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RE: ASD vs. LRFD

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> -----Original Message-----
> From: Christopher Wright [mailto:chrisw(--nospam--at)skypoint.com]
> Sent: Wednesday, June 16, 1999 10:20 AM
> To: SEAOC Newsletter
> Subject: Re: ASD vs. LRFD
>
>
> The reason they're ASD now and likely to remain so is because service
> loads govern.

This continues to be an amusing facet of the argument.

I don't remember EVER being taught (and I was taught in ASD) to pay careful
attention to service loads (meaning, in this case, deflection criteria) in
my instruction with design codes. We were too busy figuring out all the
myriad ways stresses could be computed.

This newfound preoccupation with service loads as a governing criteria
stems, I suppose, from the assumption that LRFD methods yield lighter
sections that must be checked for serviceability.

But the fact is that serviceability is one of the "limit state" criteria
that the LRFD-based design codes I'm familiar with require to be checked as
a matter of course (as opposed to viz. the AISC code which throws it in
there for secondary consideration).

If service loads (meaning "deflection") govern, then so be it, and you will
know it if you follow LRFD-based design code criteria. In fact, you will
know pretty much everything you need to know about the behavior of the
structure.

Which is more than can be said for the ASD design codes.