Column Load Calculation| How to Calculate Column Size For Building
Column Load Calculation| How to Calculate Column Size For Building
INTRODUCTION :
Column:
Column length is generally 3 times their least lateral cross-sectional dimension. The Strength of any column mainly depends on its shape and size of cross–section, length, location, and position of the column.
A Column is a vertical component in a building structure, which is mainly designed to carry the compressive and buckling load. The column is one of the important structural members of the building structure. As per Load coming on the column, size is increased or decreased.
Load Calculation on Column:
we know that the Self–weight of Concrete is around 2400 kg/m3, which is equivalent to 240 kN and the Self–weight of Steel is around 8000 kg/m3.
So, if we assume a column size of 230 mm x 600 mm with 1% steel and 3 meters standard height, the self–weight of the column is around 1000 kg per floor, which is equal to 10 kN.
Volume of Concrete = 0.23 x 0.60 x 3 =0.414m³
Weight of Concrete = 0.414 x 2400 = 993.6 kg
Weight of Steel (1%) in Concrete = 0.414x 0.01 x 8000 = 33 kg
Total Weight of Column = 994 + 33 = 1026 kg = 10KN
While doing column design calculations, we assume the self–weight of columns is between 10 to 15 kN per floor.
How to Calculate Column Size For Building:
A column is one of the important elements of any building structure. The column size for the building is calculated as per load coming on the column from the superstructure.
For buildings with heavy loading conditions, the column size is increased. The column size is an important factor while designing any building structure.
Difference column sizes used in building design,
- 9″ x 9″
- 9″ x 12″
- 12″ x 12″
- 12″ x 15″
- 15″ x 18″
- 18″ x 18″
- 20″ x 24″
As per Structural load, more sizes can be used.
For Column size calculation we required the following data,
- Grade of Steel
- Grade of Concrete
- Factored Load on Column
(Note: Minimum size of the column should not be less than 9″ x 9″ ( 230 mm x 230 mm)
The following are column design calculations steps to decide the size of the column for the building.
Pu = 0.4 fck Ac + 0.67 fy Asc ( Clause No: 39.3 Page No: 71 IS 456:2000)
- Pu = Axial Load on Column
- fck = Characteristics compressive strength of concrete
- Ac = Area of Concrete
- fy = Characteristics Tensile strength of concrete
- Asc = Area of Steel Reinforcement
- Ac = Ag – Asc
- Asc = 0.01 Ag
- Ac = 0.99 Ag
Where Ag = Gross Area of Column
Consider 1% of Steel in Column,
Ac = Ag – Asc
Example:
Design an RCC square short column subjected to an axial compressive load of 600 KN. The grade of concrete is M -20 and the Grade of steel is Fe -500. Take Steel 1% and Factor of safety = 1.5.
Pu = 600 KN, fck = 20 N/mm2, fy = 500 N/mm2, Steel = 1%, Factor of Safety = 1.5
Load on Column, Beam & Slab | Column Design Calculations pdf | How to Calculate Column Size for Building | Slab Load Calculation
RCC Column
Pu = Axial Compressive Load on Column = 600 KN
Factored load on column = Pu = 600 x 1.5 = 900 KN
Pu = 0.4 fck Ac + 0.67 fy Asc
900 x 103 = 0.4 x 20 x (0.99 Ag) + 0.67 x 500 x (0.01 Ag)
900 x 103 = 7.92 Ag + 3.35 Ag
900 x 103 = 11.27 Ag
Ag = 79858 mm2
For Square Column,
Size of Column = √79858
Size of Column = 282.59 mm
Provide square column size 285 mm x 285 mm
Ag = Provided = 81225 mm2
Asc = 0.01 Ag = 0.01 x 81225
Asc = 812.25 mm2
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RESIDENTIAL PLAN
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