An optical fiber monitoring system was designed and built into the I-25 bridge at the Dona Ana exit in Las Cruces, New Mexico. The bridge is a simple span, high performance prestressed concrete girder bridge. The girdersare six BT-63 high performance concrete (HPC) girders with a span length of 112.5 ft (34.2 m). Fiber Bragg Grating (FBG) optical fiber deformation sensors along with thermocouples were embedded in the girders during fabrication. Sensors were installed along the top and bottom flanges, at mid-span and quarter spans. Pairs of crossed sensors in a rosette configurationwere embedded in the webs at the supports. The bridge was monitored for two years, from transfer of the prestressing force through service. The sensor data was analyzed to evaluate shear and moment girder distribution factors, in-situ material properties, prestress losses, camber, dynamic load allowance, and the bridge performance under traffic loads. This paper focuses on the lateral load distribution in the bridge. Shear and moment girder distribution factors are obtained from a finite element model, sensor measurements under a live load test as well as regular traffic loading and compared to the values specified by the AASTHO Standard Specifications (2002) and the AASHTO LRFD Specifications (2007).
Abstract