Steel section for roof beams in warehouse

[OxidoTuloso]

Hi, I'm designing the roof beams for a warehouse, specifically a rigid frame one with a span of approximately 13 meters and a 6 meters space between collumns. The warehouse is under a wind load of 30-35 m/s according to my country's code, and located on the shore.
I'm looking for a reference on which steel section and grade to select, in order to use as a starting point in my design. Thanks in advance.

 

[jaskamakkara]

Hi,

This is very little information to work from. The wind speed you have given doesn't help much, you need to convert it into a peak velocity pressure (or whatever this is called in your country's code). You also haven't given the rest of the loading: snow, permanent, variable etc etc. If you want a starting point for the design of portal frames there are SCI design guides available online that can help you, you will just need to ensure that the methods are compatible with your country's code. SCI P397 is one such document, Appendix A provides starting sections sizes for different frame dimensions to give you somewhere to start.

 

[OxidoTuloso]

Thanks for the reply, that SCI guide section is the kind of thing that I'm looking for. The peak velocity pressure is around 680 Pa, and there are no other loads, because I'm not actually designing a warehouse, but a very unique structure that it's similar to the roof of a warehouse, so I'm just using that as a reference point.
I'm looking for things like the best section to use (I, Hollow, Channel, etc), the steel grade (hopefully by American standards because those are the ones used in my country), and ballpark numbers for the dimensions of the beams, so anything in those topics is helpful, even if it's just by experience and not based in documentation.

 

[jaskamakkara]

Well I sections are generally used for portal frame design since wind loading is pretty dominant and you need the section depth to resist the large in-plane bending moments. LTB of the columns and rafters becomes a problem with these sections so restraint is usually provided by the roof purlins and side rails which take those loads back to a bracing system. It's very difficult to provide much advice without more information about the particular structure since there are so many variables involved. That guide I mentioned walks you through most of the design stages so my main advice is pretty much to read that and see what questions you still have.