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RE: FEMA 350 continuity plates and panel zone thickness

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Gerard:

I was asking two questions: doubler plates, web stiffeners/continuity plates.  Mainly in regards to FEMA 350 WUF-B ordinary moment connection. 

 

Question 1: The formula for doubler plates in FEMA 350 looks like it is only for a beam on one side of a column and does not subtract out story shear.  All the text books I have show checking doubler plates / panel zone thickness adding the lateral force moments and dividing by the beam depth and then subtracting story shear.  Should you do something different formula for beams on both sides?  Multiply this formula time 2 or something.

 

Question 2: For continuity plates FEMA 350 tells you to use half the beam flange thickness for beams on one side and the flange thickness for beams on both sides and follow  K1.9 of the AISC specification. I think I may be reading into it because it does not tell you what force to use for K1.9.  Do you use the force from the plastic strength of the beam divided by the depth-flange depth or flange area times the yield stress to size continuity plates? 

 

 

Scott

 

 

 


From: Gerard Madden, SE [mailto:gmadden(--nospam--at)maddengine.com]
Sent: Tuesday, May 17, 2005 8:04 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: FEMA 350 continuity plates and panel zone thickness

 

Are you talking about a doubler plate? That’s for the panel zone, welded to the column web to essentially thicken it. The continuity plates are in plane with the flanges of the beams and are horizontal.

 

Not sure if I’m understanding correctly what you are asking.

 

-gm

 

-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)poa02.usace.army.mil]
Sent: Monday, May 16, 2005 11:26 AM
To: seaint(--nospam--at)seaint.org
Subject: FEMA 350 continuity plates and panel zone thickness

 

Anyone:

 

I don’t have an errata for FEMA 350.  FEMA 350 3.3.3.2 formula (3-7) appears to be for a beam framing into one side of a moment frame column.  AISC LRFD 2nd ed Figure C-K1.3 shows calculating panel zone shear by adding forces from moments on either side of the column and subtracting the story shear.  Formula 3-7 does not appear to cancel out the story shear or add the additional shear from a second beam on the other side of a column.  Are people using this formula (3-7) to check required panel zone thickness when there are beams framing into both sides of moment frame columns?

 

Also FEMA 350 3.3.3.1 tells you to use continuity plates that conform to K1.9 of the LRFD specification. My question is that if the full plastic moment goes through beam flanges then does the continuity plate need to be thicker than the beam flange?  It would seem if you were trying to transmit the full plastic moment through a beam flange with weld access holes the maximum force that could be transmitted would be the area of the beam flange times the yield stress. This is less then the plastic strength of the beam. Is this right?  I have a 97 UBC Seismic Design of Buildings and Bridges book that shows designing continuity plates for just the beam flange area times the yield stress. Should the continuity plates be designed for the beam flange area times the yield stress?

 

 

Scott M Haan