OasisLMS

Abstract: A replacement bridge was proposed over I-81 on Brighton Avenue in Syracuse, NY, to improve accessibility and mobility. The design features a single span bridge with integral abutments, a span of 133 feet, a maximum width of 104 feet, and a 24-degree skew angle. The bridge height is 42 feet, measured from the deck to the roadway below.

The original design presented challenges for the construction of tall integral abutments. Placement of heavy volume of concrete to a height of more than 40 ft. with a large width could lead to delays and quality control issues. The NYSDOT Bridge Manual allows standard integral abutment designs for heights up to 15 feet, but anything taller requires a finite element model to evaluate soil-structure interactions, creating additional complexity.

To address these construction and design challenges, soldier pile walls were introduced in front of the abutments to reduce their height to within standard design limits. The walls, ranging from 28 to 42 feet, were designed as soldier pile walls with lagging and supported by up to four levels of anchors: Deadman anchors in the embankment and grouted tieback anchors in the excavation area. Design included additional load evaluation to account for passive pressure from thermal movement of the bridge abutments.

The construction required careful staging to avoid conflicts of the wall anchors with the bridge piles. Bridge foundation design was modified with larger size H-piles (16x162) with increased spacing to accommodate the anchors in between the piles. Both bridge and retaining wall piles were installed in pre-augured holes to minimize vibrations and reduce impact on the existing adjacent bridges. The alignment of the retaining wall, wrapping around the abutment, posed further challenges with crisscrossing anchors, requiring anchor design revisions to accommodate tight site conditions.

Mr. Ram Kasturi; Er. Kamal Regmi

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