Novel applications of pulse pre-pump Brillouin Optical Time Domain Analysis for behavior evaluation of structures under thermal and mechanical loading

"This study aims to: (1) develop an analytical model for the strain transfer effect of distributed fiber optic sensors in a uniform or non-uniform stress field; (2) develop a measurement approach to monitor strains in concrete and detect damage (e.g. crack and delamination) in bonded and unbonded concrete overlays; (3) characterize the strain and temperature sensitivities of distributed fiber optic sensors at elevated temperatures; (4) develop a thermal annealing approach to enhance the thermal stability and temperature sensitivity of the distributed sensors; and (5) apply the distributed sensors to assess structural behaviors of concrete and steel structures exposed to fire. The pulse pre-pump Brillouin Optical Time Domain Analysis (PPP-BOTDA) was employed to measure strain and temperature distributions along a fused silica single-mode optical fiber. Strain distributions in concrete were measured from the distributed fiber optic sensors embedded in bonded and unbonded concrete overlays. Peaks of the strain distributions represent the effect of concrete cracks and delamination. The strain sensitivity coefficient of distributed sensors was reduced from 0.054 MHz/µε to 0.042 MHz/µε when temperature increased from 22 ⁰C to 750 ⁰C. The temperature sensitivity coefficient of distributed sensors was reduced from 1.349x10^-3 GHz/⁰C to 0.419x10^-3 GHz/⁰C when temperature increased from 22 ⁰C to 1000 ⁰C. The distributed sensors embedded in concrete beams measured non-uniform temperature distributions with local peaks representing a sudden increase of temperature through concrete cracks. Temperature distributions measured from the distributed sensors attached on steel beams enabled an enhanced thermo-mechanical analysis to understand the structural behaviors of steel beams subjected to fire"--Abstract, page iii.

Name thesis:degree_name

Ph. D. in Civil Engineering

Grantor

Missouri University of Science and Technology

Author dc:creator

• Bao, Yi

• Civil Engineering

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/2580

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-3585