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SHS to SHS joint desing (truss joint design)

11 REPLIES 11
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Message 1 of 12
skilak
1361 Views, 11 Replies

SHS to SHS joint desing (truss joint design)

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,

11 REPLIES 11
Message 2 of 12
Rafal.Gaweda
in reply to: skilak

Yes it is like that in Robot. Only longitudinals welds are considered in this connection check.


Rafal Gaweda
Message 3 of 12
dimogrec
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

Message 4 of 12
Artur.Kosakowski
in reply to: dimogrec

Thank you dimogrec. It is exactly as you wrote.



Artur Kosakowski
Message 5 of 12
skilak
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;)

 

Cheers,

Message 6 of 12
dimogrec
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 Smiley Wink

Message 7 of 12
skilak
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;)
Cheers,
Message 8 of 12
skilak
in reply to: skilak

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

Message 9 of 12
skilak
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.

Message 10 of 12
Artur.Kosakowski
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
Message 11 of 12
skilak
in reply to: Artur.Kosakowski

please refere to "projektowanie i obliczanie polaczen i wezlow konstrukcji stalowych" Brodka and Kozlowski , volume 1. pages 535-537. The book goes through various situations depending on the angle (chord to post) and beta ratio which impose the welds effective length. I understand that for an angle between 60-90deg the EC 3 beff for SHS shall be used (the book gives a bit more optimistic values here) , 60-50deg there is a formula to correlate within the rang and below 50deg what Robot already does (I think).

 

Best regards,

Message 12 of 12
Artur.Kosakowski
in reply to: skilak

Thank you for the reference. I have added this request to the wish list for the next versions of Robot.



Artur Kosakowski

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