Triangular steel column
Triangular steel column
(OP)
Hello!
I´m testing a FEM of a triangular column with 16.5m height which will hold a publicity screen on the top.
For the triangular column I used on the edges of the triangule tubes D244.4x5.4 and between them steel plates S275 with 10mm thickness. The edges have a distance between them of 1m.
Only submited to wind loads The result of the analysis was ok for the deflections, ok for the tubes but for the steel plates I have a stress value around 1000 N/mm2 (pressure)untill 1 meter from the bottom of fixation.
I tested the same column but instead of steel plates I created a frame work (truss column) and the result was very good.
So, how should I interpretate the stress values of 1000 N/mm2 Comparing with the fy of the steel (275) which is much less? Can I compare this values just like that?
Thank you for any answer.
agps
I´m testing a FEM of a triangular column with 16.5m height which will hold a publicity screen on the top.
For the triangular column I used on the edges of the triangule tubes D244.4x5.4 and between them steel plates S275 with 10mm thickness. The edges have a distance between them of 1m.
Only submited to wind loads The result of the analysis was ok for the deflections, ok for the tubes but for the steel plates I have a stress value around 1000 N/mm2 (pressure)untill 1 meter from the bottom of fixation.
I tested the same column but instead of steel plates I created a frame work (truss column) and the result was very good.
So, how should I interpretate the stress values of 1000 N/mm2 Comparing with the fy of the steel (275) which is much less? Can I compare this values just like that?
Thank you for any answer.
agps





RE: Triangular steel column
And what do you mean by "the bottom of fixation"? I have absolutely no concept of what you mean.
Now, I am not trying to be obtuse, and certainly not critical of your language, but if you want an answer to your problem, I think it is imperative that you state your problem clearly.
BA
RE: Triangular steel column
corus
RE: Triangular steel column
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Triangular steel column
Kind Regards,
BA
RE: Triangular steel column
I think the 'bottom of the fixation' means the base of the structure, where it's built in, by the way.
corus
RE: Triangular steel column
The height of cantilever is 16.5 m and I assumed a wind pressure of 1 kPa, so the uniform load on the column was taken as 1.0 kN/m. This gave a cantilever moment of 136 kN-m. Didn't know the area of the publicity screen, so I ignored it.
This produced a maximum fiber stress of 23 N/mm^2. How does that sound?
BA
RE: Triangular steel column
My apologies for taking so long to answer your questions and thank you all for the effort and consideration in trying to find a valid answer for my thread.
First of all let me clarify the acronym FEM. As you well understood it means Finite Element Model (never thought it will bring so many interpretation doubts).
Second, the "bottom of fixation". It´s the "base of the structure". Thank you Corus.
Regarding the problem itself, I must say that a few hours after posting this thread I found my error.
Corus, thank you for your answer about the column behavior and how to solve it.
BA, D244.4x5.4 refers to a tubular section diameter 244.4 and thickness 5.4 (mm). As you don´t have access to the loads aplied the values that you tested are a little different from mine.
I´ve in round numbers max stress value 280 N/mm2 which forced me to change the steel tensile strenght.
Anyhow, I´ve another issue to put in consideration regarding the same structure.
The moments that I´ve on the base of the structure are much less than the values found on a initial study which I applied the same loads but on a simple cantilever system (one fixed support only with the same height, 16.5m).
On this system I´ve moment values of 600 kN.m and on my computer model, where I´ve 3 supports (the edges of the triangule), I´ve max. moment values of 56 kN.m
What do you think is the reason for such low values in FEA
Note: The value of the structure self frequency (just due to self-weight) is 1.75 Hz.
Oh! One more thing.
BA, om du bor i Sverige/Stockholm blir jag glad och kan jag träffa dig då kan vi dricka en eller två glas öl tillsammans.
MHV (ooppss!! No acronymns. Med Vänliga Hälsningar!)
agps
PS - What does OP mean Greglocock?
RE: Triangular steel column
Joint 1 - -17,9 kN.m
Joint 2 - -19,3 kN.m
Joint 3 - -19.3 kN.m
RE: Triangular steel column
I don't live there, but if I am ever visiting the area, I will be happy to take you up on your offer.
Oh, yes...OP means original post...in this case that would be you.
Kind regards,
BA
RE: Triangular steel column
And please don´t spend time around my last consideration. I believe I reach what I want crossing information from two different models.
Hej då alla ni
agps
RE: Triangular steel column
BA
RE: Triangular steel column
And the final value for the moment is always there.
agps
RE: Triangular steel column
Exakt! Nu är du matlagning med gasar.
All the best,
BA