Snow loading....

[Araich]

I am in the terrible position of living in sunny old Sydney where I could never fully understand the effect of snow.
Following my confusion over that last red piece, I've made another work, for which I need to consider the weight of snow that could form in a real winter.
In an area of heavy snow fall, what sort of weight could I expect on this sculpture?

I'm looking for a ball-park figure...

Pictured is the new maquette, which I intend to scale up to 6-7 foot high.

[sculptor]

snow tends to slither off smooth nonhorizontal surfaces like butter on a hot griddle-----so only the horizontal should be effected------it's the ice storms that weigh down powerlines and snap 'em in the middle of the night, and the ice will stick to anything-(horizontal, verticle,wood,steel,glass).
that being said-----the norm in the midwest is to assume a roofload of about 40 lbs/sq ft-which would assume about 30# for the snow)----or about 135 kilograms/sq.meter.
(I'm thinking that would be a very wet snow drift about a meter deep---this is extreemly rare---most snow hereabouts melts down to less than 7 lbs/cubic foot
(guessing) if you can toss a 15-20 kilogram sandbag on the near horizontal surface and another on the peak and she don't move----you're safe

where is this one going?

nice series----i get the feeling that to blob and lines add a lot of tension----it is as though the rest of the piece is trying to drag the blob along
rod

[Araich]

about 135 kilograms/sq.meter
Thank you, that is very helpful, as I imagine this is a good guide. In bad weather then it would be safe to assume that no more than 150kg could sit on that ledge? I would have to allow for 2 drunk students and a six-pack up there anyway...

it is as though the rest of the piece is trying to drag the blob along
That is perfect. Else the blob is supporting the freedom of the ribbon.

[sculptor]

In bad weather then it would be safe to assume that no more than 150kg could sit on that ledge? I would have to allow for 2 drunk students and a six-pack up there anyway...

150kg hmmmm and I had thought that the ledge would be no larger than about 1/4-1/2 of a square meter------ergo 50-75kg......and certainly too small for 2 drunks and a sixpack or a contortionist's orgy.........(I should probably stop typing here before I offend someone)

rod

[Araich]

I guess I was looking at the worst scenerio, and total weight the sculpture could be expected to carry. Should I scale the number back to 100kg?

[sculptor]

I guess I was looking at the worst scenerio, and total weight the sculpture could be expected to carry. Should I scale the number back to 100kg?

uh........wut size is the horizontal ledge to be??

[JAZ]

Unlike Rod, I have no idea of the actual weight, but hearabouts we have storms that take down big trees. Rod's right about the ice too and lately that kind of bad weather extends as far south as Baltimore Maryland, so the climate seems to be getting wierder. I have both slender works and heftier ones outdoors with no problems, but none have the shelf effect or the precarious angle. It's certainly worth thinking about. What thickness would the full sized ribbon element be? It's one thing to use 1/4" steel in a maquette...What gauge steel are you intending to use? It does seem that the extra weight of snow and ice may be too much stress on that arc.

[Araich]

I keep leaving the maquette at the workshop, so guessing at the ledge size would be hopeless. Mostly I was just looking for a guestimate. Considering that people may be inclined to hang off the work, their body weight (x2) is a better guide.
The ribbon would be something like 20mm or 4/5" assuming I can find the money to make it. I'm about to start another work with 12mm plate, a mere 6ft long (it is horizontal) and the steel will cost around $2000 AUD ($1470 USD) formed into a compound curve.
Anyway, with good fixing to the ground, I think this could support a substantial weight. The rods would be approximately 40mm pipe.
The opposing curves pressed into the plate will cause it to be fairly rigid, and I'll factor in some tension in the work. If I get to make it, I'll hang at least a 1/4 tonne off that loop as a test, really it may happily hold 1 tonne (?).

But it is important that it look and feel somewhat fluid, in expansion or collapse - your choice. Glass half full and all that...

[novabelgica]

A good fixing to the ground will probably solve at least half of the problems where stability and strength is concerned. I've been worried myself about one of my sculptures which is going to be placed near the sea, but by using a few more bolts and an extra large base, I think it will hold. Ofcourse, in your work, visible bolts would not be very pretty.

I'm about to start on the last 2 of my 'planet' sculptures and stability is going to be an issue here as well. Saturn is going to be 10 feet in diameter and Jupiter 12 feet. It's the first time I'm working on something this big, so I don't really have much experience with it. I'm just hoping everything will be strong enough.

And, working with 12mm plate? Wow, you're a brave man. :D

[sculptor]

OK for a guestimate the 100-135 should cover anything from drunks to ice and howling winds with cross directional sheer gusts.

examples:
A) My 1st angelicus bolted to a 25 foot pole with 2-3/8" bolts has withstood 100 mph winds and snow and iceloads for 18 years.
B) ISIS is bolted to the truck with 4 5/16" threaded rods and has survived for 5 years and 50,ooo miles(when my sons drove the truck, that meant 90 mph, and with the gusts from oncoming trucks probably hit combined speeds of 110-130 mph

ergo. I'm guessing that as long as the fasteners are tight they get a friction boost, and can withstand quite a range of wind,hail,snow,ice, and human abuse.

(fingers crossed)

[JAZ]

This discussion tells me that many of the decisions that are being made are instinct and experience driven rather than the result of engineering math. This is reassuring, because I'd often wondered if others sat down at drafting tables with charts and calculators, figuring out stresses, etc.

[Araich]

I cannot even begin to imagine the math in this! How would one know the collapsing point of a compound curved, ring shaped length of steel plate?

I suspect you would have to test it to get any real idea.

I wish I had an engineer for a friend :D

[sculptorsam]

Most all of my engineering is done by instinct. If I get in a bind where I can't figure out how to solve a problem, I run a thought experiment. Looking at the work, I try to figure out what will fail. What is the weakest point. Once you've found it (or a couple perhaps) try to figure out if it will hold or how to make it so that it will. Just like a chain, a sculpture is as strong as it's weakest point. Solve that, and you're good to go. If you think the weakest point will hold fine, all should be well.

Sam

[sculptor]

Whenever the stressloads can be quantified via reasonably simple calculations, I use tables and a calculator, and any available experts-----often, that's simple, eg: I know my studio floor has a 1:364 /100kg deflection and can carry a liveload of 55lbs/sq.ft.(assuming the lumber is graded accurately and the fasteners are within the stated parameters).

Sometimes I choose or modify a design based on assumed surface loads, windloads, cantilevered stressloads, and the resultant design gains organically from the input-----

But, when we're dealing with compound curves and varying environmental factors--------------you gotta guestimate

as/re Robert's "How would one know the collapsing point of a compound curved, ring shaped length of steel plate". I'd guess that the torch moves that point (spacially and mathematically) around.

maybe, that's why they call it art?

[Araich]

Obviously there is no rest for the wicked :eek: I've made this new work over the last few days as a maquette for a corporate foyer commission, but looking at it, it would obviously be perfect big and outside... thoughts?

[novabelgica]

Oh yeah. It would definately look great as a 10 foot outdoor sculpture. What size did you originally have in mind for this? Once again, a beautiful piece. I love your work.

I'm curious. What do you use to make these maquettes?

[JAZ]

Obviously there is no rest for the wicked :eek: I've made this new work over the last few days as a maquette for a corporate foyer commission, but looking at it, it would obviously be perfect big and outside... thoughts?
You should try to talk these two clients into swapping designs - this should be the snow load one and the arced one for the foyer. Problem solved. Okay, maybe you have to convince the clients first!

[Araich]

I'm curious. What do you use to make these maquettes?
They're basically exactly the same as the full scale, welded steel, primed and painted. The only real difference is the I do not bother metalising (hot zinc) these...

The arc one is pure speculation whilst the last is as a request, but scaled to just 1.1m - it would go on an internal ledge designed for a sculpture.

I'm feeling a bit down this morning as the deposit I've been relying on for another job has not arrived. I'll be impersonating a yogi until it does, and living on air :(

[JAZ]

That little purple smilie is hopefully temporary. Maybe it'll come tomorrow. All of us have to deal with the cash flow problem now and then. At least you know you have something coming. It seems like you are doing exceptionally well overall. Hopefully you have a good solid written agreement. The problem is probably just that your regular letter carrier is on vacation or out sick.

[sculptor]

...... I'll be impersonating a yogi until it does, and living on air :(

That crazy sculptor went
and spent
his food money on welding rod, gas and steel
and now
he's living off fumes and dreams
and licking sweat from his forearms for the salt

one helluva diet

[JAZ]

That crazy sculptor went
and spent
his food money on welding rod, gas and steel
and now
he's living off fumes and dreams
and licking sweat from his forearms for the salt

one helluva diet

Man, you have no sympathy! I, personally, am in danger of having the IRS declare my "profession" a "hobby". Getting that all important check is important, but I think a lot of us are guilty of spending the little we have on the welding stuff in lieu of the more practical considerations.
(If what I wanted was a "hobby" I'd definitely pick up something easier like landscaping or interior decorating or rock climbing or something!)

[jwebb]

Cliff diving. Alligator wrestling. Hell, Snow loading....

[sculptor]

[QUOTE=JAZ]Man, you have no sympathy! I, personally, am in danger of having the IRS declare my "profession" a "hobby". Getting that all important check is important, ......QUOTE]

oftimes my peculiar commiserating comradery humor flies out as welcome as hemorroids........sigh..(even araich saw the potential dilemma and deleted a "gag me with a spoon" vignette)

as/re the IRS: You don't have to make a single dime. All you need is to "intend to make a profit" stick by that and deduct every last paper towel, q-tip, paperclip, and ...............the other 10398 things you use for the art.
Every few years they've attempted to redefine my chosen profession as a hobby----and I consistently show "intent"----e-mails, yellow page adds, brochures, letters seeking honoraria or commissions---...etc.....
One charming auditor was so impressed by my meticulous honesty and record keeping---and sensitive to my struggles, that she even helped me find more deductions in the tax code and sent me home with an extra $1,000.00.
While another was so negatively biased that I had to win that one on appeal.

What's a hobby? Does drinking irish whiskey an dancing on the deck to overloud bagpipe music qualify as a hobby? If I wuz into performance art could I deduct the whiskey? Another Rod Patterson---a folk musician from Ireland, sent me a bagpipe joke---[what's the difference between a bagpipe and an onion?]

Don't let 'em bully you JAZ-----the 748,000 pages in the tax code were written for your benefit. If nothing else, they're a great cure for insomnia.

[no one cries when you cut up a bagpipe]

[Araich]

sculptor you're one hell of a cryptic guy! :D

As it was, I'd bought a tank of argon with my last pennies (I do not lie), as I was more afraid of not being able to work than I was of eating 2 minute noodles for a week.

But late yesterday I was paid! Hallelujah.

This morning I'm off to spent 50% of it on a new MIG welder that has more grunt, now that I've wandered into the world of heavy gauge plate. The other 50% covers the steel for 2 jobs. With change for more noodles and a case of beer!

With luck I'll have enough time to spray the second maquette for this foyer, that I made yesterday...

[sculptorsam]

The sky is blue, the birds are chirping, and there is a renewed skip in your step! All is right with the world. :)

Sam