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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%.
85It is believed that the percent elongation values from the rectangular specimenswere lower than those of the round specimens as a result of the loading history of thematerial. The rectangular specimens were manufactured from eyebars taken from theBell Ford bridge. This bridge experienced extensive damage in its collapse during awinter storm. From this collapse, eyebars experienced visual damage which indicatedthat they had been stretched past yielding and some permanent deformations may havedeveloped in the material. The onset of permanent deformations in the wrought ironwould reduce the ductility or plastic strain that otherwise the wrought iron would haveexhibited. Therefore, when the strained wrought iron was tested, the percent elongationand ductility of the material was lower than expected.The strain hardening coefficient (K) and exponent (n) are variables that are usedto describe the inelastic region of the stress-strain curve. These variables are determinedby taking the log of the true strain versus the log of the true stress and fitting a line to thedata. The intercept of this line is the strain hardening coefficient and the slope is thestrain hardening exponent. The stress in the plastic region of the stress-strain curve isequal to the strain hardening coefficient multiplied by the strain in the plastic region tothe strain hardening exponent.The strain hardening exponent and coefficient was determined for every testingspecimen. The average strain hardening exponent was found to be 0.21 and the averagestrain hardening coefficient was found to be 82 ksi. These values along with the averagemodulus of elasticity were used to determine a theoretical stress strain curve for historicwrought iron. Figure 4.11 is a plot of this theoretical stress strain curve.4.4.3 Comparison of Overall Results to Historical DataA comparison of the tensile testing results to the tensile testing data collectedfrom historical sources was conducted. In this comparison, only the data from historic
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Purdue UniversityPurdue e-PubsJTRP
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1. Report No. 2. Government Accessi
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epairing a bent wrought iron tensio
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vPageCHAPTER 3TEST PROCEDURES FOR M
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ixLIST OF FIGURESFigurePageFigure 1
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xiFigurePageFigure 3.30 Top View of
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xiiiFigurePageFigure 5.12 Typical T
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xvAppendix FigurePageFigure D.7 Ini
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viiiAppendix TablePageTable A.5 Det
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iiiThe authors would also like to t
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2but also what material properties
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4microstructure of the metal. The c
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62. LITERATURE SEARCHBefore experim
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8imperfections, the performance of
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10wrought iron. Adding the slag aft
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12method for manufacturing wrought
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14patents for their process and tra
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16This method of testing of structu
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18plot of this percent elongation d
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20significant variation in the perc
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22The practice of restoring histori
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24Elleby, Wallace W. Sanders, F. Wa
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26From all the surveys that were di
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28Table 2.1 Average Ultimate Streng
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30Figure 2.3 Wrought Iron “Sponge
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32Histogram of Kirkaldy Wrought Iro
Page 54 and 55: 34Percent Occurance in Range - %45.
Page 56 and 57: 3660Combined Wrought Iron BarsTensi
Page 58 and 59: 38The Bell Ford Bridge consisted of
Page 60 and 61: 40Two. These samples were taken fro
Page 62 and 63: 42specimens were of constant cross
Page 64 and 65: 44Along with rectangular tensile co
Page 66 and 67: 46After the initial test loading wa
Page 68 and 69: 483.6 Fatigue TestingTo develop a b
Page 70 and 71: 50The final specimen category consi
Page 72 and 73: 52This analysis was completed using
Page 74 and 75: 54After the initial test was comple
Page 76 and 77: 56completed, but before the surface
Page 78 and 79: 58readings, load cell readings and
Page 80 and 81: 60Figure 3.3 Donated Eyebars 4 and
Page 82 and 83: 62Figure 3.7 Heated Areas in Blue o
Page 84 and 85: 64Figure 3.11 Detail Used in Groove
Page 86 and 87: 66900080007000y = 27.153xR 2 = 0.99
Page 88 and 89: 68Figure 3.19 Charpy Impact Testing
Page 90 and 91: 70Figure 3.23 Eyebar Connection in
Page 92 and 93: 72Figure 3.27 Eyebar A After Filler
Page 94 and 95: 74Figure 3.31 Side View of Finished
Page 96 and 97: 76Figure 3.35 Front View of Eyebar
Page 98 and 99: 78strength from the existence of pe
Page 100 and 101: 80The carbon content present in the
Page 102 and 103: 82value may not be very accurate bu
Page 106 and 107: 86wrought iron bars were investigat
Page 108 and 109: 88stresses are induced. These perma
Page 110 and 111: 90toughness the material. The test
Page 112 and 113: 92From the finite element analysis,
Page 114 and 115: 94Table 4.1 Chemical Analysis of Ey
Page 116 and 117: 96Table 4.3 Tensile Coupon Test Res
Page 118 and 119: 98Table 4.5 Charpy Impact Test Resu
Page 120 and 121: 100Table 4.7 Comparison of Strain G
Page 122 and 123: 102Figure 4.1 Typical Micrograph of
Page 124 and 125: 104Figure 4.5 Fracture Surface of D
Page 126 and 127: 106Comparison of Tensile Strengthfo
Page 128 and 129: 108Combined Wrought Iron Bar Histor
Page 130 and 131: 110Figure 4.17 Macrograph of Weld u
Page 132 and 133: 112Figure 4.21 Cleavage Fracture of
Page 134 and 135: Figure 4.25 Elongation of Hole in E
Page 136 and 137: 116signs on or near the bridge that
Page 138 and 139: 118testing of historic wrought iron
Page 140 and 141: 120so that they would act in symmet
Page 142 and 143: 122The reasons for the differences
Page 144 and 145: 124The second corrosion pattern mod
Page 146 and 147: 126Keating (1984) stated that the s
Page 148 and 149: 128charcoal fire until it is red ho
Page 150 and 151: 130Figure 5.3 Picture of Bottom Cho
Page 152 and 153: 132Figure 5.7 Using Force After Usi
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134Figure 5.11 Reassembling a Pin C
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1366. SUMMARY, CONCLUSIONS AND IMPL
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138rectangular in shape. These eyeb
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140were joined together with a full
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1424. The Charpy impact energy of t
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144connections are unsymmetrical, i
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146LIST OF REFERENCESAASHTO (1998).
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148Hodgkinson, Eaton (1840). Experi
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150Appendix A. Data Collected From
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152Table A.1 Wrought Iron Bar Tensi
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154Table A.1 (continued) Wrought Ir
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156Table A.2 (continued) Wrought Ir
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158Table A.3 Wrought Iron Angle Ten
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160Table A.4 (continued) Summary of
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162Table A.4 (continued) Summary of
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164Table A.5 (continued) Detailed I
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184Table A.7 Tensile Strength Data
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186Table B.1 Example Historic Wroug
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188DepartmentofTransportationIf you
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190CountyIf your organizationdoes m
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192County 16: County bridge inspect
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194State 13: Included in original d
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196Figure C.1 Diagrams Showing Loca
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198Figure C.3 Heating of Eyebar fro
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200Figure C.7 Double V Butt Joint u
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202Figure C. 11 Welded Tensile Coup
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204Figure C.15 Tensile Coupon from
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206Figure C.19 Cooling Bath with Su
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208Figure C.23 Side View of Eyebar
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210Figure C.27 Eyebar End Connectio
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212Appendix D. Welding Procedure fo
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214D.2 Filler Weld for Eyebar Conne
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216Figure D.1 Weld Joint Detail Use
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Figure D.5 Completed Weld Before Su
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220Figure D.7 Initial Pass Pattern
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