Structural analysis of Snowzilla

[cedarbluffranch]

I posted this in a different forum - hopefully this forum is a better place to post it.

In Anchorage, AK, a man built a 25 foot tall snowman in his front yard. The city disapproves and says the structure is unsafe without doing any sort of engineering analysis.

If I was an Alaska PE, I think this would be a very interesting engineering analysis. However - I don't have any textbook references on the structural stability of snow. I am speculating that a person would look at the load bearing capacity of snow and the estimated weight of the snowman to determine if the lowest amount of snow was likely to fail under the weight of the snow.

Can anyone offer any insights on this?

You can see an article about it at

http://abcnews.go.com/US/JustOneThing/wireStory?id=6522719

Thanks!

 

[Co]

That is hard to say. As I would suspect that the stability of the structure would depend on many thermodynamic factors that may change by the hour or even minute. If one insists, then I would say that experimentally is the way to go.

cheers,

 

[MikeHalloran]

A search like this will be somewhat productive:

http://www.google.com/search?client...+properties"&sourceid=opera&ie=utf-8&oe=utf-8

It should at least give you a sense that there are many different kinds of 'snow', all with different mechanical properties, which have been studied in the interest of avalanche prevention and mitigation.

I think the manually processed snow in a snowman is not similar to naturally deposited snow... but I get the impression that it becomes similar to the soft underlayers in an avalanche as softening proceeds to melting proceeds to structural failure, which is the circumstance under which personal injury is being speculated.

How do you feel about building a bunch of snowmen in the interest of science?





Mike Halloran
Pembroke Pines, FL, USA

 

[cedarbluffranch]

Building snowmen to do some experimental testing sounds great. I actually built three snowmen about two weeks ago.

Snowzilla is actually a really interesting engineering study. Growing up in snow country and having a lot of hands on experience with snow, I cannot believe that a large snowman presents any safety risk to anyone around it unless the snow is compacted sufficiently to become ice. The reason is compressed snow has a very low compressive strength and breaks apart upon very small compressive loads - thus preventing injury.

However, if the snow becomes ice due to rainfall or hoses, then falling ice does present a potential safety hazard because it does not break apart when falling.

The mechanics of sliding snow (avalanches) is a serious topic in engineering and I can do some research there. My professors at Montana State University did considerable experimental research in this area. Yes, they built a shelter in snow, instrumented the hillside with various sensors, and forced an avalanche to occur using dynamite. Very fun.

Hmmm, I wonder how I could write a report on this?

 

[cedarbluffranch]

My goal would not be do guarantee the structure would not collapse. Instead, I would only need to show that the probabiity of causing personal injury would be small if it did collapse.

 

[Co]

I like the ideas. I presume because of the nature of the topic it would not be too difficult to publish a work or a few papers if you can get some interesting results.
By the way, I always thought that compressed snow has a higher compressive strength then if it weren't compacted.

cheers,

 

[cedarbluffranch]

Yeah, I agree that compressed snow has more compressive strength than uncompressed snow. I wasn't trying to compare the compressed and uncompressed above, though, I was just saying that it is low in general. (Low as compared to steel, ice, concrete, etc).

 

[Co]

Ok, understood

 

[jike]

Forget about engineering analysis to provide safety....just provide enough room all around it that if it collapses, it clears all adjacent property, etc. Pretty simple....

 

[dicksewerrat]

I think it should be packed with black powder and launched. Preferably at the guy that says it has to come down.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[cedarbluffranch]

Local city councils are funny.

I can't imagine Snowzilla is an actual problem in and of itself, but the real problem is the guy has been cited for too much trash in his yard, etc. He owes like $200,000 to the city in fines that they have levied, and he simply refuses to pay for them.

So now they say his snowman is illegal because it is "structurally unsafe." I have no idea what the merits are in the fines they have levied, but I don't like city councils playing engineer and making engineering assessments on the public safety hazard without a PE license. That's not their place, and frankly, the State Board of PE's should nail them for practicing without a license.

 

[Robertmet]

What about rebar ??

 

[SkiisAndBikes]

The World's Tallest Snowwoman, built in Bethel, Maine, USA.

http://www.bethelmainesnowwoman.com/

Height = 122'-1"
Weight - 13,000,000 lbs.
Two 30ft. spruce trees for arms
Sixteen skiis for eyelashes

Construction was a volunteer effort, supervised by a P.E.

Best of all .... I'm heading there to ski in March!!

 

[cedarbluffranch]

Like I said, it's not a guarantee that it won't collapse. The engineering assessment would be to show that a collapse wouldn't cause injury.

Shouldn't be too hard. I've never heard of anybody injured by falling snow and I grew up in a ski town in Montana. We built all sorts of snow forts, snow structures, snow palaces, etc.

I did hear about people getting crush or sufficated by snow, or falling into tree wells. But never heard of anyone injured by snowmen or or other snow structures.