I-480 Cuyahoga River Br.
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開始行:
*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.
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CENTER:&aname(fig1);&attachref(I-480C18.gif);&br;
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CENTER:Fig.1 General View.
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&br;
CENTER:&aname(fig2);&attachref(I-480C19.gif);&br;
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CENTER:Fig.2 Framing plan and typical girder view.
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&br;
CENTER:&aname(fig3);&attachref(I-480C20.gif);&br;
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CENTER:Fig.3 Typical cross section.
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**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;
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CENTER:Fig.4 Typical crack initiated from the stiffener end.
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&br;
CENTER:&aname(fig5);&attachref(I-480C22.gif);&br;
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CENTER:Fig.5 Type 1 crack.
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&br;
CENTER:&aname(fig6);&attachref(I-480C23.gif);&br;
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CENTER:Fig.6 Type 2 crack.
&br;
&br;
CENTER:&aname(fig7);&attachref(I-480C24.gif);&br;
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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>#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.
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終了行:
*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>#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;
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