Introduction to column

• Columns act as vertical supports to beams and slabs, and to transmit the loads to the foundations.

• Columns are primarily compression members, although they may also have to resist bending moment transmitted by beams.

• Columns may be classified as short or slender, braced or unbraced depending on various dimensional and structural factors.

Column sections

• Common column cross sections are: (a)

square, (b) circular and (c) rectangular section.

• The greatest dimension should not exceed

four times its smaller dimension. (h ≤ 4b).

• For h>4b, the member should be regarded as a

wall for design purpose.

Failure modes of columns

• Columns may fail in one of three mechanisms:

1. Compression failure of the concrete or steel reinforcement;

2. Buckling

3. Combination of buckling and compression failure.

• Compression failure is likely to occur with columns which are short and stocky.

• Buckling is probable with columns which are long and slender.

Failure modes of columns