LRFD vs ASD
LRFD vs ASD
(OP)
Hi
I work occasionally on projects in the US. I say that because otherwise the following question might seem very odd, perhaps even stupid.
For steel, which design method is prefered today?
I have heard the explanation that for steel ASD is the standard while for concrete load factors are used. The explanation was that the load factors for steel and concrete are not the same so this is to avoid mistakes.
I have started to read the codes but some guidance would be greatly appreciated.
Thomas
I work occasionally on projects in the US. I say that because otherwise the following question might seem very odd, perhaps even stupid.
For steel, which design method is prefered today?
I have heard the explanation that for steel ASD is the standard while for concrete load factors are used. The explanation was that the load factors for steel and concrete are not the same so this is to avoid mistakes.
I have started to read the codes but some guidance would be greatly appreciated.
Thomas






RE: LRFD vs ASD
RE: LRFD vs ASD
RE: LRFD vs ASD
I have the AISC standard and like you say, it covers both. And since we normally work with Eurocode load factors are well known.
We'll see what happens but then ASD is not the obvious choice.
Thomas
RE: LRFD vs ASD
RE: LRFD vs ASD
RE: LRFD vs ASD
Main reason some still use ASD is because it's easier for some because they've been using it for a long time and don't want to change their excel connection program, etc...
RE: LRFD vs ASD
Most AISC provisions, particularly seismic design, are written based on LRFD. When possible, they provide factors to approximate getting back to ASD levels.
The safety factors (LOAD FACTORS) are also more logical when using LRFD load combinations, as compared to ASD where all load types are essentially given the same safety / load factor.
RE: LRFD vs ASD
Most engineers I know still use it.
I use ASD exclusively as 95% of my designs are controlled by serviceability and they are not very large projects.
It is faster not having to do the loads twice. I can see the benefit on larger jobs, however.
RE: LRFD vs ASD
I'm a young engineer, in an office of young engineers. While I think there is a copy of the green book floating around, that's not the cause of our choice.
RE: LRFD vs ASD
My interpretation is that there is no consensus regarding which to use. There is a PE involved so we'll also discuss it with him. I just wanted some background and I got that.
Thanks a lot
Thomas