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Approximation of maximum pull before failure of an iron bar

Approximation of maximum pull before failure of an iron bar

Approximation of maximum pull before failure of an iron bar


Kindly help me to start the resolution of this problem, I have searched for many similar problems related to anchors but most of them calculates the vertical
pull-out force which is not the case here. So lets start.

We have a flat ground surface made of rock, we already made a hole which have the same size to fit our iron bar on it
(watch the attached picture to understand).
Now our bar is pushed down to the end of the hole, we apply now a force F to the head of the bar in one single direction and this force make an angle
of 20° with the horizontal axis. The Question is to calculate the maximum load of the force F that the ground surface and the iron bar can accept
before a failure of the ground. For information, the force should be applied for a maximum time of 3 seconds.
Here are the data:
L: Length of the iron bar
a: Width of the iron bar which have a cross section in form of a square
d: Depth of penetration of the iron bar into the flat ground
20°: The degree angle between the direction of the Force F and the horizontal axis (or 70° angle to vertical axis)
F: The load in Newtons applied to the head of the bar

If you already know a solution to a similar problem found in some webpage then kindly tell me, I appreciate your help.
Thank you

RE: Approximation of maximum pull before failure of an iron bar

If your medium is rock, assume it is concrete and use appendix D of ACI.
Adjust your edge distances for any joints that are present in the rock mass.
For simplicity, I would neglect the vertical component of the force for now.

RE: Approximation of maximum pull before failure of an iron bar

If you honestly found a catch all solution to this, there's many an engineer that would owe you big time.

This is essentially the same as any old embedded post detail. Or single pile subjected to a lateral load. Just now instead of a pile it's a smaller bar. Theory should be the same. And drastically depends on the soil it's embedded in.

RE: Approximation of maximum pull before failure of an iron bar

But that +< 20 angle yields a notable (not negligible) upwards thrust that a plain hole (no cement nor bonding agent stated!) in "rock" - which, with the grinding dust and the movement of the drill as it turns with a rock-bit = loose hole.

No, rock is not same yield as concrete, because of inside flaws. Approximation? Maybe - If the hole is straight. Will the rock move?

So, the assumption of the resisting force mostly sideways is pretty good - as long as the post/rod/bat doesn't ever move in the slightest. The bending yield will likely be the bar bending as it deforms from the moment of Fsideways x HEIGHT. Which also in not stated.

Once slightly bent, the bar yields more and the pulling force is at an angle greater and greater than 20 .. 30 .. 40 so the bar pulls out of the hole with a bend starting at ground level .

So: Drill a tight hole, clean it very, very thoroughly with a blast of air several times into the bottom, and vacuum.
Using a two-part epoxy bonding agent to prevent motion and to anchor the rod.
Check your bar against bending yield as a failure mode.

RE: Approximation of maximum pull before failure of an iron bar

Thank you for your answers. I am googling so I will get back if still no clue. Bye smile2

RE: Approximation of maximum pull before failure of an iron bar

Hello smile;
I have searched and there is tons of references related to piles. According to jayrod12, this can be considered as a pile subjected to lateral load. So because the
equations that determines the maximum lateral load depends on the size and ground type, and because there is different equations for different situations, let me
further give more details hopefully someone can tell me which equation is best suited for my case. So here is the data:

- Bar length : ~7.8 inch (20 cm)
- Bar diameter : ~0.6 inch (1.5 cm)
- Bar type : Iron bar
- Depth : ~6.7 inch (17 cm)
- Soil type : Hard (old road of asphalt / compact soil)

Because there is many approaches for piles studies, such as Brinch Hansen (1961), Meyerhof et al. (1981), p-y method, Matlock, H. and Reese, L.C. (1960). I don't
know which one should I use for this case because most studies talks about big piles used for buildings, but for my case it is just a little iron bar.

So can someone give me the appropriate equation(s) name(s) to use for this case ? smile

Thank you.

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