topic Re: deflection of cantilever stairs in Robot Structural Analysis Forum

deflection of cantilever stairs

Anonymous — Thu, 02 Aug 2012 13:34:07 GMT

Afternoon,

I'm trying to model some basic stair slabs which are cantilevered off 2 RC walls. The vertical end deflection of the upper platform doesnt seem to be showing in the results. Have I missed something? I've attached the RTD file in zipped format.

Many thanks in advance for any helpful feedback! 🙂

Scott

Re: deflection of cantilever stairs

Artur.Kosakowski — Thu, 02 Aug 2012 14:07:39 GMT

Scott,

The definitions of loads in cases 2 and 3 are incorrect - you don't have results for these cases therefore you have no results for combination 4 too.

I have tried to correct these loads but check if the values are right (corrected model attached).

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.

Re: deflection of cantilever stairs

Anonymous — Thu, 02 Aug 2012 14:39:00 GMT

Many thanks for the speedy reply Artur! Excellent, nice to see it working.

The practical allocations of FE planar loading seems a bit confusing, as there seems to be multiple ways of allocating the loads to the panels. In this instance I added planar loads to each panel in turn which caused the error. Is there a particular PDF resource that you'd recommend which explains the allocation sequence fairly clearly?

Re: deflection of cantilever stairs

Anonymous — Thu, 02 Aug 2012 14:51:32 GMT

Argh, sorry back again!

On switching the uniform load back to a planar load (to simulate the area loading from a concrete screed / tiles / grout etc) the same error occurs. I've attached a screenshot and the RTD file.

If anyone knows how to deal with this error where connecting panel edges meet please let me know.

Many Thanks,

Scott

Re: deflection of cantilever stairs

Artur.Kosakowski — Thu, 02 Aug 2012 14:57:26 GMT

What is the way you define the planar load? If you use the 3 point definition (variable surface load) make sure the A,B.C points are not the same and are not defined along a line.

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.

Re: deflection of cantilever stairs

Anonymous — Thu, 02 Aug 2012 15:13:31 GMT

Hi There,

I've managed to solve the problem by specifying "surface on object" planar loads rather than "FE planar loads". It's working well now without the calculation error messages at FE panel edges coming up. Thanks for the speedy feedback