Checks for limiting parameters (pad and strip base: ACI 318)
Limiting reinforcement parameters are specified in Design Options > Foundations > Isolated Foundations > Reinforcement Layout
Limits on bar size and reinforcement quantities
For structural foundations of uniform thickness the minimum areaof tensile reinforcement shall be:
For metric units:
IF Grade 280 to 350 deformed bars are used
| As,min,reqd |
|
b*h*0.0020 |
IF Grade 350 to 420 deformed bars or welted wire reinforcement are used
| As,min,reqd |
|
b*h*0.0018 |
IF yield stress exceeds 420 MPa
| As,min,reqd |
|
b*h* [MAX(0.0014 , 0.0018*420/fy)] |
For US-units:
IF Grade 40 to 50 deformed bars are used
| As,min,reqd |
|
b*h*0.0020 |
IF Grade 50 to 60 deformed bars or welted wire reinforcement are used
| As,min,reqd |
|
b*h*0.0018 |
IF yield stress exceeds 60000 psi
| As,min,reqd |
|
b*h*[MAX(0.0014 , 0.0018*60000/fy)] |
|
where |
||
| b |
|
unit width |
The maximum area of tensile reinforcement shall be:
| As,max |
|
0.85*(f`c/fy)*β1*b*d*(3/7) |
|
where |
||
| Ag |
|
the gross area of the concrete section |
| V |
|
stress block depth factor1 |
metric-units
| β1 |
|
0.85 | for f`c ≤ 28Mpa |
|
0.85 – 0.05 *[(f'c – 28MPa)/7MPa] | for 28MPa < f`c < 55Mpa | |
|
0.65 | for f`c ≥ 55MPa |
US-units
| β1 |
|
min(max(0.85 - 0.05 ´ (f'c - 4 ksi) / 1ksi, 0.65), 0.85) | |
|
0.85 | for f`c ≤ 4000 psi | |
|
0.85 – 0.05 *[(f'c – 4ksi)/1ksi] | for 4000 psi < f`c < 8000psi | |
|
0.65 | for f`c ≥ 8000 psi | |
1 ACI 318-08, ACI 318-11, ACI 318M-08
and ACI 318M-11 Section 10.2.7.3