Case study | Structural Engineering
18-1006 I-74 over Oak/Market Street Rehabilitation (PTB 186-09)
Illinois Department of Transportation
$91,500 (KEG Fee)
Kaskaskia Engineering Group Inc. (KEG) was hired by exp. to assist with the rehabilitation of the structure carrying I-74 over Market Street in Champaign, Illinois. KEG’s services included geotechnical and structural engineering. The existing structure consists of a 3-span structure, originally constructed in 1957 and was widened in 1991. The existing structure consists of a composite concrete deck with steel beams, supported on reinforced concrete stub abutments on concrete piles and reinforced concrete hammerhead piers on a combination of concrete and timber piles. The bridge is 146’-6” back to back with a varying width from 121’-2” to 123’-11¼“. The purpose of the rehabilitation is to replace the superstructure with a shallower cross-section, improve the vertical clearance on Market Street, raise the existing substructure units to account for the new shallower superstructure, and replace the bridge approach slabs.
KEG’s structural role on this project was to provide design services for the approach slabs and rehabilitation to the substructure units. Structural design included the plan development for these specific areas and analyzing the existing substructure to ensure new design loads would not overstress the existing design. At the existing hammerhead piers, a detailed strut-tie analysis was completed because the new superstructure (designed by Lin Engineering) consisted of steel WF beams in a new arrangement, essentially transmitting the design loads to the substructure in new locations. This analysis resulted in an acceptable loading and the required plans were developed for this rehabilitation.
KEG was also responsible for performing additional borings on I-74 for the reconstruction of the overhead sign truss foundations. KEG personnel coordinated the drilling and logged the borings in the field. Laboratory testing and boring logs were prepared using gINT software.
Additionally, KEG structural personnel provided independent verification of the calculations for portions of the I-74 Bridge over the ICRR railroad. The structures carrying I-74 over ICRR are dual 4-span structures approximately 727’-8” in length. Each structure is approximately 60’-5” in width with a reinforced concrete deck supported by 80-inch deep plate girders. The abutments are open abutments founded on existing concrete piles. The piers consist of a multi-column configuration with crash walls. Piers 1 and 2 are to receive concrete repairs and pier cap extensions for the new superstructure. Pier 3 will be removed to the top of footing, with a new crashwall, columns, and pier cap to be installed. Independent calculation quality control (QA/QC) verification of the steel girder design, shear stud configuration, steel girder splices, abutment checks and Pier 3 design were completed.
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