Monitoring prestress losses in high performance concrete beams with a built-in fiber optic monitoring system

An optical fiber monitoring system was designed and built into a three-span high performance concrete highway bridge. The Rio Puerco Bridge, located 15 miles west of Albuquerque, is the first bridge to be built using HPC in New Mexico. The bridge has 3 spans with length of 29 to 30 m. It is designed to be simply supported for dead load and continuous for live load. HPC was used for the cast-in-place concrete deck and the prestressed concrete beams. A total of 40 long-gage (2-m long) deformation sensors, along with thermocouples were installed in parallel pairs at the top and bottom flange of the girders. The embedded sensors measured temperature and deformations at the supports, at quarter spans and at mid-span. Measurements were collected during: Beam Fabrication (Casting of the beams, Steam curing, Strand release, Storage), Bridge Construction and Service. The data collected was analyzed to calculate the prestress losses in the girders, compare the losses to the predicted losses using available code methods, and get a better understanding of the properties and behavior of high performance concrete. The project is funded by. the Federal Highway Administration, the New Mexico State Highway and Transportation Department, and the National Science Foundation.