Footing result
This is a sample calculation. Enter your own footing to run a real check.
Run your own footing
Combined footing
168 × 72 × 24 in
qa 4.5 ksf
f′c 4,000 psi
fy 60 ksi
#5 bottom bars
d 20.69 in
PASS
All checks pass: bearing, flexure, shear, punching shear, development length, column interface.
Soil bearing, overturning and sliding
PASS
D/C bearing (q max / q net)
0.77
- qmax (maximum service pressure)
- 3.06 ksf
- qnet (net allowable pressure)
- 3.96 ksf
| Quantity | Value |
|---|---|
| qmax (maximum pressure, ksf) | 3.06 |
| qmin (minimum pressure, ksf) | 3.01 |
| qnet (qa less overburden and self-weight, ksf) | 3.96 |
| eL (eccentricity from ML, in) | 0.00 |
| B/6 (kern limit for eL, in) | 12.00 |
| eB (eccentricity from MB, in) | 0.24 |
| L/6 (kern limit for eB, in) | 28.00 |
| Footing self-weight (kip) | 25.20 |
| Soil weight above footing (kip) | 20.16 |
| Fresist (friction resistance, kip) | 127.50 |
| FSot (overturning factor of safety, minimum 1.5) | N/A (no overturning moment) |
| FSslide (sliding factor of safety, minimum 1.5) | N/A (no lateral force) |
| Bearing (qmax ≤ qnet) | Satisfied |
| Kern (e within B/6 and L/6, full contact) | Within kern |
| Overturning (FS ≥ 1.5) | Satisfied |
| Sliding (FS ≥ 1.5) | Satisfied |
Service loads; friction-only sliding resistance
ACI 318-19 §13.2.1 · §13.2.2
Flexure
PASSLongitudinal positive moment (bottom steel)
D/C moment
0.42
- φMn (design moment capacity)
- 311.04 kip-ft
- Mu (factored moment at column face)
- 132.03 kip-ft
| Quantity | Value |
|---|---|
| b (design width, in) | 72.0 |
| d (effective depth, in) | 20.69 |
| As,req (steel required for Mu, in²) | 1.43 |
| As,min (minimum steel, in², §13.3.3.2) | 3.11 |
| Bars (number of #5 bars) | 11 |
| As,prov (steel provided, in²) | 3.41 |
| s (center-to-center spacing, in) | 6.54 |
| Clear spacing (in, minimum max(db, 1 in), §25.2.1) | 5.91 |
| a (stress block depth, in) | 0.84 |
| φMn (design moment strength, kip-ft) | 311.04 |
| Status | PASS |
Transverse band at column 1
D/C moment
0.38
- φMn (design moment capacity)
- 164.31 kip-ft
- Mu (factored moment at column face)
- 63.28 kip-ft
| Quantity | Value |
|---|---|
| b (design width, in) | 38.1 |
| d (effective depth, in) | 20.06 |
| As,req (steel required for Mu, in²) | 0.71 |
| As,min (minimum steel, in², §13.3.3.2) | 1.64 |
| Bars (number of #5 bars) | 6 |
| As,prov (steel provided, in²) | 1.86 |
| s (center-to-center spacing, in) | 6.29 |
| Clear spacing (in, minimum max(db, 1 in), §25.2.1) | 5.66 |
| a (stress block depth, in) | 0.86 |
| φMn (design moment strength, kip-ft) | 164.31 |
| Status | PASS |
Transverse band at column 2
D/C moment
0.51
- φMn (design moment capacity)
- 164.31 kip-ft
- Mu (factored moment at column face)
- 84.37 kip-ft
| Quantity | Value |
|---|---|
| b (design width, in) | 38.1 |
| d (effective depth, in) | 20.06 |
| As,req (steel required for Mu, in²) | 0.94 |
| As,min (minimum steel, in², §13.3.3.2) | 1.64 |
| Bars (number of #5 bars) | 6 |
| As,prov (steel provided, in²) | 1.86 |
| s (center-to-center spacing, in) | 6.29 |
| Clear spacing (in, minimum max(db, 1 in), §25.2.1) | 5.66 |
| a (stress block depth, in) | 0.86 |
| φMn (design moment strength, kip-ft) | 164.31 |
| Status | PASS |
φ = 0.90; critical section at the column face
ACI 318-19 §13.2.7.1 · Table 21.2.2 · §25.2.1
One-way shear
PASSLongitudinal (governing section)
D/C shear
0.51
- φVc (design shear capacity)
- 74.49 kip
- Vu (factored shear at d from the face)
- 38.15 kip
| Quantity | Value |
|---|---|
| ρw (As,prov / (bw·d)) | 0.0023 |
| Vc (concrete shear strength, kip) | 99.33 |
| φVc (design shear strength, kip) | 74.49 |
| Vu (factored shear, kip) | 38.15 |
| Status | PASS |
Transverse (governing band)
D/C shear
0.49
- φVc (design shear capacity)
- 38.99 kip
- Vu (factored shear at d from the face)
- 19.27 kip
| Quantity | Value |
|---|---|
| ρw (As,prov / (bw·d)) | 0.0024 |
| Vc (concrete shear strength, kip) | 51.99 |
| φVc (design shear strength, kip) | 38.99 |
| Vu (factored shear, kip) | 19.27 |
| Status | PASS |
φ = 0.75; no shear reinforcement
ACI 318-19 §13.2.7.2 · Table 22.5.5.1
Punching shear
PASSColumn 1
D/C punching shear Column 1
0.18
- φVc (design punching capacity)
- 593.41 kip
- Vu (factored punching demand)
- 107.39 kip
| Quantity | Value |
|---|---|
| davg (average effective depth, in) | 20.38 |
| bo (critical perimeter at d/2, in) | 153.5 |
| Area inside perimeter (in²) | 1,473 |
| β (long side / short side of column) | 1.00 |
| αs (location factor, §22.6.5.3) | 40 |
| vc (a) (4λsλ√f′c, psi) | 253.0 |
| vc (b) ((2 + 4/β)λsλ√f′c, psi) | 379.5 |
| vc (c) ((2 + αsd/bo)λsλ√f′c, psi) | 462.3 |
| vc governing (minimum of (a), (b), (c), psi) | 253.0 |
| Vc (vc·bo·d, kip) | 791.22 |
| φVc (design punching strength, kip) | 593.41 |
| Critical perimeter fits in the footing | Yes |
Column 2
D/C punching shear Column 2
0.26
- φVc (design punching capacity)
- 593.41 kip
- Vu (factored punching demand)
- 157.39 kip
| Quantity | Value |
|---|---|
| davg (average effective depth, in) | 20.38 |
| bo (critical perimeter at d/2, in) | 153.5 |
| Area inside perimeter (in²) | 1,473 |
| β (long side / short side of column) | 1.00 |
| αs (location factor, §22.6.5.3) | 40 |
| vc (a) (4λsλ√f′c, psi) | 253.0 |
| vc (b) ((2 + 4/β)λsλ√f′c, psi) | 379.5 |
| vc (c) ((2 + αsd/bo)λsλ√f′c, psi) | 462.3 |
| vc governing (minimum of (a), (b), (c), psi) | 253.0 |
| Vc (vc·bo·d, kip) | 791.22 |
| φVc (design punching strength, kip) | 593.41 |
| Critical perimeter fits in the footing | Yes |
φ = 0.75; concentric loading only
ACI 318-19 §22.6.4.1 · Table 22.6.5.2
Development length
PASSLongitudinal (governing)
D/C development length
0.50
| Quantity | Value |
|---|---|
| ld (development length, in) | 14.2 |
| ld adjusted (reduced for excess steel, minimum 12 in, in) | 12.0 |
| lavail (available length beyond the critical section, in) | 24.0 |
| cb (cover or half spacing term, in) | 3.27 |
| ψt (casting position) | 1.00 |
| ψe (coating) | 1.00 |
| ψs (bar size) | 0.80 |
| ψg (grade) | 1.00 |
| Status | PASS |
Transverse (governing)
D/C development length
0.50
| Quantity | Value |
|---|---|
| ld (development length, in) | 14.2 |
| ld adjusted (reduced for excess steel, minimum 12 in, in) | 12.0 |
| lavail (available length beyond the critical section, in) | 24.0 |
| cb (cover or half spacing term, in) | 3.14 |
| ψt (casting position) | 1.00 |
| ψe (coating) | 1.00 |
| ψs (bar size) | 0.80 |
| ψg (grade) | 1.00 |
| Status | PASS |
Straight bars in tension, no hooks
ACI 318-19 §13.2.7.1 · Eq. 25.4.2.4a · Table 25.4.2.5
Column to footing interface
PASSColumn 1
D/C bearing on concrete Column 1
0.10
- φBn (design bearing strength)
- 1,432.08 kip
- Pu (factored load)
- 150.00 kip
| Quantity | Value |
|---|---|
| A1 (loaded area, in²) | 324 |
| A2 (supporting area (frustum base), in²) | 4,356 |
| φBn (design bearing strength, kip, §22.8.3.2) | 1,432.08 |
| As,dowel,min (minimum dowel area, in², §16.3.4.1) | 1.62 |
Feasible dowel sizes (Column 1)
Sizes whose compression development length fits in the footing depth. A design aid; detailing is the engineer’s responsibility.
| Bar | Number | ldc (in) |
|---|---|---|
| #4 | 9 | 9.5 |
| #5 | 6 | 11.9 |
| #6 | 4 | 14.2 |
| #7 | 3 | 16.6 |
| #8 | 3 | 19.0 |
Column 2
D/C bearing on concrete Column 2
0.13
- φBn (design bearing strength)
- 1,432.08 kip
- Pu (factored load)
- 200.00 kip
| Quantity | Value |
|---|---|
| A1 (loaded area, in²) | 324 |
| A2 (supporting area (frustum base), in²) | 4,356 |
| φBn (design bearing strength, kip, §22.8.3.2) | 1,432.08 |
| As,dowel,min (minimum dowel area, in², §16.3.4.1) | 1.62 |
Feasible dowel sizes (Column 2)
Sizes whose compression development length fits in the footing depth. A design aid; detailing is the engineer’s responsibility.
| Bar | Number | ldc (in) |
|---|---|---|
| #4 | 9 | 9.5 |
| #5 | 6 | 11.9 |
| #6 | 4 | 14.2 |
| #7 | 3 | 16.6 |
| #8 | 3 | 19.0 |
φ = 0.65 for bearing
ACI 318-19 §22.8.3.2 · §16.3.4.1 · §25.4.9.2