Challenge

Foundation Design using SAFE

PPaul Willington18 Apr 2025

AIM: Design of Foundation using SAFE v20

INTRODUCTION:

CSI SAFE (Slab Analysis by the Finite Element method) is the best tool for designing concret slabs and foundations.
SAFE provides easiness to engineer towards the safe desing of strructures with powerful tools like draw, analyze, design and detailing, etc.

PROCEDURE:

Open the SAFE Application

Select New model
Select the units and Design codes.
Single Footing was selected next

Subgrade Modulus =

Where, FOS for soil = 3

S.B.C = 150KN/m^2

Settelement for Isolated footing = 25mm

Hence; Subgrade modulus = 18000 KN/m/m^2

The compression axial load for the load combination (1.5 DL+1.5LL) is 2000KN.

Unfactored load = 2000/1.5 = 1333.6KN

Live Load = 1333.6/2 = 666.5KN

Dead Load = 1333.6/2 = 666.5KN

Footing thickness 600mm

Column Load size = 400 x 400 mm

Given data,

Define Materials

----> Go to the Define Tab and select Material property.

Add M25 concrete
Add new propety as Rebar.

Define Section Property

Next, Define Section Property
Go to Slab property.
Add mat > Thick shell -- > Mat type < 600 mm thickness

Add next STIFF property.
Change the type as Stiff

Now right click on slab / floor and change the section Property as Mat.
Now Right Click on Column and change the section Propety as STIFF.

Check the Forces Applied by Right click on column joints.

Apply Live Load of 2KN/m on the Footing/slab
Select the Slab and assign the uniform load of 2 KN.

Check the Load Patterns

Go to Define Tab spring properties
Click on Area Spring and change the name of (ASpr) as soil.

Define Load Combintion

Go to Define Tab and select Load combination
Add new Combo as SLS

Add new combo as ULS.
Click on the icon (Concrete slab/ Beam Design ) and Check the prefences like cover, bar dia etc.
Agian click on the Icon ( Concrete slab/ beam Design ) and go the Design Load Combination.
Add the combination.

Add Design Strips

Go to the edit tab and select Add/ Edit Design Strips.
or Add Manually Design Strip from the Draw Design Strip Tool.

Check the Model and Analyse.

Check the Displacement:

Max soil Pressure = 71.486 @ (0,0.2, 3) in SLS condition.

Checking Punching Shear

Here Punching Shear is 0.701 < 1 hence Ok.

Check Strip Design

Check on Layer B

RESULT:

Hence the Isolated Footing was designed and analyzed using SAFE successfully. The results of each drawing drawn in SAFE are attached.

AIM:

To model analyze 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

INTRODUCTION:

Pile foundations are deep foundations.
They are formed by long, slender, columnar elements typically made from steel or reinforced concrete, or sometimes timber.
A foundation is described as 'pilled' when its depth is more than three time its breadth.

PROCEDURE:-

Given Data:

Column size:- 600 x600

Unfactored load:- 1175KN

Pile lenght :- 16m

Pile Diameter :- 500mm

Load carring capacity :- 200KN

Calculations:

Number of pillers:- 1175 x 1.1 / 200 = 6.4

But we take 8 piles for the symmetric load distribution.

Spring Constant :- A x E/L

Where E is :- 5000 sqroot Fck

Area (A) is :-

Open the SAFE Application.
Select New model
Followed by input settings.
Units were selected as Metric and code IS:456-2000.

Add the grid in X and Y ordinates.

Define Material Property

Go to Define Tab and select Material Property.
Add New Property.
M25 grade of concrete

Add New Property as Rebar

Define Section Properties

Go to the Define TAB and select section Property
Add new section Property as pile ( As Mat material ), pile_Cap ( As Mat material) and Column (as STIFF material)

Draw the Floor/ Slabs

Go to the Slab/ Floor tool and select property as slab as pile_Cap.
Drag diagonally and draw slab/ floor.

Draw points

Go to the Draw tab and select Draw joints objects.
Now the Draw the Joints where i want.
Now Draw the Pile
Go to the Quick draw area around point Tool.
Select Shape as Circular and Property as Pile.
Draw piles on all the joints except center joints.
Now Draw Column in center.
Again select quick draw area around point and shape as rectangle and property name as Column.

Define Point Spring