Dear Ephrem:

There are no specific limits on this quantity. However, it is easy to suggest some guidelines for design. In general, a ductile column is one in which the normalized axial load is less than 0.25, a moderately ductile column is one in which it is approximately 0.3, and a non-ductile column is one in which it is larger than 0.35. I am normalizing the axial load by the product of the gross area (b*h) and the 28-day compressive strength of concrete as defined in the US (f'c). Please see the attached document to see how the guidelines are defined.

Axial load of column will depend upon the % of reinforcement and column size for various mixes and steel.

For steel grade fy 415

CONCRETE GRADE &Axial Load carrying Capacity in KN (P)

M15 ,P= (2.7205 p + 6) b D/1500

M20, P= (2.7005 p + 8) b D/1500

M25 ,P= (2.6805 p + 10) b D/1500

M30, P= (2.6605 p + 12) b D/1500

M35, P= (2.6405 p + 14) b D/1500

M40, P= (2.6205 p + 16) b D/1500

For steel grade fy 500

CONCRETE GRADE &Axial Load carrying Capacity in KN (P)

M15 ,P= (3.29 p + 6) b D/1500

M20, P= (3.27 p + 8) b D/1500

M25, P= (3.25 p + 10) b D/1500

M30, P= (3.23 p + 12) b D/1500

M35, P= (3.21 p + 14) b D/1500

M40, P= (3.19 p + 16) b D/1500

For steel grade fy 550

CONCRETE GRADE& Axial Load carrying Capacity in KN (P)

M15, P= (3.625 p + 6) b D/1500

M20, P= (3.605 p + 8) b D/1500

M25, P= (3.585 p + 10) b D/1500

M30, P= (3.565 p + 12) b D/1500

M35, P= (3.545 p + 14) b D/1500

M40, P= (3.525 p + 16) b D/1500

Note :-

1. The axial Load carrying capacity column is arrived based on the formula

Pu =0.4 fck Ac + 0.67 fy Asc as per IS 456-2000.

2. Here in the Table P is Axial Load Carrying capacity of column in KN.

p is steel in percentage say percentage as 1

b is breadth of column in mm

D is depth of column in mm.

For preliminary design use square columns.

If the building height is 3 stories or less:

If beam span < 6000mm, h (mm) = 300

If 6000 < beam span < 9000, h = 350

If 9000 < beam span < 12000, h = 400

If the building height is 4 to 9 stories:

If beam span < 6000mm, h (mm) = 400

If 6000 < beam span < 9000, h = 500

If 9000 < beam span < 12000, h = 600

I hope it will give you clear idea about column axial load.

Ductility can be defined as the “ability of material to undergo large deformations without rupture before failure”. Ductility in concrete is defined by the percentage of steel reinforcement with in it. Mild steel is an example of a ductile material that can be bent and twisted without rupture. it has been discuses in the below attachment.

There is a thesis titled:

Ductility of rectangular reinforced concrete columns with axial load

I hope it be helpful.