Guidelines to be followed for making a column layout | ______1_7_0_3_3_f_c_b_7_b_7_e_b_2_1_a_8_2_5_4_2_d_2_5_5_3_7_5_e_f_d_a______
Today, we will discuss something very general. Inspite of knowing these general thumb rules, Civil Engineers still end up making disastrous mistakes which would not only cost them but also cost the people living in the building designed by these engineers.
Earlier, I wrote an article describing one of my projects where structural designing was executed on site (which was extremely pathetic) even before Architectural design was done. (Check out: Consequences of Wrong Structural Design | Live Project example)
In this article, we will go through the essential thumb rules to be followed for giving a column layout. Ofcourse RCC columns have to be designed in accordance to the total load on the columns but apart from that it is essential for every Civil engineer and Architect to remember a few thumb rules so that they are prevented from making mistakes.
Three thumb rules to be followed are as follows:
- Size of the Columns
- Distance between Columns
- Alignment of columns
Thumb rule no.1
Size of the columns
The size of the columns depends on the total load on the columns.
Minimum size of the column should not be less than 9”x9”.
9”x9” columns are to be used for a single storey structure with M15 grade of concrete.
In case, 9”x9” column size is to be used for 1 and half storey structure, then it is advised to use M20 grade concrete.
A safe and structurally sound column size for a 1 and half storey structure should not be less than 12”x9” using M15 grade concrete. This should be in your most preferred and practical options list.
Thumb rule no.2
Distance between the columns
Try to maintain equal distance between the centres 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 going for larger column size is to be used.
The size of the columns increase because of two factors:
- Increase in the distance between two columns (This increases the dimensions of the columns as well the depth of the beam.)
- Height of the building (Increase in the number of floors is directly proportional to the dimensions of the columns.
Thumb rule no.3
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:
- In a straight line with the help of a grid
- In a circular fashion for circular buildings.
Zigzag arrangement of columns is an absolutely wrong way of working out 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:
- Unbalanced load transfer
- Problems in wall construction
- Problems in laying beams
If these three thumb rules are followed by Civil Engineering and Architecture students, implementation of wrong Structural design can be prevented.
In the next article, I will explain these three thumb rules with the help of an example “Column Layout for a Residence“.
Building Design Guide which includes design of:
- RCC columns
- RCC beams
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