high temperature sensor with pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA), and implemented to measure spatially-distributed temperatures in reinforced concrete beams in fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9%. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Concrete Crack Detection; Temperature Distribution; Anchorages (Foundations); Brillouin Scattering; Concrete Beams And Girders; Damage Detection; Fiber Optic Sensors; Fires; Fused Silica; Optical Fibers; Optical Pumping; Reinforced Concrete; Temperature Measurement; Temperature Sensors; Thermocouples; Time Domain Analysis; PPP-BOTDA; Structural Fire Safeties

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Article - Journal

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© 2017 Institute of Physics Publishing, All rights reserved.

Publication Date

01 Sep 2017