Bent Plates in RAM Connection

In my test with 10.00.00.138 I do see a C factor being applied in checks such as the bolt shear check (beam side) for a bent plate designed to AISC 360-10, and in fact my bent plate fails when my shear plate passes.

I don't think that build is any different than yours in regard to bent plates, but send back your file so I can test it to be sure.

The file "BP vs Shr Tab Test.cnx" is uploaded to your site. Thanks.

I think the situation here is that AISC 360-10, Table 10-9 is used in the case of a single plate connection only. We opted to only implement this for shear tabs since it's within that specific section of Chapter 10, but it would be a good question for AISC if it was also intended for bent plates. 

So then single shear plates are using e from Table 10-9 at all times for the calculation of C, and the bent plates are calculating C using e=a if a>3" from what it looks like. Correct?

That's what it looks like to me, but it begs the question why the e=3" treated specially since 3.5" eccentricity has far less capacity. Still checking into that part.

Yeah, in my sample file the bent plate connection with a=3" is at 44% strength ratio, but then jumps to 72% at a=3.01", so obviously some disconnect between using the calculated bolt C factor and assuming it equal to bolt quantity there. I don't recall any significance to a=3" other than that the shear tab table values (Table 10-10 in the 14th ed) are noted as based on a=3" in both current and previous edition. The 9th ed in its "Design Procedure" section on shear tabs (p. 4-52) directs the user to assume 3" eccentricity in the C tables for the bolts (Table XI), which results in the C-factor using a=3.01". I don't think they ever gave much guidance specific to bent plates, but the single angle table, which might be comparable to single bent plates sometimes, also assumes a=3", but still comes up with C factors < bolt quantity. So it doesn't seem to match with any of the similar conditions I see.

For bent plates design and for the bolt shear capacity on the beam side, RAM Connection neglects the beam bolt eccentricity when these conditions are met:

• Bolt columns = 1
• Bolt distance to support <= 3

So if those conditions are met then e = 0 and then C = Number of bolts. In other cases, e = bolt distance to support (in the case of bolt columns =1).

This approach is the same used for single angle connections as described in the AISC Manual v13 p.10-123 and AISC Manual v14 p.10-133:

The only reference for bent plates design gives us the idea to design it as single angles, AISC Manual v13 p10-150 and AISC Manual v14 p10-160:

For bent plates design and for the bolt shear capacity on the beam side, RAM Connection neglects the beam bolt eccentricity when these conditions are met:

• Bolt columns = 1
• Bolt distance to support <= 3

So if those conditions are met then e = 0 and then C = Number of bolts. In other cases, e = bolt distance to support (in the case of bolt columns =1).

This approach is the same used for single angle connections as described in the AISC Manual v13 p.10-123 and AISC Manual v14 p.10-133:

The only reference for bent plates design gives us the idea to design it as single angles, AISC Manual v13 p10-150 and AISC Manual v14 p10-160:

OK, I think I would agree with all of that. I only have one question. Further down on p10-160, they say "In all-bolted construction, both the shop and field bolts should be designed for shear and the eccentric moment." That makes it sound like having the bent plate bolted on both legs would count eccentricity at both sets of bolts without qualification, though maybe not on the actual plate strength, just bolt strength. I realize all-bolted is a little different condition than my initial post, but just wanting to reconcile that statement with the first statement from 10-133 and Figure 10-14, which I agree, seems reasonable to apply to both angles and bent plates.