Specifications for elephant-resistant steel poles

[Peter Apps]

This is probably simple for an engineer, but I’m a zoologist and analytical chemist and so I would rather ask those who know.

I have camera traps out on the African bush, that are monitoring the responses of leopards to artificial scents. The cameras are in steel boxes to protect them from elephants, the boxes are bolted to brackets 150 mm long and the brackets are bolted to steel poles at a height of either 500 or 700 mm above ground level. The poles are 40 x 40 mm mild steel angle, either 2mm or 3mm thickness. The poles are driven deeply into the ground. The mechanical problem is that elephants push the cameras over; they bend the 2 mm thick angle through 90 degrees at ground level, or twist it through 180 degrees. They bend the 3 mm thickness through 45 degrees.

I have videos from the cameras as they are being wrenched around and most of the work is done by the elephants’ trunks, with some kicking and stamping once the pole is bent over. Elephants are alleged to be able to lift 350 kg with their trunks. How hard the they can kick is an open question.

So my question is; what size and gauge angle iron or square tube would I need for a pole that could withstand twisting when 350 kg is applied sideways to a 150 mm lever bolted at right angles to the pole, without exceeding its elastic limit (camera aim is critical so the pole needs to recover after an elephant has tried to bend it) . And, similarly, what pole, standing 1 m out of the ground, could withstand being pushed at the top by an elephant – say 500 kg sustained force.

Thank you.

 

[jedishrfu]

It might help if you provide a drawing or picture of your setup.

My feeling though is that you may need a different kind of deterrent like flashing lights, sound of a predator, some kind of spray deterrent, bushes planted around your pole or something else that will keep them away from it.

What if you disguised your cameras as trees?

More costly but perhaps they won't look at it as something out of the ordinary.

 

[Peter Apps]

Here is a picture of the camera mount. This shows only the back of the camera box, when the cameras are in the field they are enclosed in steel.

It might help if you provide a drawing or picture of your setup.

My feeling though is that you may need a different kind of deterrent like flashing lights, sound of a predator, some kind of spray deterrent, bushes planted around your pole or something else that will keep them away from it.

What if you disguised your cameras as trees?

More costly but perhaps they won't look at it as something out of the ordinary.

Since I am testing the repellent effects of chemicals from scent marks I cannot add any extra repellents to the setup. Elephants knock down trees with the same enthusiasm as they re-adjust my cameras - it seems that they have switched from ecosystem engineering to mechanical engineering !

 

[jedishrfu]

How about a Go Pro attached to the elephant ala elephant-cam? :-)

Could you string a camera up between trees or would that be too low?

Also didn't see your photo in the post.

 

[anorlunda]

Here is a picture of the camera mount.

Use the upload button on the post editor.

How about a Go Pro attached to the elephant ala elephant-cam? :-)

LOL, that would be fun.

But it suggests another possibility. Might a Go Pro be rugged enough to survive without an enclosure? A very small thing might have a better chance of escaping notice by the angry elephant. Smaller things are also easier to camouflage.

 

[mfb]

But it suggests another possibility. Might a Go Pro be rugged enough to survive without an enclosure? A very small thing might have a better chance of escaping notice by the angry elephant. Smaller things are also easier to camouflage.

There is still the steel beam, and it is hard to hide that completely.

If the elephants want to break it for some reason, they'll apply more force to a more durable structure, so we cannot use the current damage as estimate how much they can do.

How difficult is it to test different beam profiles? If you can change them easily, you can do a test series. Use something with twice the thickness, if it works, go down a bit (if cost/weight is an issue), if it doesn't work, go up a bit.

 

[anorlunda]

There is still the steel beam, and it is hard to hide that completely.

Why have any beam or box at all?

The camera could be concealed in a birds nest, or a bee hive, or under a pile of bird poo, anything that occurs naturally in the tree that the elephant is likely to ignore.

Go Pro camera are so much cheaper than professional cameras, that many of them could be concealed in the area to capture different angle. If some are lost, no big deal.

 

[mfb]

I don't know the details of the biology experiment, but it might be favorable to have the camera away from other points of interest.

 

[Peter Apps]

How about a Go Pro attached to the elephant ala elephant-cam? :-)

Could you string a camera up between trees or would that be too low?

Also didn't see your photo in the post.

The camera setup has all sorts of constraints on camera siting and aim that make it impossible to attach the cameras to trees - the trees just don't grow in the right places ! Cameras on elephants has already been done - by National Geographic if memory serves - cameras on animals are generically called crittercams.

I did not insert the picture correctly - I just cut and pasted. I'll try again with the upload button. SUCCESS !

 

[Peter Apps]

Why have any beam or box at all?

The camera could be concealed in a birds nest, or a bee hive, or under a pile of bird poo, anything that occurs naturally in the tree that the elephant is likely to ignore.

Go Pro camera are so much cheaper than professional cameras, that many of them could be concealed in the area to capture different angle. If some are lost, no big deal.

Unlike GoPros the camera traps do not record continuously - they are triggered by sensing moving body heat and shoot 30s of video per trigger. They stay out for weeks at a time in very specific configurations that I have validated to capture and record activities specifically of leopards. They have to be sited to within abut 10 cm over 15 m and aimed to within a degree of arc - hence my use of steel posts that I can place at specific positions, brackets that can be tilted and bolted into place, boxes that can be swivelled and bolted, and protective cases for the cameras - on a previous project we lost five unprotected cameras to elephants in three weeks.

And I am afraid that with the budget constraints that wildlife research operates under the loss of any camera is a very big deal indeed.

 

[Nidum]

Squirrel cage .

 

[Peter Apps]

Squirrel cage .

Apart from it's literal meaning, which I suspect is not the sense you are using it in, I have no clue what a squirrel cage is or how it would help calculate the dimensions of a steel pole.

 

[anorlunda]

The camera setup has all sorts of constraints on camera siting and aim that make it impossible to attach the cameras to trees - the trees just don't grow in the right places ! Cameras on elephants has already been done - by National Geographic if memory serves - cameras on animals are generically called crittercams.

I did not insert the picture correctly

OK, with the additional info you provided it is more difficult. This is a very interesting problem.

I would guess that steel beams even 10x times stronger than the one in your picture could still be knocked down by an angry elephant. Worse, the sharp corners on those beams and angle irons could injure the elephant regardless of whether the mount is damaged. The steel should be encased in concrete to protect the animals; but that's probably not practical either.

I remain skeptical of the brute force/massive structure approach. Surely, even a steel structure might shift one degree during the attack. Therefore, I presume that your criteria is not to continue video recording during and after the attack with one degree accuracy, but rather to rescue the equipment.

I would concentrate on concealment and deception. I would perhaps make the mount very easy to knock down without injury to the animals. Then I would tie the camera to the ground with a security cable to prevent it from disappearing even if the mount was destroyed and the camera knocked down. If the camera didn't look man-made, then the elephant may be less motivated to crush it.

 

[Nidum]

A squirrel cage is a common name for a strong equipment protection cage which is round and made from metal bars .

Something like a ring of metal poles (at say 1 m radius) around the camera pole and tied together with metal hoops .

Solution really depends on required field of view and whether the equipment has to be moved frequently or permanently sited .

 

[jedishrfu]

Found some deterrents that might work here:

http://www.bbc.com/earth/story/20141204-five-ways-to-scare-off-elephants

The interesting one is African bees.

 

[Peter Apps]

Found some deterrents that might work here:

http://www.bbc.com/earth/story/20141204-five-ways-to-scare-off-elephants

The interesting one is African bees.

The universal problem with all the suggestions about elephant repellants is that they will probably also repel leopards (or at least alter their behaviour in ways that have nothing to do with the experiment) and so render the entire exercise pointless.

 

[Peter Apps]

OK, with the additional info you provided it is more difficult. This is a very interesting problem.

I would guess that steel beams even 10x times stronger than the one in your picture could still be knocked down by an angry elephant. Worse, the sharp corners on those beams and angle irons could injure the elephant regardless of whether the mount is damaged. The steel should be encased in concrete to protect the animals; but that's probably not practical either.

I remain skeptical of the brute force/massive structure approach. Surely, even a steel structure might shift one degree during the attack. Therefore, I presume that your criteria is not to continue video recording during and after the attack with one degree accuracy, but rather to rescue the equipment.

I would concentrate on concealment and deception. I would perhaps make the mount very easy to knock down without injury to the animals. Then I would tie the camera to the ground with a security cable to prevent it from disappearing even if the mount was destroyed and the camera knocked down. If the camera didn't look man-made, then the elephant may be less motivated to crush it.

I am not worried if the camera moves during an elephant attack - the aim is not to record elephant behaviour, I get elephant videos as an inevitable spin off of recording leopards. What I would like is for the poles etc to be strong enough that they resist elephant attacks and return to their original position after the elephant has had its fun. An approximate return would be better than the camera being left at ground level looking down at a patch of grass or up at the sky which is what happens with the 40 x 40 angles. I have thought about, and tested, putting the poles on springs - it does not work even in prototype. The present setup returns to position after gentle shoves and nudges by elephants and other big animals like giraffes and hippos, so that approach can work if the mechanics are strong enough.

Making the mount easy to break for elephants means that it is possible for it to be broken by smaller animals, so the camera will spend most of their time lying on the ground instead of collecting data.

The elephants are slow and deliberate in their attacks on the cameras - they do not come charging in from a distance - so they are not likely to injure themselves on the corners of ordinary steel work.

We already camouflage with branches and foliage, it helps a bit but not enough to be practical.

It is possible to design steel work that elephants cannot bend - zoos use it in their elephant exhibits but it is on a scale that is impractical for field work. My question is aimed at finding out whether there is a size of steel tube or angle that will adequately resist the forces that elephants exert on the camera installations and that is small enough for field work, and within our budget.

 

[jedishrfu]

What if you used helical springs like what's used on some childrens playground toys and enclose your camera in a cylnder-like object attached to the springs?

The elephant can hit it or push it and it will pop back up.

 

[anorlunda]

Perhaps you can get some ideas from circus elephant cages.
But I don't see how a cage, or a strong pole in the ground solves the problem of being moved or knocked over by the attack.

I presume that the tubes seen in these cages were cheap galvanized pipe. Here's a table with some strength numbers. The cantilever is closest to the case of a pole stuck in the ground. But don't forget that the bracket to hold the camera and the camera case itself can be the weakest link in the chain.

 

[Peter Apps]

What if you used helical springs like what's used on some childrens playground toys and enclose your camera in a cylnder-like object attached to the springs?

The elephant can hit it or push it and it will pop back up.

I tried that with coil springs from a vehicle. The two main problems are that if an elephant pushes one down with its foot and then steps off it, it will whip upright and probably inflict some damage, and that it needs some damping to stop it jiggling around for several minutes after it has been displaced and released. A heavily over-engineered solution would be an industrial strength door closer that can move on more than one axis.

 

[Peter Apps]

Perhaps you can get some ideas from circus elephant cages.
But I don't see how a cage, or a strong pole in the ground solves the problem of being moved or knocked over by the attack.

I presume that the tubes seen in these cages were cheap galvanized pipe. Here's a table with some strength numbers. The cantilever is closest to the case of a pole stuck in the ground. But don't forget that the bracket to hold the camera and the camera case itself can be the weakest link in the chain.

View attachment 114585

 

[Peter Apps]

The crush cage at the top is proper structural steel, the vertical bars with the mother and baby are probably solid rod and will be anchored top and bottom, I suspect that the the rusty old iron at the bottom is drill casing, which has thick walls.

What I need is for one of you engineers to translate that table into the dimensions of a pipe in cantilever loading that will not go outside its elastic limit when carrying a 500 kg mass 1m from its fixed point. I need to use square tube or angle to resist rotation in the ground (a round tube will just rotate) and to provide a flat surface for the bracket to bear on.

 

[jedishrfu]

Punching bags:

or

 

[Peter Apps]

Punching bags:

or

Brilliant idea, as long as they don't cost any more than 2m of 50x50 square tube

 

[JBA]

This might be condemned by some as "animal cruelty" but what about equipping a few units with small circular battery powered electrified wire ring enclosures and painting all enclosures including the electrified ones a bright distinctive color. The idea being that after a couple elephant encounters with the electrified ones the elephants would begin to assume that all such type and colored enclosures are something to painful to play with.

 

[Peter Apps]

This might be condemned by some as "animal cruelty" but what about equipping a few units with small circular battery powered electrified wire ring enclosures and painting all enclosures including the electrified ones a bright distinctive color. The idea being that after a couple elephant encounters with the electrified ones the elephants would begin to assume that all such type and colored enclosures are something to painful to play with.

Electric fencing that is strong enough to deter elephants works at 80 000 V and makes a loud click every time a pulse fires down the wire - the clicks will deter other animals from coming near the site, so I will get no useful data. Also the fences are power hungry and very difficult to isolate from earth. A bright distinctive colour is exactly what I do not want - the cameras need to be inconspicuous so as not to affect animal behaviour. Teaching elephants to avoid cameras by giving them electric shocks will work only on the elephants that encounter an electrified camera, the rest of them will carry on trashing cameras if the mood takes them. There are over 100 000 elephants in northern Botswana, and probably at least 5 000 in and around our study area - it would take ahuge effort to teach all of them not to mess with camera traps.

 

[JBA]

All points well taken.
What about a structure shape that could not be simply bent and therefore not much fun to play with such as a three legged pyramid made from angle or pipe that is staked down with the camera located inside the structure for protection. The only problem is that the elephants could still grab the supports with their trunks and pull the structure loose. A solution to that could be to make the pyramid with solid metal sheet sides; but, in that case they would probably standout too much in the local environment unless possibly painted in camouflage to blend with their surroundings.

 

[Peter Apps]

All points well taken.
What about a structure shape that could not be simply bent and therefore not much fun to play with such as a three legged pyramid made from angle or pipe that is staked down with the camera located inside the structure for protection. The only problem is that the elephants could still grab the supports with their trunks and pull the structure loose. A solution to that could be to make the pyramid with solid metal sheet sides; but, in that case they would probably standout too much in the local environment unless possibly painted in camouflage to blend with their surroundings.

It's a thought, but has two disadvantages that I can think of. First how to anchor it to the ground - driving in three poles to the depth and angle to allow them to be joined at the top will not be simple. Screw anchors might work, but up goes the cost and complexity. Second - the elephants will probably kick a bend into one of the three poles unless it is as strong as a single pole would need to be to resist being pushed over.

 

[mfb]

Where does the 1 degree requirement for the camera come from? Cameras typically have quite a wide viewing angle, why do you need such a precision?

Simply taking a stronger beam still looks like the easiest option to me.

 

[JBA]

I was thinking more of a rigid welded pyramid structure with pipe collars at the bottom of the corners for retaining stakes to be driven through. You are right about the structure legs needing to be as strong as a single pole but a welded pyramid joined at the top and with base pipe pieces connecting the bottoms of the three legs is an extremely strong structure (but not necessarily a light weight one for handling purposes).

 

[Peter Apps]

Where does the 1 degree requirement for the camera come from? Cameras typically have quite a wide viewing angle, why do you need such a precision?

Simply taking a stronger beam still looks like the easiest option to me.

The 1 degree repeatability in aim comes from tests I did on angle of dip and tilt using a dog the same size as a leopard as a target under controlled test conditions, and from the requirement to have the cameras covering overlapping areas but not dazzling one another with their IR floodlights.

Amen to the stronger beam - but nobody wants to answer that question

 

[Peter Apps]

I was thinking more of a rigid welded pyramid structure with pipe collars at the bottom of the corners for retaining stakes to be driven through. You are right about the structure legs needing to be as strong as a single pole but a welded pyramid joined at the top and with base pipe pieces connecting the bottoms of the three legs is an extremely strong structure (but not necessarily a light weight one for handling purposes).

That would work but would need three times as much steel and three times as much hammering of stakes into the ground.

 

[anorlunda]

nobody wants to answer that question

I think I can get you an answer when I get to my computer tomorrow.

 

[Nidum]

I did a sample case just to see what the magnitude of the problem is .

Simple cantilever / Hollow square steel tube / 1000 mm high / 75 mm across flats / 5 mm wall thickness / Mild steel / 4000 N horizontal load at top

That gives a safety factor of about 1.45 on yield for maximum fibre stress .

 

[Peter Apps]

I did a sample case just to see what the magnitude of the problem is .

Simple cantilever / Hollow square steel tube / 1000 mm high / 75 mm across flats / 5 mm wall thickness / Mild steel / 4000 N horizontal load at top

View attachment 114598

That gives a safety factor of about 1.45 on yield for maximum fibre stress .

Great ! That's what I've been looking for. That is a much heavier pole than I had thought, though not entirely impractical. Hammering it into the ground will be a mission though ! Would you mind looking at what load a 50 x 50 x 3mm square tube could recover from under the same conditions. I already know that I can get 50 x 50 mm into the ground without machinery. Thanks again.

 

[Peter Apps]

I think I can get you an answer when I get to my computer tomorrow.

Thank you - I look forward to seeing what you get.

 

[Nidum]

Problem with more slender poles will be deflection .

For the 50 mm square tube you mention a load of 1100 N will give same SF but top deflection now > 8 mm .

 

[Peter Apps]

Problem with more slender poles will be deflection .

For the 50 mm square tube you mention a load of 1100 N will give same SF but top deflection now > 8 mm .

Problem with more slender poles will be deflection .

For the 50 mm square tube you mention a load of 1100 N will give same SF but top deflection now > 8 mm .

Thank you again. Deflection while the elephant is busy with its engineering is no problem, as long as the pole recovers to its original position afterwards. If I could make a flexible pole that would stand up again I would give it a try. I suspect that a determined elephant could exert more than 1100 N, but 50 x 50 might be worth trying on the basis that if the first shove does not yield any results it might go away.

Final question; how much stronger in bending and torsion is square tube compared to angle with the same dimensions ? Is there a simple relationship ?

 

[anorlunda]

I'm pretty busy today. I was going to look up the answer here
http://www.midaliasteel.com/files/3813/6394/3187/DCT_CF_Small.pdf
but perhaps you can look it up yourself. You want the maximum bending load for a cantilever 1m long. The tables include different sizes of square structural steel tubes. My guess is 100 mm or 4 inches.

But 1m is pretty short. It won't make much difference in cost or weight to go for gross overkill with a 6 inch or 8 inch square tube. Then you don't need the answer for the minimum size that does the job. After all, your 500 kg number is, I assume, just a guess. An elephant might be able to do many times as much.

I still haven't heard an answer to preventing the post from being moved regardless of strength. Unless the tube is anchored in concrete (or buried 3-4 meters deep), a strong push will move the dirt and make the post lean no matter how strong the tube. Focus on tube strength is only a partial answer.

Edit: good luck. Perhaps you can post again in the future to let us know how it worked.

 

[anorlunda]

Final question; how much stronger in bending and torsion is square tube compared to angle with the same dimensions ? Is there a simple relationship ?

Not a formula, but just google for sources of angle iron for sale. You should be able to find manufacturer's specs for max bending load.

 

[Nidum]

Final question; how much stronger in bending and torsion is square tube compared to angle with the same dimensions ? Is there a simple relationship ?

Answer to specific question is that angle would be a lot weaker . More generally though it's better to compare strengths of beams of different sections but same weight . There are no simple formula relationships as such but it would be quite easy to prepare some strength comparison charts with a spread sheet .

In many of these types of problem it is usually easier to just select and compare a few sizes and shapes of beam until you find something suitable .

A problem with angles is that they do not have the same strength in all directions and they can twist as well as bend even with simple direct loads .

What would be a good size of angle to suit your purposes if it could be shown to be strong enough ?

 

[Nidum]

Unless the tube is anchored in concrete (or buried 3-4 meters deep), a strong push will move the dirt and make the post lean no matter how strong the tube

Certainly a problem to be investigated . What sort of ground is there where this camera is to be set up ?

 

[Peter Apps]

Answer to specific question is that angle would be a lot weaker . More generally though it's better to compare strengths of beams of different sections but same weight . There are no simple formula relationships as such but it would be quite easy to prepare some strength comparison charts with a spread sheet .

In many of these types of problem it is usually easier to just select and compare a few sizes and shapes of beam until you find something suitable .

A problem with angles is that they do not have the same strength in all directions and they can twist as well as bend even with simple direct loads .

What would be a good size of angle to suit your purposes if it could be shown to be strong enough ?

If angle is a lot weaker than square tube of similar dimensions then the square tube would be the way to go, and there would be no good size of angle. From looking at the videos and the state of the poles after elephants have finished with them I suspect that the elephants first twist the pole using the camera box and bracket as a lever, that flattens the angle at ground level and then it is easy for them to bend it over. If I had my way we would already have replaced all the 40x40 angle with 50x50 square tube (which I know I can drive into the ground if the lower edges are sharpened), which from an earlier answer can handle 1100 N 1m above the ground, but my boss said that it was too expensive. I was hoping to be able to present him with some hard evidence that the square tube is the way to go. It might not prevent all the elephant damage but it would reduce its rate to something I can live with.

 

[bsheikho]

Why don't you disguise the camera inside another animal's costume? How often do animals kick other animals?

 

[Peter Apps]

Certainly a problem to be investigated . What sort of ground is there where this camera is to be set up ?

The ground is for the most part a sandy clay mix. It gets very soft when it is wet - and this year we have had getting on for three times the annual average rain - which makes it easier for animals to push things over, but also easier to drive the poles in deeper. There is nothing I can do about the soil, but I can do something about the strength of the poles, and even in wet sand the 40x40 mm angles were being bent over at ground level, so were weaker than the soil. There are a total of 19 cameras at five sites, and they have been out there for just over two months recording with no scent in the dispensers. Next week I add scent to the dispensers and the cameras record the animals' responses. I wish there was a detailed description I could link to, it is part of this project; https://www.bpctrust.org/bioboundary-project.asp .

 

[Peter Apps]

I'm pretty busy today. I was going to look up the answer here
http://www.midaliasteel.com/files/3813/6394/3187/DCT_CF_Small.pdf
but perhaps you can look it up yourself. You want the maximum bending load for a cantilever 1m long. The tables include different sizes of square structural steel tubes. My guess is 100 mm or 4 inches.

But 1m is pretty short. It won't make much difference in cost or weight to go for gross overkill with a 6 inch or 8 inch square tube. Then you don't need the answer for the minimum size that does the job. After all, your 500 kg number is, I assume, just a guess. An elephant might be able to do many times as much.

I still haven't heard an answer to preventing the post from being moved regardless of strength. Unless the tube is anchored in concrete (or buried 3-4 meters deep), a strong push will move the dirt and make the post lean no matter how strong the tube. Focus on tube strength is only a partial answer.

Edit: good luck. Perhaps you can post again in the future to let us know how it worked.

That's a very handy document, though I will have to look at very carefully to make sure I interpret in correctly. The 500 kg is a guess, but an informed one based on elephants being able to kick harder than they can lift. They will not get their heads down to 1 m to push with their heads. Worse case is a six ton bull putting one front foot on top of the camera box with the other front foot off the ground - that applies more than half his body weight downwards. I have video of a bull casually aiming a camera at the ground by standing on its box with one front foot - both from the camera in the box, and from one of the others in the array. The bracket rotated on the bolt that holds it to the pole, but nothing bent.

I understand that the pole is only one part of the whole picture, but it is very obvious that 40x40 mm angle is too weak, and I was wondering what size of steel would be elephant resistant. Once I know that I can start worrying about the strength of the soil, which I can do nothing about apart from driving the poles deeper. Casting concrete footings is out of the question.

The test scent goes into the dispensers next week, so in any case I cannot now change the setup. But the second phase of the experiment will have the cameras in a more remote area where they will not be visited as often, so the ironwork needs to be more resilient. I will keep you posted.

 

[mfb]

There are a total of 19 cameras at five sites, and they have been out there for just over two months recording with no scent in the dispensers. Next week I add scent to the dispensers and the cameras record the animals' responses.

Not directly on topic, but I wonder if it could be a problem if your "no scent" and "with scent" samples are not collected at different times of the year.

 

[Peter Apps]

Not directly on topic, but I wonder if it could be a problem if your "no scent" and "with scent" samples are not collected at different times of the year.

Potentially it is a confounding factor, and I am sure that referees will bring it up when I submit the paper, but the two conditions happen consecutively and the repellent effect I am looking for is a very obvious contrast to the leopards usual behaviour of ignoring the dispensers completely - I am not looking for subtle effects that need sophisticated statistics to tease out the control vs experiment differences. The alternative of doing controls and experiment in the same places at different time is to do them at the same time in different places - but then the exactly equivalent criticism can be levelled. Same places different times also avoids complications with animals getting habituated to the odour.

 

[pervect]

Rampaging elephants have been known to uproot trees and "mow down" telephone poles. (See for instance http://www.historylink.org/File/5270). So I suspect that an attempt to make a mounting proof against an elephant will probably be expensive. It's not quite clear to me how the telephone poles failed - did the poles break, or were their foundations inadequate? (I suspect the later, especially given that the trees were listed as being uprooted).

In either case, I would think that It would be better to find a mounting system that doesn't irritate the elephants than to try to engineer one that can resist them. Which also allows us to pass the buck back to the zoologists :-). I wouldn't be surprised if there's an opportunity for a paper on the solution, once the problem is solved.

More research on the historical incident in question might give more insight into just what an elephants destructive capabilities are.

For the engineering aspects, I found https://www.clear.rice.edu/mech403/HelpFiles/ImpactLoadFactors.pdf which looked interesting. If I'm reading the article right, you might need a beam (pole) that could support 100 or even 1000 elephants statically to withstand the dynamic impact force. I'd guess an elephant might weight between 5-10 tons, at the higher figure we'd need a beam that could support 10,000 tons. And foundations to match.

Using the approach from this paper, to get a better answer, one would need to estimate the velocity of impact of the elephant. I'm not going to hazard a guess, but just outline the general approach from the paper I mentioend. Conservatively assuming the efficiency factor is 100 percent, one would assume the pole had to store that much energy. (Perhaps one could argue that a lower efficiency is needed, I don't have a good grasp on it though.). This would give the peak deflection, a static analysis of the beam (which is the engineering model for the pole) would have to be done to assure that the beam (pole) didn't fail under these conditions.

 

[Peter Apps]

Rampaging elephants have been known to uproot trees and "mow down" telephone poles. (See for instance http://www.historylink.org/File/5270). So I suspect that an attempt to make a mounting proof against an elephant will probably be expensive. It's not quite clear to me how the telephone poles failed - did the poles break, or were their foundations inadequate? (I suspect the later, especially given that the trees were listed as being uprooted).

In either case, I would think that It would be better to find a mounting system that doesn't irritate the elephants than to try to engineer one that can resist them. Which also allows us to pass the buck back to the zoologists :-). I wouldn't be surprised if there's an opportunity for a paper on the solution, once the problem is solved.

More research on the historical incident in question might give more insight into just what an elephants destructive capabilities are.

For the engineering aspects, I found https://www.clear.rice.edu/mech403/HelpFiles/ImpactLoadFactors.pdf which looked interesting. If I'm reading the article right, you might need a beam (pole) that could support 100 or even 1000 elephants statically to withstand the dynamic impact force. I'd guess an elephant might weight between 5-10 tons, at the higher figure we'd need a beam that could support 10,000 tons. And foundations to match.

Using the approach from this paper, to get a better answer, one would need to estimate the velocity of impact of the elephant. I'm not going to hazard a guess, but just outline the general approach from the paper I mentioend. Conservatively assuming the efficiency factor is 100 percent, one would assume the pole had to store that much energy. (Perhaps one could argue that a lower efficiency is needed, I don't have a good grasp on it though.). This would give the peak deflection, a static analysis of the beam (which is the engineering model for the pole) would have to be done to assure that the beam (pole) didn't fail under these conditions.

I am sure that you are right that there will be paper or two on successful solutions.

I think that it is important to stress that these elephants are not "rampaging"; they do not come charging in and butt the poles with their heads, they approach quite deliberately, sniff around, then kick or pull on the cameras and poles. Any impact from kicking is nowhere near the impact load of a charging elephant. I would upload videos from the cameras but they are 15 MByte each and my internet is not up to it.

Also I do not expect to have mountings that resist all elephants all the time. If I could reduce current rates of damage by 90% while still using steelwork that can be installed in the field without heavy machinery I would be happy. Asking how strong different sizes of steel are was one step towards that goal. I designed the camera boxes by rule of thumb applied to what I can buy locally (lip channel) and they have protected the cameras against elephants, baboons, hippos, hyaenas, and wild dogs (just from memory) - the only camera that has been damaged while in a case was one where an elephant uprooted the pole and dropped the pole and camera in the road, where it was run over by a ten-ton truck (sadly the elephant put the camera face down so there is no video but the tyre tracks tell the story). As you can imagine the box was considerably squashed and the camera case was cracked, but the camera still works. Making the boxes to resist ten-ton trucks would be the design overkill equivalent of designing a pole to resist a full scale elephant attack from a bull n musth.

There is a limit to how concealed the cameras can be - they use IR floodlights at night and although I cannot see the glow I suspect that elephants and other animals can (there is literature on animal responses to camera light and sound, but it does not necessarily apply to the cameras I am using). Also, when the cameras are installed and serviced it is inevitable that they get human scent on them, which may upset elephants. For my particular application I cannot use scented repellents like chillis, or masking scents.

Snapshot Serengeti https://www.snapshotserengeti.org/#/home put cameras on 75x75 mm poles for a long-term fixed point survey. I will contact them to find out how they got them into the ground.