Based on FBG self-sensing steel wire for prestressed concrete beam bending performance monitoring
In order t o solve the problem that the flexural performance of prestressed concrete beams is difficult to achieve real-time monitoring,it designs and fabricates two prestressed concrete beams with different line types,and uses the tandem FBG sensor embedded in steel strand technology to monitor the flexural performance of prestressed concrete beams in real-time.A three-point symmetric concentrated force loading test was conducted on the prestressed concrete beams with linear and curved apertures to analyze the monitoring effect of the FBG sensors on the flexural performance of the beams.The monitoring results show that the survival rate of FBG sensor is 100%,and the monitoring data are stable,which is more suitable for monitoring the flexural performance of prestressed concrete beams than resistance strain gauges.The strain development trend of FBG sensor at each measurement point of the same tendon is basically the same,and the actual stress state reflected by the load-strain curve is consistent with the theoretical description of the stress state.The maximum error of FBG monitoring the strain in the beam before concrete cracking is 9.77%,which is much smaller than the maximum error of 47.63%for resistive strain gauges.When concrete cracks,FBG self-sensing steel strand can mutate with the crack development.After the tensile steel bar yielding,FBG self-sensing steel strand can accurately identify the external load,and the error between the force borne in the beam and the increase of the external load is less than 12%.This technology realizes real-time monitoring of prestressing strands and beam stressing process in the beam.
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