The City of South Bend’s Main and Colfax Parking Structure is a seven-story parking garage constructed in 1969. The two-bay structure consists of a slab-on-grade level and six supported levels of cast-in-place, monostrand post-tensioned concrete slabs supported by precast, post-tensioned beams, and columns. The framing of the structure forms a double-threaded helix with short ramps at each end and traffic crossovers at every other level. The structure provides 420 parking spaces with angled parking and one-way traffic flow. The original design of the supported levels consists of a 5 1/2” one-way post-tensioned slab. Previous repairs performed in 2004 installed nine galvanized, supplemental steel beams equally spaced in the east-west direction in each bay to help support the slab and change the span direction from the designed north-south. Because of this repair, the original structural post-tensioning tendons have been abandoned, though the temperature tendons spanning east to west are still required.

Project Highlights 

• WGI’s previous 2019 repairs consisted of slab and wall repairs at each level of the structure. 
• The 2020 repair program focused on full-depth slab replacement across Level 5, the level with the highest concentration of delaminations. 
• 2020 repairs included large-scale slab repair/replacement, sealant repairs, and deck coating repairs in the east bay of Level 5. 
• Design challenges included accounting for the supplemental steel beams, which fundamentally changed the structural action of the facility 
• The project was completed on time and within budget