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Re: Bolting issues

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Dear Charlie,

I am glad you finally joined us in discussing these issues. 

>Unfortunately, a great many
>statements were, in my (humble) opinion, incorrect. For example, a few
>messages indicated concerns about over-pretensioning and subsequent
>failure in service (RCSC Specification states that pretension in excess
>of the minimum required pretension is not cause for rejection).

Does it says who many turns? or how much extra tension is okay? 

For days another member of the list who has been very kind and knowledgable
continued this discussion with me in the background. We both agreed that the
excessive pretensioning load must affect shear capcity of the bolt at
"factored loads" not "service loads", specially when shear plane passing
through threads.

There is basically two figures in the book by Kulak et. al. One figure
(4.17) supports this idea and one does not (4.15). So if you think that RCSC
Spec. on this issue is only based on this book, which is regarded as its
commentary, then I ,for one, would be curious to know why it is based on
something that does not appear to be conclusive enough. 

I have sound theoretical reasons for why shear-tension interaction exist,
and therefore, it must be applicable to bolts as well, and one figure in
that book supports this. But to argue against this I know of only one Figure
in the same book (based on limited no of tests for specific bolt size and
grip length, which I think can not be general) and no other reasons, I would
greatly appreciate it if you or any other respected member of this list
substanciate it.
  
>I regret that I don't have the time to detail out the answers and/or
>technical justification to all the questions that have been asked in the
>bolt "thread". Ha! Pun intended! But you can all find the answers to
>these and a whole lot of other questions on your own in two documents:
>
>1. The RCSC Specification for Structural Joints Using ASTM A325 or A490
>Bolts (note: the 1994 LRFD version is the best one by far for technical
>information)

Is there any thing regarding over-pretensioning of bolts? Page no.? 

Sincerely,

Majid Sarraf 
www.uottawa.ca/~msarraf


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