How much thickness makes "thick member" in punching shear resistance to drop to 2sqrt(f'c) 3

[NewbieInSE]

Hello dear Engineers,
It would be great to know your understanding on how much thickness makes a "thick member" in punching shear resistance to drop to 2sqrt(f'c)b.d? Also what is meant by low reinforcement ratios? Is it flexural reinf. ratio?
The following snippet is taken from Seismic Design of Reinforced Concrete Mat Foundations, NIST GCR 12-917-22.

Thanks for your feedback

 

[lexpatrie]

See for yourself:

Punching Tests of Slabs with Low Reinforcement Ratios, Guandalini, Burdet, Muttoni, ACI Journal 2009.

 

[HTURKAK]

Pls look ACI 318- 19 (Building Code Requirements for structural concrete )

The following excerpt is for nominal two-way shear strength provided by concrete. Notice that the size effect incorporated .

......

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[CDLD]

Newbie that article was written before size effect factor was introduced into ACI.
A great reference at the time for one-way and two-way shear.

 

[NewbieInSE]

Thanks lexpatrie for the link of the research paper.
Thanks HTURKAK & CDLD.
I was checking ACI 318-11 and didn't find anything. But ACI 318-19 has incorporated it well. Wow. Thanks HTURKAK & CDLD.

 

[NewbieInSE]

Also the Seismic Design of Reinforced Concrete Mat Foundations, NIST GCR 12-917-22 has been written based on ACI 318-11 as CDLD indicated. That's why they left it to open guess using judgements probably.