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120so that they would act in symmetry again. Also, the deck and certain members werereplaced, and the bridge was sandblasted and repainted. The overall cost of the bridgerehabilitation was $300,000 dollars and the operating rating for H and HS trucks was 23and 37 tons, respectively (Taavoni, 1994). This proved to be a very affordable method torehabilitate this bridge for the state of Maryland.5.4 Investigation of Crack Growth in EyebarsWhen investigating the capacity of pin connections of an existing historicwrought iron truss bridge, it is also important to investigate the strength of theconnections at the end of the eyebars of the bottom tension cord. These eyebars aretypically fracture critical members and should be thoroughly checked for any sign ofdistress due to fatigue or corrosion.The eyebar end connections found from the historic wrought iron trusses have avariety of different geometries. Under dynamic and cyclic conditions, the strength of theeyebar end connections vary due to geometrical differences. Therefore, the geometry ofthe eyebar should be analyzed to determine any points of higher stress that might inducefatigue cracking. These stress concentrations are typically found in the eyebar at the pinhole and the fillet where the eye head meets the shank.In the testing completed for this study, an analysis of the resulting stress found inthe eyebar connection from the Bell Ford Bridge under elastic loading was completed.The resulting stress distribution, of the eyebar connections showed that very high stressconcentrations were located on the outside of the pin hole. This suggests that crackingmight develop in this area under cyclic loading and lead to failure of the connectiondetail.
121A study conducted at Iowa State University in 1976 on the strength of eyebarconnections included some fatigue testing on damaged and undamaged eyebars. Fatiguetests were completed on twenty three undamaged eyebars and nine damaged and repairedeyebars. Of the undamaged eyebars, twenty one failed in one of the eyes of the eyebar.Of the damaged and repaired eyebars only two fractured in the presence of a repair andthe rest failed in the eyes (Elleby, 1976).The results from testing completed in this study and from the testing at Iowa StateUniversity support the need to check for fatigue cracking at the holes of the eyebars.This is especially true since these members are considered to be fracture critical and havebeen in service for such a long time.Regardless of the geometry, existing eyebars tend to perform well and fail outsideof the connection area under static loading conditions. Evidence of this can be seen inthe testing that was completed during this research study. Four eyebar connections werestatically tested in tension until they failed. All of the eyebar connections failed outsideof the connection detail area.Testing that was completed at Iowa State University in 1976 also included statictesting on eyebars. In this testing, seventeen undamaged specimens and three damagedand repaired specimens were tested. Of these eyebars, none failed in the eye and allfailed either in the shank of the eyebar or at an original forging (Elleby, 1976).Therefore, for the statically tested specimens, the eye connections of the eyebars areadequate but the forgings in the eyebars need to also be checked for cracking.Charpy impact testing of historic wrought iron was also completed in the presentstudy to determine the fracture toughness of the material. Charpy impact specimens weremachined from eyebars in different orientations simulating crack growth in differentdirection along the eyebar. It was determined that the fracture toughness of wrought ironvaries according to the direction of crack growth in the material.
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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
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34Percent Occurance in Range - %45.
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3660Combined Wrought Iron BarsTensi
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38The Bell Ford Bridge consisted of
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40Two. These samples were taken fro
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42specimens were of constant cross
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44Along with rectangular tensile co
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46After the initial test loading wa
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483.6 Fatigue TestingTo develop a b
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50The final specimen category consi
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52This analysis was completed using
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54After the initial test was comple
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56completed, but before the surface
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58readings, load cell readings and
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60Figure 3.3 Donated Eyebars 4 and
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62Figure 3.7 Heated Areas in Blue o
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64Figure 3.11 Detail Used in Groove
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66900080007000y = 27.153xR 2 = 0.99
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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 104 and 105: 84strengths was found to be 29,940
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 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
Page 154 and 155: 134Figure 5.11 Reassembling a Pin C
Page 156 and 157: 1366. SUMMARY, CONCLUSIONS AND IMPL
Page 158 and 159: 138rectangular in shape. These eyeb
Page 160 and 161: 140were joined together with a full
Page 162 and 163: 1424. The Charpy impact energy of t
Page 164 and 165: 144connections are unsymmetrical, i
Page 166 and 167: 146LIST OF REFERENCESAASHTO (1998).
Page 168 and 169: 148Hodgkinson, Eaton (1840). Experi
Page 170 and 171: 150Appendix A. Data Collected From
Page 172 and 173: 152Table A.1 Wrought Iron Bar Tensi
Page 174 and 175: 154Table A.1 (continued) Wrought Ir
Page 176 and 177: 156Table A.2 (continued) Wrought Ir
Page 178 and 179: 158Table A.3 Wrought Iron Angle Ten
Page 180 and 181: 160Table A.4 (continued) Summary of
Page 182 and 183: 162Table A.4 (continued) Summary of
Page 184 and 185: 164Table A.5 (continued) Detailed I
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170Table 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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