This 200,000 square-foot parking structure in Menands, New York was constructed approximately 35 years ago and was comprised of three supported levels and an additional on grade level. Each floor was constructed with precast single tee-beams supported by precast columns founded on cast-in-place concrete piers and spread footings. The 6" cast-in-place floors were constructed with eight wire button head post-tensioned reinforced concrete and mild steel reinforcement.
When the garage experienced a failure at the second supported level, the owners focused their attention on repairing the structure.
Due to the garage condition, the owner decided to close the garage during the project. Closing the garage would allow multi-tasking on multiple levels to occur. This alternative strategy saved four months compared to a phased repair schedule. To accommodate the displaced cars, an outside parking lot was built on adjacent vacant property.
The structural integrity of the second level was fully compromised by the failure of slab button head tendons. Conventional repair methods would require full removal and replacement of the slab. Design engineers developed an innovative strategy to repair the concrete deck and install a monostrand post-tensioning system. The construction sequencing and tensioning sequencing omitted the need for additional shoring. This strategy saved time, money and prolonged the useful life of the structure.
Additional repair items included the removal of the existing cantilevered expansion joints and replacing them with a highly reinforced short span support. Teflon slide bearing plates were installed at the seat and new traffic bearing glands were installed. The new expansion joint concrete headers were placed so that water would run off away from the expansion joint.
Approximately 12,000 square feet of concrete spalls were repaired using conventional ICRI (International Concrete Repair Institute) standards, and cracked structural members were injected with epoxy resin.
To protect the repaired structure, the entire deck surface was shot blasted and sandblasted clean so that a silane sealer could be applied.
Quality control was ensured by regular testing of the concrete repair materials. Post-tensioning data was collected and cataloged for each tendon that was stressed and reviewed by design engineers. Design engineers were also present at critical milestone tasks such as tensioning and pre-concrete placement inspections. Manufacturers were also on-site during installation of specific products, such as silane sealers and expansion joints to ensure product installation in accordance with manufacturer's standards.
The team-oriented approach involving the engineer, contractor and owner resulted in a successful, timely and economical solution.