Foundation Design using SAFE
Aim – to Model the isolated footing provided in week 11 challenge on SAFE and Analyze and design it to verify the size, depth and steel provided as per calculations.
Procedure –
- Open safe 2020 and set the model initialization.
- To design a single isolated footing according to week 11.
Given data
- Square footing for a column size of 400 x 400.
- Factored compression axial load is 2000 kN.
- SBC is 150kN/m2 at a depth of 2m below EGL.
- M25 grade of concrete is used.
Assume data
- Unfactored load = 2000/1.5 = 1333.3kN
- L breakup = 1333.3/2 = 666.6kN
- LL breakup = 1333.3/2 = 666.6 kN
- Subgrade Modulus of the soil = (SBC x factor of safety)/ max settlement allowed.
= 150 x 3 / 0.05
= 9000 kN/m3
- Footing thickness = 800mm
- Safe Modelling
- Select single footing and input the data accordingly
- Now define materials,
- Now add load patterns
- Define subgrade modulus
- Assign both dead and live loads on the surface.
- Assign load combination
- Check for cover preferences
- Run analysis of the model.
Result
The given footing for a column size of 400 x 400 was designed and analyzed in the safe 2020 software.
Top an bottom flexural reinforcement requirement
Displacements
Punching shear
Aim – to model ,analyse and design the pile foundation on safe.
Procedure-
Given data-
- Column size = 600 x 600
- Unfactored load = 1175 kN
- DL breakup = 1175/2 = 587.5kN
- LL breakup = 1175/2 = 587.5 kN
- Pile dia = 500mm
- Load carrying capacity = 200kN
- Pile length = 16m
- Point spring of pile = A x E / L
- Where, A = Π/4 x 500^2 = 196349mm2
- E = 25000 N/mm2
- = 196349 x 25000 / 16000 = 306795 N/mm2
Modelling on safe
- Define material properties.
- Draw pile cap using quick draw tool
- Add reference points to place piles and column .
- Add column in between.
- Define load combinations for serviceability Limit state and ultimate limit state.
- Add load patterns and load combustions on the structure.
- Both dead and live load. And load combination.
- Run analysis on the model.
Result
- Displacement
- Max displacement is less than 0.84 hence safe
- Top and bottom reinforcement requirement
