Foundation Design using SAFE
Q1
AIM:- to design a isolated footing
GIVEN DATA:-
- size of the footing is taken as 3.2 x 3.2m
- size of the column is taken as 400 x 400mm
- safe bearing capacity of the soil is 150KN/m^2
- factored load is given as 2000kn
- assume the depth of the footing as 500mm
- grade of the concrete as M25
- grade of the steel as Fe500
- subgrade of the soil is taken as 9000
subgrade of the soil is (FOS X SBC)/SETTLEMENT
(3 x 150)/0.05= 9000
- unfactored load is 2000/1.5=1333.3
- take dead load and iive load as 50% of the total load
- dead load is taken as 1333.3/2=666.5kn
- live load is taken as 1333.3/2=666.5 kn
SAFE MODELING
to open a safe and give input as single footing and define the properties of the footing
to define material properties, slab propeties
- go to define
- click on material>add new properties
- add the grade of concrete and grade of the steel and its properties
to add slab properties
- go to define
- click on slab propeties
- add properties of the footing material and its depth
to add load patterns and load combinations
- go to define
- click on load patterns
- add dead , live and surcharge load of the soil
- then go to load combinations
- apart from the defaut load combinations
- define a additional load combination with factor of 1
To define design strips along X and Y direction
- go to draw
- click on draw design strips
- specify the direction and edge distance of the strip and draw the strips
run analysis to view the deformations and settlements
soil pressure under service loads
click on show reactions forces
select the load combinations and click on apply
settlements under service loads
click on show deformed shapes
select the load combination and click on apply
punching shear check
check moments along the strips
REULTS:-
- soil pressure under service load is between 143 and 145 which is less than SBC of the soil
- punching shear of the column is 1.121
- settlements under service condition is 16mm which is less than permissible settlement
Q2
AIM:- to model and deisgn a pile cap
GIVEN DATA:-
- size of the column is taken as 600 x 600mm
- unfoctored load carried by the column is 1175KN
- dia of the pile is given as 500mm
- length of the pile is 16m
- individual capacity of the pile is 200kn
NO OF PILES REQUIRED IS (1175 x 1.1)/200 = 6.5
take no of piles as 8 no.s
center to center distance between the piles is taken as 3d= 3 x 500=1500mm
edge distance from the center of the pile is taken as d=500mm
size of the pile cap is 4 x 4m
assume the gradeof concrete as M25
grade of the steel as fe500
point sping of the pile is taken as AE/L
=306796.15n/mm^2=306.7kn/mm^2
unfactored dead load is taken as 600kn
unfactored live load is taken as 600kn
SAFE MODLIING
- to create a grids
to define material properties
- go to define
- click on materials> add new materials
- add grade of concrete and steel and modify its parameters
to define slab properties
- go to define
- click on slab properties>ass new property
- add the propeties of the pile cap, piles, column
to draw pile cap and add points to draw piles and columns
- go to draw
- click on qucik draw slabs/area
- go to draw
- click on draw points and specify the offset from X and Y direcion to draw the points
- go to draw
- click on quick draw areas around point to draw piles and column
to assign loads and point springs to the piles
- select all the points of piles
- go to assign
- click on supportdata> point springs
- specify the value and click on ok
- select the column pile
- go to assign
- click on load data>point load
- specify the load as dead 1175kn
to add strips along the pile group
- go to draw
- click on draw design strip
- specify the start distance and end distance
then run analysis to view the deformations
deformed shape of the pile cap under dead load
punnching shear failure of the pile cap
reaction on the piles under dead load
slab design details
RESULTS:-
- 8 no of piles is to be used
- depth of the pile cap is 600mm
- since the reactions under the piles are within the capacity of the pile design is correct