In this article, we explain the criteria of axial stress for column as per is 13920, how to check axial compressive stress in column using etabs software, etc.
So please read the article till the end, and if you get any valuable information from this then please share it with your friends. Let’s Start.
Table of Contents
Axial Compressive stress criteria for Column as per IS 13920
Before going to see, how to check axial compressive stress using Etabs, let’s first see the criteria of axial stress for column as per IS 13920 code.
As per IS 13920 : 2016 clause no: 7.1, The factored axial compressive stress considering all load combination relating to seismic loads shall be limited to 0.4 Fck.
Means, axial stress in column related to all load combination of earthquake force shall not be more than 0.4 Fck.
Let’s See, how you check the axial stress in column using Etabs software to fulfil this criteria.
Also Read : All Shortcut Keys in Staad Pro Software
How to Check Axial Compressive Stress Criteria of Column in Etabs
There is no direct way to check the axial stress of column in etabs software. No option available in etabs which shows that the section of column exceeding the limiting value of axial compressive stress as per IS 13920.
You need to check it either manually or based on axial force. Let’s me explain both.
How to check axial compressive stress of column in etabs based on axial force
This is very simple way to check that column sections are within the limit of axial stress criteria of IS 13920 – 2016.
As per the IS 13920:2016, the limiting value of axial stress in column is 0.4 fck related to factored earthquake force load combination.
That means, If the axial force on column is less than the 0.4 Fck x Ag, than column can pass the axial compressive stress criteria of IS 13920.
For Example, if your column have size of 400×800, grade of concrete M30 and it is loaded with axial force of 3800 KN in load combination of 1.2 DL + 1.2 LL + 1.2 EQ. That means the column is within limit of axial stress criteria. Because,
Axial force limiting value (Pulim) = (0.4 x 30 x 400 x 800) / 1000 = 3840 KN
While the actual axial force is 3800 KN which is less than limiting axial force.
So, based on limiting axial force you can easily find out that columns are within limit or not. Just find the limting axial stress of column as per their size and Fck.
And, Check the actual axial force on column related to factored earthquake load combination in etabs. If the force exceed the limiting value, means column not pass the IS 13920 – 2016 Axial stress criteria.
Also Read: Deep Beam Design Criteria as per IS456
To check the axial force in column you need to follow the navigation as shown below.
Click on Display, Force Stress Diagram, Frame/Pier/Spandrel/ Link force option.
Select Load combination related to earthquake force, axial force, and click OK. Now the diagram shown in etabs software is related to axial force, just move the cursor to see the actual axial force on column in particular combination.
How to check axial compressive stress of column manually using Etabs Software
Let’s see the manual way to check the axial stress of column using etabs software.
First, you need to extract the forces of column from etabs to Excel by doing process as shown below.
Go to Display option, Click on Show Table,
Go to Analysis Result, then Element Output, then Frame Output, then select Element forces – columns.
Select the applicable load combinations. For example, in our case the criteria say that axial stress related to earthquake force. Then select the all factored load combination related to earthquake forces.
Copy the shown result and paste into excel. Delete the unnecessary columns, Add columns for Axial Stress, Stress Limiting Value, to check the axial stress of column is within limit or not as shown below. Add filters on every column to filter out the column which are not within the axial limit.
So this are the two ways to check the axial stress of column using etabs software. Please share your thought about this post, how would you like this post. Can we post more post related to structure design and software’s. Reply in Comment Box.
To Download the Sample Excel sheet of given example as shown in figure, link given as below.