Benging moment in release

[Anonymous]

Hi to all,

I'm getting really frustrating problem. I have defined 3D metallic structure in Robot. All calculation seems to be fine, except one thing. I've got some bars with defined release. And for some combinations Robot is attaching them bending moment at the ends, which is totally wrong, since they should work as simple supported beam. How is it possible, that moments appear in releases?

Thanks in advance for help.

[Artur.Kosakowski]

Have you ignored any reported instability? Has the analysis converged (for non linear model)? 

[Anonymous]

No instabilities, no errors, even no warnings. Moreover, problem appears only for some combinations and only for specific elements. This is 3d structure and error is occuring in horizontal bars of the longitudinal wall and not in all of them.

I´m not sure if it could be connected, but it seems to me that it appears on bars where I´ve put trapezoidal loading. I used that to obtain bars, loaded with two diferrent rectangular loading. Let´s say one bar is loaded with 2kNm along 2m and the rest 5m is loaded with 1kNm.

I´m using also DSC algorithm.

[Artur.Kosakowski]

Attach the model and indicate bar numbers and load cases/combinations to look art please.

[Anonymous]

Here you have my model:

https://dl.dropboxusercontent.com/u/104840801/Final_model_konstrukcji_v17.zip

Look for example at bar number 3003 and load case number 23.

[Artur.Kosakowski · Accepted solution]

Try to generate some nodes along the bar.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Pawel.Pulak]

The original reason of this effect is the incorrect definition of trapezoidal load in for points which you defined in load case 7.

When using RSA Pro 2014 and defining such load using the dialog it is not possible to define the load with x2 and x3 point in the same location - the message shown below is displayed:

Anly after defining x3 slightly different than x2 (for instance 5.101)  the load can be applied.

Unfortunately when using the table of loads to define or modify such load the analogous verification cannot be done.

It is recommended to open the table of loads and to correct x3 in appropiate loads of the type "trapezoidal loads (4p)"

The suggestion to add such verification to general verification of the model was registered.

---------------------------------------------
If this post answers your question please click the "Accept as Solution" button. It will help everyone to find answer more quickly!

Regards,

[Anonymous]

Well, actually I've added "slightly diffrent" trapezoidal load, because it wasn't possible to put the same distance value. My aim was to obtain one bar with two diffrent, rectangular loads.

Adding some nodes help me indeed. Thanks a lot for efficient support. 🙂