RC Beam calculations

[jpo82]

Hi

Has anyone else encountered any problems when you have tried to do RC beam calculations in Robot? In my case I have a ribbed RC slab, slab thickness is 250 mm and height of conrete beams (modelled as simple bars) is 1000 mm. I do get some results but when I try considering axial forces in calculations Robot crashes everytime.

I think these axial forces should be taken into account since now I have a maximum bending moment ~500kNm in ULS and at same point I have also a 500 kN axial force. If you multiply this axial force with eccentricity of beam you get additional 200 kNm of bending moment. So does anyone know can I take this axial force into account in Robot or do Ihave to design these beams by hand calculations?

[pawel.pulak]

Can you attach the model for which Robot scrashes when trying to design the RC beam considering axial forces?

Regards,

[jpo82]

I did a simpler example model which behaves exactly sameway. See file attached.

Example_model.zip

We have verified this example case with one old FEM software designed in particular for RC slabs. While comparising result we noticed that Robot gives about 40 % smaller bending moment for beam than this old FEM software. But if you multiply axial force with offset you have applied in model and add that moment to My moment that Robot has given then results are quite same.

[jpo82]

Some additional information for this case. From anoter attachment you can see which setting I'm trying to apply and the other attachemnt shows bending moment and axial force for one example beam. So if I check box "take axial force into account" then Robot seems to calculate beam but after calculation nothing happens. Calculation information box is on screen and it doesn't go away and you can't do anything but shut Robot using task manager.

beam_results.png
setup.png

[teixeirahnuno421232]

What do you mean by considering axial forces in the calculations? Does the program crashes for a linear analysis?

[pawel.pulak]

Yes, there is some issue when:
1/ bar 5 is exported to RC Beam design with manual combinations
2/ and "Display diagrams for all combinations" is active in settings of RC Beam design (this setting is automatically activated when "Axial force taken into account" is activated)
It results in hanging of Robot when trying to calculate reinforcement for such beam or in the crash when trying to activate "Beam - Diagrams" tab for it
It was reported to dev team to be investigated.

Regards,

[pawel.pulak]

It was fixed in Service Pack 3 for ARSAPro 2014. The update can be downloaded using Live Update or the link below:
http://usa.autodesk.com/adsk/servlet...inkID=13140816

Regards,

[jpo82]

OK, that fix seems to do it. Now Robot doesn't hang anymore on that stage. However I still have problems since I can't print calculation note of beam. I can't copy it, I cannot print it. All I can do is view it Robot. Print or print view won't do anything for beam note layout. For instance on beam reinforcement layout they do work. Am I missing something here?

[pawel.pulak]

Notes from RC provided reinforcement modules can be copied and printed when using Results > Calculation Note from the pull-down text menu.