Bx. Chen et al., FIBEROPTIC BRAGG GRATING SENSOR FOR NONDESTRUCTIVE EVALUATION OF COMPOSITE BEAMS, Journal of structural engineering, 120(12), 1994, pp. 3456-3470
Citations number
11
Categorie Soggetti
Engineering, Civil","Construcion & Building Technology
Extensive testing of control specimens and large-scale models of high-
strength concrete composite beams, 3,048-mm (10-ft) length, reinforced
with prestressed prisms, have resulted in deformation readings that a
re consistent with those obtained from classical measuring methods suc
h as electric strain gauges and linear voltage differential transforme
rs. The present paper provides the research findings of fiber-optic Br
agg gratings as strain/stress sensors for monitoring the critical sect
ions of a series of this type of composite beams. The optical fibers u
sed in this study had a numerical aperture of approximately 0.22 and a
V-value (reduced frequency) of 2.2 at 1,300-nm operating wavelength.
The theoretical strain coefficient of the optical fiber had a typical
value of 0.762, which agreed quite well with the calibration test perf
ormed. A successful packaging of the fiber-optic Bragg grating was use
d and modeled. Good bonding of sensor to the structure was shown to be
imperative for maximum transfer of load-induced strain. The average s
trains in the main tension reinforcement embedded in the concrete beam
s, the plane section assumption of the strain distributions across the
critical section depth, the flexural stiffness of the beams, and the
crack widths at service loads are evaluated.