AS NZS 3101 - 17.5.8.2 can shear area be ignored?

[Backcheckrage]

I have a situation where I have a precast panel suspended with gravity support anchors along the bottom.
They are embedded in the panel so therefore AS/NZS 3101 section 17.5.8.2 should apply for calculation the effective project shear prism project area (Av). I get a very small value due to the area being truncated by a thin concrete panel!... my question is can this equation be ignored if the anchors are "far" from concrete edge (C1 dimension)... see attached.

In other words, I would expect the capacity of the steel bolts to govern (or bolt pry-out from concrete).... and not the shear cone failure?

Any thoughts or experience is appreciated.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1634323830/tips/image_for_query_jfjgnv.pdf[/url]

 

[Agent666]

I wouldn't go ignoring it, however let me explain:-

In ACI318 there is a breakout thickness factor that is supposed to correct the capacity in thinner members with larger edge distances. This factor is not present in NZS3101 (because the provisions in NZS3101 are based on ACI318-04 (I think) which is obviously many versions behind the latest 2019 version), but the intent is that it should be included to consider the correct theories involved in the CCD methods underlying the provisions in chapter 17.

Including this scaling factor will usually factor up the capacity in shear breakout to the point where shear pryout or steel failure is the critical mechanism which addresses your underlying query. So yes, you do get to a point where the capacity is limited to that where pryout or steel would govern.

Additionally, you get to a point where the reinforcement designed as anchor reinforcement can substitute for the breakout capacity. ACI318 also covers this, but NZS3101 does not cover it. But the intent of the underlying methods is that you can follow the logic in ACI318 without sweating it. I've certainly had no issues with utilising it in peer reviews, etc. In fact, I'd prefer someone to use the latest provisions as NZS3101 is unlikely to be updated anytime soon and it is actually incorrect in this instance based on the updates to ACI318 which occurred in 2008 version. If you use software utilising the ACI318 methods (which is most commercial software, from the likes of Ramset, Simpson, etc this is what it will be doing).

Hope that helps?

https://engineervsheep.com

 

[Backcheckrage]

Agent666, thank you for this very detailed response. Amazing. I get a better reply from you than I did some product reps in my area.

I've decided to advance the design utilizing the member thickness factor ψ_h,v which gets it all to work out.

Cheers!

 

[Agent666]

Haha, there's probably a reason those engineers are sales people and not practicing design engineers... Maybe if they payed more attention at University!

https://engineervsheep.com