AS 3600 - 2018 8.3.2.4 Anchorage of shear reinforcement

[Legoman92]

Hi Guys,

Just was having a browse of the AS3600 Commentary regarding shear reinforcement development.
8.3.2.4 states

"Shear reinforcement shall be deemed to be anchored provided the following criteria are
met:"

b) "The fitment spacing shall comply with Clause 8.3.2.2. Provided the hook comply with
Clause 13.1.2.7, anchorage shall be deemed to be satisfied."

However the commentary rambles on that ideally hooks should be only present in the compressive zones, which just completely contradicts the actual code.
Anyone have any comments about this? Why put in this commentary if the actual code makes no distinction in these situations?

Currently, I'm designing a wide, deep slab (700mm) which has areas of high shear, and the neutral axis is above the longitudinal reinforcement, so really, it isn't actually possible to place the hooks in the compressive zone.

 

[rapt]

At one stage, the code penalised stirrup development in the tension zone. If there is a tension or a crack at the hook/cog, it logically has less capacity than the concrete being in compression there basically providing a clamping action. So there is a logical reason why you should try to do it.

The code was suggesting the best approach was to reverse the ties in negative/positive moment regions and put a 20% penalty on capacity otherwise.

We eventually convinced the person making the suggesting that it as impractical in general (getting a reinforcing installer to actually read the drawing and do it), and in cases of moment reversal , earthquake, moving loads and high LL, that it is impossible as either face could be in tension under some load condition.

Presumably the discussion is still in the commentary.

.

 

[Legoman92]

Thanks for the reply, rapt.