Basic Tutorial about buckling lengths in SCIA Engineer 19.1

The basic tutorial about the handling of buckling lengths in SCIA Engineer 19.1.
I explain the input of system lengths, internal calculation of buckling lengths from the stiffness of the nodes and beams, and also the usage of stability calculation for buckling lengths.
Theory for buckling lengths in SCIA Engineer: bit.ly/3ec5gfn
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Linked In ► / ivanbeles

[@fredericobaiao1463]

Great explanation, great video, help me a lot to understanding buckling behavior at SCIA!

[@daibang11]

I used version 21 of SCIA and noticed that all the results in Slenderness menu (Ly, ky, lam y...) are in section coordinate system (CS) and NOT beam's or column's CS. For section CS, y-y is always strong axis and zz is always weak axis.

[@jaak170]

Excellent videos. Thank you!

[@robertasz9458]

Nice video. Clear explanation. Thumbs up. Now we will wait for tutorial covering nonlinear buckling. P.S. small correction. The results of buckling length would be closer if you would take second buckling mode for weak axis.

[@IvanBeles]

yes, maybe. I don't have so much experience, and didn't found some rules how to select the buckling shape. Maybe, because of the bending moment shape, it would better fit to use the clear buckling around weak axis.

[@robertasz9458]

​@@IvanBeles I just meant that you missed to change the buckling mode for weak axis (time 36:18). Once again, tutorial is great.

[@djamilahad9179]

For the combinaison of stability , should we chose the same of uls combinaison

[@IvanBeles]

First, this should answer some professor from University. I think, the buckling shape should be affine to the deformation from the combination in the static analysis. Important is, to have the members under pressure, and best way with constant axial force. I try to get all columns to lose stability at the same or near level of load. Lateral forces are not important, because the stiffness matrix will be weaker due to the negative axial force. Sometimes, if I have to find only the buckling length, I define a special load case with ľ forces on the member. One from left one from right. Then the first buckling shape is the buckling around the weak axis. Because sometimes you have structures, where the important buckling shape is after 50.th or later. For the evaluation of buckling length, I think, the level of the load is not so much important, because the buckling length will be calculated from Ncr. And this is N * Lambda. If you use a smaller "N", you will get higher Lambda, and vice versa.

[@ΓιώργοςΧρυσόπουλος-χ2ε]

in this example you have λmin=16 . You must change or not the sway type (from sway to non sway)? If do it this change, the "k" decreases and have more economical design.

[@IvanBeles]

For this example I used the characteristic load to determine the "Lambda". So, if you use the design load it will be less than 16. But in the check itself, SCIA Engineer checks the ratio between N.crit and NEd. And if it is not necessary, the buckling check will be not performed.

[@georgechrisopoulos540]

Yes I understand is not necessary the stability analysis. In this example (ok with characteristics loads) you have Ncr=16N. If you put all uls combination maybe have smaller lamda. But if you do stability analysis and have lamda bigger 10 then you have non sway type of construction and “k”

[@IvanBeles]

Maybe you are right. I don't know about such rules in Eurocode. But this discussion is more for professors from universities. The goal of this video was to show how SCIA Engineer works and give this information to customers.

[@mohamedhousni5792]

@@georgechrisopoulos540 According to Eurocode3, you need to calculate a certain factor alpha_cr and check if it is bigger or lower than 10. If alpha_cr >= 10, the structure is non-sway. If alpha_cr < 10, the structure is sway. If I am not mistaken.

[@mohamedhousni5792]

@@IvanBeles Maybe it would be nice to have a tutorial on how to check if a structure is sway or non-sway. This has indeed a big impact on the buckling factor and so also on the dimensioning of the columns.

[@camsect4619]

Thanks you so much

[@saeidmahmoudimotlagh5701]

Could you make a distinction between ""beam"" and ""column"? You call everything ""beam""!!

[@IvanBeles]

Aha, sorry. All are 1D members. For the buckling length calculation, there is different loading in the background for columns and beams. Columns are 1D members, they go vertical or +/- 10 Degree from the vertical. All other members are beams. This was for the loads for the buckling length calculation. For the checks of steel structures, it doesn't matter if you call the 1D member beam or column. For concrete 1D members, there is a distinction dur it is in the EN 1998-1 and not in EN 1992-1-1. If NEd>0,1Ac*fcd, then it is a compressed member and is calculated as a column with all the eccentricities.