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*I-480 Cuyahoga River Br. [#mbee81fa] **1.Field of application [#j8881d67] >I-480 Cuyahoga River Bridge over Ohio Canal, B & O Rail Road and scrapped Penn Central Railroad roadway near Independence, Ohio. **2.Circumstances of repair [#tdd7ebee] >In Apr. 1973, fatigue cracks were found in the intermediate stiffener ends (the girder web gaps) in inspection at the time when the steel members had been erecting. **3.Types of structure [#ifa48319] >The continuous girder bridge is composed of four I-beam girders which are hunched at the support, floorbeams, stringers and transverse cross bracings ([[Fig.1>#fig1]],[[2>#fig2]],[[3>#fig3]]). Two stringers exist between the girders and were supported by the floorbeam. The web of the main girders was fabricated from ASTM A588 steel. &br; CENTER:&aname(fig1);&attachref(I-480C18.gif);&br; &br; CENTER:Fig.1 General View. &br; &br; CENTER:&aname(fig2);&attachref(I-480C19.gif);&br; &br; CENTER:Fig.2 Framing plan and typical girder view. &br; &br; CENTER:&aname(fig3);&attachref(I-480C20.gif);&br; &br; CENTER:Fig.3 Typical cross section. &br; **4.Details of loading [#f144ecca] >Fatigue cracks were found in pre-loading. **5.Description of damage [#p593a657] >Fatigue cracks were found in the ends of the intermediate stiffeners (the girder web gap) ([[Fig.4>#fig4]]). &br; >Fatigue cracks were classified in four types. &br; >Ⅰ. The crack between the girder web and the stiffener weld ([[Fig.5>#fig5]]). -This type of the cracks occupied 80 to 90 percent. The cracks tore the weld parts from the girder web surface. &br; >Ⅱ．The crack which occurred into the weld ([[Fig.6>#fig6]]). -This type of the cracks was observed in the stiffener ends. &br; >Ⅲ．The crack of the fillet weld toe ([[Fig.7>#fig7]]). -This type of the cracks occurred in the weld toes of the stiffener ends at the tension flange side. &br; >Ⅲ．The crack on the web surface opposite the stiffener ([[Fig.7>#fig7]]). -The surface cracks were observed in the girder web opposite the stiffener. &br; &br; CENTER:&aname(fig4);&attachref(I-480C21.gif);&br; &br; CENTER:Fig.4 Typical crack initiated from the stiffener end. &br; &br; CENTER:&aname(fig5);&attachref(I-480C22.gif);&br; &br; CENTER:Fig.5 Type 1 crack. &br; &br; CENTER:&aname(fig6);&attachref(I-480C23.gif);&br; &br; CENTER:Fig.6 Type 2 crack. &br; &br; CENTER:&aname(fig7);&attachref(I-480C24.gif);&br; &br; CENTER:Fig.7 Type 3 crack. &br; >The girders were carried by railway from Chicago to the field. The girders carried by railway had been loaded as shown in [[figure 8>#fig8]]. >Causes of fatigue cracks were as follows: -Out-of-plane distortion of the girder web gaps which resulted from the vibration of the girder during transportation. -Out-of-plane distortion of the girder web gaps which resulted from the horizontal sway due to the strong wind at the temporary set of the members. &br; CENTER:&aname(fig8);&attachref(I-480C25.gif);&br; &br; CENTER:Fig.8 Fixed method of the girder during transport. &br; **6.Repair method applied [#sc1db684] >ⅰ．The crack between the girder web and the stiffener weld -For cracking, repair was not performed due to the parallel cracks to the stress. >ⅱ．The crack which occurred into the weld. -The cracks which propagated into the weld near the stiffener end were removed by grinding out. >The crack which propagated into the girder web. >The 11mm holes were drilled at both sides of the crack tips ([[Fig.9]]). The inside faces of the holes were ground smooth. >The 11mm holes were drilled at both sides of the crack tips ([[Fig.9>#fig9]]). The inside faces of the holes were ground smooth. &br; CENTER:&aname(fig9);&attachref(I-480C26.gif);&br; &br; CENTER:Fig.9 Recommended repair method. &br; &br;
