Innovative Parking Garage P-T Repair

PROJECT DETAILS

Riata Holdings acquired a ten-year old encapsulated post-tensioned parking garage as part of a property purchase. During an initial inspection, six unbonded tendons were identified as suspicious due to severe corrosion. Four of the corroded tendons were in three girders and two other tendons were in the seven inch slab. Tstrata was engaged to investigate the identified tendons and provide repair support, if necessary.

Tstrata began the investigation by removing the end pour back concrete on a 25-tendon girder. After removing the concrete, nine more heavily corroded anchorages were discovered. Concerned with the amount of corrosion on the anchors, Tstrata later removed the end pour back concrete on other girders and discovered severe corrosion existed in most of the tendons. The team also observed that no grease cap had been installed on any of the tendons, as is customary for encapsulated post-tension systems. These findings were brought to the attention of the site engineer. After coordinating with the owner and the engineering team, Tstrata was instructed to perform an investigation on the entire parking garage.

During the investigation, crews removed the concrete anchor pockets on all the girders, beams, and slab tendons throughout the parking garage – exposing severe corrosion of many of the tendon anchorages.  In several locations, the strand was completely disintegrated to the extent that the anchor could be removed by hand once the concrete pour back was removed. Once all the anchorage pockets were exposed, they were inspected by the owner’s team and Tstrata. Based on this inspection, it was concluded that all of the beam and girder tendons would need to be replaced (anchorages included ) along with over 60% of the slab tendons.