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

84strengths was found to be 29,940 psi with a standard deviation of 2,400 psi, which is 8%of the average. The average yield strength of the rectangular specimens was 31,600 psiwith a standard deviation of 1,280 psi, which is 4.05% of the average. The average yieldstrength of the round specimens was 28,000 psi with a standard deviation of 1,790 psiwhich was 6.39% of the average.Tensile strength, or ultimate stress, is the stress at which failure occurs. Thispoint of failure was well defined and easy to determine from the stress strain curvesdeveloped from testing. Figure 4.9 is a plot showing the tensile strength results from alltensile testing coupons for both the rectangular and round specimens. The plot indicatesthat, with some exceptions, there is little variation between the tensile strengths obtainedfrom testing. The average tensile strength of the wrought iron was 47,000 psi with astandard deviation of 3,000 psi, which was 6.5% of the average. The average tensilestrength of the rectangular specimens was 47,200 psi with a standard deviation of 3,380psi which was 7.16% of the average. The average tensile strength of the round specimenswas 46,800 psi with a standard deviation of 2,470 psi which was 5.28% of the average.The percent elongation results from testing were determined by measuring thechange in length of the predetermined 8” gauge length for the rectangular specimensfrom the eyebars and a 2” gauge length from the round specimens, and dividing thatvalue by the original gage length. This variable was also compared to the total strain thatoccurred in the specimen to check the results obtained. Figure 4.10 is a plot of thepercent elongation values determined from the rectangular and round tensile testingcoupons. The plot indicates that the percent elongation values of the rectangularspecimens were considerably lower than the resulting percent elongations for the roundspecimens. The average percent elongation for the round specimens was 25% with astandard deviation of 6%, while the average percent elongation for the rectangularspecimens was 12% with a standard deviation of 5%.