Structural Faults & Repair-2008
12th International Conference 発表論文
■MONITORING OF TUNNEL DEFORMATION BY MEANS OF TDM BASED FBG OPTICAL FIBRE
MEASUREMENT SYSTEM
T.Tamura, K.Kumagai, H.Motoyama, T.Shiotani and R. Knapp
■概要
Recently Fiber Bragg Grating (FBG) based optical fiber sensing systems have been applied widely
for many civil structures. Contrary to the Wavelength Division Multiplexing (WDM), in FBG adapting
Time Division Multiplexing (TDM), multiple points of more than 100 points on a single line can be
monitored, that is suitable for long-term health monitoring of large civil structures. In the present
paper, this TDM based FBG sensing system was installed at a deformed tunnel in a cold region. A total
of 100 strain and deformation on the surface of lining concrete was measured with the optical
interrogator at about 1 km away from the sensors. So far even under such a severe monitoring condition,
continuous data acquisition with good accuracy has been successfully conducted.
■COMBINED STRESS WAVE TECHNIQUES FOR MONITORING OF FRACTURE IN CONCRETE SLABS
S.Momoki, D.G.Aggelis, A. Hirama and T.Shiotani
■概要
In the present paper the mechanical and acoustic emission behavior of concrete slabs tested in four
point bending is discussed. The specimens consisted of two layers of plain and vinyl fiber concrete
with metal rebars. The aim was to assess the effect of fibers on the strength, as well as the cohesion
obtained between the layers by different binding conditions. At different loading steps, ultrasound
pulse velocity was measured and a three dimensional tomographic reconstruction of the internal
condition of the specimen was obtained. Although cracking decreases the accuracy of source location,
the results for any loading stage show good agreement between the acoustic emission event location,
the ultrasound structure and the visual observation of the actual cracks.
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