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AS3600-2018 Shear reinforcement for pad footings

AS3600-2018 Shear reinforcement for pad footings

AS3600-2018 Shear reinforcement for pad footings

Hi all
I have noticed that the new concrete code has removed the clause that in the 2009 version allowed to waive the minimum shear reinforcement for elements deeper than 750mm if they were considered as slabs. In particular this allowed engineers to generally specify pad footings with no shear reinforcement, as long as the design shear was less than the concrete shear capacity (φVuo).

Now with the new code, clause specifies that minimum reinforcement is required for members with overall depth >750mm, no matter what the load is or if it's considered as a beam or a slab.

There are two things to consider which may allow to waive minimum reinforcement for footings:

1) Clause 21.3.1 prescribes the Sections to be used for designing footings, however it doesn't mention Section 8, so we could argue that clause doesn't appliy to footings. However, one way shear is a failure mode for pad footings, so when we check/design a pad footing we have to rely on chapter 8 no matter what, in which case clause comes back into play

2) Clause 21.3.2 allows to design footings as Plain concrete (although they haven't bothered referring to the correct clause, in fact 15.4 was the plain concrete footing clause in the 2009 code, in this one would be clause 20.4). So we can check one-way shear and punching shear on a footing using plain concrete formulas. Although I don' feel it is entirely in the spirit of the code to design flexure (bottom bars) as reinforced, then just shear as plain concrete.

I would like to hear some comments on the above, and what is your interpretation fo the code on this matter.
Thank you in advance.

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