Pedelta was retained by Signature on the Saint Lawrence Constructors (SNC Lavalin, Dragados and Flatiron CJV) to develop the erection procedures (girder lifting and installation, cambers, and temporary elements) for the Île des Soeurs bridge. The structure is part of the New Champlain Bridge Corridor Project in Montréal, which is a PPP project.
The new crossing is a continuous bridge consisting of two independent structures named North Bridge (NB) and South Bridge (SB), spaced at 20m, connecting Montréal and the Nun´s Island. The NB has an overall length of 460.55 m and the SB is 490.21 m long, and variable widths ranging from 17.3m to 19.8m. Each superstructure has seven continuous spans with expansion joints at the abutments, and consists of a cast-in-place concrete slab on steel I-plate girders with a maximum span length of 70m. The girders have a constant depth of 3.2m and they are spaced between 3.6 m and 4.3 m.
The erection procedures include the following:
- Detailed erection sequence drawings.
- Erection stresses in temporary and permanent members.
- Pier and falsework reactions.
- Internal forces and capacity check of steel members.
- Step-by-step erection procedures.
- Details of camber and anticipated stage deflections and rotations at each stage.
The whole structure was studied at each construction stage. A detailed analysis with a 3D structural model was made for each stage. An additional buckling analysis with a Finite Element Model (with shell elements) for the critical stages during lifting operations was completed as well.
The Project also includes the design of the following temporary structures:
- Stabilization truss for the installation of the first lift of mid-span segments before connecting them to the second beam with the cross frames.
- Angel wings to temporarily support the segments of the girders over the piers.