huangyhg

an old structural paper / question
hello all;
having contributed to another thread has made me think of a rather old engineering mystery. i'm hoping someone out there *cough* insert standard regulars here *cough* might be able to help:
i don't suppose anyone knows the "mythical" paper from the 1910s or 20s that discusses how much fixity a truss gusset connection needs to actually affect the system sufficiently to make a pin-pin analytical solution inappropriate? i've always wanted to get my hands on a copy, but have never found out even the paper or author name. the paper became a bit of a legend at public works canada (now pwgsc, long story), but no one could find the thing for me... the department was being wrapped up when i was brought on board as a bit of "young blood", but all of the old training materials had disappeared in a recent move. the remaining engineers were wonderful and very giving of their time, however it would have been good to get a bit more documentation for some of the tips and tricks i learnt.
the evidence of the paper's effect is clear: most bridge structures before the 1920s had enormous pins, then after they had fixed-style gussets. none of the analysis methods changed, engineers just learnt to recognize that a fairly innocuous redistribution of forces occured and the structure's true behaviour "came out in the wash". my mentor once told me that he felt the work likely inspired, or potentially even underlaid, hardy cross' pioneering methods.
knowing it exists, and never finding it, always makes me wonder just how much we must repeat simply by being unable to locate original papers!
hope someone can help,
cheers,
ys
b.eng (carleton), p.eng (ontario), mipenz (structural-new zealand)
working in canada, and missing my adoptive new zealand family... at least i brought the little kiwi with me!

contact the linda hall library. they are on the web. i would call, as the people that work there are very helpful. cost once they find the papers are very reasonable. i would call rather than try to contact by e-mail as there will be several questions i am sure.
good luck!
sre - can't you help???
wasn't there a lot of discussion in the forum here on this subject relative to the minneapolis bridge failure recently?
mike mccann
mmc engineering
youngstructural - have no clue to the paper you are referring. see links below that might be of some interest. however, the one article suggests that you might try contacting some professor emeriti of various universities and they might be able to help. my original advisor at school worked on the hoover dam. they might be a start.
ys...i don't know either, but a paper of that vintage would have dealt with riveted connections rather than bolted. the leap to assume pinned action in riveted joints is probably not as big as for bolted joints, as rivets are much softer.
gentlemen: some interesting leads, and i'll do a bit more digging. i think i'm finally motivated enough to use what little spare time i have to run this mystery to ground. i'll let you know if i find out more.
cheers,
ys
b.eng (carleton), p.eng (ontario), mipenz (structural-new zealand)
working in canada, and missing my adoptive new zealand family... at least i brought the little kiwi with me!
ys, bigh - this sounds interesting, will try to turn something up on this - may take some time.
good news... the paper does exist. it is titled "secondary stresses in framed structures" and was written by e. w. pittman and presented, by him, in 1909.
mr. pittman addresses several potential improvements in riveted structures, such as proper alignment of members at the joints. the ground-breaking part is to increase the thickness of gusset plates so that each rivet is fully loaded (bearing) in double shear. this will decrease the number of rivets needed in any particular joint. therefore, the gusset plate will be much smaller. his insight is that the smaller gusset plate will decrease the fixity of a
nice job sre...came through as usual.
ron
slideruleera: you are the structural man. i am so very, very impressed!!! i can tell you that there are several (retired) engineers in canada who are going to be super keen to hear that!
well impressed am i; yet another star for you!
sorry for the delay; i'm out in the field at the moment, so this is the first time i've been on the net in four days. please don't let the delay be interpreted as a reduced gratitude, i greatly appreciate you effort.
now if you'll excuse me i believe i have a couple of papers to read. *smiles*
regards,
ys
b.eng (carleton), p.eng (ontario), mipenz (structural-new zealand)
working in canada, and missing my adoptive new zealand family... at least i brought the little kiwi with me!

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