Post-Tensioning on Texas Skyscraper

STRUCTURAL TECHNOLOGIES worked with J.E. Dunn Construction to furnish an unbonded post-tensioning system for 360 Condominiums – a high-profile residential development in the heart of Austin, Texas.

As part of the City of Austin’s Green Building Program, the 44-story cast-in-place concrete structure includes environmentally friendly features, such as high-efficiency air filters, an Energy Star roof, low-flow toilets, high-performance glass, low-VOC paints and finishes, water-efficient landscaping, and reflective surfaces on the pool deck and patio designed to deflect heat build-up. The building also incorporates sustainable practices with indoor air quality control and reliance on regional materials.

Post-tensioned concrete played a major role in keeping the construction process and the structure green. Because of its durability, ease of production and cooling properties, concrete is already widely accepted as a viable green building material. The use of post-tensioning further elevates its sustainability by ensuring a more efficient use of materials. It is estimated that post-tensioned concrete can save up to a foot of floor space per level versus traditionally reinforced concrete. The amount of concrete and reinforcement saved by using post-tensioned concrete for 10 floors can be enough to create an additional floor.

On this project, post-tensioning materials were utilized on 44 levels. In total, over 1.1M feet of monostrand was installed along with 29,453 anchors. Level nine of the structure is the transfer level between the parking garage and the residential portion of the complex. The design included nine transfer girders measuring 72 inches wide and 88 inches deep. Stressing of the girders took place in three stages as the levels on top of the garage were constructed.

At 567 feet tall, 360 Condominiums holds the distinction of being one of the tallest buildings not only in Austin, but also in the state of Texas.