Using double washers in structural applications?
Using double washers in structural applications?
(OP)
Hi there, I am working on a bridge repair project and the bolts used are being pretensioned with the turn of the nut method (1/3 turn). The contractor was meant to use fully threaded M20s but they ran out so they decided to use M22s with a shank. The shank was too long so in order to space the bolt correctly they used two square spacers under the bolt head and two washers on the other side. My boss has told me not to allow double washers. When I was asked on site by the workers why not, I wasn't able to give them a proper answer. Can you please provide an explanation as to why double washers should never be used?





RE: Using double washers in structural applications?
RE: Using double washers in structural applications?
RE: Using double washers in structural applications?
What assumptions were made when you worked out the pretensioning 1/3 turn of the nut?
--
JHG
RE: Using double washers in structural applications?
RE: Using double washers in structural applications?
I'm wondering about things like -
- how an M22 with a "shank" can replace an M20 , and especially still be threaded M22 on both ends
- the size of the fastener passing through the holes in the steel, and what size the holes are.
- how thick the washers are
Has your boss offered his explanation for not wanting doubled washers ?
How thick are the washers being used now?
These are ~ 3/8 ~ 10 mm thick
https://www.mcmaster.com/#91117a249/=16kjo7q
Extra thick specials could made from bar stock pretty economically.
RE: Using double washers in structural applications?
RE: Using double washers in structural applications?
I would be concerned as well about what CompositePro noted....longer bolts will likely need more than the 1/3 turn you described.
RCSC also gives criteria for plate washers (5/16" minimum thickness). Hardened washers must be used under the turned part.
RE: Using double washers in structural applications?
RE: Using double washers in structural applications?
In my opinion double washers would work, however you would imo be outside of the application rules as per your applicable standard and this might not be permitted as per the AHJ.
But:
There's a company distributing locking washers (Nord - Lock, no rel.) also for structural purposes, perhaps you contact them at
http://www.nord-lock.com/nord-lock/wedge-locking/w...
Or:
Why not (worst case) have manufactured something like a spacer sleeve, making up for the surplus length so that you can apply the bolts / nuts as per textbook?!
Regards
Roland Heilmann
Lpz FRG
RE: Using double washers in structural applications?
RE: Using double washers in structural applications?
RE: Using double washers in structural applications?