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Re: AP: Wash. State bridge

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I was just following on from Hassan's opinion. I haven't done bridge design 
 since the 80's in Japan but I was suggesting that if the structure was 
fracture-critical then the original design maybe has to take some 
responsibility so to speak. I don't want to extrapolate my thinking too far 
 past the point I show my ignorance. My use of "fragile" was a suggestion 
that if a structure is vulnerable to an element being removed, then it's 
"fragile". Thor Sent on the TELUS Mobility network with BlackBerry

-----Original Message-----
From: nma <nma(--nospam--at)nma-se.com>
Sender: seaint-seaosc(--nospam--at)mail-list.com
Date: Sun, 26 May 2013 22:08:40
To: <seaint-seaosc(--nospam--at)mail-list.com>
Reply-To: seaint-seaosc(--nospam--at)mail-list.com
Subject: Re: [SEAINT-SEAOSC] AP: Wash. State bridge

Thor:

I guess I missed something some place.  I haven't heard that the bridge
was designed (originally) in a fragile condition.  I don't think that a
computer program would actually design the bridge to much better than
what I might do with my old slide rule.  Basically in the 50's we weren't
checking for secondary moments.  But I have checked bridges of that era
for very heavy (purple) loads, using the standard axle spacing with a FEM
program and found that they are still robust and within the AASHTO code.

What we might argue about then would be maintenance.  Or if you are
saying that the bridge should be able to resist any kind of impact from
any  truck at any point on the bridge, then that is a different matter.

I once investigated (for Transport Indemnity) a dropped gantry on the
Golden Gate Bridge.  The next day our office investigated a dropped
missile at a large aircraft company.  Both preliminary (guesses) were
operator error.  The discussion at that moment with the adjuster was that
these events usually happened in three's.  A couple of days later the
adjuster informed me that there had been another accident in Mare Island.

Truncated 1390 characters in the previous message to save energy.

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