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

 

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 

 

 

Q1. 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.

 

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

 

 

 

 

 

 

 

Q2)  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

 

AIM: to deisgn a pile foundation usig safe software 

 

Introduction: design pile footing by using safe software and do all required check, and try to design economic and safe structure, pile footing is done where hard strata available on depth  

 

Data required

unfactored load = 1175KN

dead load breakup = 1175/2 = 587.5 KN

Live load breakup = 1175/2 = 587.2

 

Point spring of pile = A X E / L

= 196349 X 25000/ 16000 = 306796 KN 

k for SAFE analysis = 306.8 KN/m 

 

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

rebar ultimate strength = 575 N/mm^2

Elastic modulus of M25 concrete = 25000N/mm^2 

 

number of piles required = unfactored load with self weight addition / indivisual pile capacity 

= 1175 X 1.1/200 = 6.5

consider 8 piles 

 

take center to center distance between piles = 3 X piles diameter = (1500 mm)

Edge distance from pile center = 1 X pile dimeter = (500mm) 

 

Assume pile cap depth = 500mm 

 

step 2) 

safe design 

open new model 

and put all required information 

 

step 3) 

material properties

click on material property from define 

add M25 grade concrete material 

and 500fy reabar material 

 

 

 

step 4) 

define slab property 

 

step 5) 

draw slab 

draw the slab by using quick draw tool 

 

 

 

step 6) draw refrence point: 

draw refrence point 

where we loacate the pile by the help of draw refrence point and replicate option from edit 

like that 

 

step 7) add the pile 

add the piles at the point 

draw the pile by using quick draw area around pint 

set dia as 500mm 

and draw by cursor 

 

like that 

 

step 8) same draw column 

by choosing rectangular slab 

 

step 9) assign a spring 

selcect all the pile point 

now go to draw 

then support data and point spring 

 

step 10) add load 

assign load to column 

simply select the column point 

go to assign 

go to joint load 

and then select garvity dead and live load are 587.5 kn 

 

 

 

 

step 11) check design preference 

check design prefrence before analysis from design option

 

step 12) run the analysis 

 

 

step 13) check for rection 

check base rection for unfactored load 

when we design for steel we need to check for factored load 

 

 

 

step 14) check for punching shear design

from disply option 

 

step 15) design strip 

to know the area of steel required 

go to edit option

and click on add design strip 

 

same do for Y direction and strip layer B 

 

so strip is assign for X and Y direction 

check width of strip 

from display option 

 

step 16) define load combination 

from define option 

 

 

step 16) again run the analysis 

and check the r/f required

go to display option then slab design

and strip A press apply

 

and for strip B for y direction steel 

 

Result: design of pile foundation is done successfully with given data 

and also done all check satisfy 

and get quantity of steel required