Bolted Repair of Fractured I-79 Girder

The scheme used to repair an 11-ft (3.36-m) deep web of a welded girder is described. Design checks and repair studies begun immediately after the failure are explained. After rejecting several repair schemes, the scheme chosen required work to be performed from a barge platform moored in the river under the bridge. Large test coupons were removed from the girder flange and web and fills inserted. The fractured halves of the girder bottom flange were jacked longitudinally to closure by four 300-ton (2,670-kN) hydraulic jacks. A force of approximately 2,000 kips (8,900-kN) was needed to reintroduce the dead-load moment. Bottom flange and web repair splices were made using A490 friction bolts to develop the full design capacity of the girder. The entire jacking operation was closely monitored by hydraulic gages and electrical resistance gages on the bridge.