Gerber bridge on roadway bridge の変更点

追加された行はこの色です。
削除された行はこの色です。
Gerber bridge on roadway bridge へ行く。
Gerber bridge on roadway bridge の差分を削除
*Gerber bridge on roadway bridge [#e015eecd]

**1.Field of application [#bc9627eb]

>Gerber bridge on the roadway bridge, Japan.&br;

**2.Circumstances of Repair [#wf1bcbea]

>Fatigue cracks were found in the coped corner at hinge location of the Gerber bridge in 1984 after 29 years of service.&br;

**3.Types of structure [#s28dd9c1]
>The outline of the bridge structure is as follows.
-Bridge length : 38.5 m
-Span length : 23.8m + 11 @ 30.6m + 23.8m
-Structure : non-composite plate girder bridge.
-Deck : Reinforced concrete deck ( 18.0 cm thickness )
-Structural steel : SM 41
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>Elevation and cross section are shown in [[figure 1>#fig1]]. The corner plates were weld connected to the top and bottom flanges.
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CENTER:&aname(fig1);&attachref(Gerber24.jpg);&br;
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CENTER:Fig.1 Elevation and cross section.&br;
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**4.Details of loading [#uf3d51f6]
>Fluctuating loads due to vehicles live load.

**5.Description of damage [#f31fc91c]
>Fatigue cracks were found in the coped corner at the hinge locations of Gerber bridge ([[Fig.2>#fig2]]). The fatigue cracks occurred along the fillet weld beads at the coped corners ([[Fig.2>#fig2]],[[3>#fig3]]). There were some cracks that propagated into the girder webs from the corner ends.&br;
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>Cause of fatigue cracks was thought as follows:
-Stress concentration due to the cope.

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CENTER:&aname(fig2);&attachref(Gerber25.jpg);&br;
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CENTER:Fig.2 Crack location.&br;
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CENTER:&aname(fig3);&attachref(Gerber26.jpg);&br;
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CENTER:Fig.3 Crack along the weld root of the coped corner.&br;
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**6.Repair method applied [#w0f794dd]
-Emergency repair

>Repair of parts subjected to cracking was performed by 24mm diameter stop holes at the crack tips.
>High strength bolts (M22,F10T) were fastened there ([[Fig.4>#fig4]]).
>Because it was thought that the cracks initiated from the fillet weld root at the coped corner, all the fillet weld parts at the coped corners were gouged out and full penetration welded ([[Fig.5>#fig5]],[[6>fig6]]).

>Because it was thought that the cracks initiated from the fillet weld root at the coped corner, all the fillet weld parts at the coped corners were gouged out and full penetration welded ([[Fig.5>#fig5]],[[6>#fig6]]).


-Permanent repair

>After the completion of the repair weld, Strengthening was performed by bolt connection with the rib plates ([[Fig.7>#fig7]]). 

CENTER:&aname(fig4);&attachref(Gerber27.jpg);&br;
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CENTER:Fig.4 Emergency repair.&br;
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CENTER:&aname(fig5);&attachref(Gerber28.jpg);&br;
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CENTER:Fig.5 Range of the full penetration weld.&br;
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CENTER:&aname(fig6);&attachref(Gerber29.jpg);&br;
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CENTER:Fig.6 Repair weld (Full penetration weld.)&br;
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CENTER:&aname(fig7);&attachref(Gerber30.jpg);&br;
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CENTER:Fig.7 Permanent repair.&br;
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