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# ADOSS users and Round vs. Square columns

• To: "INTERNET:seaint(--nospam--at)seaint.org" <seaint(--nospam--at)seaint.org>
• Subject: ADOSS users and Round vs. Square columns
• From: Mark Gilligan <MarkKGilligan(--nospam--at)compuserve.com>
• Date: Sun, 12 Sep 1999 23:16:27 -0400

```You might find thetechnical paper on how SAFE calculates punching shear of
interest.  It can be found at
http://www.csiberkeley.com/Tutorials/SAFE/SAFETUTOR.htm.

On  a related topic ADOSS calculates the punching shear stress contributed
by bending based on the uni-axial bending calculated from the equivalent
frame analysis.  This isall it can do since the program dosen't have the
moment about the other axis.  On the other hand SAFE calculates punching
shear stresses based on biaxial bending.

Mark Gilligan

----------------------------------------------------------------------
>>>Attention Fellow Engineers;

I recently have been using ADOSS after years away from designing flat
slabs.
I  note in the punching shear  and moment transfer analysis, the computer
program uses a critical section as d  (eff)  away from the perimeter of
column as per ACI code.

However for round columns this defines a round critical section and a
square
or rectilinear plane for square or rectangular columns.

At a previous employer modifications were made to an early version of a
flat
plate - flat analysis design program to treat round columns as equilvalent
squares.

Why to I bring this up??  I recently analyzed a flat slab with 24 dia.
round
columns and found the slab overstressed in punching shear.  ADOSS was using
a
round critcal section.

(equilvalent squares) the slab was OK in shear.  INTERESTING

In fact if the slab was analyzed with 18 inch square columns  (Inscribe
within a 24 inch column)  shear stresses were comparable with 24 round
columns.

Is anyone familar with punching shear effects in round columns.

It appears ACI  - code is not clear on this issue  for shear.
ACI does permit round columns to be treated  as equivalent squares for
flexural design calculations  (in reducing moments to face of support)

Couldn't round columns be treated as equilavent squares for shear calcs  ?

IF SO,  punching shear stresses  would be less.
ADOSS analysis is conservative  using  round critical sections for round
columns  ??<<<

```