I've made a simple support structure on which about 150kg load is applied and the structure is attached to other frames.
I did natural frequency analysis (modal analysis) on the structure itself for constrained condition with displacement constraints to the frames.
I was asked whether I included the force (150kg) on the structure for the analysis.
I thought any external load would not be considered for natural frequency analysis. Anyway, I ran the same analysis with the load on top and I got the exactly same result.
Did I do something wrong? Or external load wouldn't matter for the analysis.
Also I see gravity load on the tap. What would be the effect on the analysis by applying gravity load?
Thank you in advance!
Thank you, Paul!
I should've used prestress modal analysis...
One more question. When do you need gravity load on the analysis?
Thank you again!
big effect by prestress: pretension is applied to ropes
and gravity load is transversely