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Valued Contributor
Opel5
Posts: 81
Registered: ‎08-02-2012

Tapered cantilever steps, polyline face connection & block repetition

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08-03-2012 06:50 AM

Afternoon All,

I'm looking at another unusual stair situation and was wondering the possibilities of the following (refer to 2 PDF sketches & RTD attachments):

 

1) Tapered cantilever steps - referring to the attachments, the steps are solid with a chamfered sloped underside. I can't model it with polylines and panels due to the 3D nature (a solid block) but can't find an option to build up a solid shape?

 

2) block repetition - thie above 3D tapered "block" would need to be repeated at regular intervals. Is there a feature to copy and paste blocks such as this at set intervals?

 

3) polyline face connection where nodes don't match up (referring to "end 1" in PDF sketches & RTD file) - the rectangular end of each 3D block would need to be connected to the side face of a RC torsion beam. The problem is that the nodes of each 3D block would not match any nodes on the sloped RC torsion beam. How is it possible to integrate the 2 surfaces to allow for moment transfer from each cantilevered reinforced concrete step into the torsion beam?

 

Any feedback is greatly appreciated!

Thanks,

Scott

 

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Artur.Kosakowski
Posts: 4,750
Registered: ‎12-17-2010

Re: Tapered cantilever steps, polyline face connection & block repetition

08-03-2012 08:00 AM in reply to: Opel5

Before you start modelling you need to ask yourself a question about what kind of results do you need from a model and what kind of accuracy is required  (what kind of model you want to create). If you need bending moments, torsional moments, shear forces directly then it is going to be 3D frame with bar elements, if you are prepared to calulate torsion and in plane moments based on other results for surface elements then a shel with panels, if you need stress distribution along and across each of the steps as well as torsion beam then a solid but in such case having simple shear forces, bending moments etc. will require additional hand calcs.

 

What is it going to be then?



Artur Kosakowski
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Valued Contributor
Opel5
Posts: 81
Registered: ‎08-02-2012

Re: Tapered cantilever steps, polyline face connection & block repetition

08-03-2012 08:13 AM in reply to: Opel5

Hi Artur,

The main objective of modelling would be to find:

 

1) the total deflection at the tapered tip of each step with combination of twist deflection from the slender torsion beam. The tapered steps would be resisting an overturning moment from side fixed handrails. I was thinking of taking the reinforcement out through the tapered end to provide fixing points for the handrails.

 

2) provided reinforcement mm^2/m in the tapered steps and torsion beam.

 

Which method do you consider would give both of the above?

Thanks,

Scott

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Artur.Kosakowski
Posts: 4,750
Registered: ‎12-17-2010

Re: Tapered cantilever steps, polyline face connection & block repetition

08-06-2012 12:42 AM in reply to: Opel5

I would start with the bar model as bending/torsional moments as well as shear forces will be needed go calculate reinforcement.

For modeling check: http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Spiral-stair-slab/m-p/3529144/

 



Artur Kosakowski
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Valued Contributor
Opel5
Posts: 81
Registered: ‎08-02-2012

Re: Tapered cantilever steps, polyline face connection & block repetition

08-06-2012 07:53 AM in reply to: Artur.Kosakowski

Afternoon All,

I've put together a very basic representation of the steps but have a few problems:


1) In the "RC Design" section, I only get deflection values for panel 36. Any idea why deflections are not being calculated for panels 2 and 22? No errors seem to be popping up.

2) How can I add "uniform moment" loads to panel 2 edge 2 & panel 36 edge 2 to simulate balustrade lateral loadings?

Any feedback is much appreciated!

Thanks

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Artur.Kosakowski
Posts: 4,750
Registered: ‎12-17-2010

Re: Tapered cantilever steps, polyline face connection & block repetition

08-06-2012 11:39 PM in reply to: Opel5

1. Currently panels with variable thickness (panel 2) are not supported for cracked deflections calculations. The request for such development is on the wish list. On the other hand cracked deflection is calculated for panel 22.

2. See the attached picture.



Artur Kosakowski
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Valued Contributor
Opel5
Posts: 81
Registered: ‎08-02-2012

Re: Tapered cantilever steps, polyline face connection & block repetition

08-13-2012 07:27 AM in reply to: Artur.Kosakowski

Thanks Artur,

I've run through RC design (attached). Is there a full calculation printout option available for torsion beam 32, 33, 35? I'd like to make sure the required reinforcement includes UK design code checks for the induced torsional load.

 

Three of the RC stub beams which are being buried within supporting masonry walls are highlighted red, which I'm presumign means the beam doesn't pass RC design in some way. Is there an option buried somewhere to find out what is causing it to fail? The stubs will be continuous with the adjacent parallel and horizontal landing platform beams.

 

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Artur.Kosakowski
Posts: 4,750
Registered: ‎12-17-2010

Re: Tapered cantilever steps, polyline face connection & block repetition

08-14-2012 01:07 AM in reply to: Opel5

I've run through RC design (attached). Is there a full calculation printout option available for torsion beam 32, 33, 35? I'd like to make sure the required reinforcement includes UK design code checks for the induced torsional load.

 

The detailed calculation note is available only when you design your beams in the RC Beam Design module of Robot.

 

Three of the RC stub beams which are being buried within supporting masonry walls are highlighted red, which I'm presumign means the beam doesn't pass RC design in some way. Is there an option buried somewhere to find out what is causing it to fail?

 

Add the remarks column.

 



Artur Kosakowski
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