steel purlins, what do i enter?

[gehngus]

Hi.
I'm a bit confused on what to enter and where. also what beam i should select.

I need calcs for steel purlins (girders/beam that is an I shape?) to span a maximum span is 3.4M

the roof is to be slate, 150x47 wooden rafters at 600 centers.

ridge to wall plate is 5M

id like to know what to enter in these boxes? can anyone help me or does anyone have a calc for this type of span

many thanks

[Tony Bryer]

Generally we don't like to answer this sort of question except to say that taking off loads is such a crucial part of the calculation process that you do need to be able to do this accurately if you're using our software.

In this case, assuming I have visualised the situation correctly, you need to calculate the roof load per square metre. The required load on the purlin needs to be entered in kn/m run - this will be your load per square metre x rafter length eaves-ridge/2.