Pont Perley Bridge

Geometry
The new bridge has a total overall width of 21.8 m (4 - 3.65 m traffic lanes, 2 - 2m shoulders and a protected 2 m sidewalk on the west side). The bridge has 10 spans (8 main spans of 68.5 m and 2 end spans of 51 m) for a total length of 650 m.

Structure
Parallel tenders were prepared in steel and concrete. The steel alternate had three trapezoidal box girders. The concrete alternate had 7 lines of precast prestressed concrete girders at 3.1 m c/c. Dufferin Construction, the low bidder, selected the precast concrete alternate with a bid price of $27.2 million. This price included the main bridge, an access bridge, services, roadwork and the removal of the old 2-lane bridge (built in 1931).

Construction
The bridge site is on a narrow fast-flowing section of the Ottawa River founded on rock. This required special procedures for pier construction and precast girder erection. The contractor elected to use a specially built launching truss to erect the precast girder sections. A staging area for precast girder assembly was built behind the abutment on the Ontario side.

Precast segments were manufactured using steel formwork at the Pre-Con Inc. plant in Belleville, ON and trucked to the jobsite. Post-tensioning ducts were cast in the segments at the plant to accommodate the prestressing at different stages of construction. This required end-blocks and concrete blisters on the top and bottom girder flanges for the post-tensioning anchorages. Heavy reinforcing cages provided the necessary shear reinforcement for the bridge. Concrete strengths ranged from 50 to 60 MPa for the girder segments.

Girder sections consisted of three 16 m long 2450 mm deep I-girder segments and a 19 m long haunched I-girder pier girder segment (varying in depth from 2450 mm at the ends to 3400 mm in the middle). The four girder segments were assembled into a 68 m long section. 300 mm joints between the segments were concreted. The 4 segments were post-tensioned together. Girders were assembled in groups of 7 and rolled sideways - ready for erection.

Tracks were installed to the abutment and continued over the deck to reach each pier. Both ends of the girder sections were placed on a steel dolly and the girders were winched along the bridge to reach the launching truss as construction progressed. Two large vertical post-tensioning rods, anchored in the girders were used to suspend the girder sections from the overhead launching truss. The launcher moved the girder section across each span and then moved the girder laterally to its final position - resting on the cantilevered end of the previous span girder at the near end and on the next pier at the far end.

Second-stage post-tensioning was applied after the joints between the ends of the girder sections had been concreted. The design required that the girders be fully post-tensioned before the deck was cast. The bridge deck was constructed span by span using 35 MPa concrete. The deck was wet cured for 7 days.

Construction of the superstructure went smoothly - beginning in the summer of 1997 and completed in the fall of 1998. The bridge opened for traffic in December 1998.

Availability
CPCI members can generally deliver precast prestressed girders to jobsites in lengths from 40 to 50 m all across Canada. The benefits of fast construction, plant quality, durability and overall economy will apply whether the girders are designed as full spans or as spliced girder segments.

This project demonstrates the use of plant-cast girder segments for much longer spans. Spans of 90 to 100 m may be feasible using variations of the techniques developed for the Perley Bridge.

Owners: Project was financed and built by the Government of Canada and the governments of Ontario and Quebec.
Structural Engineer: DS-Lea Associates Limited
General Contractor: Dufferin Construction Company
Construction Engineering: John Otter Engineering Services Ltd.
Precast Concrete: Pre-Con Inc.

 
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