A column or pillar in civil engineering and architecture is a vertical member that transmits the loads from the above structural element to the below member through compression. Hence, it is a compression member. It can be made out of steel, reinforced concrete, wood, or composite types. They can take square, round, I, etc cross-section based on the load to be sustained and the material used for column construction.

Columns are generally categorized as vertical members, whose length is three times greater than the least cross-sectional dimension of the column.

Columns in Building Structure

The figure below shows the general arrangement of building elements in a structure. It is mainly comprised of footing, columns, beams, and slabs. Columns are the vertical members that span between the substructure to the superstructure.

Structural Elements of a Building

The columns take the axial compressive loads coming from the top beam and slab elements and transfer them safely to the footing and then to the soil. It has an important role in the load transfer mechanism of a complete building structure. A building structure does not exist without column members.

Classification of Columns

Columns can be classified into several types based on:
  1. Length to depth ratio
  2. Loading condition
  3. Cross-section

1. Column  Types Based on L/d ratio

A column is said to be short if the ratio of the effective length of the column to its least lateral dimension is less than 12. If the l/d ratio is greater than 12, it's a long column.

2. Column Type based on Loading Condition

Based on loading conditions, columns can be classified into:
  1. Axially loaded column
  2. Axially loaded and uni-axial bending
  3. Axially loaded and bi-axial bending

3. Column Type Based on Cross-Section

Based on cross-section, the column can be classified into:
  1. Square column
  2. L-column
  3. T-Column
  4. Circular column
  5. Rectangular column
The failure of the column would result in sudden failure, unlike beams and slabs. Hence, it demands accurate design and careful construction.