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RE: Bolt Head Pull Through

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Any chance we could get a picture of that?  Maybe Dennis will let us post them on the Structuralist?
 
I'm always interested in failures and their mechanisms.  The general consensus seems to be that we so over design things that failures never occur.  Having worked in a small office supporting local industrial plants.  We often got called 10 years after the construction when something broke and the plant was tired of fixing it.  About half my time was spent on these types of projects, so I started questioning that "failures never occur".   Having now worked on the original design side, I realize what a complete lack of feedback is generated in the system.  "Design" structural engineers don't have lessons learned because they rarely know when their designs failed.
 
Mark Jones
 
-----Original Message-----
From: Laurence B. Oeth [mailto:viacalx(--nospam--at)europa.com]
Sent: Thursday, April 19, 2001 12:20 AM
To: seaint(--nospam--at)seaint.org
Subject: Bolt Head Pull Through

OK here's an interesting one for your forensic fancies. 
 
I'm looking at a failed connection, fab'd from a 1/4" plate, probably A36, welded to a 1/2-round piece of pipe (Sch80).  5/8" dia 316SS hex head bolt (no washer) pulled neatly through the 11/16" dia hole.  Very nice, uniform curling down of the steel all around the hole which enlarged it enough for the bolt to slip through.  This was repeated 2 times each support on about 16 supports all around a tank.  The bolt did not fail, and does not visually appear to have bent/sheared/necked down.
 
I shudder at estimating based on energy methods applied to the deflected shape.  Anyone know of an empirical or analytical report to aid in determining what the force was at pull-through? 
 
Laurence B. Oeth PE