Capacity Evaluation of a Severely Distressed and Deteriorated 50-Year-Old Box Beam with Limited Data

In 2005, 15 adjacent box-beam bridges were randomly selected and inspected to document their performance with consideration of the evolving design procedures. Longitudinal cracking along the soffit of several fascia beams was documented. After evaluating inspection data, the bridge engineer recommended the replacement of a severely distressed fascia beam from the Hawkins Road Bridge in Jackson County, Michigan. The beam was salvaged and the capacity was evaluated through load testing. The remaining prestress was 75% of the initial prestress, which is 5% less than the final prestress used for the design. Concrete modulus of elasticity was evaluated as 35.4 GPa and the nominal compressive strength as 54.4 MPa. Analysis of load test data indicated that a bridge with the beam in this distressed state is safe to operate. This is assuming that the transverse connectivity between the beams is sufficient for load distribution as envisioned in the design. The importance of identifying concealed corrosion, and quantifying material properties and load distribution is highlighted in this paper.