Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]


[Subject Prev][Subject Next][Thread Prev][Thread Next]
>LRFD is the best way to address the uncertainy of Loads and the Resistance of
>materials to the load by adjusting the Factor for the load based upon the
>accuracy of determination of the load. The Design is further adjusted for the
>uncertainy of the material's strength by introducing a strength reduction

And the reason we can't adjust load values in ASD is...? It's not like 
the applied loads are a lot better than an educated guess, anyway (based 
on judgement that works fine up until the event when they don't work so 
fine any more.). I confess, as a poor be-nighted ME, I am puzzled by the 
distinction between an allowable stress margin, a 'strength reduction 
factor,'  and 'the Factor for the load.'

It seems like a distinction without a difference. I'm really not trying 
to be obtuse, but I have yet to hear an answer that makes sense to the 
question of why LRFD or ASD is better. The fact that you can diddle the 
design margin doesn't make the methodology necessarily more 
sound--conservative people will still pick conservative factors, and 
imprudent designers are gonna remain imprudent--what's changed? Then 
there's the question of determining where repetitive service loads might 
govern beyond than a single ultimate load.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)