## Shear force values of concrete in shear pin design

## Shear force values of concrete in shear pin design

(OP)

As stability analysis software becomes more sophisticated, we can now realistically incorporate stabilization mitigation methods into the slopes - specifcally - shear pins.

Typicaly we find that shear pins are either driven steel piles or CIP bored piles with either a cage or a beam and CIP's are 2-6 feet diameter. The range of shear forces we see that are used for the steel and concrete section are 11,000 to 75,000 lbs per foot of pile out of plane spacing.

My question is - what is an appropriate shear force to be used for a preliminary shear pin design assuming a CIP aproach with a reinforcing cage ? There are so many combinations that can be used by the structural engineer after we are finished with our stability analyses - so are we being too liberal or too conservative for the preliminary analyses ?

Typicaly we find that shear pins are either driven steel piles or CIP bored piles with either a cage or a beam and CIP's are 2-6 feet diameter. The range of shear forces we see that are used for the steel and concrete section are 11,000 to 75,000 lbs per foot of pile out of plane spacing.

My question is - what is an appropriate shear force to be used for a preliminary shear pin design assuming a CIP aproach with a reinforcing cage ? There are so many combinations that can be used by the structural engineer after we are finished with our stability analyses - so are we being too liberal or too conservative for the preliminary analyses ?

## RE: Shear force values of concrete in shear pin design

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## RE: Shear force values of concrete in shear pin design

## RE: Shear force values of concrete in shear pin design

For your numbers, each 2 ft pile would be able (more or less) to take shearing action, service level, normal to the pile, just with the concrete, 4x11=44 kip and each 6 ft pile, 4x75=300 kips total service level reaction for the tributary arc of underground volume of earth tributary to the pile.

In all this I have reduced by 1.6 the limit strength of the code, to get the corresponding allowable.

Shear reinforcement at the interface will make these numbers more sure, since spiral or stirrups add to shear strength, and the numbers above are a bit optimistic. A more proper analysis would require the study of the pile under lateral loads, and a proper reinforcement may be found meeting as well what happens upwards of this bottom stub. The capacity in shear rarely would be compromised by that study (otherwise our main arcing action would be being quite underestimated or misplaced) but it may drive the design of longitudinal rebar in the pile, out of sheer projection from the bedrock.

## RE: Shear force values of concrete in shear pin design

Regards,

Dave