Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

ADOSS users and Round vs. Square columns

[Subject Prev][Subject Next][Thread Prev][Thread Next]
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.

  Yet, when the same slab geometry- loading was analyzed with 21.2  
(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  ??

Your thoughts on this subject

Bob  Johnson