Node Precision

Anonymous · ‎09-22-2014

I am having a problem where I have a multi-sloped roof on a structure. The precision of the nodes seems to be an issue. I have looked at:

http://forums.autodesk.com/t5/robot-structural-analysis/rounding-up-coordinates-api/td-p/3430533/hig...

and have used tried to use the add-in described there, as well as trying to correct the model, but still no luck. Any help would be greatly appreciated.

FYI: This model originated from Revit 2015, and I am using Robot 2015 as well.

Model link: https://SSend.it/mvwxzy

Artur.Kosakowski · ‎09-23-2014

Indeed the problem is with the precision of the model. Before correcting the planes and positions of the edges of panels could you have a look at the locations I indicated in red and check if you need to make changes there as well.

Artur Kosakowski

Anonymous · ‎09-23-2014

Artur,

I simplified the model to have a flat roof for now, and still getting the precision error. Please see attached. I just need the precision of the nodes not to me so fine, but can not seem to get that to work.

Link: https://SSend.it/e5kdel

Anonymous · ‎09-23-2014

I have also Attached my Revit Model here. Not sure if I need to fix the precision in Revit 2015 before I integrate to Robot. I would like to fix the precision issue before I start to introduce all the various roof slopes.

Link:https://SSend.it/7wj072

Artur.Kosakowski · ‎09-23-2014

I'll try to help you with this model but before addressing geometry of the panels I'd like to ask you to look at the arrangement of the vertical and horizontal (parallel to X and Y) bar elements in the plane of the roof and make sure their end

nodes have correct X and Y coordinates (in other words that they are parallel to the global X and Y axes).

In addition make sure that the common nodes of the inclined bars that start in the corners of the roof are in the right positions along the middle line of the roof. At this stage it doesn't matter if other bars are too short or too long and their nodes are not exactly along the skewed ones as long they are vertical and hoizontal.

Artur Kosakowski

Anonymous · ‎09-23-2014

Artur,

I have modifed the nodes per the way you have indicated, however, now the model is stuck under model consolidation when trying to run. Please see attached:

Link:

https://SSend.it/1aus5x

Anonymous · ‎09-23-2014

I have re-done the previous step, but still seems like the mesh node precision is a problem...

See attached: https://SSend.it/9ael2t.

It just seems like the framing becomes detached from the floor planes for some reason...

Artur.Kosakowski · ‎09-24-2014

I have used the model from the one before the last link as the last one doesn't work.

https://screencast.autodesk.com/Main/Details/d9ee2346-13fa-4b0d-9e1d-24698d13edd8

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.

Artur Kosakowski

Anonymous · ‎09-24-2014

Artur,

Your method explained above has worked for the flat roof condition. However, I have now added the true roof slopes to the model. It seems like the model is almost there, but some load distribution seems to be incorrect. I believe has to do with a node instability, and incoherent mesh on edges, but cannot figure out how to fix it. Just by inspecting the moment diagrams of the hip and ridge beams, it is apparent that the rafter loading isn't being transfered correctly. It looks like the roof diaphragm isn't attached correctly to the ridge/hips (May have to do with precision of nodes again), but I am having a hard time trying to join the diaphragm to the ridge/hip beams. I appreciate your help!

Latest Model: https://SSend.it/kmok5k

Artur.Kosakowski · ‎09-25-2014

I have deleted the original roof panels and defined them again. I'll send you this file separately. Please check the assigned thicknesses as I used the one from the list as well as redefine loads.

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.

Artur Kosakowski

Anonymous · ‎09-25-2014

Artur,

Your modification fixed the instabilities. However, it still seems like load isn't transfering to the ridge/hip beams correctly. The one thing I did notice however was that the load was indeed transfering to the steel beam correctly. See attached screenshot.

Artur.Kosakowski · ‎09-25-2014

Try the following:

1. Reduce the thickness of the roof panels to e.g. 0.1 in

2. Increase the height of the ridge beams e.g. 2-3 times

Has this changed the behavior of the model? Mind that Robot distributes forces based on stiffness rather than LTD approach.

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.

Artur Kosakowski

Anonymous · ‎09-25-2014

Artur,

By reducing the thickness of the roof panel, it was closer to the results I was expecting to see. Is there a way to force panels in robot to behave as a 1-way distribution, while maintaining a semi-flexible/rigid diaphragm action?

Thanks!