Foundation Design using SAFE

Foundation Design using SAFE

1. 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.

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

1.Ans

• AIM: To Analyse and model Isolated footing as per calculations by using SAFE.

Introduction: design isolated single footing by using safe software and do all required check, and try to design economic and safe structure

Given:

square footing for a column size of 400X400

compression axial load for the load combination of ( 1.5 DL + 1.5 LL ) is 2000Kn

the safe soil bearing capacity is 150KN/M^2 at a depth of 2 meters below EGL

Assume M25 concrete grade

Solution:

step 1)

required data

unfactored load = 2000/1.5 = 1333.3 KN

Dead load breakup = 1333.3/2 = 666.7 KN

Live load breakup = 1333.3/2 = 666.7 KN

subgrade modulus of soil = safe bearing capcity X factored to ultimate / maximum settlement

= 150 X 3 / 0.05 = k = 9000 KN/m^3

Rebar yeild strength ( Fy ) = 500N/mm^2

Rebar ultimate strength ( Fu ) = Say 575 N/mm^2

Elastic modulus of M25 Concrete = 2500 n/mm^2

Step 2)

safe design

open the safe software

click on the new model

in that choose single footing option

and press ok

after that fill all information like this \

and press ok

Step 3)

define material property

from define

then same for rebar

step 4)

Slab Properties

define slab properties from define

step 5) load cases

go to load cases from define

step 6) load combination

go to define

and click on the load combination

step 7) Run the analysis

step 8) draw design strip

step 9)

check

safe bearing capacity

from reaction

punching shear design

step 10)

strip forces

flexural reinforcement

Result: our sqaure isometric footing done successfully with all checkn

2.Ans

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:

• CSI SAFE (Slab Analysis by the Finite Element method) is the best tool for designing concrete slabs and foundations.
• SAFE provides easiness to engineer towards the safe design of structures with powerful tools like draw, analyze, design and detailing, etc.
• Laying out models is the quick and efficient way with the user-friendly drawing tools or users can import models from AutoCAD or loading conditions from the other software like CSI ETABS and CSI SAP2000.

Procedure in Detail

The given parameters were

Column size 600 x 600 mm

Unfactored Load = 1175 kN

Length of the Pile 16m

Pile Diameter 500mm

Pile Capacity 200kN

Solution

Number of piles required 1175/200= 5.875 therefore 6 nos

Spring Constant = EA/L

E--> young modulus of concrete

As per IS 456 E for M25 grade concrete is 5000.√fck�.��=25000N/mm^2

A--> Cross sectional area of pile 0.785 x 500^2 = 196250mm^2

Pile length --> 16000mm

Substitute the value we get spring constant as 306640N/mm

Once the grid dimensions and Material properties given then provide the slab properties

Here for Pile Foundation total three properties to be given i.e pile cap, pile and colum stiff

1. Define Pile Cap

Go to Define--> Slab Properties--> Add New

2. Define Column

3. Define Pile

4. Draw model of slab using Quick draw tools

To draw piles first add points

Go to Drawpoints--> Dialog box open at top right corner--> Give the type of object as point and then provide the coordinate point

Add piles to the points we marked

Create Columns of size 600x 600 mm Draw column in center using coordinates

5. Assign Spring to Piles

Assign-->Support Data-->Point Springs

6.Assign Load and Load Combination

7. Analysis

Once the load and load combination were design then run analysis and check the displacement and punching shear

Point Reaction

All the above parameters are within the limit therefore satisfies.

Design reinforcement Details

Once the analysis were completed then design the model by design strip

Results

Thus the Pile cap were designed using SAFE were done and verified