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RE: Bay Bridge Broken Bolts

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That is a bit odd.  If the A 490 bolts are tensioned per the RCSC, the 
stress remains static until you exceed the tensioning force.  That should 
never happen.  If the issue is hot dipped galvanized, I don't blame them 
for not allowing them.  Hydrogen embrittlement is not well understood.

Regards, Harold Sprague

> Date: Mon, 13 May 2013 08:02:14 -0400
> From: design(--nospam--at)hodgsoneng.ca
> Subject: Re: [SEAINT-SEAOSC] Bay Bridge Broken Bolts
> To: seaint-seaosc(--nospam--at)mail-list.com
> 
> Back in the 1970's, we were supplying steel to the New York Transit
> Authority and they would not allow A490 bolts in any dynamically loaded
> structures. This occurred again in the 1980's on a bridge for Rochester,
> NY. I don't know if these restrictions are still being applied.
> Gary
> 
> On 2013/05/11 6:06 PM, Bill Polhemus wrote:
>> On 5/11/2013 4:27 PM, Harold Sprague wrote:
>>> The bolts specified were ASTM A354 BD, hot dipped galvanized.
>> Just interested: Why not use A490, assuming these are all for structural
>> steel connections? I'm no expert in this but I seem to recall that A490
>> is equivalent in strength to A354 BD but has more stringent quality
>> control requirements. Surely they would be more readily available and
>> less expensive than some sort of proprietary alloy.
>> 

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