Historic Pretensioned Concrete Bridge Girder

This girder has been salvaged from a bridge built soon after the development of pretensioned concrete. This example, circa 1950s, was removed from a bridge on Florida State Road 72 in Sarasota County, FL. Six girders from the bridge, each with over 55 years of service, were salvaged and tested to better understand the shear behavior and remaining capacity of this early generation of Florida prestressed girders. These beams are of particular interest because:

• Early Florida girder designs featured thin webs and very limited vertical (shear) reinforcement, raising concern about their shear capacity today.
• The girders were cast with pretensioned strands, not post‑tensioned bars as in another historic concrete bridge girder on display.
• Portions of the cast‑in‑place deck and curb were intentionally left attached during removal so researchers could evaluate the slab/curb contribution to shear strength. 

Overall, despite age and deterioration, the girders performed significantly above their nominal code‑calculated shear capacities, with failure modes dominated by tied‑arch behavior.

Girder Cross-Section