Design of column footing



In this article I will Design the square column footing in detail. but this is the part -1 and part -2 will be coming soon. after reading this article you will be able to design the square column in detail. and this is the important article for all civil engineers students.

In this procedure I am just assuming the data for column footing so, you are also able to change this value and use in these formula which I am showing you here in this article.

Required steps to design a column:

1: Area of column footing

2: Soil Reaction

3: Factor moment

4: Required depth of footing (d)

Given data:

Applied load on the column = p = 2000 kN

Size of column = 400mm x 400mm

Soil bearing capacity = S.B.C = 150 KN/m2

we will use here M20 grade of concrete in this column

Grade of Steel = fe = 415
compressive strength of concrete = fy = 20 N/mm2

Solution of first step: Area of footing

Area of footing  = 10% of P+P / S.B.C

Here we increase the applied load 10% of P

Here (P) is applied load and S.B.C ( Soil bearing capacity)



 

Solution:

Area of footing = 10% of P+P / S.B.C = 0.1 x 2200 + 2200 / 150  = 14.55 m2

now footing one side = √A = √14.55 = 3.28 m     say 4 meter.

Solution of second step: Soil Reaction

use the given formula for soil reaction

qu = Pu / A     where pu is the factor load of the column and A is the area of footing

the value of pu = 1.5 x P  so  = 1.5 x 2200 = 3300 KN

so now .  qu = Pu / A  = 3300 / 14.55 = 225.10 KN/m2

Solution of 3rd Step : Factor movment

use the given formula for factor moment

Mu = P x B x (S – b/ 2 )2 1/2         where P =Load , B = breadth of footing , S = Side of footing , b = side of column.

so,    P x B x (S – b/ 2 )2 1/2 = 2200 x 4 x (4 – 0.40/ 2 )2 1/2 = 1780 KN.



Solution of 4th Step : required depth of footing (d)

use the given formula for  depth of footing (d)

d = √ Mu / 0.138 x fck x B         where Mu = factor moment ,  fck  = compresive strength of concrete , B = Breadth of footing.

so,

d = √ Mu / 0.138 x fck x B                But here we will change Mu value to N.mm so Mu multiply x 106

d = √ 17820 x 106  / 0.138 x 20 x 4000   so , d = 401 mm  say 0.4m

 

Note: In this next Article part -2 we will discuss about the steel design in this column but it will be the full design of column footing. so read this article carefully and do your own design of any column and assume the data for the column footing , and make it easy for your self. wait for next part -2 article.

 

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