Foundation Design using SAFE
Aim:
Model the isolated footing provided in week 11 challenge on SAFE. Analyze and design it to verify the size, depth and steel provided as per calculations.
Procedure :
- Open the safe softwar
- Now select single footing
- Subgrade modulus = FOS x SBC / settlement
- Safe bearing capacity = 150 Kn / m^2
- FOS= 3
- Settlement = 50 mm
- Subgrade modulus = 3x 150/0.05= 9000 Kn/m^3
- The compression axial load for the load combination of (1.5 DL + 1.5 LL) is 2000 KN
- Unfactored load = 2000/1.5 = 1333.33 KN ==>1333.33 /2 = 666.65 KN
- Square footing for a column size of 400x400
- The thickness of the concrete footing to be 0.8m
- Define>material properties
- Add rebar as material property
- Define>section property>slab slection ther u can modify the slab properties
- give the thickness as 300mm
add stiffness property and give 800mm as thickness
- Add footing property and give 900mm as thickness
- Here all the values that we have given
- To assign the loads go the dra tab and point loads give the vakues
- load combinations as comb1 and load scale factor 1.5 for both the loads
- Run the analysis and click on the disoplay shell stress/forces
- values of the different regions are shown below
RESULT: The dispalcement of the deformed shape is less than 25mm
QUESTION 2
AIM:
A column of size 600x600 carrying an unfactored gravity load (DL+LL) of 1175 KN is to be supported on pile cap, which ultimately transfers load to the piles underneath. Piles of 16 metres length and 500 mm diameter are to be used. Each pile has a load carrying capacity of 200 KN. Model, analyse and design the pile cap on SAFE to evaluate the following:
- Pile group to be used
- Depth of pile cap
- Longitudinal steel on top and bottom face in both directions
PROCEDURE:
HERE IS THE SIXE OF THE FOOTING
set the material properties
and now set the slab properties as per the give in the question
set the refereral points to assign the loads
and for the set the point proprties
joint assignment has been set
set the load combinatuions of servicebility limit state method and ultimate limit state method
we should design the footing for ultimate design combinations
RUN the analysis
1) Check for settlement (Unfactored load) [SLS] (Serviceability limit state) (Limited to 50mm):
Hence all settlements are under satisfactory limit.
2) Check for soil pressure (Unfactored load) [SLS] (Serviceability limit state)
(should be within load bearing capacity of pile which is 200KN.
Click to display support reaction-
Support reactions are not exceeded safe bearing capacity of pile which is 200KN
3) Check for two way shear or punching shear (Factored load) [ULS] (Ultimate limit state) which should be less than 1.
All ratio is less than 1.
Hence okay.
4) Checking for reinforcement (Factored) [ULS] (Ultimate limit state). Minimum reinforcement should be 0.12% FOR HYSD as per IS-456:
