A seven level parking garage located in Milwaukee, Wisconsin was in need of significant repair. Throughout the garage, on every slab, post-tensioned tendons needed replacement and deteriorating concrete required repair.

Because the garage needed to remain in operation, the owner’s major concerns included maintaining safety, minimizing disruption and keeping as much of the garage available for use during the extensive repairs.

Understanding the technical challenges of repairing post-tensioned cables and the safety issues relating to the structure, the patrons, and the workers when highly tensioned cables are repaired, the owner selected STRUCTURAL to perform the work. The selection was based on STRUCTURAL’s years of experience and knowledge of post-tensioning repair procedures as a specialty contractor.  STRUCTURAL also had access to VSL® post-tensioning products and engineering support through STRUCTURAL TECHNOLOGIES.

Repair Strategy

The scope of the project included providing extensive general concrete repair and maintenance and post-tensioned repair. In total, the repair included the installation of 631 new post-tensioned end anchors and more than five miles of new post-tensioned tendons. The project also required 5,000 square feet of partial-depth concrete repair and 8,800 square feet of full-depth repair.

The techniques used were designed to enhance the efficiency of the repairs and durability of the structure. The project also used external post-tensioning to strengthen beams where tendons had been damaged due to corrosion.

Project Execution

To perform the general repairs, STRUCTURAL’s crews performed demolition on the needed areas, prepared the surface, supported structural members as necessary, and poured and cured new concrete. The concrete mix design included high early strength cement to help shorten the schedule. By using rapid-setting repair materials, STRUCTURAL’s crews could pour the concrete and within two to three days stress the tendons.

As the project was underway, the scope of needed repairs increased which put pressure on the schedule and budget. STRUCTURAL worked closely with the engineer and owner to develop the most efficient repair solutions and phasing approaches to minimize disruption. STRUCTURAL’s coordination helped maintain the traffic flow while keeping the work area separate from the public. In all, 13 phases of construction were completed over a two and a half year period.

As a result of STRUCTURAL’s innovative repairs, the parking garage was a 2013 winner of the Post Tensioning Institute’s Award of Merit: Rehabilitation of a Parking Garage.