Ahh, i understand.
We have two plates bolted together,
one is 1/2" 50w and the other is 3/4" 44w. My thoughts being that if the friction generated is sufficient to prevent slip, that both plates can work together as one. When that doesnt happen, and slip occurs, obviously the 1/2" plate fails...
desert fox,
its the same as a bolt group on the end of a cantelever, why would they "rotate" about the bolt centroid, you would think they would pivot about the bolt closest the load, but that is not the case. Its an egg before the chicken scenario i think. Which is applying the load to...
Yeah, and there is no picture. I drove out and inspected the failure myself, the second was just described to me and it was exactly as the first. Unsuprisingly. They also were being operated in similar environments. We built a couple "one-off" parts with alot of "extra" steel to be sure...
DesertFox,
I get a value for an 3/4 UNC SAE grade 5 bolt, assuming a lubricated coefficient of friction at 0.18 of 223.5 ft-lbs, and using a preload of 0.7 proof(source Bowman Distribution, from Mechanical Engineering Design, 7th ed, by Joseph Shigley). From this i expect it is unlikely the...
dhengr,
That is exactly my plan of attack for this going forward. I will take some time in the future to try and compare this to the AISC specified abilities for the connection. We do like many things about building this unit in this manner so I want to ensure that going forward with new...
Oh and btw, bolts are 3/4" SAE Grade 5 UNC.
With hardened plate washers. The washers are stamped F436, and are assembled with chamfer facing bolt head.
Bolts are torqued using a 4' long torque wrench, so there is not jerking going on, its very smooth.
My fear was stripping the threads as the tapped holes are simply HR 50w (CAN GR 40.21 50W, i know i said 44w above, i always assume 44w when in fact our suppliers use 50w minimum).
The torque i believe relates to around 70% proof load.
It is in fact 200 ft-lbs. Its been a long time since i did...
well, there are 5 bolts. Also hundreds of this exact design working in the field with no issues. Failures are not common, however have happened.
My understanding of slip critical connections is that when properly designed and assembled act to limit fatigue stresses by spreading the loading...
Wow, I've been on this forum for less than a week and already 2 books i need. I like this forum. Only wish that CISC book was dual unit, but oh well. conversion time. or maybe i can convince my boss we should switch to metric.
dhengr,
The hidden tube is 85" long,
on the opposite end is an identical plate to what you see.
The moment is 27400 in-lbs generated by the force of a slurry on a large panel which is attached with structural uprights to the bottom of the cross-tube (uprights not shown).
I am considering that...
I understand how to do those calculations and they are present in my available texts (although that website just found a home in my favorites). What i need is a way to design or verify the design of bolted connection which will not slip. The bolts are not shearing, the plates are breaking.
I...
Well, i suppose im lacking the information in the drawing. Also I may have posted this in an incorrect location. This is very much not a static structure. It is a mechanical component, and it is secured, very securely at either end. The moment appears to be generating enough force to cause...
Hi, I'm working on some joints, an example of which is attached. I am looking for some calculation or formula for calculating the resistance or ability of these bolts to resist slip from a moment and shear load.
The plain shear load is fairly easy to figure out, but throw in the moment and I...
Yes, I did intend for that h^3 to be there at that point.
Thanks, i will look into that book. Looks like I would have little trouble finding plenty of use for it.
Could someone please look this over and see if I'm on the right track? What really gets me is unstated assumptions.
Using these same numbers it appears the shigley formula, and the roymech formula supply the same numbers (after adding the weld height to the shigly...
