Low stability check ratio of steel column in canopy

[dnkerceg]

Greetings,
I have doubts about the accuracy of the stability calculation of the column IPE 360 ( for example member no. 5) shown in attached picture.

It is a column for canopy dimensions aprox. 40 x 20 x 6,0 m as a part of portal frame. Buckling length for both axis are the same . Ly = 1,0 x L, and Lz = 1,0 x L.
In the RSA c, XLT (reduction factor for lateral-torsional buckling) is calculated with a value of 1,0.

By manual calculation (and checking in other software) I get  value of XLT much lower and thus a higher ratio of the stability calculation.
I tried to changing the number of characteristic points for dimensioning, using only max values of forces and changing the conditions of bracing of upper and lower flange due to relative length of element within  parametric values of dimensioning in RSA, but I still get the same value of stability calculation.
If it adopt the value XLT = 1.0, my manual calculation matches the calculation in RSA.
In the attachment I submit the model from RSA and the manual calculation.

I think I left something out somewhere, but I can't find out exactly what so I am asking you for help, and fresh set of eyes of the problem.

With best regards.

[Krzysztof_Wasik · Accepted solution]

HI @dnkerceg 

You are verifying member 5 

For this member Simple bar set of design parameters is set

Simple bar parameters set has lateral buckling verification disabled.

Define for bar 5 set of parameters with Lateral buckling verification enabled. Then XLT will be reduced.

[dnkerceg]

Thank you for help.