AS 4100 vs. AISC Manual of Steel Construction

[dozer]

Does anyone know how Australian Standard AS 4100 - 1998 compares with AISC 9th edition as far as optimum weight of structure goes? I would assume you would get about the same weight of structure designing with either of these but you know what assuming does.

Asked another way, is there anything(s) in AS 4100 that makes it more or less conservative than AISC?

And speaking of assuming, I'm assuming you've used just one source for loads and you've applied the correct factors based on which design code you are using. Yes, I realize AS is limit states (what we would call LRFD) and AISC 9th edition is ASD.

 

[asixth]

Being Australian I have never used AISC first hand however, I did work for a company that did alot of fabric work worldwide who had a programmer who was putting together a design package that designed to both AS4100 and AISC amongst other codes.

I was speaking to this person one day about how their software was coming together and they did mention a significant steel tonnage saving when designing to the American code versus the Australian code.

Like I said, I have never worked to AISC first hand and this design package was in development (not by myself) at the time so I guess you can take or leave this advice.

Another aspect I guess is that this package was for designing tensioned roofs, so I guess the dominant features would have been ligtweight tensile edge cables and connection details resisting large tearout forces, as opposed to heavyweight flexural beams and columns that would be used in steel-framed buildings.

 

[hokie66]

I have no idea if one code is more conservative than the other. However, it would be very difficult to compare economy of steel structures because of the very different way the material is used in the two countries. Some of the major differences are:

1. There are relatively few multi-storey steel buildings in Australia.

2. Bar joists are not used in Australia.

3. Steel roof deck is not used for diaphragm action in Australia, because it is generally the waterproofing membrane.

4. A much wider range of shapes is available in the US.

In addition to these and other construction methods, there are a lot of economic factors, e.g. cost of labour, which differ significantly. I know you just wanted to know about relative tonnage, but that is only part of the story.

The thought just struck me, you may be trying to decide which code to use in a third country. If so, ignore my ramblings.

 

[csd72]

dozer,

I have used both:

1. the formulii for buckling e.t.c. are very different between these codes.
2. There is no longer ASD for Australian steel codes, it is all in limit states (LRFD). The 9th edition refers to the old (now superseded) australian steel code AS1250 so I would imagine its formulii are closer to that.
3. The devil is in the details - many of the specific regulations on required buckling restraint, analysis methods e.t.c. are completely different.

I would imagine that it is probably more conservative in some areas and less in others.

I would suggest that you see if your analysis package has an analysis tool for australian shapes and codes so that you can compare it that way.

Are you travelling to Australia?

 

[msquared48]

Hokie:

Bar joists are used in Australia. All the bars I have been in there have floor joists...

Mike McCann
MMC Engineering

 

[hokie66]

Mike,

Unreliable testimony. Are you sure you weren't flat on the pub floor looking at the roof joists?

 

[dozer]

Thanks for the replies. No, I'm not traveling to Australia. We make equipment that is basically a giant metal box that will be installed in Australia. The spec requires we use Australian codes but I wonder if it is even mandated by law that a piece of equipment, albeit rather larger, say about 12m x 18m x 20m, be in accordance with the Building Code of Australia and I suppose by reference, AS 4100 and no telling what else.

I do use STAAD.Pro so I could try applying the correct factors to the loads and let it do unity checks per the Australian code and see how it compares as csd72 suggested.