Purlin Design Software using AS1170.2 and AS4600

[blihpandgeorge]

Hi

I wanted to get some opinions on what is the easiest / best software for purlin / girt design, i am Aus based so prefer something that uses AZ/NZS 4600. If it doesnt have Aus section properties built in i am happy to import them manually if needed.

In particular i would like something that automatically address the various patch / local pressure loadings required in AS1170.2. Manually determing the correct 4:1 aspect patch for different Kl values and placing them in different spans / locations is pretty laborious to do manually and properly.

I have seen the Stramit EX-Facta which is pretty good but requires application of local pressures manually. I have also seen Supa-Purlin and it also requires manual input of loads.

Any other suggestions?

 

[Agent666]

Last place I worked used to use Purlin (by the same people that did Supa-Purlin) out of University of Sydney, that also got no tools for automating this type of thing.

You can obviously automate in a spreadsheet the process of telling you how far along the member and what loading applies which I guess is better than having to calculate it each time by hand. After a while you'll get to know what always governs. You may be able to work out the load over and above the typical UDL and apply that as a 2nd loadcase, then you only need to alter the load and location of that one patch UDL (I can't recall exactly, but I think Purlin let you do that).

I've never really thought of it as much of an issue to be honest as there is only a few checks on the 3 different scenarios (K_l = 1.0/1.5/2.0) if you are dealing with simply supported purlins. For larger buildings the entire tributary area becomes the patch I guess... easy!. But I could see if you were designing purlins day in day out 300 days a year that it would get pretty monotonous compared with doing some purlins once a month for an hour or so like I was typically doing.

I do see some people sometimes try calculate out an average loading to represent the patch plus the lower loads either side and they just use that as a rough pass. Any that are close they might look at in more detail and model the loads more accurately.

 

[Tomfh]

Yes the local pressure rules are fairly tedious, and with every new edition they seem to refine it further.

I’m not aware of any software which does it automatically.

In my spreadsheet I enter ‘a’ and ‘L’, etc, and it gives me an equivalent blanket load based on the 4:1 rule and those conversion formulas in the purlin manuals.