Foundation Design using SAFE
AIM:
- To analyze and design the isolated footing from week 11 challenge on Safe
- To verify the size, depth and steel provided as per calculations
INTRODUCTION:
- csi safe ( slab analysis by the finite element mehod) is the best tool for designing concrete slabs and foundations.
- safe provide easiness to engineeer towards the safe design of structures with powerful tools like draw, analyze, design and detailing etc.
- laying out models is quick and efficient way with the user- friendly drawing tools, or user can import model from autocad or loading conditions from other softwares like CSI ETABS and csi SAP2000.
PROCEDURE:
STEP: 1
open the SAFE application
selct new model
followed by input settings,
unit was selected as metric and code IS 456- 2000.
SINGLE FOOTING was selected next
subgrade modulus= F.O.S x S.B.C/Settelment = 3 x 150/ 0.05
= 9000 KN/ m^3
The compression axial load for the load combination ( 1.5 DL + 1.5 LL) is 2000KN.
Unfactored load = 2000/ 1.5 = 1333.3 KN
1333.3/2 = 667 KN
Footing thickness 800mm
Step : 2
Define materials
- add M25 concrete
- Add rebar fe500
Material property data:
click define folloed by material properties
M25 grade of concrete
modulus of elasticity,
E = √25 X 5000
= 25000 N/ mm ^2
Step : 3
Define slab properties
Define properties for MAT
Define properties for stiff
Step : 4
Step : 5
Define soil subgrade modulus
STEP: 6
Assign point load
STEP: 7
Assign load combinamtions
STEP: 8
check design preference (min cover 50mm)
STEP: 9
run analysis and design
RESULT:
HENCE, THE ISOLATED FOOTING WAS DESIGNED AMD ANALYIZED IN SAFE SUCCESSFULLY.
2. 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
ans :
AIM:
- To model analysis, 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
INTRODUCTION:
- Csi safe (Slab analysis by the fifnite element method) is the best tool for desining concrete slabs and foundation.
- Safe provide easiness to engineer towards the safe design of structures with powerful tools like draw, analysis, design, and detailing etc.
- laying out models is quick and efficient way with the user- freiendly drawing tools, or user can import model from autocad or loading conditions from other softwares like CSI SAP 2000 and CSI ETABS.
PROCEDURE:
GIVEN DATA:
column size 600 X 600
Unfactored load 1175 KN
Pile length 16 m
pile diameter 500mm
Load carrying capacity 200 KN
Calculations:
Number of pilers 1175/200 = 5.8 = 6
spring constant E x A/ L
Where E is 25000 N/ mm^2
Area A Π/4 X 500^2 = 196349 mm^2
Pile length , L 16000 mm
Spring constant E x A /L = 25000 x 196349 / 16000 = 306795 N/mm
Edge spacing is taken as 200 mm or 300mm
stap 1:
Open the SAFE Application
select New Model
followed by Input Settings,
Units was selected as Metric and Code IS 456-2000.
50mm each was provided as cover at top and bottom and Bar size was defined as 16mm
step 2:
Once you click Okay
- Model Quick Template box will open
- Click on grid only
- Enter No of grids in X and Y = 2
- Enter spacing in X=3.1m
- Enter Spacing in Y = 1.85 m
- Now we have to assign the Material proprties
- Define - Material Properties
- Click on Add new materials
- Once you click Add new material add the following parameters
- Material Type-Concrete
- Grade - M25
- Click on okay.
- Similarly add the Rebar Properties
- Now we have to define Slab properties
- In pile cap we have to define 3 slabs properties
- Footing
- For Column
- For Pile cap
- Once slab proerties are defined
- Now we have to start the modeling
- Select Quick draw slab options
- Draw the slab select Footing as property
- Now we have to mark the position of Pile cap
- For that we have to add the points
- Draw - Draw reference points
- Add piles at the point
- Modify the edge distance to 0.2m
- Create a column of 600 x 600 mm
- Draw the column in center using quick draw tool.
.
- Spring were added.
- Define spring property data, as shown below.
- Select pile > assign > support data > point springs.
- Springs constant is taken from above calculation.
- Dead load & live load of 587.5 KN are added next.
- Load case combination was define next.
- After defining the load combination run the analysis.
- Max displacement was found as shown, So its Safe.
- Also, all the punching shear values are less the 1, So its Safe.
- Joint reaction diagram, as all the reaction forces are according to the limit, So its Safe.
- Reinforcement details are added next as shown in both X & Y-direction.
- Run the analysis again.
- Reinforcement Slab Design.
- Pile cap foundation design. (or)
- Ultimate Bending moment & shear force check.
Bending Moment.
Shear Force.
RESULT:
- Complete design of pile cap foundation using SAFE software is done successfully.
- Max displacement was found as shown, So its Safe.
- All the punching shear values are less the 1, So its Safe.
- Ultimate Bending moment & shear force check done successfully.
- Flexural Reinforcement design for slab done successfully.