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RE: UFC 3-340-01 "Design and Analysis of Hardened Structures to Conventional Weapons Effects"

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Based on the title of this thread, I assume that you have a copy of the UFC 3-340-01 (AKA TM 5-855-1).  You should be looking at Section 10.8.5.  The structural steel section is a bit thin based on the amount of research done at the time this publication was developed.  Structural steel connections are the last thing you want to fail in a blast design.  They should be designed to remain elastic for most all blast resistant conditions. 

The rise time of a blast load, the fact that high strength bolts are relatively brittle, and the nature of connection failures make conservativism for connection blast design very prudent.  A properly designed window jamb connection for AT/FP is a sight to behold. 
There has been some testing done and anecdotal evidence in "normal" structural steel connections subjected to accidental blast loading.  You may feel that you are being overly conservative, but when you see the damage in a real incident, you will be comforted by conservativism.  Incipient failure is best evidenced in a flexural member not in the connection.  Otherwise the flexural member becomes a blast borne missile. 
If this (blast engineering) is something in which you are new, I would strongly suggest a peer review by someone seasoned and skilled in blast design.  Blast engineering is post-steroidal dynamic design.  You may want to check into attending the next SAVIAC conference to learn from the people who really know the topic...  (I am not worthy to carry their calculators)

Harold Sprague

Date: Thu, 10 Jan 2008 08:09:15 -0700
To: TDavidson(--nospam--at)
From: gpappas(--nospam--at)
Subject: RE: UFC 3-340-01 "Design and Analysis of Hardened Structures to Conventional Weapons Effects"
CC: seaint(--nospam--at)

On Jan 9, 2008 1:57 PM, Thomas Davidson <TDavidson(--nospam--at)>
> I am new to this blast analysis and was kind of thrown a project.  But, I
> was wondering, since this thread came up; if I could get some advice on how
> to analyze bolted connections.  I went a conservative route; I got the peak
> overburden pressure and applied it as a wind pressure on the structure
> itself and the "structure" works, the connections however fail miserably.
> Because the load is only going to be applied for a few milliseconds is there
> a justified Dynamic Increase Factor (DIF) for bolts?  Or is there some way I
> can justify that the bolts will not fail?
> Thanks
> *Thomas Davidson*

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