# Civil Engineering - RCC Structures Design - Discussion

Discussion Forum : RCC Structures Design - Section 1 (Q.No. 4)
4.
The minimum number of main steel bars provided in R.C.C.
rectangular columns is 4
circular columns is 6
octagonal columns is 8
all the above.
Explanation:
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Discussion:
23 comments Page 1 of 3.

Each corner one main longitudinal steel bar has to be arranged.

According to this shape member each corner has one main longitudinal steel bar to be arranged.

Kanhaiya lal said:   1 decade ago
In Column reversal of bending moment may be occurred, hence, to column are reinforced on both faces. To fulfill the reversal condition of BM minimum no of bars in rectangular is taken as 4, in circular 6 and in octagon 8.

In column there is a buckling moment due to the up coming load so at each corner there should be a longitudinal main steel bar is provided.

But In case of circular column, why only 6 nos of bars provided? Why not 4 or 5? Can anyone clarify?

Qammar Qureshi said:   9 years ago
Min. 4 bars in rectangular/square column and min. 6 bars in circular shape column.

The bar shall not be less than 12mm. The nominal cover shall any case not be less than 40mm.

In our site they provided 40mm cover. Min. Distance b/w individual bars -the dia of larger bar -5mm more.

Nominal max. Size of coarse aggregate.

Arun said:   9 years ago
What is the Max diameter used for the longitudinal bars?

Rohit nagarwal said:   9 years ago
Why use circular shape bar why not use other shape bar?

Samba said:   9 years ago
@Arun.

Max diameter used in longitudinal bars depends upon size of the beam.

Samba said:   9 years ago
India 4 & 5 bars used the column spacing can more than 300 mm so the column concrete will be out side in column. Next the strength will be reduce.