Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...

1416.2 ConclusionsBased upon information gathered through the literary search and the experimentaltesting program, a number of conclusions about wrought iron material properties andsuitable repair procedures were obtained.1. Wrought iron mainly consists of ferrite particles with numerous deposits ofimpurities due to the manufacturing process. In this process iron ore is heateduntil it is in a pasty condition and then squeezed and rolled into shapes used forconstruction purposes. Since the iron ore is never heated to a fluid condition,many impurities become imbedded throughout the metal. These impurities,which are mostly categorized as slag, or iron oxide, are dispersed in elongateddeposits throughout the iron leading to a fibrous structure in the metal. This leadsto lower strength than most common steels.2. The average tensile strength from materials testing completed in this study was47,000 psi, while the tensile strength found from historical sources was 54,000psi. The lower second standard deviation for the tensile strength of wrought ironfrom historical sources was 40,000 psi. This means that 97.7% of the historicalwrought iron specimens have tensile strengths greater than this value and it maybe a conservative estimate for the tensile strength of wrought iron in existingbridges.3. The percent elongation data from the tensile coupons machined from the damagedeyebars from the Bell Ford Bridge were much lower than the percent elongationof the testing coupons machined from the replaced diagonal tension rods from theAdams Mill Bridge. This may be due to the amount of plastic strain that wasinduced during the collapse of the bridge. This overload condition may havedepleted the amount of plastic strain available and, therefore effectively reducedthe ductility and the resulting percent elongations.