Lift-Slab Construction
Definition
A method in which floor slabs are cast at ground level and hydraulically jacked up steel columns to their final position. The method was used at L'Ambiance Plaza and is associated with punching-shear hazard during the lifting sequence.
- Method
- Slabs cast at ground level, jacked up columns
- Known case
- L'Ambiance Plaza
- Hazard
- Punching shear during the lifting sequence
Common questions
Why is the lifting sequence itself the dangerous phase in lift-slab construction?+
During lifting, a slab is temporarily supported only at the jacking collars around the columns rather than by a fully cured, permanently connected structural system, so loads concentrate at those collar points and can trigger localised punching-shear failure before the structure is complete.
What does punching shear mean in this context?+
It refers to a slab failing by a column or collar effectively punching a cone-shaped hole through the concrete around it, a failure mode that concentrated point loads during temporary lifting stages can trigger even when the slab would be adequate once fully installed.
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...
- Post-Tensioned Slab
- A concrete slab in which steel tendons running through plastic ducts are tensioned after the concrete hardens, improving span capacity. Corrosion of...
- Punching Shear
- A failure mode in which a concentrated load punches through a concrete slab around its bearing perimeter. It can occur at a...