How to find Strain

[Shz713]

Hi,

I'm interested to find out the strain change along length of a member due to the applied stress/load. Can SAP2K provide such graph like displacement or moment? I think I can find it indirectly but not sure what exactly I'm supposed to do. Any comment guys?

Peace[highlight #F57900][/highlight]

 

[Kristene]

Hi,

In the past I tried to do the same, No Luck . SAP doesn't report strain directly. You need to do post processing to arrive at that.

Step 1. Find Initial position of i and j nodes of sap - Arrive at Initial Length
Step 2. From the displacement + initial coordinates, calculate the displaced position. - Arrive at the deformed length
Step 3. Strain Calc

You can automate this using API or Excel (after exporting tables).

Thanks,

 

[Shz713]

Dear Kristene

Thanks for your response. Sorry but I couldn't figure out your explanation. Let's say I have a S.S beam and run the analysis for point load @ center. From output tables, I export the joint coordinates and displacement (due to load) to the excel. Then what? Would you elaborate it for me possibly with an example?

Heaps of thanks

 

[Kristene]

Hi,

For SS beam, create a point near each support, SAP reports displacement at joints. If you restrain Joint, No displacement.

Step 1, i = (0,0,0), J= (5,0,0) length = 5'
Step 2: under load, i+di = (0.01,0,0) j +dj = (5.05,0,0), Note sap reported disp are based on initail co-ordinates
Step 3: Calc length = sqrt((5.05-0.1)^2 +(0)^2 + (0)^2) = 5.04'

Strain = .04/5

Cheers!

 

[Shz713]

Dear Kristene

Thanks again.

How you got 5.05 while the displacement is 0.01?
Plus, I reckon in sqrt((5.05-0.1)^2 length due to external load needs to be deducted from 0.01 not 0.1, right?

lastly, in Strain = .04/5 you used the strain formula (change in length divided the original length).

Thanks mate

 

[Nepalengineer]

can you help me to find the strain in the shear wall with this

 

[Nepalengineer]

can you help me in finding out the failure of non-linear shell element modeled using multi layer shell theory in sap 2000