Modelling horizontal(in-plan) bracings in the ETABS.

[M_U]

Hi,
I am trying to model horizontal bracing in ETABS. But if I model them at the floor level it starts taking gravity loads from secondary beam which should not be the case. I can not use the exclude frame from shell option because I am using membrane for deck. So, how to model them correctly?

 

[M_U]

Can someone help me out with the above problem.

 

[HDStructural]

Have you tried inputting the load as uniform loads across each beam rather than an area load?

 

[M_U]

I tried but the software is taking the point loads from the secondary beam as shown in the bending diagram of bracing. Ideally it should be zero.

 

[HDStructural]

Something weird is happening. Why is one of the secondary beam reactions on the brace an uplift load, while the other two are downward loads?

Other weird stuff seems to be up.

You could try lowering the nodes for the brace in your model by 1 cm or something small like that. That will separate the secondary beams from the braces.

 

[Luceid]

HDStructural's method would work.

Alternatively you can use assign->Frame->Frame Floor Meshing Options, and assign the brace to "Do Not Include Selected Frame Objects in Mesh". This ensures the meshing algorithm does not grab onto the brace. Then I'd probably for the frame to not automesh at all, using Assign->Frame->Frame Auto Mesh Options.

In SAP there is a specific tool to force one-way load distribution to skip over certain frames, but I believe this has the same effect. Good on you for noticing this is causing problems, I've seen a lot of ETABS models where people glance past this without thinking.

 

[Luceid]

Ah I didn't see that it was specifically about the point loads because the braces are crossing the secondary beams. You should only need to remove the automesh from the brace element to fix this issue