Footing geometry
Column
Loads (unfactored)
ULS: 1.35G + 1.5Q
Soil (geotech report)
Must come from a geotechnical investigation — never assumed.
Materials & bars
Extra main-direction layer(s)
Extra secondary-direction layer(s)
Extra layers stack additional bars beyond the auto-sized layout, for congested footings — the effective depth stays tied to the governing (auto-sized) layer.
Foundation Design
Isolated · EN 1992-1-1 · C25/30 · B500 (fyk 500)Governing checkSoil bearing95.4%ALL CHECKS PASS
Checks
| Check | Demand | Capacity | Util. | Status |
|---|---|---|---|---|
| Soil bearingGOVERNS | 190.7 kPa | 200.0 kPa | 95.4% | PASS |
| Flexure ∥ L | 2027 mm² | 2212 mm² | 91.6% | PASS |
| Flexure ∥ B | 2099 mm² | 2212 mm² | 94.9% | PASS |
| One-way shear (∥ B) | 419.4 kN | 441.2 kN | 95.0% | PASS |
| Punching shear | 0.628 MPa | 0.749 MPa | 83.9% | PASS |
| Development | 592 mm | 1025 mm | 57.7% | PASS |
Reinforcement
| Location | As req (mm²) | As min (mm²) | Provide | As prov (mm²) |
|---|---|---|---|---|
| Bars ∥ L (bottom) | 2027 | 1619 | 11φ16 @ 236 mm | 2212 |
| Bars ∥ B | 2099 | 1564 | 11φ16 @ 236 mm | 2212 |
Related calculators
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Axial and biaxial bending design with interaction diagram per EC2 and ACI.
⦿Rebar Calculator
Calculate rebar areas, number of bars and spacing for any diameter. Supports EC and ACI bar designations.
Foundation Design v1.0Validated against 5 benchmark cases →Learn: Development length and anchorage: why rebar needs to "grip" the concrete →Learn: Effective depth (d) vs overall depth (h): why the distinction matters →Learn: Understanding punching shear in slabs and footings →Learn: Bearing capacity: ultimate vs allowable, and why the tools take it as an input →Learn: Isolated, combined, strip, mat, or pile cap: what actually decides footing type →Learn: Why bearing pressure under a footing isn't uniform: eccentricity and the middle-third rule →Learn: Load paths: how a load actually gets from a slab to the foundation →Learn: ULS vs SLS: the two questions every structural check is really asking →
Bearing & sizing (service)▼
Service load on soil (self-weight + surcharge included)
P = N_D + N_L + W_f + q_s·A
P = 800 + 400 + 89.2 + 0.0
P = 1289.2 kN
Eccentricity along L
e = M/P
e = 0.0/1289.2
e = 0 mm ≤ L/6 = 433 mm
Peak service pressure
q = P/A · (1 ± 6e/L)
A = 6.76 m²
q_max = 190.7 kPa, q_min = 190.7 kPa
EN 1997 / geotechAllowable pressure comparison
q_max ≤ q_allow (from the geotechnical report)
190.7 vs 200.0
Ratio = 0.954 → OK
Suggested minimum area (concentric)
A_req = P/q_allow
A_req = 1289.2/200.0
A_req = 6.45 m² (provided 6.76 m²)
Factored net pressure (strength)▼
EN 1990Factored column load (net — footing weight causes no footing shear/moment)
Pu = 1.35·N_D + 1.5·N_L; Mu = 1.35·M_D + 1.5·M_L
Pu = 1.35×800 + 1.5×400
Pu = 1680.0 kN, Mu = 0.0 kN·m
Net factored pressure distribution along L
q_u = Pu/A · (1 ± 6e_u/L)
e_u = 0 mm
q_u = 248.5 … 248.5 kPa (avg 248.5)
Flexure (critical sections at column faces)▼
EC2 9.8Cantilever moments at the column faces
M = ∫q_u·x dA over the cantilever
cant_L = 1100 mm (q from 248.5 kPa edge), cant_B = 1100 mm (avg q)
Mu,L = 390.9 kN·m; Mu,B = 390.9 kN·m
EC2 6.1Bending along L: section design
K = MEd/(b·d²·fck); z = d·[0.5+√(0.25−K/1.134)] ≤ 0.95d
K = 390.9×10⁶/(2600×467²×25) = 0.0276
z = 444 mm
EC2 6.1Bending along L: required steel
As = MEd/(fyd·z), fyd = fyk/1.15
As = 390.9×10⁶/(435×444)
As,req = 2027 mm²
EC2 6.1Bending along B: section design
K = MEd/(b·d²·fck); z = d·[0.5+√(0.25−K/1.134)] ≤ 0.95d
K = 390.9×10⁶/(2600×451²×25) = 0.0296
z = 428 mm
EC2 6.1Bending along B: required steel
As = MEd/(fyd·z), fyd = fyk/1.15
As = 390.9×10⁶/(435×428)
As,req = 2099 mm²
EC2 9.2.1.1 / 9.3.1.1Minimum reinforcement
As,min = max(0.26·fctm/fyk, 0.0013)·b·d
along L: 1619 mm²; along B: 1564 mm²
Provide: 11φ16 @ 236 mm ∥L; 11φ16 @ 236 mm ∥B
One-way (beam) shear▼
EC2 6.2.2Critical sections at d from each column face
V = resultant of q_u outside the section
x_L = 633 mm, x_B = 649 mm from edges
Vu,L = 409.0 kN; Vu,B = 419.4 kN
Concrete shear resistance ∥ L
VRd,c = max(0.12·k·(100ρ·fck)^⅓, vmin)·b·d
k = 1.654, ρl = 0.182%, vRd,c = 0.372 MPa
VRd,c = 452.2 kN → ratio 0.905
Concrete shear resistance ∥ B
same provision, d of the upper layer
k = 1.666, ρl = 0.189%, vRd,c = 0.376 MPa
VRd,c = 441.2 kN → ratio 0.950
EC2 6.2.2(6)Note
Loads within 2d of the face may be reduced by a_v/2d — enhancement conservatively ignored here
Conservative
Two-way (punching) shear▼
EC2 6.4.4(2)Foundation punching: perimeters within 2d, resistance enhanced by 2d/a, load reduced by soil reaction inside
vEd = β·VEd,red/(u·d) ≤ vRd,c·2d/a
checked a = 2d and a = d; β = 1.00
governing a = 1.0d
At a = 2d
u = 7368 mm, VEd,red = 617.3 kN
u = 7368 mm at a = 2.00d, β = 1.00, vRd,c·2d/a = 0.374 MPa
vEd = 0.183 vs 0.374 MPa → 48.8%
At a = d
u = 4484 mm, VEd,red = 1293.2 kN
u = 4484 mm at a = 1.00d, β = 1.00, vRd,c·2d/a = 0.749 MPa
vEd = 0.628 vs 0.749 MPa → 83.9%
EC2 6.4.5(3)Maximum shear at the column perimeter
vEd,0 = β·VEd/(u0·d) ≤ vRd,max
u0 = 1600 mm, ν = 0.540, vRd,max = 4.50 MPa
vEd,0 = 2.288 MPa → 50.8% OK
Development / anchorage▼
EC2 8.4.3 / 8.4.4Straight development of bottom bars beyond the column face
lbd = (φ/4)·(σsd/fbd) ≥ max(0.3·lb,rqd, 10φ, 100)
available = cantilever − end cover = 1100 − 75
required 592 mm vs available 1025 mm → OK (straight)
Step values are shown in SI (kN, kN·m, mm, kPa, MPa) regardless of the display-unit toggle. Utilization of 100% means fully stressed.