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## How does Robot determine the parallel tangent stress between the stiffener and the column?

2 REPLIES 2
Message 1 of 3
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## How does Robot determine the parallel tangent stress between the stiffener and the column?

Hello,

I would like to know how Robot determines the tangent parallel stress in a Fixed column based design connection, with reinforcement stiffners on both sides of the column, as shown in the following image:

I've already looked in robot help, but among the various welds explained, this one doesn't appear.

I would like to know the acting forces considered, what length of welding is considered and where it is applied, whether just on one side or both, since this case does not appear in the connection definition menu either.

I know it depends of the moment in the column and in the height of the stiffener hs:
Due to MEdy => Ftf = (315.59/310-15.5) = 1071.61kN (flange in tension)
Due to NEd => Ftf = 131.92/2 = 65.96kN (compression)
Ftf = 1005.65kN
Stress = 1005.65/(0.008*0.2*4) = 157133kPa = 157MPa >111.94MPa ?!!

Thanks...

2 REPLIES 2
Message 2 of 3

You are correct in thinking that the stress in these welds is much higher than what is typically considered, especially given the challenges associated with performing the interior weld..

A possible hypothesis to partly explain that your result is superior lies in the fact that part of the forces in the calculation note are distributed in the front welds connecting the post to the base plate. (see "Welds between the column and the base plate"). It would be advisable to verify whether the steel used type is "S235", as the weld ratio appears to be low for the indicated stress. (see Also)

Furthermore, given the forces provided by the anchor rods, the welds closest to the stiffeners and the base of the column should take into account localized diffusion and be part of the capacity calculation as is the case in the assemblies using end plate.

All this considered, the calculation cannot replace a more in-depth analysis by shell modeling. You would be even more surprised to see how lever effects and local moments in the plates can cause plasticization.

Best Regards

Message 3 of 3

hi everyone,

I'd like to introduce you to AutoConnectFE, a small utility designed to help you create finite element (FE) models for your fixed column base connections. This software, combined with the Eurocodes justifications already integrated into Robot Structural Analysis, will enable you to quickly assess the forces acting on plates, gussets, rods and at part junctions for welds.
This tool allows you to go beyond manual methods based on material resistance formulae, while keeping in mind the regulatory framework of the codes in force.
AutoConnectFE facilitates the exploration of complex configurations by allowing you to discretise particular cases without leaving them out, and to analyse critical points where stresses are particularly high.

Best Regards

To use AutoConnectFE, it's simple: refresh the list of connections, select one, define the forces for the analysis, and launch the creation. The program will generate a new model (don't forget to save yours). Once the analysis is complete, you'll be able to inspect the results.