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I have a structure like such:

Structure

Due to my lack of knowledge of ANSYS, I have made the singular distributed loading (GI) represented as two distributed loadings (GH and HI). Would this be an accurate model? Model

I feel like there should be some bending in the middle (HE to EB).

When I model it is a singular 240kN force on the center points I get: Model with Singular force

Which of these would be more accurate?

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    $\begingroup$ I just want to point out that by adding additional parts to your question, you have messed up the answers that were posted previously. $\endgroup$ – hazzey Apr 28 '15 at 1:06
  • $\begingroup$ I agree. This is not a forum. Should I remove the additional parts the most relevant answer? $\endgroup$ – General Stubbs Apr 28 '15 at 1:21
  • $\begingroup$ Don't worry about changing things now, just be aware of it in the future. $\endgroup$ – hazzey Apr 28 '15 at 1:23
  • $\begingroup$ I think this is a living question for now until we figure out the constraints on all the points in the model. Once the author configures the constraints correctly, we're all expecting that the result is same for a single load or several loads. $\endgroup$ – user823629 Apr 28 '15 at 3:14
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I would expect the modeling as a single load to be accurate. Force per linear area is the same expressed either way. You could look at a linear load on a single beam and just add more points of integration analytically and try it in ANSYS to see it.

The HE and BE segments will undergo buckling as its deformation mechanism after modest compression. The single load would logically be larger in aggregate since it is also applied to the small area supported directly by HE, but an eyeball examination says that this will be negligible and not affect the prediction that buckling is what you watch for in HE and BE. Are G, I, D, and F constrained in the model or free to move? Could affect buckling strength.

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  • $\begingroup$ When I model the force as a singular 240kN force I get the following i.imgur.com/DiL7olx.png $\endgroup$ – General Stubbs Apr 27 '15 at 23:40
  • $\begingroup$ While it would be expected that the center beam would be under the most compression (handling more vertical load than the sides), there's no logical reason to get two results from the way the load is broken up. Also, the top corners appear to have slid inward. Are there mechanical connections between the top corners and the beam? Last, there should be finite deflection/stress in the side beams. You can't have a beam connection bending without some reaction in what it's connected to. If it's zero (you can measure) then ANSYS is missing some information. $\endgroup$ – user823629 Apr 28 '15 at 3:27
  • $\begingroup$ Evidently I am doing something wrong with ANSYS then. Thank you. $\endgroup$ – General Stubbs Apr 28 '15 at 4:27
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Splitting a uniform load into separate pieces that are still continuous will have no effect. This is frequently done.

As far as your question about bending in HE and EB, there shouldn't be any bending because all of the forces are balanced. A sum of the moments at H or E will show that the moments from the beams on either side are opposite and equal. That means that the resulting moment at the joint is zero.

To answer your added question, a single point load is not a replacement for the distributed load. The distributed load causes bending in the horizontal members. The distributed load also distributes load to the vertical members on each side. The single concentrated load focuses all of the force in the central column.

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Adding just a slight notion:

Your experience would always expect the beam HE to buckle, because it is a Eulerian buckling beam (don't know if it's also called like this in English). The numeric only sees an evenly distributed load, so there will be no buckling... Try to alter your forces to the left and right of H a bit and you will get a moment which will cause HE to bend (If its support is rigid).

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