Foundation Design

Punching shear check — Isolated Footing & Raft Foundation · ACI 318-25 · Eurocode 2 · IS 456:2000

Input Parameters

ACI 318-25 · kN-m
Raft foundation: Vu entered directly. Drop panel and edge/corner columns supported.
Slab Properties
m
MPa
m
m
d = h − cv − db = 0.259 m
Column
m
m
Loading
kN
kN·m
kN·m
Shear Reinforcement (optional)
Drop Panel (optional)
📋
Enter values and click Calculate.

Input Parameters

EN 1992-1-1 · kN-m
Raft foundation: VEd entered directly. Drop panel and edge/corner columns supported.
Slab Properties
m
MPa
m
m
d = h − cv − db = 0.259 m
%
%
Column
m
m
Loading
kN
kN·m
kN·m
Shear Reinforcement (optional)
Drop Panel (optional)
📋
Enter values and click Calculate.

Input Parameters

IS 456:2000 · kN-m
Raft foundation: Vu entered directly. Drop panel and edge/corner columns supported.
Slab Properties
mm
N/mm²
mm
mm
d = h − cv − db = 259 mm
Column
mm
mm
Loading
kN
Shear Reinforcement (optional)
Drop Panel (optional)
📋
Enter values and click Calculate.

📚 Design Background & Code References

Punching Shear in Foundations

A column punching through its foundation creates a truncated cone failure surface. The critical check is whether the shear stress on the control perimeter exceeds the concrete capacity.

Isolated Footing — Net Force

The upward soil reaction within the critical perimeter partially counteracts the column load. Only the net force outside the critical area contributes to punching:

Net Punching Force (ACI / IS 456)
Vu,net = Pu − qu × Acrit
qu = Pu / (B × L)   Acrit = (c1+d)(c2+d) [interior rect.]
Net Punching Force (EC2 §6.4.4)
VEd,red = VEd − qEd × Aenc
Aenc = c1c2 + 4d(c1+c2) + 4πd² [interior rect. at 2d]

Raft Foundation

For mat/raft slabs, the punching check is equivalent to a flat slab. Vu/VEd is the column reaction from structural analysis. Drop panels may reduce the demand-to-capacity ratio by locally increasing depth.