Hi everyone
I'm modeling in StaadPro a vertical mechanical equipment, so it has vacuum weight and operational weight (+ it selfweight).
Also I’m doing a dynamic analysis using Spectrum.
The model is very simple, it has:
- two nodes
- one fixed support
- as a property it has Steel Tapered Tube (Round shape)
To have an idea on how its looks like, here is a screenshot:
Image may be NSFW.
Clik here to view.
You can see there is two load cases that I want to extract and compare, those are (illustrated in the screenshot) seismic load case for vacuum with his respective load and another load cases for seismic in operation state with his respective. Obviously these loads are different taken form the datasheet of the equipment.
When the program preform the analysis and I select the Postprocessing-Node-Reaction and I’m filtering the results for my main loadcases who I want to compare there something that not very logical.
I want to share another screenshot, so maybe that’s help to explain better
Image may be NSFW.
Clik here to view.
You can see that the values of forces and moments are the same, which is not logical because these two load cases have different loads as you see in my previous screenshot. In my opinion it should give different results.
So, I was making several attempts changing and modifying the model to see why this is happening to the model. My conclusion is that StaadPro, using the spectrum it takes just the selfweight as a participation mass and ignore the vacuum or operation weights. (This conclusion came because I changed the thickness of my equipment and it’s actually change the results).
So, I need to know:
- Why the programs ignore the vacuum and operational weights?
- If I’m modeling in the right way?
- If there is any command or trick to let the program take these weights.
I know my post was too long, so thank you for your time. And sorry for my bad English
I hope engineer’s communities can help me.
Thank you
