Punching Shear check at Wall Ends and Wall Corners

[wcfrobert]

Hi All,

This topic has been bothering me for the past few weeks. What are your thoughts about punching shear check at wall ends and wall corners?
The CSA and ACI codes are strangely silence on this subject. Personally, I don't see how the slab can punch through at just the wall ends? What's the failure like? Does it "zipper" across the length of the wall?

I'm getting different answers from the senior engineers at the office. some uses (t+2d) for the influence length, others use (2t). Apparently, these cases require some engineering judgement (which is something I dread as a junior...)

I recently came across the Model Code 2010, which specifies 1.5d for the influence length. Do you guys think this requirement is a little too extreme? If I have a 200 slab, the equivalent column at a shaft corner would be 216x216 (bo=576mm)... that seems ridiculously conservative.

How do you guys deal with these cases?

Thanks!


RW

 

[WARose]

What are your thoughts about punching shear check at wall ends and wall corners?

Are you talking from a slab framing into the wall or something else?

Typically (with a slab) I take a look at the stresses and compare them to the allowable(s). (You have to back figure the allowable from the one/two-way equation in the code.)

 

[wcfrobert]

@WARose

Yes, I'm talking about slabs framing into wall ends. Obviously, along the length of the wall we have to check one-way shear. But I am interested in what happens at the end of the wall.


The model code 2010 provision I'm talking about are shown below.

 

[WARose]

Obviously, along the length of the wall we have to check one-way shear. But I am interested in what happens at the end of the wall.

It's the same concept as a slab framing into a corner column or something similar.

EDIT: A good reference on this (i.e. force transfer at a slab joint) is ACI 352.1 R-89.

 

[Trenno]

For comparison and reference, the Halfen technical guide, page 14, offers similar control perimeters to above with a Eurocode flavour.

I'm not sure of the exact references that Halfen use to generate these cases though.

[URL unfurl="true"]http://downloads.halfen.com/catalogues/de/media/catalogues/reinforcementsystems/HDB_17.1-E.pdf[/url]

 

[JasonMcKee71]

ETABS can't to that, please use SAFE instead.

Jason McKee
proud R&D Manager of
Cross Section Analysis & Design
Software for the structural design of cross sections
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