Monitoring a prestressed high performance concrete bridge using an embedded optical fiber sensor system in Dona Ana County, New Mexico

A high performance concrete girder bridge was instrumented and monitored using an embedded optical fiber sensor system in Dona Ana, New Mexico. The bridge consisted of six BT-63 girders with a span length of 112.5 ft (34.2 m). The instrumented beams were fabricated with 6/10 inch (1.5 cm) low relaxation strands and concrete with design compressive strength 8 ksi (55.2 MPa) at release and 9.5 ksi (66.5 MPa) at 28 days.;The bridge was monitored from transfer of prestressing force until two years after the fabrication of the girders. Several topics that are considered areas of priority for the design and maintenance of bridge structures were studied in this project, which included prestress loss, camber, modulus of elasticity, girder distribution factor, impact factor, stress limit and serviceability. In each topic, the results from sensor measurements were compared to the values predicted by the AASTHO codes and other design codes or empirical equations, to check the accuracy of these codes when applied to HPC girder bridges.;It was found in this project that the PCI General, ACI-ASCE, AASHTO LRDF and Lump Sum methods all overestimated the long-term prestress losses. The NCHRP detailed and approximate methods yielded satisfying results on predicting prestress losses since those two methods were developed specifically for HPC. Both the PCI multiplier method and improved multiplier method largely over-predicted the camber at erection due to the lack of camber growth during storage. Both the AASHTO Standard and LRFD Specifications were conservative in predicting the moment and shear girder distribution factors for the study bridge. The modulus of elasticity obtained from sensor measurements closely agreed with the laboratory test results, but all the code and empirical equations considered in this project all overestimated the modulus of elasticity at transfer and deck pour. The stresses at the top and bottom of the girders, as well as the deflection under regular traffic, were found to be well below the AASHTO limits.