Keeping Travelers Safe while Replacing Truss Bearings at Pulaski Skyway
Under Contract 8B, the existing steel bearings atop Piers 44 through 56 in the Pulaski Skyway required replacement with new HLMR bearings, a mounting to a total of 34 bearing replacements. Each bearing withstands extremely high dead and live loads, with the maximum dead and live load reactions for a single bearing reaching approximately 1,100 tons and 290 tons, respectively.
To facilitate the replacement of the existing steel bearings and ensure the safety of traveling public, CHI Consulting Engineers devised innovative and robust jacking frames and temporary supports. These consist of temporary diagonal members within existing trusses and triangular frames situated on top of existing concrete steps at the peak of pile caps. At expansion piers, temporary sliding bearings are necessary.
On August 20, 2022, the two steel bearings atop Pier 50 were successfully unloaded. The lift-off jacking force per bearing amounted to around 725 tons, a mere 5% above the 692-ton value derived from the global analysis model. The temporary jacking frames supported the dead and live loads while also accommodating thermal movements during the replacement of the existing steel bearings and upper portions of concrete pier columns.
By September 30, 2022, the steel trusses at Pier 50 were de-jacked with full live loads, and the loads were successfully transferred to the new HLMR bearings. As of April 17, 2023, the steel trusses at Piers 46 and 51 also rested on new bearings. The successful bearing replacement at these piers demonstrated the robustness and efficiency of the jacking and temporary support frames designed by CHI.
Acknowledgements: Skanska USA Civil (GC), NJ DOT (Owner), GPI (EOR of permanent structures), and HNTB (REI).