An experimental evaluation of pretensioned, prestressed bridge girders manufactured using high strength concrete was conducted. Three 70ft (21.3 m) long, 54 in. (1372 mm) deep bulb-tee girders were fabricated and tested. The design concrete compressive strength for the girders was 10,000 psi (69 MPa). A deck slab was cast on two of the three bridge girder test specimens. One of the two girders with a deck slab and the girder without a deck slab were tested to evaluate flexure and shear strength. The second girder with a deck slab was used to determine long-term behavior under full design dead load over an 18-month period. Results of this experimental evaluation indicate that use of high strength concrete for prestressed bridge girders is both feasible and beneficial. The two girders tested in flexure and shear performed adequately with respect to both design and specification requirements. Interim results from the girder currently being monitored to determine long-term behavior have indicated prestress losses that are significantly less than expected. Measured camber correlated well with deflections calculated using the measured prestress losses and conventional analyses.
