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skilak
Posts: 44
Registered: ‎08-13-2013
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SHS to SHS joint desing (truss joint design)

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05-08-2014 03:56 AM

Hi,

 

We have tried to design a SHS to SHS joint 90 deg both 150x150x6 and we have found that when checking the welds it takes into account the longitudinal weld only. We have check the EC3 1-8 and could not find anything saying that we cannot.

Please see attached advice.

 

Best regards,

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Rafal.Gaweda
Posts: 5,005
Registered: ‎04-26-2010

Re: SHS to SHS joint desing (truss joint design)

05-08-2014 07:42 AM in reply to: skilak
Yes it is like that in Robot. Only longitudinals welds are considered in this connection check.


Rafal Gaweda
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Valued Contributor
dimogrec
Posts: 97
Registered: ‎07-16-2011

Re: SHS to SHS joint desing (truss joint design)

05-08-2014 08:55 AM in reply to: skilak

skilak you're right there's no such limitation in EC3 1-8.

Anyway Robot's truss node verification is based on EC3 1-8 and CIDECT publications as it is described in help page:  http://docs.autodesk.com/RSAPRO/2014/ENU/index.html?url=filesROBOT/GUID-7D953AA2-D6C2-4646-A5FA-A038... (if the page isn't shown properly do a search under "truss node" on Robot's help page )

I remember asking the same thing some years ago.  ( http://forums.autodesk.com/t5/Robot-Structural-Analysis/welded-truss-node-connection/m-p/3737103 )

So generaly Robot assumes the effective length of the weld depending on the joint type (K , T,  N, X) based on what is written in "Design Guide for Rectangular Hollow Section (RHS) joint under Predominantly Static Loading"  par. 3.9

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Artur.Kosakowski
Posts: 4,618
Registered: ‎12-17-2010

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 12:06 AM in reply to: dimogrec

Thank you dimogrec. It is exactly as you wrote.



Artur Kosakowski
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Active Contributor
skilak
Posts: 44
Registered: ‎08-13-2013

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 01:15 AM in reply to: Artur.Kosakowski

So, if there is no limitation, why not to amend the feature in Robot? I guess it is not a big deal but so much benefits? Is it sorted in version 2015?

I have check Corus "Design of SHS welded joints"  and the weld has to match the tube properties e.g. b eff. Also, Prof. Dr. J. Wardenier CIDECT "Hollow Sections in Structural Applications" 8.2 "to avoid weld failure it is recommended to design the welds to be stronger than the connected members, i.e. according to EC3......."

 

PowerConnectsoft does it right:smileywink:

 

Cheers,

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Valued Contributor
dimogrec
Posts: 97
Registered: ‎07-16-2011

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 01:52 AM in reply to: skilak

Since there's no direct restriction by the EC3, it would be nice, for such types of connections, to let the user deside (by adding an option) which weld length to assume for the calculations. Total length (as EC3) or effective length (as CIDECT)

I guess it's not so hard to do :smileywink:

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Active Contributor
skilak
Posts: 44
Registered: ‎08-13-2013

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 01:57 AM in reply to: dimogrec
Yes, at least to match b eff as per EC3 1-8 Figure 4.8 and I would be a happy bunny:smileywink:
Cheers,
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Active Contributor
skilak
Posts: 44
Registered: ‎08-13-2013

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 02:38 AM in reply to: skilak

or,    could we add "full strength welds" and therefore no welds check required??

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Active Contributor
skilak
Posts: 44
Registered: ‎08-13-2013

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 03:27 AM in reply to: skilak

Further to my reserch Robot can calculate transverse welde but only if the diagonal is less or equall to 50deg (what we can find in CIDET or other publications as well). For the range 50 -90 deg no transverse weld taken into account. I think that little extra from EC 3 1-8 4.10 (4) would be safe.

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Artur.Kosakowski
Posts: 4,618
Registered: ‎12-17-2010

Re: SHS to SHS joint desing (truss joint design)

05-09-2014 06:38 AM in reply to: skilak

Further to my reserch Robot can calculate transverse welde but only if the diagonal is less or equall to 50deg (what we can find in CIDET or other publications as well). For the range 50 -90 deg no transverse weld taken into account. I think that little extra from EC 3 1-8 4.10 (4) would be safe.

 

 

I'm not sure if I understand you correctly. The proposed switch to 'according to EC3' should allow for including transverse welds of beff length for both above situations or for the prior one only?

 



Artur Kosakowski
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