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*I-95 [#o65685f2] *2680 Br. [#n46ca1ae] **1.Field of application [#v3088e1f] >I-95 over Rappahannock River , Virginia. >The 2680 bridges on I-79 cross Big Sandy Creek 26 miles (42km) north of Charleston, West Virginia. **2.Circumstances of repair [#vb8560e3] >Fatigue crack were found in the girder web in 1981 after approximately 20 years of service. >Fatigue cracking was found in the intermediate transverse stiffener end and along the girder web-flange welds in May 1984 after 12 years of service. >Inspection of bridge structures indicated that the cracked locations required repair. **3.Types of structure [#a8d98161] >The structure is composite construction with multiple longitudinal plate girders. The interior girder and interior of the fascia girder webs are strengthened with transverse stiffeners and lateral bracing. >The structure consists of multiple continuous curved girders which are spliced by field bolting, transverse cross bracing, and lateral bracing. The girder elevation and framing plan are shown in [[figure 1>#fig1]]. Transverse cross bracing is connected to the transverse connection plates which are weld connected to the girder webs. No positive attachment exists between the transverse connection plates and the girder top or bottom flanges. Transverse web stiffeners exist on both sides of the girders. >The exterior of the fascia girder webs are strengthened with two continuous longitudinal stiffeners. >The longitudinal stiffeners are butt splice connected with vee groove welds and then fillet welded to the girder web([[Fig1>#fig1]]).The plate girders are thought to be fabricated from ASTM A373. >The structural steel was ASTM A36. &br; CENTER:&aname(fig1);&attachref(i95_ht83.gif);&br; CENTER:&aname(fig1);&attachref(2680%20B44.jpg);&br; &br; CENTER:Fig.1 Schematic of the exterior web face of fascia girders.&br; CENTER:Fig.1 Framing Plan and girder elevation, northbound. &br; **4.Details of loading [#gb82482c] >Fluctuating loads due to vehicles live load. >Fluctuating loads due to vehicles live load. This resulted in large cyclic stresses at the web-flange weld toe and the transverse connection plate weld termination. **5.Description of damage [#we6dd771] >The crack occurred in the butt connection groove weld of a continuous tension-side longitudinal stiffener, continued through the web between the stiffener and bottom flanges, and penetrated the bottom flange. &br; >Initially, fatigue cracks were found in the bottom web gaps at the web stiffener ends near the field splices Additional crack indications were later detected in the girder top web gaps at the transverse connection plate end and along the web-flange weld toe ([[Fig.2>#fig2]]). >Cause of fatigue crack was as follows: -Separational discontinuities in the butt connection groove weld of the continuous tension longitudinal stiffener. >Causes of fatigue crack were as follows: -The cyclic stress due to shipping and handling. -The web vibration resulting in the paint breaking. -Out-of-plane bending in the top web gaps. **6.Repair method applied [#tb1a3c59] >The fatigue cracked girder web and bottom tension flange were bolt spliced ([[Fig2>#fig2]]). &br; CENTER:&aname(fig2);&attachref(i95_ht84.gif);&br; CENTER:&aname(fig2);&attachref(2680%20B45.jpg);&br; &br; CENTER:Fig.2 Bolt splice repair of fatigue cracked girder web and bottom flange.&br; CENTER:Fig.1 Schematic of fatigue cracking in the girder top web gaps. &br; > The possibility existed for fatigue crack growth in the butt connection groove welds of other tension longitudinal stiffeners. Therefore, from the exterior of the fascia girder web, small hole was drilled through the girder web at the top of the fillet weld toe centered over the tension groove weld. **6.Repair method applied [#tb1a3c59] >A 51mm diameter holes were trepanned from the interior of the fascia girder web centered on the longitudinal stiffener groove weld ([[Fig.3>#fig3]]).The holes extended through the web into the longitudinal stiffener a maximum 3mm past the stiffener fillet weld toe. >The repairs of parts subjected to cracking were performed by hole-drilling at the tips of all cracks and positively bolt-connecting with an angle at the girder web and flange. >The repairs for the top web gap were performed by drilling 51mm holes on each side of the transverse connection plate adjacent to the girder top flange. &br; CENTER:&aname(fig3);&attachref(i95_ht85.gif);&br; &br; CENTER:Fig.3 Retrofit of tension longitudinal stiffeners.&br; &br; &br;
