Rivet Design
Rivet Design
(OP)
Anyone ever seen rivets designed as see in the attachment? Seems overly simplistic.
(I know that no one uses rivets anymore).
(I know that no one uses rivets anymore).
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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RE: Rivet Design
However for a modern design better one would check for one of the latest specifications dealing with them, that would have the latest knowledge incorporated. Yet awareness of the old pertaining facts would be paramount if for rivet works predating the era of the specification.
RE: Rivet Design
RE: Rivet Design
Numbers I'm getting using a classical shear flow formula and including the web are considerably lower. But I guess that makes sense if I am using VQ/I and 'I' includes the web.
RE: Rivet Design
RE: Rivet Design
As an aside, but not for Toad's eyes: The interesting thing about the 'old fashioned' rivet (which some people do still use) was, that when driven, the rivets actually tended to fill the holes, so they did take there proportional share of the load. Unlike bolts, and bolt holes and fit-up, where some percentage of the bolts are either yielding in shear, or causing plate/hole bearing yielding, to bring the other half of the bolts into real loading and bearing, thus joint slip.
RE: Rivet Design
RE: Rivet Design
For Case I, "Web Member Disregarded", V/h is identical to VQ/I. For Case II, "Web Member Considered", presumably on the next page, they probably use VQ/I.
BA
RE: Rivet Design
I was being a dummy... I checked VQ/I using 'I' for the pair of angles only, matches exactly.
And yes, you are correct, they show two cases "Web MOMENT Disregarded" and "Web MOMENT Considered".
For the case where they take into account the web, they don't use VQ/I but rather an approximation taking into account 1/8 of the web depth....
H.I. = V/h x {Af/(Af + 1/8Aw)}
Af= area of flange
Aw= area of web
RE: Rivet Design
the web Might be fully effective in bending, depending on the buckling of the thin sheet under the bendng compression stresses. At a minimum the web stabilised by the angles won't buckle, so a estimate of h/8 doesn't sound unreasonable. but then the tension side would be fully effective.
the problems of using old textbooks ...
RE: Rivet Design
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Rivet Design
RE: Rivet Design
RE: Rivet Design
Q = Af.h/2
I = Af.h^2/2 + t.d^3/12
= Af.h^2/2 + Aw.d^2/12
I/Q = h + (Aw.d^2/12)/(Af.h/2) = h + Aw.d^2/6Af.h
If we assume that d = 1.22h, then d^2 = 1.5h^2
so I/Q = h + Aw.h/4Af = h(Af + Aw/4)/Af
and Q/I = Af/h(Af + Aw/4)
VQ/I = V.Af/h(Af + Aw/4) seems reasonable for Case II. I wonder why they didn't come up with that. Anyone know?
BA
RE: Rivet Design
RE: Rivet Design
I was referring to the Case II formula at the end of Toad's 15 April 11 16:07 post. They had Aw/8 instead of Aw/4.
BA
RE: Rivet Design
RE: Rivet Design
RE: Rivet Design
BA
RE: Rivet Design
Is that because you are not old enough to have designed a rivet, or for some other reason
RE: Rivet Design
BA
RE: Rivet Design
Unless I'm over thinking this, its not making sense to me.
check rivet shear, bearing at the rivet hole. Should I be checking bearing on the rivet itself?>
RE: Rivet Design
The best thing about rivets, for me, was drawing the girders, I worked with a designer who was assigned to the "Cat Cracker" structure for Fawley Refinery, I had just enough drawing experience that he let me do the drawing. The vessels weighed in the region of a thousand tons so the structure was massive.
I found a picture of the actual unit that I worked on:
htt
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Rivet Design
My take on soft pins, rivets or bolts; without the benefit of Toad's "allowable shear and allowable bearing values for rivets" is that given a dia. and a matching steel grade, the shear stress at yield or ultimate is generally enough lower than the bearing stress at ultimate, that the shear stress usually governed the design. I considered bolt bearing in some joints because, given fit-up and over sized holes, I knew that some bolts would be causing considerable yielding in bearing on the hole edges (and thus high shears at those bolts) before all the bolts were brought into play, thus joint slip. This was not a perfectly rigid joint it had to move some before it became fully effective. And, this same thinking is likely what causes some of the cracking you see in your crane rail girder webs. Despite the fact that you didn't read that into one of my earlier posts. That's very high localized stresses and fairly low cycle fatigue or fracture problem. This same thinking is why bolts and welds in a joint are not additive for a total joint capacity, the bolted joint must move and the weld is rigid and takes all the load. If we cared, and particularly on plate girders, we decreased the hole oversize and match drilled the holes on splice plates and webs or flanges. This minimized the joint movement and gave us more confidence that most of the bolts were acting. Since rivets filled the holes they tended to act in proportion to their number too.
RE: Rivet Design
RE: Rivet Design
Maybe we should collaborate on a text book and save the bottle for the good stuff.
BA
RE: Rivet Design
RE: Rivet Design
Brad
RE: Rivet Design
RE: Rivet Design
You didn't mention the author of the book the page is from, could you??
RE: Rivet Design