- About Us
- Current Jobs
- R & D
Location: Garden City Skyway, St. Catharines
Description: Structure Rehabilitation, Jacking
The Garden City Skyway Bridge (GCS) is located along the Queen Elizabeth Way in the City of St. Catharines. It consists of forty-eight spans for a total length of 2,200 m. The superstructure is constructed of steel box and I-girders with concrete deck and the substructure consists of solid and hollow core concrete piers, ranging in height from 5.9 m near the abutments to 34.1 m supporting the main span over the St-Lawrence Seaway Canal. The rehabilitation of the main superstructure was carried out in early 2002. This rehabilitation of the substructure was carried out in medium size contracts over an approximate 10 year period.
The repair and rehabilitation of the GCS bridge substructure components involved rehabilitation of the concrete surface with form and pump technology utilizing self-consolidating concrete. The scope of work also included the upgrading of the bridge bearing and structural steel system at the bridge piers.
The existing bearings were rocker bearings at all expansion joint locations, with the exception of the abutments. Some of the bearings, which are in fair condition, exhibit minor pitting from corrosion. Significant debris was observed on the pier caps and in the bearing mating surfaces. The original contract called for pin replacement at the long span high load rocker bearing locations. The original structure was not designed for jacking therefore major modifications had to be completed prior to lifting and replacing of the bearings. Very limited space was available for installation of the components included in the lifting system. Several detailed field surveys were completed to ensure the proper fit of the additional steel members. The jacking design included an entire jacking system & procedure that was able to sustain and resolve field conflicts, which included rocker bearing pin replacement, structural steel support design with all the details including temporary slide bearings, which were used on top of the upper steel members. The total required lifting capacity was: 11,500 KN. All eight pins of the rocker bearings were successfully removed and the jacking operation was extremely successful. This custom jacking design included a multi-point jacking design, utilizing multi jacks synchronized to perform as one unit.
For this project, access design included a multipoint suspended platform for the pier cap rehabilitation work. The platform was anchored to the bottom flange of the girders without damaging the existing structure. Structural analysis was carried out for different types of loading conditions to ensure the structural stability of the platform. The platform was approximately 30m from the ground elevation. Stair towers were used to provide access. Due to the depth of the pier cap and the steel girders, additional scaffolding design was needed to be used on top of the suspended platform. Again, several different structural analyses were completed to ensure that the “leg” loads were located at the best possible position of the platform and provide the required workspace for the workers. High wind loads also had to be considered into this access design.