Wind load from Equipment on a structure

[Antnyt23]

I am trying to model/analyze a structure on RISA 3D. I built the structure which has some equipment on it. I have applied a downward load due to the equipment. Afterward I built walls to resemble the equipment and gave the material 0 density so weight was not factored in since I already accounted for it. I wanted to model the equipment in order to apply a wind load to the equipment and to the structure. Is what I did an appopriate method? I was not sure how to represent the walls fastened to the structure so i fixed them in their locations.

Additionally, I have been putting grating in my models however i do not model it i just apply a deadload for the weight it would apply so that it is factored in. Would it be better to apply plates to the top of my structure?

Any helpful tips from people who do similar modeling would be excellent.

 

[msquared48]

Can't open the file without the proper security information, so you may have to create a sketch, scan and post that.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Antnyt23]

PDF with explanation. See if that works and covers everything.

 

[JoshPlumSE]

I was able to open that model. The wall panels you used to define the equipment do not look like they have been defined correctly. Double-Click each wall in the Wall Panel Editor and assign a "free" boundary condition to all four edges. As it is now those pieces of equipment are rigidly suppported on three sides. Therefore, they are providing support for your structure rather then the other way around.

 

[Antnyt23]

I now get the error p delta diverging at WP12. Do I need to provide some type of structural support to these wall panels that are representing the equipment?

 

[JoshPlumSE]

You have a very slender wall. So, including P-Delta effect for those walls is causing a buckling or instability in that wall.

This may be the result of some un-realistic parameters for the wall. If so, then just go to the Solution tab of the Global Parameters and un-check the box which includes P-Delta for wall panels. Note: the P-Delta effect will still be considered for the beam and column members, just not the wall panels.

If you think the wall panels may have a genuine stability issue, then you should take a look at the parameters which define that wall (thickness and material properties) and see if those should be changed.