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Re: FW: Q: Weld QA/QC per FEMA 350

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Catherine,

I have used both the FEMA 350 welded WUF-W and the bolted end plate WFP moment connections.  My experience is that it is more a construction preference more than anything else.  In heavy industrial work, especially petrochemical and power, most of the moment connections are bolted end plate.  I used this on a large power plant facility and the field loved it.  The structures went up very fast and the critical welds were made in the shop under potentially better quality control measures.  We used twist-off bolts and every morning the field engineer tested a random sample of bolts in a Skidmore to provide documented QC.  In the commercial (buildings) world they almost exclusively use welded connections.  I once suggested a bolted moment connection for a large bay single story building structure and all I got was an open jaw and bug eyed response.

Just to clarify my previous response, FEMA 350/353 are not part of the code.  However some jurisdiction, but not all, will accept the FEMA 350 connections as meeting the UBC requirements for "tested" connections.  Be sure and verify which ones, if any, of the FEMA 350 connections are acceptable to your building official.

If you choose to use the bolted end plate (WFP) connection, note that there were a lot of bugs in the original equations.  Be sure and get the errata.

Thomas Hunt, S.E.
ABS Consulting




Catherine Pagni <CPagni(--nospam--at)pacecivil.com>

04/13/2004 12:03 PM

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FW: Q: Weld QA/QC per FEMA 350





Thank you Tom.

Regarding the same WUF- welded web connection, the beam has a very shallow
depth. Would a bolted web connection be a better choice? Advice on selecting
between these connection is appreciated.

Thanks, Catherine


-----Original Message-----
From: THunt(--nospam--at)absconsulting.com [mailto:THunt(--nospam--at)absconsulting.com]
Sent: Tuesday, April 13, 2004 11:12 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Q: Weld QA/QC per FEMA 350



Catherine,

The L and T indicate whether the weld is loaded Longitudinally or
Transversely.  This may change the NDE requirements as shown in Table 6.3 of
FEMA 353.

As to whether you are allowed to use Omega forces or Beam Capacity will
depend on the Building Official.   I suggest you have a long talk with them.


Thomas Hunt, S.E.
ABS Consulting





Catherine Pagni <CPagni(--nospam--at)pacecivil.com>


04/13/2004 10:51 AM


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Q: Weld QA/QC per FEMA 350

               




The engineer is required to specify the Seismic Weld Demand Category per
FEMA 350. Using the detail for WUF-W, the category is given for each weld as
QA/QC Category AH/T or BH/L or sim. I understand the BH indicates the
seismic demand/consequence category per table 6-1 FEMA 353. What does the T
or L indicate?

Second question; Where this building is located, the governing code is the
97 UBC. Can I detail the connection using the reacting moments due to the
lateral forces increased by Omega, 2.8, or must the internal forces be
calculated using the equations in FEMA 350 Section 3.2?

Your help is very much appreciated,
Catherine A Pagni, MSCE
PACE Civil, Inc.
Staff Engineer
1730 South St.
Redding, CA 96001
(530) 244-0202



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