Measurement of the internal strain in concrete elements using embedded fiber sensors

摘要

Experimental results are presented on the embedding of optical fiber cables into cement specimens in order to determine the feasibility and limitations of using said fibers as sensors for the measurement of internal stresses as well as the evaluation of structural integrity. Pull-out tests have revealed that the surface bonding between the plastic jacket of a fiber cable and the cement matrix is poor and inadequate for an effective load transfer. Experiments using loaded cement specimens with embedded fiber cables inside suggest that the various protective layers present in the cable's construction prevent the fibers from properly sensing any external perturbations up to the specimen's failure and, in some instances, even after failure. Therefore, use of optical fiber cables as direct sensing elements for stress/strain measurement is not recommended for most applications, due to the lack of an appropriate load transfer mechanism and sensitivity. However, they can instead be used as leads to communicate the actual embedded sensors with the outside world.