Structural Inspection and Evaluation
Great Lakes Engineering Group (GLEG) partnered with Janssen & Spaans Engineering, Inc (JSE) and was selected by the Michigan Department of Transportation to perform the Structural Inspection and Evaluation of the Zilwaukee Bridge located in Bay City, MI. The Zilwaukee Bridge has a total deck area of 1.2Million SFT and consist of 3 different structures; northbound, southbound and Ramp H. GLEG provided engineering inspection teams that visually inspected, within arm’s length, the areas of the structure that are of concern based upon previous inspections and areas of high stress. Site reviews were performed during non-peak hours to minimize motorist inconvenience. Extensive coordination with the Bay Region, MDOT Reach-All Crew, and the Zilwaukee Bridge Crew were required to set up required lane closures and utilized the under bridge cranes for access.
Unique and Complex Structures. The mainline superstructures are single-cell, post-tensioned precast concrete segmental box girders. The decks of the mainline box girders are transversely post-tensioned. All spans except Spans H3 and H4 of Ramp H are variable depth with a variable bottom slab thickness. A latex modified concrete overlay was placed on the decks after the segments were erected. The superstructure is supported on twin, reinforced, hollow concrete shafts and reinforced concrete abutments. The substructure units are supported by reinforced concrete footings on steel H-piles driven to bedrock or to refusal. Disk bearing assemblies (previously pot bearings) are located at each pier and abutment unit to transfer the superstructure loads to the substructure units. Disk bearings are also located at the bridge expansion joint segments to transfer vertical and horizontal forces between the adjacent segments.
GLEG and JSE have both received outstanding performance reviews from our work on the Zilwaukee Bridge.