AISC Simple Shear Connection? 2

[SteelPE]

I am looking at designing a connection and I am beginning to become a little confused. Currently I am looking at a simple double angle shear connection with 2-3/4” dia bolts placed in SSL holes. The connecting angles will be 2-L4x4x5/16”x8-1/2”. I am trying to back figure the capacity of the angle capacity found in table 10-1 (page 10-23) of the AISC 13th edition manual.

For some reason I can’t seem to get the same answer they are getting for the capacity of the connection (I calculate 42.3 kips and they calculate 40.8kips). What parameters are they using to set up these charts? What size angle L4x3-1/2” or L4x4? What size of holes are they using, STD vs SSL? Also, it appears as if block shear is controlling the connection is this correct or am I just missing the failure mode?

 

[SteelPE]

OK, I found where they state that they state they are using a L4x3-1/2" angle in a round about way. However, my connection calculation above was based upon a L4x3-1/2" angle. I must be missing a failure mode?

 

[port125]

The limit state for that conenciton is shear rupture (J4-4) theay add 1/16" to the edge of the hole for damage to the material due to punching.
(0.6/2)*58*(5.5-(2*(13/16+1/16)))*(5/16)*2=40.8

 

[connectegr]

Note that the tabulated double angles tables don't account for beam web bearing, block shear, cope capacity, etc.

http://www.FerrellEngineering.com

 

[SteelPE]

OK, I have another question.

I have a 3 bolt connection with ¾” diameter bolts. I am using Leh = 2 in (1.75 calculated) and Lev = 1.5 in. The connected beam is a W18x35. I calculated an Agv=2.25 in2, Ant=0.395in2 and Anv=1.59in2 for Rn/Omega = 43.9 kips. The chart on page 10-22 gives Rn/Omega = 0.3*138=41.4 kips.

I used standard sized holes and no additional reductions to Lev (unlike the ¼” reduction to Leh). What variables are they using to calculate the values given in the table?

 

[PUEngineer]

I think you're misunderstanding the incorporation of the 1/4" reduction for Leh. The table already has that reduction incorporated, so the column you're looking at with Leh=1.75, is calculated based on Leh=1.5. So, that would have Ant=0.32in2, then the rest checks out at 41.4k.

 

[SteelPE]

Yes,

My actual Leh was 2" and I was using the values for 1-3/4" because I thought you needed to reduce the value yourself. When I ran the hand calc I was using the full 1-3/4" when I should have been using 1-1/2" to get the values in the chart. No wonder why I couldn't get it to work out exactly.