Monitoring the early age behaviour of prestressed concrete beams using fibre optic sensors

Prestressed precast TY beams were monitored for strain and temperature using two embedded fibre optic monitoring technologies, allowing for both distributed static measurements using Brillouin optical time domain reflectometry and dynamic measurements at discrete locations using fibre Bragg gratings at 1 m spacing. The prestressed beams were monitored for thermal and shrinkage strains during initial concrete curing and immediately before and after release of the prestressing strands with the aim of quantifying the immediate loss of prestress due to elastic shortening of the concrete and to provide baseline measurements for time dependent losses and other aspects of the monitoring programme. This work represents the initial phase of a larger programme of research investigating load transfer through multiple elements of the track and bridge superstructure, from the point of application down to the supports, and the dynamic strain response under in-service loads for two new railway bridges being constructed as part of the Stafford Area Improvements Programme on the West Coast Main Line.