Analysis and rehabilitation of the 1882 wrought iron bridge

The Friends of Historic Northport in conjunction with the City of Northport planned to relocate and preserve an existing span of a bridge that originally crossed the Black Warrior River in 1882. The 1882 Bridge is an old wrought iron arch-shaped truss bridge manufactured by the King Iron and Bridge Company of Ohio. A tensile test and metallographic analysis were performed on samples taken from the bridge, and it was determined that the bridge is composed of at least two grades of wrought iron. The tests also indicated the presence of brittle iron. The wood decking system, the concrete bridge abutments, and the keystone retaining wall for the bridge approaches were designed for material quantities for the relocation project. A structural analysis of the bridge at its new location showed that some of the bridge members were slightly overstressed under certain loading conditions. Parts of the top chord, floor beam, and diagonals were overstressed under the dead and pedestrian loads, and the bottom diagonals were overstressed under the wind load. Four lifting methods were analyzed for the bridge's relocation. The method considered the most efficient was to attach the lifting cables directly to the top chord near the ends of the bridge. (Published By University of Alabama Libraries