Learning Forum

[Fabricio.Urquhart]

Hello people!

I would like to know, if somebody could help me with the load application. The model is composed for solids and cross-section, connected for a rigid joint. Now I am applying the load. It is distributed load along the cross-section and solid.

But when I apply a line pressure in the solid and the cross-section the model does not converge. If I apply only in the cross-section it is ok. The objective is to analyse the connection, so I have to apply load along all the beam of the portic.

The picture below, shows the model with the line pressure applied only on the cross-section.

 

Attention, that I have a plane of symmetry. With concentrate load, it is ok, but distributed load I have problems with convergence.

 

Thank you!!!

[Sandeep Medikonda]

Hello Fabricio,

  Can you explain a little about the type of error you are seeing? What kind of material and contact's are you using?

  I see plasticity in the model, do you have large deformation effects ON? If not, can you try turning those on?

  Have you looked at the Newton-Raphson residuals and tried the tips and tricks suggested in this article?

Thanks,

Sandeep

[Fabricio.Urquhart]

It was an unknown error. The materials are:

- Bolt: ASTM A325

- Beam and column: ASTM A572

- Plates: ASTM A36.

Yes, I have large deformation effects ON. Oh! I have not looked at the Newton-Raphson residuals, I will read the article, thank you.

But the problem was that I was applying the load in a edge of the solid parts, so I applyed a pressure on the beam flange with the same value of the crosssection (line pressure) and it converged. The results are OK, now I posted another topic: Symmetry.

 

Thank you, very much!!!

[Fabricio.Urquhart]

 Hello Sandeep, 

The materials are:

- Bolts: ASTM A325

- Beam and columns: ASTM A572

- Plates: ASTM A36

Yes I have large deformation effects ON. I have not looked at the Newton-Raphson residual, I will look and read the article!

Now I have wrote another post: Symmetry. I am trying to model the half portic, because the other side is impacting in the connection results that I am studying.

 

Thank you ver much!!

[peteroznewman]

I have changed your model that was posted in the Symmetry post and have results.

[Fabricio.Urquhart]

Thank you Peter.

Using Pressure as load on the solid's face, appear local forces as you have seen in your model. I would not like that local forces appear. Do you know anyway to apply the load in the solid?I tried to apply in the edges, but it did not converges.

Thank you!!

[peteroznewman]

But Fabricio, that is a real effect of applying a pressure load. The more flexible outer flange deforms more than the center of the flange that has the vertical face of the I-beam under it. If you look at the magnitude of the flange flexing down below the center of the beam, it is only 0.068 mm or 68 microns.  Can you even measure that?  Why do you care?

In a real structure, there might be a reinforced concrete slab resting on the I beam. You could model that and it would press with much more pressure on the part of the face above the vertical face of the I beam under it and the pressure would ramp off to nearly zero at the outer part of the top flange. If the concrete slab was flexible, it would make contact along the full length of the I-beam. But if that slab was stiffer than the I-beam, it would only touch out near the joint and the center of the beam would have no contact.

I expect you don't want to add a slab. What you can do instead is split the top face of the I-beam at the plane of the vertical face, and apply the pressure to the newly created narrow face. That should avoid the convergence problems of applying a force to an edge of solid elements (which is never good), and avoid local flexing of the flange.

Regards,
Peter