×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Eccentricity in single shear connection

 Forum Search FAQs Links MVPs

## Eccentricity in single shear connection

(OP)
I'm curious as to how moment is resisted at a joint in a single shear bolted connection. I'm specifically concerned with wood, but I imagine the same question applies to steel members that are bolted together. See the attached pdf. If you look at the Mode II yield mode, is that what is checking and making sure that the moment of the connection can be resisted (Since that one doesn't apply to the symmetric double shear connection)? I assume there is a simple answer to this question, but I can't seem to figure it out.

The specific example I have and reason I ask is for a wood ledger screwed to the thin face of wood studs. Do I need to consider tension withdrawal values in any of those screws or just shear?

### RE: Eccentricity in single shear connection

Moment in a ledger may be resisted by the supported joists acting in compression, tension in the fasteners or by a combination of those actions. If you are relying on screws alone, you must consider withdrawal in combination with shear.

BA

### RE: Eccentricity in single shear connection

I believe your assessment is correct. I have wondered the same thing--and with steel connections as well (as you mentioned).

I think a few things are at play here:
* The eccentricity is small enough to be ignored for practical situations
* The rotation of the fastener (bolt, screw, nail, etc.) takes care of some of the moment (Mode II yield mode, which probably applies to steel in some ways as well)
* The lap of the two members creates the ability for the moment to be resisted by a couple, which puts compression between the two members, and tension in the fastener

DaveAtkins

### RE: Eccentricity in single shear connection

Since wood is not very ductile, I imagine that the fasteners would fail in shear or cause tearout (fracture) of the wood. Since steel is ductile, I think the first thing you would see is a rotation of the lapped portion. Almost like a prying action of sorts.

### RE: Eccentricity in single shear connection

For both steel and concrete connections, looking only at the connections, we're making the assumption that the eccentricity related moments are a small fraction of what the connected members can take. There's no doubt in my mind that the moments exist. I remember dealing with a field problem on a very serious steel connection that ended up requiring lots of shimming to make a go of it. It was astonishing to me how much shimming you can do without actually running afoul of standard AISC bolt design methodology.

For your specific ledger, there's more at play. As I see it, your shear enters the connection over the seat of the joist hanger and leaves it at the face of the supporting stud work. As such, your real eccentricity is really the distance between those. And it can add up, especially with multi-ply ledgers. In that case, I feel that the moment does need to be explicitly resolved somewhere, most plausibly by using your bolts in combined shear and tension as mentioned by others. For what it's worth, it is my impression that very few designers are taking this into consideration.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!