shear breakout and shear pry-out 2

[yavier]

hi all, I'm wondering if ACI design code shear strength is based on elastic or plastic?
I try to make an Abaqus model of a shear pry-out/breakout and compared it to result obtain in ACI design code.
the result shown in the attachment where the elastic can be seen stop around 11-12ton which is similar to the result obtained in ACI design code then it continues its plastic till 16-17 ton.
from this result does it mean ACI design code strength is only elastic strength?
but I have a feeling that it should be plastic since it's a pry-out and breakout case where it's a behavior happen when the concrete already totally fails?
so, I became not sure either my Abaqus model is right or wrong....

 

[KootK]

When considering the development of a concrete breakout frustum, elastic modeling would be more appropriate that plastic. Worse than elastic, really, as capacity will be governed by localized fracture mechanics stuff.

When considering the capacity of a concrete frustum where the concrete has already failed and the load is being transferred to rebar, then consideration of rebar plasticity may have some merit.

Frankly, I'd be reluctant to put much stock in FEM modelling for something like this without it first being extensively validated through testing.

 

[icebloom]

If you are referring to the anchoring to concrete (chap 17) then the method it employs is an elastic design approach. While there are plastic design procedures these are not codified in any major national code that I know of. If you design supplementary reinforcement then you theoretically have full capacity even after cracking of the concrete, however I suspect this may not be what you are referring to.

 

[yavier]

i see, thankyou guys for your reply. it really meant a lot to me. From your reply i get that comparing the ACI code (chap 17) result with the elastic result from FEM is more reasonable.
well i agree with you that FEM model usually used when we got experiment result to compare with, but i personally think result obtain from ACI design code can also be made for FEM validation with accuracy around 80% since the code also result from experiment hahahaha