RCC · foundation
Footing
1
Footing and design mode
plan on a 50 mm grid
Design mode
Footing type
Plan — searched
Thickness — searched
plan and thickness both searchedL along the frame’s X, B along Y
A step divides the projection and the thickness equally — this practice’s rule, which cl 34.1.3 does not fix. Stepping is less concrete but a deeper section, so cl 26.5.2.1’s minimum steel on the gross section rises with it. Every step face is checked in its own right — shear, bending, punching and development — and the section dimensions every course. Where the thickness will not divide into the courses asked for, a pad is designed instead. The results panel reports both.
2
The column it carries
cl 34.4 · cl 34.4.3
Grade of the column's concrete
Column tie, where ductile-detailed — IS 13920 cl 7.6.2
cl 34.4 takes the bearing stress on the weaker of the two concretes — M 20 here√(A₁/A₂) = 2.000 (capped)
3
The ground
cl 34.1.1 — the capacity is read as gross
p,max = 291.2 of 300 kN/m²own weight 16 kN · earth 96 kN
The capacity is taken as gross, so the footing’s own weight and the earth standing on it are added to the load rather than allowed for as a percentage. A net figure from a soil report has already had the overburden taken out of it and must not be entered here.
4
Loads at the base of the column
at service · cl 36.4.1 factors them
Pu = 750 kN · Mux = 0.0 · Muy = 0.0 kN·me = 0.000 / 0.000 m against L/6 and B/6 = 0.242 / 0.242
5
Materials and cover
Tables 3, 5, 16 · cl 26.4.2.2
Grade of concrete
Grade of steel
Exposure
Moderate needs M 25 — M 25 clears itcover 50 mm
cl 26.4.2.2 floors a footing’s cover at 50 mm. It raises Table 16 and never lowers it, so an extreme-exposure footing still takes its 75.
6
Reinforcement
the least-waste bar that is placeable
Bar sizes permitted
Top cage
L mat 12 Ø @ 180 · B mat 12 Ø @ 180governed by cl 26.5.2.1
Top cage 10 Ø and 10 Ø — the practice's own, not required by design: one size under the mat at its pitch, legs down onto it, and the mat turned up to the top of the footing slab to meet them. The least mat is 12 Ø @ 180 c/c, the practice’s own floor rather than a clause.