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*Cleveland I-90 (vibration while the girders carried by train) [#h732a62d] **1.Field of application [#ncb133e9] **2.Circumstances of repair [#r3990cde] -Location of transformation >Web of the main girder >Weld at the lower and of vertical stiffener **3.Types of structure [#g79e4b04] >5 span bridge (east bound and west bound lanes were separated), each of them consists of 9 welded steel girders. >Floor system is non-composite reinforced concrete. Vertical stiffeners are attached to the main girder but separated from the lower flange. CENTER:&aname(fig1);&attachref(clevel31.gif);&br; &br; CENTER:&aname(fig2);&attachref(clevel32.gif);&br; &br; **4.Details of loading [#f5a7b46e] >Opened in 1973, found in 1973, found by inspection at erection. **5.Description of damage and Repair method applied [#q092a67b] -Detail of fatigue transformation >There are 2 types of cracks. One is originated at the welding end of vertical stiffener propagates to the end of vertical stiffener and propagates to the end of weld at the web of main girder. The other is originate the toe of vertical stiffener and propagates to the web of main girder. >Those locations were supported points when they were carried by train. >Vertical stiffeners were attached to the both sides main girder and most of the cracks were originated on the both sides. CENTER:&aname(fig3);&attachref(clevel33.gif);&br; &br; -Cause >All the points cracks were generated were located around vertical stiffener with wooden blocks supporting girders while the girder was carried by train. >Due to transverse out-of vibration when it was carried, large out-of-plane stress was brought to the end of vertical stiffener. >It turned out that those fatigue cracks were propagated by large bending stress, judged from the interval of striation. &br; CENTER:&aname(fig4);&attachref(clevel34.gif);&br; &br; CENTER:&aname(fig5);&attachref(clevel35.gif);&br; &br; CENTER:&aname(fig6);&attachref(clevel36.gif);&br; &br; -Maintenance and reinforcement >1.Cracks at weld of stiffener >Crack and welding metal of its vicinity was ground. &br; &br; >2.Cracks which propagated into the web >Holes of 11mm diameter are made and the inner face was smoothened. After that, it was repaired by high-tension bolt (with high axial force). >The recommended retrofit for improving the cover plate girder in span 10 was peening the weld ends and Gas Tungsten re-weld ([[Fig.8>#fig8]],[[9>#fig9]]). The retrofits of the fatigue cracking which are more than 38mm in length along the weld toe were bolt spliced ([[Fig.10>#fig10]]) and hole-drilling in the girder webs just above the cracking. &br; CENTER:&aname(fig8);&attachref(yellow7.jpg);&br; &br; CENTER:Fig.8 Weld toe re-welded by Gas Tungsten arc.&br; CENTER:&aname(fig6);&attachref(clevel37.gif);&br; &br; CENTER:&aname(fig9);&attachref(yellow8.jpg);&br; &br; CENTER:Fig.9 Weld toe peened.&br; &br; CENTER:&aname(fig10);&attachref(yellow9.jpg);&br; &br; CENTER:Fig.10 Detail of the bolt splice.&br; &br; &br;
