How the orientation of the column is decided? / How to position & orient the column in buildings?

 Following are the 3 points to be considered while deciding the orientation of the column.

1. The directional ratio of the column should be nearer to 60:40 for the x & y-axis.

This helps to resist the lateral loads on the building from all directions. 

What does that mean?

As you can observe in the above drawing,

Columns having their major axis in the x-direction  👉  C1, C2, C3, C4, & C7

             Total no. of columns in x-direction = 5 nos.                                                  

Columns having their major axis in the y-direction  👉  C5, C6, C8, & C9

            Total no. of columns in y-direction = 4 nos.

The ratio by percentage = 56: 44 ✔ OK

2. The structural & architectural requirements.

As you can observe in the above drawing,

Columns C2, C4, C5, & C8 intruded into the room space of the building. From a structural point of view, designing those columns might be efficient & economical. When you observe those columns from an architectural point of view, they are not aesthetic & appealing.  

So, to satisfy the structural as well as architectural requirements, columns are designed to have the width of the wall. 

Usually, columns are oriented in such a way that it falls in line with the masonry walls having no offsets in any direction. 

3. The sectional length of the column should be in the major plane of bending. This helps to enhance the moment-resisting capacity of the column.

Again, your mind raises the question, what does that mean? 😄

1. Column C1:

As you can observe in the above drawing,

Column C1 supports the beams B1 & B4

The span of B1 = 3.5m. > span of B4 = 2.5m.

Therefore, the moment created by B1 will be greater than that of B4.

So, the major axis of the column should be oriented in alignment with beam B1.

2. Column C2:

Column C2 supports the beams B1, B2, & B4.

Here, beams B1 & B2 are on the same axis, but in opposite directions.

Therefore, the net moment along this axis is generated by the difference in the span of  B1 & B2 

   = [5m -3m.] = 2m. < span of B4 = 2.5m.

 The moment created by B4 will be greater than  (B1 + B2).

So, the major axis of the column should be oriented in alignment with beam B4.

3. Column C3:

Column C3 supports the beams B2 & B4

The span of B2 = 5m. > span of B4 = 2.5m.

Therefore, the moment created by B2 will be greater than B4.

So, the major axis of the column should be oriented in alignment with beam B2.

4. Column C4:

Column C4 supports the beams B2, B3, & B4.

Here, the beams B3 & B4 are on the same axis, but in opposite directions.

Therefore, the net moment along this axis is generated by the difference in the span of  B3 & B4 

   = [4m -2.5m.] = 1.5m. < span of B2 = 5m.

 The moment generated by B2 > net moment of (B3 + B4).

So, the major axis of the column should be oriented in alignment with beam B2.

5. Column C5:

Column C5 supports the beams B1, B2, B3 & B4.

Here, the beams B1 & B2 are on the same X-axis, but in opposite directions.

Therefore, the net moment along this axis is generated by the difference in the span of  B1 & B2 

   = [5m -3.5m.] = 1.5m. 

The beams B3 & B4 are on the same Y-axis but in opposite directions.

Therefore, the net moment along this axis is generated by the difference in the span of  B3 & B4 

   = [4m -2.5m.] = 1.5m. 

 The moment created by [B1 + B2] =  [B3 + B4].

Now, what should be the orientation? 😲

You can orient the column in any direction as an equal moment will be created.

But to satisfy the directional ratio of 60:40 (condition-1), the major axis of the column should be kept in the y-direction.

6. Column C6:

Column C6 supports the beams B1, B3, & B4.

Here, the beams B3 & B4 are on the same axis, but in opposite directions.

Therefore, the net moment along this axis is generated by the difference in the span of  B3 & B4 

   = [4m -2.5m.] = 1.5m. < span of B1 = 3.5m.

 The moment created by B1 will be greater than  (B3 + B4).

So, the major axis of the column should be oriented in alignment with beam B1.

7. Column C7:

Column C7 supports the beams B1 & B3

The span of B3 = 4m. > span of B1 = 3.5m.

Therefore, the moment created by B3 will be greater than B1.

So, the major axis of the column should be oriented in alignment with beam B3.

8. Column C8:

Column C8 supports the beams B1, B2, & B3.

Here, beams B1 & B2 are on the same axis, but in opposite directions.

Therefore, the net moment along this axis is generated by the difference in the span of  B1 & B2 

   = [5m -3.5m.] = 1.5m. < span of B3 = 4m.

 The moment generated by B3 > net moment of (B1 + B2).

So, the major axis of the column should be oriented in alignment with beam B3.

9. Column C9:

Column C9 supports the beams B2 & B3

The span of B2= 5m. > span of B3 = 4m.

Therefore, the moment created by B2 will be greater than B3.

So, the major axis of the column should be oriented in alignment with beam B2.

I think you understood the concept.👍

Note: In multi-storeyed buildings having complicated designs, several other factors are considered to decide the column orientation.

For all such articles over useful tips, click here.

Thank you for going through this article❤. Have a good day 😄.

Share: