Located in Austin, TX, the Austonian is a 59-story, 683-foot tall high-rise condominium. The building is comprised of reinforced concrete structural elements and unbonded, post-tensioned concrete slabs.
Six years after its original construction, a five-foot long concrete spall fell from a balcony edge and landed on the base of the building. Fortunately, no one was injured and there was minimal property damage. After the incident, an inspection was conducted and signs of distress were found around many areas around the balcony edges and eyebrows of the building. The investigation also found a misplaced bar in the slab had created a low cover condition that led to delamination spall for much of the buildings slab edges. To mitigate the risk of falling hazards, numerous temporary protective measures, such as steel plating anchored to deteriorated slab edges, were put in place to secure the delaminated concrete until a permanent solution was installed.
The Engineer of Record, Pivot Engineers, reached out to STRUCTURAL TECHNOLOGIES to assist with the design, materials, and constructability of the final repairs. The team then brought STRUCTURAL, an exclusive licensee of STRUCTURAL TECHNOLOGIES, on to the project to remove 10,000 LF and 4 inches of every slab edge back to expose the post-tensioning system, install galvanic anodes, remove corroded rebar, install new GFRP slab edge reinforcement, and recoat all balconies, slab edges, and balcony soffits. The team also removed the misplaced bar causing corrosion and installed new GFRP composite slab edge reinforcement.
As one of the tallest buildings in Austin, safely accessing and completing the work via swing-stages was a challenge that the team had to overcome. In order to keep everyone safe, the team created a safety plan for working at extreme heights over a busy metropolitan area, and a 100% tool tie off and dropped object protection plan was used to mitigate the risk of dropped objects. The crew also created a sidewalk bridging system around the building that didn’t interfere with pedestrian, vehicular or delivery truck traffic to add extra protection. Also, due to the shape of the building, wind could easily pick up speed around it, so the team set up a system to make sure team was safe around wind conditions hanging on swing stages.
The Owner, Pivot Engineers, and City of Austin inspectors required stringent QA/QC documentation and reporting to sign off on the repairs. To satisfy these requirements, the team employed a cloud-based project management software program and captured over 5,000 progress photographs to successfully document and update the project stakeholders as needed. This allowed for someone who was working on the swing stages to communicate conditions in real time as the work was being done.
The project was completed safely, on time and within the budget constraints