Post-Tensioning Innovation: Turning Columns into Structural Suspension Systems
At Interspan, we are continually exploring innovative ways to extend the application of post-tensioning beyond conventional slabs and beams.
On a recent project, our team encountered a complex structural challenge: Levels 1 and 2 were required to be supported by hanging columns suspended below Level 3, a scenario where traditional compression-based column design was not feasible.
Our solution redefined the column’s role entirely.
Stress Bar Post-tensioning Solution
Each of the three hanging columns was transformed into a tensile structural element by installing a 40 mm-high-strength stress bar. Each bar was carefully stressed to 900 kN, creating a robust suspension system that allows the upper floors to be effectively hung from the structure above.
This approach replaced conventional load paths with a controlled tensioning strategy, delivering both structural efficiency and architectural flexibility.
Read more about Stress Bar Post-tensioning
Project highlights:
- Hanging columns designed as tensile elements
- 40 mm stress bars stressed to 900 kN
- Upper floors suspended from the structure above
- Non-traditional application of post-tensioning technology
The result is a clear demonstration of how post-tensioning technology can be adapted to solve highly specialised engineering challenges—unlocking new design possibilities where conventional solutions fall short.
Interspan Strengthening & RepairÂ
Interspan uniquely integrates in-house post-tensioning expertise, advanced forensic diagnostics, and cutting-edge strengthening technologies to enable a single-source delivery model trusted by global developers for complex retrofit and reuse projects.
NEW STRUCTURES
The Interspan Group brings unique expertise in post-tensioning, construction methodology, and lifting operations that reduce CO₂ emissions, material use, and construction program duration.
EXISTING STRUCTURES
We specialise in helping clients extend the lifespan of concrete structures through advanced repair, strengthening, and carbon-fibre solutions. Adaptive reuse projects are a perfect fit for our expertise, helping to minimise waste while delivering safe, modern outcomes that support community growth.
Over the last decade, the Interspan Group has become a market leader in the application of CFRP-strengthening solutions, with notable projects including the award-winning The Space House in London and the Quay Quarter Tower in Sydney.
Quality Assurance
Quality Assurance is of immense significance to Interspan because it impacts the safety of our operatives and future occupants, the long-term durability of our structures, and our client satisfaction and relationships.
Interspan is accredited under CARES APTO1 for the Production and Supply of Post-tensioning Anchorage Systems and is the only post-tension contractor in Australia accredited under CARES APTO4 for the supply and installation of Post-tensioning systems in concrete structures.
Sustainability
Post-tensioning and adaptive reuse are powerful design approaches that reduce material use and embodied carbon—delivering more efficient, resilient, and sustainable structures for the future.
