ISOLATED FOOTING

FORMWORK · NP112 PRESSURES · FOOTING REINFORCEMENT · PEDESTAL REINFORCEMENT — EN 1992

⬡ FOOTING GEOMETRY — BASE

Lx — Talpa m

Ly — Talpa m

ht — Talpa m

Acoperire mm

⬡ FOOTING GEOMETRY — PEDESTAL

lx — Soclu m

ly — Soclu m

hs — Soclu m

ht — H Teren m

⬡ SITE DESCRIPTION

Pconv kPa

φ °

Analysis method

k — coef. pat kN/m³

⬡ LOADS ON THE PEDESTAL

N kN

Mx kNm

My kNm

Fx kN

Fy kN

⬡ PLAN VIEW AND SECTION

Tool information

What this page computes

This is the full design page for an isolated footing — from ground pressures through reinforcement to the construction drawing. Unlike calculators that return a single check, here the whole design chain of a column footing is carried out:

Ground pressures — the contact distribution under the footing, per NP 112
Footing reinforcement — in bending, from the moment in the footing cantilever (EN 1992)
Pedestal reinforcement — the connection to the column
Punching shear — the check of the slab against being punched by the column (EN 1992 §6.4)
Word calculation brief and DXF drawing — the final deliverables

Ground pressures (NP 112)

The pressure distribution under the footing is determined from the load eccentricity, over the zones of NP 112 Annex E:

full contact — when the eccentricity stays within the middle third; a bilinear distribution, all corners compressed
partial contact — when a corner or edge lifts off; the pressure concentrates on the remaining area, with a larger \(p_{max}\)

The lifted-corner zone, which has no simple formula, is solved exactly by the iterative Winkler solver. The maximum pressure is compared with the allowable soil pressure.

Reinforcement and punching

From the pressure distribution follows the moment in the footing cantilever, at the column face, from which the bottom reinforcement of the footing is computed (EN 1992). Separately, the slab is checked for punching on the control perimeter around the column — the failure by which the column would punch through the footing. For footings, the specific rule §6.4.4(2) applies, with the soil reaction inside the perimeter subtracted from the punching force.

The deliverables

The Word brief — a complete calculation report, with assumptions, formulas and checks, for the project documentation.
The DXF drawing — the parametric drawing of the footing (formwork and reinforcement, several views), ready to open in AutoCAD.

Input data

Geometry — the dimensions of the footing and the pedestal, the heights.
The column — the section dimensions, the position.
Loads — the axial force and the moments at the column base.
The soil — the allowable pressure.
Materials — the concrete class, the steel grade, the cover.

Assumptions and limitations

An isolated footing under a single column; strip footings, rafts and piled foundations are not covered.
The footing is taken as rigid when determining pressures (see also Winkler pressures).
The bearing-capacity and settlement check of the soil is geotechnical, outside this structural calculation.
Seismic actions and uplift (tensile axial force) are not treated.

Winkler pressures — just the pressure distribution, without reinforcement
Punching shear — the punching check, in detail
Stress bulb — the diffusion of stress in the ground under the footing
Concrete cover — for footings cast against the ground