Oversized purlins

[Anonymous]

Hi,

I have designed a steel hall, but I have a problem with oversized purlins. The current profile for purlins is IPE 500 wich is quite huge.

What might be a problem? Maybe a load that is applied to the web, but in reality it would be transferred by roof covering to the top flange of purling? How can I deal with that?

[Artur.Kosakowski]

The design seems to be governed by the bending in the weak direction of the purlin. I would check the model to determine why this value is so large and think what to change to have it smaller.

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[Anonymous]

I would be grateful if you will find a solution for this problem.
I was thinking of rotating purlins to the vertical direction of load operation, but the model will be disturbed.

[Artur.Kosakowski · Accepted solution]

You may consider use of wide flanges sections such HEA which are better for bi-directional bending.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[t.sautierr]

Usually what is done to design a roof like yours is to add anti lateral buckling element in order to avoid to increase too much purlins weight :

this has two goal : divide lateral buckling lenght in the weak direction, divide the span and then the deflection (latera) in the plane of the roof.

see picture of an example, other similar system can exist with the same purpose.

trick : this can also be use to windbrace your building.

conclusion : there wasn't any oversizing, this is a matter of statical scheme.

[Anonymous]

Thank you guys for your help! I realy appreciate it. The problem is solved. I have change IPE profile to HEA. The size of all elements are much smaller.

I'm still a student, but with your help I understand much more everytime!