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RE: Edge Distance for Steel Plate

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Hi Brad,
 
The min. edge distance rule in our Aust. standard applies to all situations regardless of direction of force - I have always had a problem with the logic surrounding this.  There is also a formula to check plate tearout which would often or always require less material than provided by the min. edge distance, when forces act in that direction.
 
When something has already been built, often it puts us in a position where we have to challenge some of those code rules, rather than reject items that don't conform.
 
How about the bolt detail associated with hinge bolts (swing bolts) on manhole covers for vessels.  The bolt holes in the flange are open to the outside to allow the bolt to swing out when sufficiently loosened.  When fully tightened, the bolt is in tension, in a direction normal to the edge.  The actual edge distance is zero!
 
I think if you can demonstrate that stresses under all possible load scenarios are acceptable, and that the fabricator is happy that he can construct the (non-conforming) detail (not a problem here!), then you should accept it.
 
Regards
 
Dave Meney
 -----Original Message-----
From: Brad Friederichs [mailto:brad(--nospam--at)ve-solutions.com]
Sent: Friday, 12 February 1999 8:04 am
To: seaint(--nospam--at)seaint.org
Subject: Edge Distance for Steel Plate

A design build contractor called me today with a lot of frustration in his voice.  He has fabricated 84 anchor plates 2" thk x 12" wide x 36" long with a 1-1/2" dia hole at each end (in the center of the 12" side).  The edge distance of the hole is less than AISC minimums (1-1/2" vs 2-1/2").

A #11 dwiydag rod goes through the hole with a working load of 41 kips.  A nut is fastened to the rod on each side of the plate. 


The plates are on-site and ready to be installed.  He's looking at a horrendous cost (from his perspective) of $12,000 to replace the plates plus delay of job.

In trying to resolve the problem, I have the following:

The force in the line of edge distance is zero.

The punching shear stress around one-half the perimeter (ignoring the outside circumference on the edge side) is 6.8 ksi (A36 steel).

This ignores any moment transfer into the rod and eccentric shear effects.  The rod is very flexible in relation to the plate so ignoring the moment seems reasonable. (which may not be valid).

How would you resolve this problem?  (Other than replacing the plates).


Brad Friederichs
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