Design of R.C.C. Column
Column:
“A column is a vertical member of the structure that takes loads
from the beams and transfers it safely to the foundation. A column
upon which load is acting on its center is called an axially loaded
column.”
Types of bars in Column:
There are following types of bars used in columns:
Longitudinal bars
Lateral ties/spiral
Important Formulae:
Pitch of spiral = S = π(dsp)2 * fyt/[0.45Dchfc’(Ag/Ach)-1]
Size of column = Ag = PU/(0.43fc’ + 0.008fy) —------(With lateral ties)
Size of column = Ag = PU/(0.5fc’ + 0.01fy) —------(With spiral)
Safe Load = PU = 0.80*0.65[0.85fc’(Ag - Ast) + fy Ast]----(for lateral ties)
Safe Load = PU = 0.80*0.75[0.85fc’(Ag - Ast) + fy Ast]----(for spiral)
Area of steel = As = (PU/0.80*0.65)-(0.85fc’*Ag)/(fy-0.85fc’) (for lateral
ties)
Area of steel = As = (PU/0.85*0.75)-(0.85fc’*Ag)/(fy-0.85fc’) (for spiral)
Slenderness ratio:
The ratio between the length of the column and the
least dimension of its cross section is called slenderness ratio. If this
ratio is greater than 15, then the column is called a long column,
otherwise a short column.
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Q1: A reinforced concrete column is 400 x 400 mm in size, and has
an effective length of 4500 mm. Assuming 2% steel. Find the safe
load that this column can carry. Take fc’ = 20MPa, fy = 300MPa
Given Data:
Size of column = Ag = 400*400 = 160000 mm2
Column:
“A column is a vertical member of the structure that takes loads
from the beams and transfers it safely to the foundation. A column
upon which load is acting on its center is called an axially loaded
column.”
Types of bars in Column:
There are following types of bars used in columns:
Longitudinal bars
Lateral ties/spiral
Important Formulae:
Pitch of spiral = S = π(dsp)2 * fyt/[0.45Dchfc’(Ag/Ach)-1]
Size of column = Ag = PU/(0.43fc’ + 0.008fy) —------(With lateral ties)
Size of column = Ag = PU/(0.5fc’ + 0.01fy) —------(With spiral)
Safe Load = PU = 0.80*0.65[0.85fc’(Ag - Ast) + fy Ast]----(for lateral ties)
Safe Load = PU = 0.80*0.75[0.85fc’(Ag - Ast) + fy Ast]----(for spiral)
Area of steel = As = (PU/0.80*0.65)-(0.85fc’*Ag)/(fy-0.85fc’) (for lateral
ties)
Area of steel = As = (PU/0.85*0.75)-(0.85fc’*Ag)/(fy-0.85fc’) (for spiral)
Slenderness ratio:
The ratio between the length of the column and the
least dimension of its cross section is called slenderness ratio. If this
ratio is greater than 15, then the column is called a long column,
otherwise a short column.
________________________________________________
Q1: A reinforced concrete column is 400 x 400 mm in size, and has
an effective length of 4500 mm. Assuming 2% steel. Find the safe
load that this column can carry. Take fc’ = 20MPa, fy = 300MPa
Given Data:
Size of column = Ag = 400*400 = 160000 mm2
