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

139percent elongation found from testing was 47,000 psi, 30,000 psi, 27,900 ksi, and 18.1percent, respectively. The strain hardening coefficient and exponent were alsodetermined for each tensile coupon test. These values were then averaged together and atheoretical stress-strain curve was developed for wrought iron.The average percent elongation for the specimens from the Bell Ford Bridge was11.7% which was much lower than the average percent elongation for the specimensfrom the Adams Mill Covered Bridge (25.7%). This might be due to the damage that theBell Ford material had endured in the collapse of the bridge. The specimens have beenplastically strained and, therefore, lost some ductility, which effectively lowered theamount of available plastic strain in the wrought iron.To evaluate the adequacy of some common repairs, tensile coupons were preparedthat utilized heat straightening, mechanically straightening, and welding. The heatstraightened specimens were machined from areas of damaged eyebars from the BellFord Bridge that had been straightened by repeatedly heating the metal until it was a redhot color and then beating it into a desired shape. Little variation in the tensile strength,yield strength, and percent elongation compared to the non-repaired specimens wasobserved.Along with the heat straightened specimens, a single mechanically straightenedspecimen was tested. This specimen was machined from an 18” section of an eyebarfrom the Bell Ford Bridge that was still bent from the collapse of the bridge. This sectionwas mechanically straightened using a three point force method and then a tensile testcoupon was machined from it. The mechanically straightened specimen had a muchlower tensile strength (37,500 psi) and percent elongation (3.1%) compared to the othertest specimens.Welded tensile test coupons were also investigated during this study. Thesespecimens consisted of two wrought iron pieces from eyebars of the Bell Ford Bridge that