Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...
Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ... Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...
38The Bell Ford Bridge consisted of timber compression members and wrought irontension members. The wrought iron tension members were the same size and shape aseach other and made of the same material found in many wrought iron truss bridges. Itwas believed that testing these tension members would provide a reasonable estimate ofthe material properties of the wrought iron used in other historic wrought iron bridges.The wrought iron tension members donated to this research project consisted offive bottom tension bars, also known as eyebars. Figure 3.2 is a photograph of eyebars,arbitrarily labeled one, two and three. These eyebars had been severely damaged in thecollapse of the bridge. Two of them had been heat straightened in some areas while thethird had only been heat straightened on the far end and was still disfigured. Figure 3.3 isa photograph which includes eyebars four and five. These eyebars had not encounteredas much visible damage as eyebars one, two and three.Other material that was tested in this study came from the Adams Mill CoveredBridge in Carroll County, Indiana. This bridge was built in 1873 by the WheelockBridge Company. Similarly to the Bell Ford Bridge, it is also a covered bridge thatutilizes wrought iron members in tension. The pieces utilized for testing from this bridge,however, consisted of round tension rods that were the diagonal members of the AdamsMill Covered bridge. These tension rods were replaced with steel tension rods and thewrought iron was then stored. This stored wrought iron was donated for research. Figure3.4 shows the round wrought iron tension rods from the bridge.3.2 MicrostructureThe specimens used to determine the microstructure of wrought iron weremachined from two of the eyebars of the Bell Ford Bridge. Eyebar one and two wereheat straightened and had some visible damage. From each eyebar, a piece about oneinch square was cut from an area that had not been heat treated or visibly damaged. The
39surfaces of these pieces were then ground smooth to remove the outer corrosive surfaces.Once the corrosion was removed, the pieces were then polished.This was done using a range of metallic grit paper of varying roughness. Initiallya very coarse paper was used to polish the specimens. Then finer grains of papers wereused to polish the specimens until finally a diamond powder and polishing wheel wasused to make the surfaces as smooth as possible. After polishing, a 2% Nitol solutionwas applied to the surface of the specimens to etch and make the microstructure visible.This same specimen preparation procedure was used to prepare a piece of carbon steelfrom the testing laboratory. The steel and wrought iron specimens were then comparedso that the differences in the microstructures of the two metals could be observed.To view the microstructure of the wrought iron, a microscope with a light sourcewas used to magnify the microstructure of the metal. A digital camera was attached tothis microscope and was used to photograph the magnified microstructure. To accuratelydetermine the magnification of the pictures, a magnifying ruler was placed onphotographs at various magnifications. The magnification of each photograph was thenfound by measuring the distance between the ruler marks on the photographs andcomparing that distance to the known distance between the marks of the ruler.The data acquired from the micrographs consisted of photographs taken of thewrought iron and steel. These photographs were magnified to approximately 100 timesand accurately showed the microstructure of both wrought iron and steel. An example ofthe photographs acquired can be seen in Figure 3.5.3.3 Chemical AnalysisThe specimens for the chemical analysis of wrought iron were taken frommembers of the Bell Ford Bridge. Two separate samples were cut from Eyebars One and
- Page 8 and 9: vPageCHAPTER 3TEST PROCEDURES FOR M
- Page 10 and 11: ixLIST OF FIGURESFigurePageFigure 1
- Page 12 and 13: xiFigurePageFigure 3.30 Top View of
- Page 14 and 15: xiiiFigurePageFigure 5.12 Typical T
- Page 16 and 17: xvAppendix FigurePageFigure D.7 Ini
- Page 18 and 19: viiiAppendix TablePageTable A.5 Det
- Page 20 and 21: iiiThe authors would also like to t
- Page 22 and 23: 2but also what material properties
- Page 24 and 25: 4microstructure of the metal. The c
- Page 26 and 27: 62. LITERATURE SEARCHBefore experim
- Page 28 and 29: 8imperfections, the performance of
- Page 30 and 31: 10wrought iron. Adding the slag aft
- Page 32 and 33: 12method for manufacturing wrought
- Page 34 and 35: 14patents for their process and tra
- Page 36 and 37: 16This method of testing of structu
- Page 38 and 39: 18plot of this percent elongation d
- Page 40 and 41: 20significant variation in the perc
- Page 42 and 43: 22The practice of restoring histori
- Page 44 and 45: 24Elleby, Wallace W. Sanders, F. Wa
- Page 46 and 47: 26From all the surveys that were di
- Page 48 and 49: 28Table 2.1 Average Ultimate Streng
- Page 50 and 51: 30Figure 2.3 Wrought Iron “Sponge
- Page 52 and 53: 32Histogram of Kirkaldy Wrought Iro
- Page 54 and 55: 34Percent Occurance in Range - %45.
- Page 56 and 57: 3660Combined Wrought Iron BarsTensi
- 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 104 and 105: 84strengths was found to be 29,940
- Page 106 and 107: 86wrought iron bars were investigat
38The Bell Ford Bridge consisted <strong>of</strong> timber compression members <strong>and</strong> wrought irontension members. The wrought iron tension members were the same size <strong>and</strong> shape aseach other <strong>and</strong> made <strong>of</strong> the same material found in many wrought iron truss bridges. Itwas believed that testing these tension members would provide a reasonable estimate <strong>of</strong>the material properties <strong>of</strong> the wrought iron used in other historic wrought iron bridges.The wrought iron tension members donated to this research project consisted <strong>of</strong>five bottom tension bars, also known as eyebars. Figure 3.2 is a photograph <strong>of</strong> eyebars,arbitrarily labeled one, two <strong>and</strong> three. These eyebars had been severely damaged in thecollapse <strong>of</strong> the bridge. Two <strong>of</strong> them had been heat straightened in some areas while thethird had only been heat straightened on the far end <strong>and</strong> was still disfigured. Figure 3.3 isa photograph which includes eyebars four <strong>and</strong> five. These eyebars had not encounteredas much visible damage as eyebars one, two <strong>and</strong> three.Other material that was tested in this study came from the Adams Mill CoveredBridge in Carroll County, Indiana. This bridge was built in 1873 by the WheelockBridge Company. Similarly to the Bell Ford Bridge, it is also a covered bridge thatutilizes wrought iron members in tension. The pieces utilized for testing from this bridge,however, consisted <strong>of</strong> round tension rods that were the diagonal members <strong>of</strong> the AdamsMill Covered bridge. These tension rods were replaced with steel tension rods <strong>and</strong> thewrought iron was then stored. This stored wrought iron was donated for research. Figure3.4 shows the round wrought iron tension rods from the bridge.3.2 MicrostructureThe specimens used to determine the microstructure <strong>of</strong> wrought iron weremachined from two <strong>of</strong> the eyebars <strong>of</strong> the Bell Ford Bridge. Eyebar one <strong>and</strong> two wereheat straightened <strong>and</strong> had some visible damage. From each eyebar, a piece about oneinch square was cut from an area that had not been heat treated or visibly damaged. The
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