Critical Perimeter

Summary

Critical Perimeter - The critical perimeter is an interface across which shear resistance must be checked when calculating whether a slab will fail by punching shear.

Technical Information

The critical perimeter is considered lie a distance of 2d from the face of the loaded contact area, where d is the effective depth of the slab. Where multiple point loads are applied within a small area, the combined critical perimeter must be checked.

The position of the critical perimeter must always be checked when calculating the capacity of load transfer systems; there are instances where they overlap reducing the overall capacity of the system.

Loads applied adjacent to joints or the edges of the slab will have a reduced critical perimeter. It is not recommended to apply significant point loads at the edge of the slab.