AISC Table 10-1 and 10-10 2

[StrEng007]

Referring to AISC 360-16, Section J1.2 I understand their statement about Simple Connections.

Below is a snapshot from the Manual regarding the simple connections presented in table 10-1:

I've provided a couple images attempting to explain my understanding of the statements above.

For any given connection, we'll have the supported (beam) side, and the support (another beam or column, etc.) Here (Fig. 1) I'm showing a typical W-beam simple connection to a W-column.

On the supported side, if the anchor bolts have ≤ 3" eccentricity from the support, we can treat this reaction as a simple connection. Here, the support reaction will impart an equal reaction on the bolt group attached to the supported beam's web. This is applied as direct shear through the bolt group centroid, and does not have any additional shear stress due to moment.

However, if there is a double vertical row of anchor bolts at the supported beam, or the eccentricity exceeds 3", we must consider the additional moment in the form Ve.

Assuming the statements above are correct, here is where AISC starts lacking some information.

From the information above, there is no mention about (regarding the bolts connected at the support column) limit state of bolt tension, or combined tension and shear. Naturally, I would assume there would be some form of moment induced tension normal to the faying surface of the bolt connection.

Similarly, how does the same concept apply to a Single-Plate Connection from table 10-10? I don't see how the single plate is not checked for flat bar flexure in addition to there being weld tension normal to the faying surface of the weld? In this situation, to me it doesn't matter if eccentricity exceeds 3" or not, there would always be some form of moment applied to the weld at the support column.

 

[StrEng007]

An even better question... does any know of a resource that shows the manual calculation used to achieve the values in Table 10-1 or 10-10?

 

[DaveAtkins]

I have always assumed the reaction is at the face of the SUPPORTING member, hence no moment to the supporting member. But then I don't understand why the moment to the bolt line at the SUPPORTED member can be ignored for a single vertical row of bolts. Maybe it doesn't make much difference, hence it can be ignored.

DaveAtkins

 

[BulbTheBuilder]

StrEng007 (Structural)

I would refer to AISC example manual. I have not gone into the details but I have done a couple of hand calc and compared to Table 10-10 and both were pretty close ...just off by decimals

 

[ProgrammingPE]

On the supported side, if the anchor bolts have ≤ 3" eccentricity from the support, we can treat this reaction as a simple connection. Here, the support reaction will impart an equal reaction on the bolt group attached to the supported beam's web. This is applied as direct shear through the bolt group centroid, and does not have any additional shear stress due to moment.

However, if there is a double vertical row of anchor bolts at the supported beam, or the eccentricity exceeds 3", we must consider the additional moment in the form Ve.

This is all correct. Figure 2 and Figure 3 that you provided need some corrections, though. The dimension for determining if eccentricity is required is from the nearest face of the support (same as dimension "a" in Figure 10-4a of the Steel Construction Manual), but your drawings are showing it from the back side of the support's web.

From the information above, there is no mention about (regarding the bolts connected at the support column) limit state of bolt tension, or combined tension and shear. Naturally, I would assume there would be some form of moment induced tension normal to the faying surface of the bolt connection.

The pin is considered to be at the face of the support, since the top of the angle will pull away from the support. This means the reaction is in the same plane as the bolts at the support, so they do not have any eccentricity.

Similarly, how does the same concept apply to a Single-Plate Connection from table 10-10? I don't see how the single plate is not checked for flat bar flexure in addition to there being weld tension normal to the faying surface of the weld? In this situation, to me it doesn't matter if eccentricity exceeds 3" or not, there would always be some form of moment applied to the weld at the support column.

Single-Plate connections always do have eccentricity. Their pin is located at the bolt holes due to the bolts driving through the plate in bearing as the beam rotates. The eccentricity is typically equal to the dimension "a", but can be reduced to "a/2" per Table 10-9 if you meet the Conventional Configuration. The welds don't get explicitly checked for the tension that is caused by the eccentricity since they are just sized to be 5/8*tp to make sure that the plate fails before the welds. The plate also gets checked for flexure for the Extended Configuration per Equation 10-5.

An even better question... does any know of a resource that shows the manual calculation used to achieve the values in Table 10-1 or 10-10?

I've back-calculated the values in the AISC design tables, so if you have any specific questions about them I can help you out. The AISC Design Examples refer you to their tables for answers instead of telling you how the tables came up with the values.

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