Beam shear critical section on a pile

[nrjdjjs]

Attached is a sketch showing a pile cap with two closely spaced pedestals, supported on two piles 1 & 2. If normal beam shear critical section in accordance with ACI 318 code is considered on either side of the two pedestals, for the given geometry configuration, it so happens that the beam shear critical section when considered from the right face of the left pedestal will fall on the right pile 2. Would determining shear at this critical section apply since it is directly on the pile? If not, what is the best way to analyze this scenario and where should the shear section be considered to determine if the shear is within allowable limits? Should CRSI guidelines be considered in this scenario to determine the shear at the right face of the pedestal instead of at the critical section falling on the pile, even though the d/w ratio is less than 1. Any thoughts, comments in this regard would be sincerely appreciated. Thank you.

 

[KootK]

Strut and tie would be a good design method for something of these proportions. The CRSI guide on pile caps has a method for checking shear on planes steeper than 45 deg. You could do that as a secondary check perhaps. Your shear plane will be practically vertical though so unlikely to govern. I think there is also a 10(sqrt(f'c)) limit in ACI.

 

[Just Some Nerd]

+1 to strut-and-tie, generally more fond it for this sort of scenario

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Why yes, I do in fact have no idea what I'm talking about

 

[nrjdjjs]

Thank you for the replies.
Assuming that CRSI guideline may be used to check the shear at the face of the pedestal, in this particular scenario, the w/d ratio is greater than 1. So it seems that a higher allowable shear strength of upto a max of 10*sqrt(fc') may not be applicable at the face of the pedestal. Would appreciate more insight in this matter in case I am reading the CRSI guideline incorrectly.

Thank you