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Multi-row bolted lap joint calculations 6
- Thread starter vagulus
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maybe this will help:-
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
- Thread starter
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Thanks desertfox. That covers the basic issues but not how to allow for multiple rows of bolts/rivets. You see in my drawing that the two rows of bolts have different numbers of bolts and also they are staggered.
I have a feeling that that will complicate the issue, but it is a common occurrence in industry. I need to know how to make those allowances.
Cheers
I have a feeling that that will complicate the issue, but it is a common occurrence in industry. I need to know how to make those allowances.
Cheers
Hi vagulus
The rivet joints shown on that link show multi rows of rivets with varying numbers of rivets/bolts and I can't see the difference between your example and theirs, what am I missing?
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
The rivet joints shown on that link show multi rows of rivets with varying numbers of rivets/bolts and I can't see the difference between your example and theirs, what am I missing?
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
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Guide to Design Criteria for Bolted and Riveted Joints by Kulak, Fisher, and Struik, available from RCSC at:
NASA RP-1228 Fastener Design Manual by Richard Barrett, available from NASA at:
NASA RP-1228 Fastener Design Manual by Richard Barrett, available from NASA at:
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Vagulus:
You might want to dig out your old Strength of Materials or Machine Design text books, assuming you didn’t sell them used, for a six-pack. Good texts will have something on bolted connections. Also, any of the Structural, and specifically structural steel codes, will have info on bolted joints; spacing, edge distances, spacing btwn. rows, etc. And, they will also have info and methods for analyzing net sections around the various bolt patterns to determine the critical load path for a given bolt pattern. Right now, in your sketches and with their proportions, it looks like your bolt size, spacings and edge distances are much to tight for a practical joint. And, in a more detailed analysis of a bolted joint, you should give some thought to the fact that all the bolts don’t come into play at once. Some of them must be in bearing and starting to yield in bearing before others really come into play. There are also issues of how tightly you fix (tighten) the bolts.
You might want to dig out your old Strength of Materials or Machine Design text books, assuming you didn’t sell them used, for a six-pack. Good texts will have something on bolted connections. Also, any of the Structural, and specifically structural steel codes, will have info on bolted joints; spacing, edge distances, spacing btwn. rows, etc. And, they will also have info and methods for analyzing net sections around the various bolt patterns to determine the critical load path for a given bolt pattern. Right now, in your sketches and with their proportions, it looks like your bolt size, spacings and edge distances are much to tight for a practical joint. And, in a more detailed analysis of a bolted joint, you should give some thought to the fact that all the bolts don’t come into play at once. Some of them must be in bearing and starting to yield in bearing before others really come into play. There are also issues of how tightly you fix (tighten) the bolts.
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- #8
Ah Ha! dhengr
You are right on the money with the things I am trying to address. Sadly, I am just a beginner in this game, and it is not a case of digging out old Strength of Materials or Machine Design text books as a case of digging them up.
You wrote of: ... your bolt size, spacings and edge distances are much to tight for a practical joint. And, in a more detailed analysis of a bolted joint, you should give some thought to the fact that all the bolts don’t come into play at once. Some of them must be in bearing and starting to yield in bearing before others really come into play.
This is the heart of my enquiry. Would you be good enough to suggest some old text books which deal with these issues? It appears that modern textbooks have other issues at heart.
Thanks
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Artificial Intelligence is no match for Natural Stupidity
You are right on the money with the things I am trying to address. Sadly, I am just a beginner in this game, and it is not a case of digging out old Strength of Materials or Machine Design text books as a case of digging them up.
You wrote of: ... your bolt size, spacings and edge distances are much to tight for a practical joint. And, in a more detailed analysis of a bolted joint, you should give some thought to the fact that all the bolts don’t come into play at once. Some of them must be in bearing and starting to yield in bearing before others really come into play.
This is the heart of my enquiry. Would you be good enough to suggest some old text books which deal with these issues? It appears that modern textbooks have other issues at heart.
Thanks
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Artificial Intelligence is no match for Natural Stupidity
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Lomarandil
Structural
Unless I'm missing something, all of your concerns should be addressed in the AISC specification (structural steel code):
You'll be most interested in sections J3 (related to bolt capacity, spacing, edge distances, etc), J4 (for capacity of connected elements, your plates) and B3 (which defines gross and net areas -- this will address your staggered holes concern). The commentary portion in the latter half of the document may also be useful.
Regarding dhengr's point about bolts coming into play at different times -- for a typical bolted connection with standard size holes (1/16" larger than nominal bolt diameter), we typically assume that structural grade steel bolts can yield and act in a ductile fashion until all the bolts in the connection are engaged -- regardless of the initial fit-up "scatter". Of course, if you have oversized holes (for example, in a foundation anchor bolt application), this assumption requires further consideration.
You'll be most interested in sections J3 (related to bolt capacity, spacing, edge distances, etc), J4 (for capacity of connected elements, your plates) and B3 (which defines gross and net areas -- this will address your staggered holes concern). The commentary portion in the latter half of the document may also be useful.
Regarding dhengr's point about bolts coming into play at different times -- for a typical bolted connection with standard size holes (1/16" larger than nominal bolt diameter), we typically assume that structural grade steel bolts can yield and act in a ductile fashion until all the bolts in the connection are engaged -- regardless of the initial fit-up "scatter". Of course, if you have oversized holes (for example, in a foundation anchor bolt application), this assumption requires further consideration.
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