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Re: aluminum HSS connection design

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Op-

Chris is correct about the loss of stength.  Unless you can
re-heattreat, I'd use O condition properties.

As extruded you have ~40ksi yield.  
Depending on the amount of weld & configuration you could go all the
way down to "O" ~8ksi yield.

Where you actually wind up, I don't know for sure

"what do folks think about using the AWS D1.1 equations for steel
(substituting strengths appropriate for the aluminum
materials...)"

No way.

What kind of structure are we talking about?

cheers
Bob


On 4/13/05, Christopher Wright <chrisw(--nospam--at)skypoint.com> wrote:
> 
> On Apr 13, 2005, at 11:49 AM, Gale45man wrote:
> 
> > If there are no such guides or manuals, what do folks
> > think about using the AWS D1.1 equations for steel
> I'd be real careful about this--your best bet is to go into the ASCE
> archives and see what you can find. The first problem with aluminum is
> that the allowable stress for weldments goes way down becasue aluminum
> invariably loses its temper to varying degrees depending on the alloy
> and the weld metal. Aluminum is very sensitive to fatigue failures for
> a couple of reasons: it accumulates plastic strain faster because of
> the lower modulus and it's not as forgiving of cracks and stress
> concentrations as steel.
> 
> I did an investigation a while back of some aluminum compactors which
> were tearing themselves apart under service loading. The compactors
> apparently were copied from similar steel structures but after a few
> load cycles (and some wretched attempts at repairs) they had cracked
> all to hell.
> 
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
> .......................................| John Sedgwick, Spotsylvania
> 1864)
> http://www.skypoint.com/~chrisw/
> 
> 
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