407ETR WB to 410 Flyover
The Hwy 407WB to Hwy 410SB Flyover Structure is a third level interchange bridge which carries westbound Highway 407 traffic to southbound Highway 410. The structure is a curved, six-span, post tensioned concrete box with an overall length of approximately 300m and was constructed in 1995. Brown & Company Engineering Ltd. was retained to review and assess the condition of the bridge's existing pot bearings and to determine replacement plans for the bearings as required. The existing bearings at the abutments and piers had visible signs of deterioration in their PTFE sliding surfaces and were required to be replaced. Two of the piers were single round concrete columns with diameters only slightly larger than the plan area of the bearings they supported, thereby prohibiting placement of the jacks directly on the piers. The footings for these piers were relatively close to their respective grades so the decision was made to excavate and to erect large steel jacking frames from the tops of the existing footings. A 14m high, four-column structural steel frame with heavy jacking beams placed under the deck soffit was designed to support 20-200t hydraulic jacks for lifting the structure. The structured was jacked approximately 20mm at each pier and the bearings were successfully replaced. The third pier and each abutment had adequate room for placement of the jacks directly on the substructures so more conventional jacking operations were utilized at these locations.