BS EN1993-1-8:2005 design of steel joints

[galaxy212]

Morning All,

I'm currently in the process of designing a CHS truss with welded gapped K and KT joints. I have been referencing 'BS EN1993-1-8:2005 design of steel joints' for design guidance though have come a bit stuck. I'm looking to calculate the joint resistances but am not really sure how to go about calculating the stress's in (5) of section 1.5 'Symbols' (see attachment picture). As the truss is overly stiff for me to do a quick pin-jointed hand calc on it, can I use the principle the stress's in the cord and braces from an FEA of the truss ?. Any guidance would be must appreciated ?. Thanks.

 

[JoshPlumSE]

I'm not sure that reference is really up to date for hollow structural section connections. You might check out the CIDECT design guides as an alternate reference.

 

[creampuff]

The design of joints isn't that simple and there is a lot of scope to make a mistake if you do it by hand.

Are you using some kind of structural beam design software to do your analysis? If you say you are using FEA my first thought is why? If so, then it will almost certainly have the option to also check the joints. Also beware your welds - your strength will depend on if you use full penetration or fillet welds.

 

[galaxy212]

Thanks creampuff,

I'm using the CATIA GAS FEA package to analysis the truss as a whole structure and so the K and KT joints have been idealized to some extent. I want to cross check the member forces from the FEA against the calculated joint resistances from the standard to avoid chord face failure and punching shear. I'm not sure how to calculate the stress's in (5) of section 1.5 'Symbols' is all.

 

[creampuff]

galaxy212, not sure if you have sorted your problem yet.

I'm not that familiar with BS EN1993, however most design codes when checking joints will require a value for axial, inplane bending and out of plane bending loads in both the incoming brace and the chord. The code check is based on all these parameters.

This is why I do not recommend designing joints to a design code using FEA - because it is a significant post processing effort to determine the axial, IPB and OOPB stresses. I recommend a beam-type analysis program like SACS or STAAD.

You may want to eyeball the von-Mises stress plot for your whole joint and check that it is within your limit for a start before doing any further checks.

 

[saruncivil]

Hi galaxy212,
for stresses formulas are given in same code please refer clause 7.2.1 (3) and refer figure 1.4, then you can get idea sir.
direction of force flow should be know according to that sign will change.

you can refer CIDECT (

http://www.cidect.org/en/Publications/)

too.

This calculation is simple only, if any doubt please ask.

 

[Bagman2524]

There's an online link for cidect.

http://212.150.245.105/shared/eBooks/DG1-Eng-edt-2008-version-02-11-2009-complete.pdf

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