ICC-ES Reports for Stud Rails

[slickdeals]

All,

Please be aware that the latest ICC-ESR Reports for punching shear reinforcement in the form of stud rails lowers the concrete shear capacity to 1.5 (f'c)^0.5 instead of 3 (f'c)^0.5. This includes even structures in SDC "C".

ICC ESR 2494 (Decon), ICC ESR 2708 (Suncoast).

We are not sure why the ICC has decided to include Seismic Design Category C in the reports. Their response has been that it's more conservative. Apparently, the only people that can request SDC "C" to be excluded is the people the stud rail manufacturers. We don't see that happening as the new requirement forces more stud rails to be used.

ACI 421 limits the stress to 1.5 (f'c)^0.5 for seismic design (which is categorized as SDC D-F in ACI 421.2).

It is interesting to note that neither ACI 318 nor IBC impose these reductions, but it doesn't appear that there is any way to supersede the requirements spelled out in the ICC-ESR's.

If anyone that is a member of ACI 318 or ACI 421 committees has come across this requirement, I would like to hear their opinions.

 

[Ingenuity]

I guess this was in response to the research/testing from 2011 at UofM...ENR article

 

[slickdeals]

Well, that's what we thought. I had a conversation with SK Ghosh about it and he did not seem to think it made sense that ICC would lower the concrete capacity. (other than a stop gap measure). The failure pattern observed by Parra was attributed to the orthogonal layout of studs, which can be improved by a radial pattern. Apparently, Parra made a presentation to the ACI committee, but due to lack of time, it was not incorporated in 318-14. But they are taking it up in the current code cycle, leading up to ACI 318-19/20.

 

[hokie66]

While a radial pattern may be better, I doubt that it is being done that way in many cases.