Strut-Tie - Tie Development at Nodes (Starter Bars) 1

[BacBac]

Reviving this thread:

Strut And Tie - Tie Development At Nodes - Structural engineering general discussion

Hi All, Looking for some input on how you all handle ACI requiring tension ties anchorage at nodes. ACI Section 23.8.2 states Tie reinforcement shall be anchored by mechanical devices, post tensioning anchorage devices, standard hooks or straight bar development in accordance with 23.8.3 (Tie...

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Does anyone have any ideas on how to justify the starter bars reinforcement is developed at the node?
For the shear ties, reference from Australian Standards, it's said to be fully anchored if shear ties detail is followed (AS3600-2018 clause 12.2.1 that refers back to Clause 8.3.2.4 for anchorage of shear ties).

However, nothing is referred for the development of the starter bars of the column.
Any help would be appreciated
Thanks!.

 

[KootK]

But I guess OP could place transverse bars to decrease the anchorage. Does that work?

I suspect not if it's the arrangement that I'm thinking of. In ACI, those are often termed "supplementary reinforcement". It runs across the breakout frustum and gives a pretty modest increase in capacity. Something like 15% if I recall correctly.

 

[KootK]

But generally speaking a hoop can only fail by bursting in a perpendicular direction

I feel that the most important failure mode of a hoop will usually be the development of a breakout frustum. Obviously, the fact that a hoop is perfectly developed does not obviate such a failure mode.

Eurocode (if I'm interpreting it correctly) says that a hoop is by default anchored, no need to check it. Leonhardt said something like anchorage length = 3D so it is a huge difference to the standard hook.

Can you direct me to that information (clause / section)? I have access to Eurocode and a lot of Leonhardt's stuff.