Post-Tensioned Slab
Definition
A concrete slab in which steel tendons running through plastic ducts are tensioned after the concrete hardens, improving span capacity. Corrosion of tendons or the reinforcing steel in the slab was a key factor in the Surfside collapse.
- Construction
- Steel tendons in plastic ducts, tensioned after concrete hardens
- Benefit
- Increased span capacity
- Failure factor
- Corrosion of tendons or reinforcing steel
- Case example
- Surfside condominium collapse
Common questions
Why is corrosion especially dangerous in a post-tensioned slab compared to conventionally reinforced concrete?+
The tendons carry the slab's load in high tension, so corrosion-induced section loss or a snapped tendon removes load-bearing capacity abruptly rather than gradually, and damage inside the duct is often hidden from routine visual inspection until failure is imminent.
What investigative role does the slab design play in a structural collapse inquiry?+
Forensic engineers examine tendon condition, duct grouting quality, and corrosion evidence at the failure origin to determine whether design, construction defects, or long-term maintenance neglect caused the loss of tensioning capacity that preceded collapse.
Related terms
- Carbonation Depth
- The depth to which CO2 has penetrated concrete and neutralised its alkalinity, destroying the protective environment around embedded steel and initiating corrosion....
- Column Tributary Area
- The floor area whose load is carried by a given column. Adding floors or placing heavy equipment increases the load on existing...
- Disproportionate Collapse
- Collapse extent that is far greater than would be expected from the triggering event. Ronan Point is the canonical example: a small...
- Lift-Slab Construction
- A method in which floor slabs are cast at ground level and hydraulically jacked up steel columns to their final position. The...
- Punching Shear
- A failure mode in which a concentrated load punches through a concrete slab around its bearing perimeter. It can occur at a...