Abstract

BANDA, P.; DELIA TAMIN, M.  and  MEYER, J.. Applied Quasi-Distributed Fibre Bragg Grating Strain Sensors in Structural Damage Sensing of a Bridge Structure. SAIEE ARJ [online]. 2022, vol.113, n.2, pp.1-13. ISSN 1991-1696.

Bridge structural decay is a prevalent problem around the world. Consequently, most structurally deficient bridges are characterized by unknown levels of damage, which impose high socio-economic risks to society. To address these concerns, this study is aimed at determining how to accurately sense the damage present in a bridge structure. Owing to the pitfalls of conventional sensing technologies and the complexities associated with civil structure instrumentation, the use of fibre optics sensors is found to be relevant for this study. While the employment of quasi distributed fibre Bragg grating strain sensors is not a relatively new concept, research is still necessary for their effective deployment in structural damage monitoring systems. A proof of concept for the developed sensing system is primarily simulated and thereafter demonstrated in the laboratory through a series of strain measurements tests conducted on a reinforced concrete slab. The experimental set-up consisted of a serial array of five wavelength division multiplexed fibre Bragg grating sensors, which were coupled with swept wavelength laser scanning technology. The experimental sensing resolution of less than 0.5 uεwas achieved. Structural damage information was extracted from the measured multipoint flexural strains, using our developed macro-modal strain ratio cross correlation algorithm. Alternatively, to simulate our sensor system response, vibration field tests, and finite element analysis were conducted on the Beatrice Bridge in Zimbabwe. Therefore, this paper presents the simulation and experimental results of a simulated and designed structural damage sensing system, based on quasi-distributed fibre Bragg grating strain sensors.

Keywords : Fibre Bragg grating; macro modal strain ratio; quasi distributed sensors; structural damage.

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