Ever Wondered why Circular Column Designs are preferred for bridges construction, and NOT Square or rectangular ones? Here's Why
What is the main difference between square column and circular column?
Here are some thoughts:
Circular columns are symmetric about any centroidal axis. Square columns have only 4 axes of symmetry.
If you compare a square column with a circular column having the same diameter as the side of the square column, circular column has a smaller cross section area (0.785 times the square column) but larger second moment of area (1.178 times the square column).
Thus is less prone to buckling and may require slightly more reinforcement to carry the same load as a square column.
Minimum number of bars required in a square column is 4 while for circular columns, it is 6. Form work for square columns is simpler (due to the straight sides) compared to circular columns.
Circular columns are considered aesthetically pleasing compared to square columns (but that is subjective).