[Ravensfort] showers / Re: [rfofficers] Gundy's Find

[Catie Clark]

SF Tester wrote:
> On Sun, Oct 12, 2008 at 10:44 PM, byzytym <byzytym at att.net 
> <mailto:byzytym at att.net>> wrote:
>     Good info. 
>     I think you are going too tick on the metal though.  I'm talking
>     about thin and light.
> The problem with thin metal is that it dents, fasteners rip through, and 
> it rusts through way faster than you'd think. Think about how thick a 50 
> gallon drum is and how quickly they rot at the site.

I agree strongly with the above. The drums I used to use 
back in my superfund days were 10 guage or better. In 
addition, you improve the yield strength by forming the 
steel into the round and ribbed cylinder.  The whole 
cylinder can support a lot of stacking compression, both 
normal and axial, which is one of the things it was designed 
for.  But it's still lousy on spot failures - for example, 
the plastic deformation failure induced by a dropped hammer 
(better known as a dent...).

Now consider the drunken kid in great kilt who takes his 
great sword into the shower and falls, banging the big brass 
pommel against the sheet steel...  what, you don't believe 
it's likely to get some clueless drunk showering in his 
clothes and his sword???  It's the SCA, dude!  I'm surprised 
it doesn't happen more often!

okay, okay, maybe I exaggerate...but only a little...

> Ok, grab your latest Quoth. Open the cover, 1st, and 2nd pages. Those 3 
> pages combined are about .010". 4x8 feet of that, in steel, would be 
> somewhere around 13 pounds, but would last a few months. Wind would 
> shred it pretty quick.

Okay, let's do some numbers.  Pulling my copy of Abrose's 
Building Structures (1993 edition), we find that the minimum
recommended guage steel for building applications is 22 
guage.  These applications include interior non-load bearing 
walls and enclosure walls, regardless of suspension.  This 
is adequate to support maximum recommended lateral loads of 
10 psf.  So 22 guage (@1.6 #/ft^2) is good enough - but is 
32 guage, which is close to the 10# weight limit requested?

Consider that the load bearing strength of a sheet should 
drop by the square of the thickness.  22 guage is three 
times as thick as 32 guage - so it has roughly one ninth the 
strength.  Seriously, I don't think we want to go there.  It 
might be light but it would be dead enclosure walling as 
soon as the first severe thunderstorm blew though.  I think 
the assessment of 32 guage being shredded in the wind is 
defensible.  And I think Gundy et al. are dead on the money. 
  The new structural plastic and plastic composites are a 
good way to go, and if you get the right stuff, it really 
lasts and can withstand all sorts of weather too (excluding 
tornadoes, of course...but nothing short of bank vaults or 
nuclear hardening can stand up to an F4).

I crunched a couple of numbers [well, okay, the wind loading 
equation to be exact, {(rho/2)(fps^2)Cd(area)] and the force 
thus calculated on a 4 by 8 sheet in a 40 mph wind using a 
drag coef of 1 is 132#.  I can't begin to image an 
unsupported 32 guage sheet surviving that kind of load. 
Don't compare this to the 32 guage sheeting in those car 
port things, since most of those use some kind of 
corrigation AND none of the panels is ever bigger than 2x3 
(and most are smaller); the reason those things work is the 
design of the support frame, not the integrity of the sheet 
steel.  Nope, I really don't think unsupported 32 gauge is a 
good idea.

Ahhhh...there's nothing like a little civil engineering at 
lunch to make up for a lack of caffeine...

ttfn
Therasia's inner nerd






> 
>     Can you price the sheets of the stuff you are talking about and see
>     if larger sheets are available ?  I'm guessing that have the right
>     UV inhibitor or gelcoat will cost more ??
> 
> 
> I'll see what I can dig up. I need to go find some stuff anyway. Don't 
> really need the UV inhibitor if we paint it. House paint (at least the 
> half decent stuff) has it.
>  
> 
>     You will have to spell out the UHMW.  Again, those of us that do not
>     use the terms every day do not know what the hell you are talkin' 'bout.
> 
> 
> Didn't spell that one because it's long and multisyllable grunts aren't 
> my bag ;)
> 
> Ultra-high molecular weight. Same stuff pickle barrels are made of. 
> Nothing short of a miracle will keep paint attached more than a 
> nanosecond, but it's tough stuff.
> 
> Another possibility is Tyvek. It's something like paper, but won't tear. 
> If we came up with the right method to attach it, it may work out since 
> it's cheap enough to replace it every couple of years.
> 
> If I was making the decisions, I would weld a frame out of 2" square 
> tubing, then mount FRP or ABS panels on floating studs so the framework 
> can move some without stressing the walls. Throw in some cedar slats for 
> a floor and it'll last longer than me (and I'm fairly well pickled after 
> close to 2 decades in Swein camp :P)
> --
> Gundy