First Of all, there is no standard size of columns. The size of column depends on several factors such as the type of column, load to be resisted and architectural utility of that column. Depending upon these factors we have to adopt or assume the column size and then need to check for safety.
There are different types of columns such as timber columns, RCC columns, etc. Nowadays RCC columns are widely being used in structures, So in this article, I will discuss the sizes of RCC columns.
The minimum size of a column should not be less than 9”x9” for single story structure with M15 (1:2:4) concrete.
If 9”x9” columns are to be used in one and half story building, always use M20 (1:1.5:3) concrete. If you use M15 concrete for one and half story structure the column size should not be less than 12”x9”.
Distance Between Columns:
Try to maintain equal distance between the centers of two columns. Always plan a column layout on a grid. The distance between two columns of size 9”x9” should not be more than 4m centre to centre of column.
If larger barrier-free distances are required then larger size columns should be used. The size of the columns should be increased because of two factors:
1. Increase in the distance between two columns (this increases the dimensions of the columns as well as the depth of the beam).
2. Height of the building (increase in the number of floors is directly proportional to the dimensions of the columns).
Alignment of Columns:
A rectangular grid is to be made for placing the columns. This helps in avoiding mistakes and placing in columns can be done in the right way. The columns can preferably be arranged in two different fashions:
1. In a straight line with the help of a grid.
2. In a circular fashion for circular buildings.
Zigzag arrangement of columns is an absolutely wrong way of working out in structural design. It should be remembered that when columns are erected, beams are laid connecting the columns. The Zigzag column placement causes three major issues:
1. Unbalanced load transfer.
2. Problems in wall construction.
3. Problems in laying beams.
The below table shows a rough estimate of column sizes for multi-story buildings.
The below table shows different sizes of columns in structures: