Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Lag screws in withdrawal from end gr

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Roger,

I still want to know why they used the word "should not".

What I meant when I asked how the withdrawal values were obtained was that I
assume that these values were obtained using test results of ultimate capacity
and then applying a factor of safety to obtain a working stress allowable
value and then maybe coming up with a formula. Somehow, I suspect that during
the testing for withdrawal of lag screws at end grain condition, something
unusual happened that they added the restriction that these application
"should not" be used unless it cannot be avoided......

Maybe a sudden catastropic failure that they do not want to happen when the
ultimate load is reached, maybe the connection  does not work at certain
conditions such as cyclic wet and dry weather or earthquake, or maybe it does
not work if the lag bolt is installed improperly such as excessive turn of the
screw or oversize holes,......I'm just guessing here.

If we know the real reason for this "shoud not" restriction, maybe we can have
a better feel or judgement of whether to use it for certain conditions, with
certain limitations, or not use it at all under any conditions. 

Ernie Natividad