Pedelta was retained by Allnorth to provide engineering services for the erection of the deck and hangers installation of the new Walterdale Bridge over the Saskatchewan River in Edmonton, Alberta.
The bridge has a 230 m deck and a single span with two 206 m thrust-arches, 54 m tall. The arches rest on massive thrust blocks supported by micro piles. The traffic deck has three lanes of northbound traffic with a separate shared-use path (SUP) on the east side and a walkway on the west side. The traffic deck is 22.4 m wide and accommodates three lanes, two lateral shoulders, barriers and a lateral sidewalk. The SUP deck consists of a tube box steel of variable width. This traffic deck is suspended by two planes of 16 hangers each spaced at 10 m at centers and the SUP girder by one plane of 16 hangers.
Pedelta was assigned to develop complete erection procedures, including drawings and structural calculations, for the traffic and pedestrian decks and hanger installation. The project includes two distinct options: preassembly of 88 m of the mid span and lifting it into final position, and stick-build of the mid span in cantilever.
Two distinct options for the deck steel members’ installation procedure were analyzed. Both of them were fully engineered. The first option consists of stick-build for the mid span deck. For the second option, the central part of the deck is preassembled and floated on barges across the river to be lifted into place.
The analysis of the structure has been conducted with a 3D model with RMBridge v8i Software from Bentley Systems that incorporates all the construction stages. Due to the complexity and relevance of the bridge geometry, all the structure elements were incorporated into the model in their exact three-dimensional position. RM Bridge allows for construction staging and time-dependent material properties, such as creep & shrinkage. The hangers were defined as non-linear cable-elements.
The main project challenge was to meet the tight project tolerances such as target final geometry (tolerance specification 25mm) for the arch, main deck and SUP; and target hanger forces (tolerance specification 5%), after all dead loads are applied.