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Elephant Enclosures 3

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Civ-StructEIT

Civ-StructEIT

Civil/Environmental
Aug 25, 2016
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I have an odd question for everyone. Has anyone every designed an elephant enclosure? I currently have a project, where they asked us to re-design an elephant enclosure.

The only parameters that I have are that there are Concrete Filled Steel Posts, spaced at 10'-0" O.C., with (4EA) 3/4" diameter galvanized steel cables equally spaced along the posts.
Does anyone know of any design criteria resources to use for Elephant enclosures? I am having trouble finding any engineering resources for this one.

Thanks!
 
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I'm going to assume something like this is akin to bollard design. It's more a deterrent. I'm sure if an elephant wanted to destroy whatever it's holding structure is made of, it would.
 
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Why is it being re-designed? Is there some reason why the current enclosure is not working? I assume you cannot simply replace to match existing. We are talking about huge elephants, right? The 10' post spacing and 4 cables does not look like a very imposing barrier with an elephant standing next to it. Not sure what your cable arrangement or spacing is, but it seems like the elephant could simply put his foot on one or more of the cables and cause the two supporting posts to tilt toward each other. I have seen two different elephant enclosures: a very high barrier wall with a viewing platform near the top of the wall, and a "moat" around the elephant area that is deep enough and wide enough to discourage the elephants from crossing it.
 
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Have you checked with local zoos?

Woodland Park Zoo in Seattle had a similar enclosure barrier, but the exhibit has been closed as the elephants were transferred to another facility some years ago.

City of Tacoma did too before Cindy died....

Still might have something in their records...



Mike McCann, PE, SE (WA)


 
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Thank you for the notes everyone.

MotorCity - There are no issues with the current barrier function, but they are developing a new layout for the entire zoo and want to modernize the look a little and think they existing posts and foundations are "way over designed". Of course, this is a common statement from non-engineers, so I am not worried about that. I would just like some type of criteria for what is acceptable for loading, deflection, etc. to develop a good understanding of the final purpose of the enclosure.

Additionally, the top cable will be electrified.
 
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I cannot assist directly, however, for those "non-engineer" Monday-morning quarter-back types: Several years ago my brother re-constructed an elephant enclosure that had previously failed and caused a serious injury to the keeper. The bollards were ok, as such, but it ripped and overturned the whole footing system (very stout shallow footings). The keeper sustained life-long injuries.

The zoo was Taronga Zoo in Sydney, Australia. My memory is not too clear on the details, but the re-build generally consisted of a huge, thick RC mat foundation.
 
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I'd like to see the client provide the design criteria to you, even if that means procuring them from another consultant. If people safety is part of this, it's a fair bit of liability for you to assume on something that's really difficult to quantify. I remember a thread a while back where somebody was designing CMU barrier walls within a barn for horse stalls and trying to design them for horse-kick impact loads. That's the only related info that comes to mind.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
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Link

That was easy. "horse kick" narrowed the search down in a hurry which, I suppose, is unsurprising. There's even a research paper in there. Not sure elephants actually kick things though. And a raging stamped would seem to be of greater concern.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
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Back around 2004, The Texas Transportation Institute did some testing for the State Department on embassy protection barriers. I believe their test load was a 24,000 lb truck at 55 mph, which might be a little overdesigned for this application. I'm bringing it up because they had some architecturally pleasing barricades that may appeal to the zoo.

I recall the test engineer saying it was a big change from their usual work crash testing highway barrier. FHWA is very concerned about occupant protection, but the State Department didn't much care.
 
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IRstuff: I came across a couple of those references as well with some valuable information. I did come across a reference that mentions a 14,000 lb elephant traveling at 20 mph. I guess I will proceed with checking the loading capacity of the cables and the concrete filled steel tube based on that loading criteria. It appears that overturning of the foundation is going to be a pretty significant issue at that loading...
 
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I have the same question from a client. The client was able to show me pictures of a corral under construction. Client thought the fence was 5" Sch. 80 pipe on 24" centers with 2x5 tube at top to keep alignment. Height was 7'.

I considered using a human guardrail as a example and scaling it up. Current US male average is 5'-9" tall and weighs 195#.
A 42" guardrail is 60% of that height and is required to carry a 200# load (100% of weight) in any direction.

Scaling up to an 11' tall elephant at 13,000#, you come to a 6.6' tall rail with a 13,000" load at top.
With a spreader at the top to carry the load over 3 posts at 7' height, that calculates to a 6" Sch. 80, 50 ksi pipe.

Does this sound realistic?

 
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Just a quick update: Due to my lack of confidence in designing what the original post was describing, we have kicked the design back to the Zoo who has hired another structural engineer familiar with zoo design. I have asked to see the design criteria that that they are using for future reference, but have not heard back yet.

I stated a little earlier that I found something indicating that you need to account for the max speed of the elephant running into the enclosure, which is approximately 20 mph depending on the type of elephant. This obviously increases the loading significantly if indeed it needs to be accounted for in that manner.

Bill A - Please keep us updated if you find out any valuable information from contacting the zoos.
 
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Regarding loads- Yes, Force = Mass x Acceleration, with a differential for time. Back to the no accurate data. How fast can an 13,000# elephant accelerate?
I need to call Rich Purnell in Astrodynamics.
 
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It has been a long time since I have cracked a physics book, but the way I see it, the impact force should be independent of an elephant's acceleration (unless you are going to limit the traveling speed based on available "speed-up" space). If a 13000# elephant is traveling at 20 mph towards your fence, I don't care if it happens to put on the brakes just before impact (negative acceleration) or is still gaining speed (positive acceleration). The fence will see roughly the same force either way.

If you are looking for traditional physics equations to apply you might look at something like 1/2 M V^2. Also make sure you consider slowdown distance in your analysis.
 
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