Evaluating existing 14-Bolt Moment Connection

[BadgerPE]

I am working on a project in which we are increasing the loading on an existing PEMB. Significant retrofit of the framing will need to be completed to meet the required strength. By analysis we are increasing the moment at a particular connection by 15-20%. This connection, which can be seen in the attachment, is an extended end plate connection which has 14 bolts on the tension flange side and 4 on the compression flange side. I have evaluated the capacity of this connection by extrapolating the example of a 1/3 (1 row outside tension flange/3 rows inside tension flange) extended end plate in AISC DG 16. I am fairly confident in the method in which I have calculated the capacity. However, I am a little unsure of the validity of modifying the example to cover the case in question.

Does anyone have any literature on a connection similar to this or large moment connections like this in general? Anything from AISC would be great as we have full access to all of their literature. Also, I was doing some research on plate girder connections but couldn't find anything that really matched what I was looking for.

Thanks in advance for the help!

 

[JoshPlumSE]

I don't think you're going to see anything with quite as many bolts as that connection. But, I would look at some of the underlying papers referenced in DG-16. In theory, you can extend the yield line procedure described in that manual out to cover a case like this. Though, it's different enough that I wouldn't personally feel comfortable doing so. You might even contact the author of the Design Guide to see if he has any recommendations. Honestly, even if you pay him a $500 consulting fee, it would probably be worth it to get his two cents worth.

 

[TLycan]

Cracker

refer to SCI moment connections, they have it all. but once I tried to make a spreadsheet for End-plate moment connection it took almost 10 pages to make a general spreadsheet. Also refer to the EC3:1-8 it is the same as SCI
I have the two publications, but I don't know how to give it to you since it is forbidden to but the email in threads

 

[Splitrings]

Even if that end plate were stiff enough to tranfer the moment from the top completely to the bottom, it would be a very inefficient use of bolts. The bottom bolts would be stressed many times greater than the ones at the top of the 14 bolt group. I have seen very long connections like this used in glulam frames and wondered if the end plate was stiff enough in the plane of the plate to transfer the shear force alone.

 

[BadgerPE]

Thanks for all the replies.

To follow up, I basically started with the moment capacity of a 1/3 moment connection which is the largest detailed in DG-16. For those of you unfamiliar with DG-16 this means 1 row of bolts outside the tension flange and 3 rows inside the flange. By only using the bottom 4 rows of bolts I determined the bolt capacity of the connection to be slightly more than needed. I am unsure how the connection was designed as it was built in the early 90's but I feel confident that "neglecting" the top three rows of tension bolts is an accurate assumption to make.

 

[Splitrings]

You could calculate the moment of inertia of the bolt group by summing the distances squared from the NA.. Then the stress in each bolt is easy to calculate. You'd need to calculate where the NA is similarly to a RC section.

 

[ajh1]

Strange connection. It is unlikely that the inner 3 rows of bolts are going to see much load at all from a moment connection perspective. As long as you appear to have sufficient capacity for your needs from the 1-3 condition I would probably ignore the other rows completely.

 

[mcclain]

http://www.fgg.uni-lj.si/kmk/esdep/master/wg11/toc.htm

should show how to analyse this connection if you choose to go that way.
Note that the highest loaded bolt pair in tension will be the pair at H1, given the general thicknesses indicated (see Figure 15 in the introduction section of Lecture 11.4.1).

Mark