I-83 and I-695 Interchange
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開始行:
*I-83 and I-695 Interchange : Stop hole and Tab connection [#i634303e]
**1.Field of application [#u2579b15]
>Interstate Route I-83 southbound connects to I-695 eastbound via the Ramp C viaduct near Baltimore, Maryland.
**2.Circumstances of repair [#kb78af43]
>Fatigue cracks ware found in the box girder web gaps of the positive and negative moment regions in Oct. 1980 after 6 years of service. Full inspection indicated that retrofit was required.
>In 1982, shear tabs were installed between the box girder tension flange and the transverse connection plates. In Nov. 1984, fatigue cracking was found in these shear tab welds. In Sep. 1986,These shear tabs were replaced. The strain measurements indicated that an additional retrofit was required.
**3.Types of structure [#ed23fd96]
>The Ramp C is an elevated and curved structure and is comprised of four units with each unit continuous for three spans ([[Fig.1>#fig1]]). The structure is composed of a reinforced concrete deck of composite construction with shear connectors in the positive and negative moment regions and two curved steel box girders. The interior of the box girders contains radial diaphragms of three types ([[Fig.2>#fig2]]).
>The structural steel is ASTM A36.
&br;
CENTER:&aname(fig1);&attachref(I-83an50.gif);&br;
&br;
CENTER:Fig.1 Typical portion of framing plane.
&br;
&br;
CENTER:&aname(fig2);&attachref(I-83an51.gif);&br;
&br;
CENTER:Fig.2 Cross sections at diaphragms showing the 1982 shear tab retrofit for D2,D3, and D4 diaphragms locations.
&br;
**4.Details of loading [#k8ca430a]
>Fluctuating loads due to vehicles live load.
**5.Description of damage [#qa0af890]
>Cracking was found in the box girder webs in the top web gaps of the negative moment regions at the diaphragm D4 locations, in the top web gaps of the piers at the diaphragm D2 locations and in the bottom web gaps of the positive moment regions for the D3 diaphragms.
&br;
>Cause of fatigue crack was as follows:
-Out-of-plane bending caused by the diaphragm forces in the box girder web gaps adjacent to the tension flange ([[Fig.3>#fig3]]).
&br;
CENTER:&aname(fig3);&attachref(I-83an52.gif);&br;
&br;
CENTER:Fig.3 Direction of the diaphragm forces on the outside and inside webs.
&br;
>Fatigue cracking was found along the single bevel full penetration groove welds which connected the 1982 shear tabs to the top flange.
&br;
>Cause of fatigue crack was as follows.
-Undersized and poor quality welds ([[Fig.4>#fig4]],[[5>#fig5]]).
&br;
CENTER:&aname(fig4);&attachref(I-83an53.gif);&br;
&br;
CENTER:Fig.4 Undersized and poor quality weld connecting the shear tab to the top flange, D4 diaphragm location.
&br;
CENTER:&aname(fig5);&attachref(I-83an54.gif);&br;
&br;
CENTER:Fig.5 Undersized and poor quality welds connecting the shear tab to the to flange and to the transverse connection plate, D3 diaphragm location.
&br;
**6.Repair method applied [#q59282f8]
>The retrofit for the 1980 cracking was a positive attachment between the transverse connection plate and the box-girder tension flange.
-A weld connection using a shear tab or angle in the negative moment regions and at the piers, a weld or bolt connection in the positive moment regions.
>The retrofit for the 1984 cracking was the replacement of all of the 1982 shear tabs.
-The 1986 retrofit was to install 14 by 230mm (thickness by width) shear tab and of increased length which would provide a single bevel full penetration groove weld for the tab-flange weld ([[Fig.6>#fig6]],[[7>#fig7]],[[8>#fig8]]).
>The potential of continued crack growth from the crack tips was possible under the remaining stress range with the 1986 retrofit shear tabs.
-An additional retrofit recommended was to the hole-drillings in the box girder webs at all of the crack tips ([[Fig.9>#fig9]],[[10>#fig10]]).
&br;
CENTER:&aname(fig6);&attachref(I-83an55.gif);&br;
&br;
CENTER:Fig.6 1986 retrofit shear tab procedure at a D3 and D4 diaphragm location.
&br;
CENTER:&aname(fig7);&attachref(I-83an56.gif);&br;
&br;
CENTER:Fig.7 1986 retrofit shear tab at a D4 diaphragm location.
&br;
CENTER:&aname(fig8);&attachref(I-83an57.gif);&br;
&br;
CENTER:Fig.8 Close-up 1986 retrofit shear tab
&br;
CENTER:&aname(fig9);&attachref(I-83an58.gif);&br;
&br;
CENTER:Fig.9 Retrofit holes at crack tips in negative moment regions.
&br;
CENTER:&aname(fig10);&attachref(I-83an59.gif);&br;
&br;
CENTER:Fig.10 Retrofit holes at crack tips in positive moment regions.
&br;
&br;
終了行:
*I-83 and I-695 Interchange : Stop hole and Tab connection [#i634303e]
**1.Field of application [#u2579b15]
>Interstate Route I-83 southbound connects to I-695 eastbound via the Ramp C viaduct near Baltimore, Maryland.
**2.Circumstances of repair [#kb78af43]
>Fatigue cracks ware found in the box girder web gaps of the positive and negative moment regions in Oct. 1980 after 6 years of service. Full inspection indicated that retrofit was required.
>In 1982, shear tabs were installed between the box girder tension flange and the transverse connection plates. In Nov. 1984, fatigue cracking was found in these shear tab welds. In Sep. 1986,These shear tabs were replaced. The strain measurements indicated that an additional retrofit was required.
**3.Types of structure [#ed23fd96]
>The Ramp C is an elevated and curved structure and is comprised of four units with each unit continuous for three spans ([[Fig.1>#fig1]]). The structure is composed of a reinforced concrete deck of composite construction with shear connectors in the positive and negative moment regions and two curved steel box girders. The interior of the box girders contains radial diaphragms of three types ([[Fig.2>#fig2]]).
>The structural steel is ASTM A36.
&br;
CENTER:&aname(fig1);&attachref(I-83an50.gif);&br;
&br;
CENTER:Fig.1 Typical portion of framing plane.
&br;
&br;
CENTER:&aname(fig2);&attachref(I-83an51.gif);&br;
&br;
CENTER:Fig.2 Cross sections at diaphragms showing the 1982 shear tab retrofit for D2,D3, and D4 diaphragms locations.
&br;
**4.Details of loading [#k8ca430a]
>Fluctuating loads due to vehicles live load.
**5.Description of damage [#qa0af890]
>Cracking was found in the box girder webs in the top web gaps of the negative moment regions at the diaphragm D4 locations, in the top web gaps of the piers at the diaphragm D2 locations and in the bottom web gaps of the positive moment regions for the D3 diaphragms.
&br;
>Cause of fatigue crack was as follows:
-Out-of-plane bending caused by the diaphragm forces in the box girder web gaps adjacent to the tension flange ([[Fig.3>#fig3]]).
&br;
CENTER:&aname(fig3);&attachref(I-83an52.gif);&br;
&br;
CENTER:Fig.3 Direction of the diaphragm forces on the outside and inside webs.
&br;
>Fatigue cracking was found along the single bevel full penetration groove welds which connected the 1982 shear tabs to the top flange.
&br;
>Cause of fatigue crack was as follows.
-Undersized and poor quality welds ([[Fig.4>#fig4]],[[5>#fig5]]).
&br;
CENTER:&aname(fig4);&attachref(I-83an53.gif);&br;
&br;
CENTER:Fig.4 Undersized and poor quality weld connecting the shear tab to the top flange, D4 diaphragm location.
&br;
CENTER:&aname(fig5);&attachref(I-83an54.gif);&br;
&br;
CENTER:Fig.5 Undersized and poor quality welds connecting the shear tab to the to flange and to the transverse connection plate, D3 diaphragm location.
&br;
**6.Repair method applied [#q59282f8]
>The retrofit for the 1980 cracking was a positive attachment between the transverse connection plate and the box-girder tension flange.
-A weld connection using a shear tab or angle in the negative moment regions and at the piers, a weld or bolt connection in the positive moment regions.
>The retrofit for the 1984 cracking was the replacement of all of the 1982 shear tabs.
-The 1986 retrofit was to install 14 by 230mm (thickness by width) shear tab and of increased length which would provide a single bevel full penetration groove weld for the tab-flange weld ([[Fig.6>#fig6]],[[7>#fig7]],[[8>#fig8]]).
>The potential of continued crack growth from the crack tips was possible under the remaining stress range with the 1986 retrofit shear tabs.
-An additional retrofit recommended was to the hole-drillings in the box girder webs at all of the crack tips ([[Fig.9>#fig9]],[[10>#fig10]]).
&br;
CENTER:&aname(fig6);&attachref(I-83an55.gif);&br;
&br;
CENTER:Fig.6 1986 retrofit shear tab procedure at a D3 and D4 diaphragm location.
&br;
CENTER:&aname(fig7);&attachref(I-83an56.gif);&br;
&br;
CENTER:Fig.7 1986 retrofit shear tab at a D4 diaphragm location.
&br;
CENTER:&aname(fig8);&attachref(I-83an57.gif);&br;
&br;
CENTER:Fig.8 Close-up 1986 retrofit shear tab
&br;
CENTER:&aname(fig9);&attachref(I-83an58.gif);&br;
&br;
CENTER:Fig.9 Retrofit holes at crack tips in negative moment regions.
&br;
CENTER:&aname(fig10);&attachref(I-83an59.gif);&br;
&br;
CENTER:Fig.10 Retrofit holes at crack tips in positive moment regions.
&br;
&br;
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