SDC D Ordinary Moment frame connection using HSS sections
Joseph R. Grill
Can HSS sections be used in an Ordinary Moment Frame in a SDC D. I can’t see, in the seismic design manual, where it is specifically excluded, but I can’t find any information for the HSS Beam to HSS column connection design. It seems that it can’t be done since a full pen weld is difficult if not impossible to do for a HSS beam to HSS Column face. If there is an example out there I would love to see it. I am doing some work for a fabricator and they are expecting HSS sections due to what is seen in the construction documents. I have to let him know real soon if he will need to go to wide flange members.
Thanks for the help,
Joe Grill
Joseph R. Grill, PE
Verde Valley Engineering, PLLC
2220 Sky Drive
Clarkdale, AZ 86324
Ph. (928) 600-5459
Fax (928) 649-3659
email: VV...@cableone.net
Conrad Harrison
I wouldn’t say it was impossible it just has to be from one side, using backing plates: which may still be the preferred practice if using wide flange beams especially if they lack depth. The Seismic requirements I cannot comment on.
Regards
Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust
Adelaide
South Australia
Joseph R. Grill
Thank you. The fabricator doing this is the one saying no full pen welds. I’m not sure other detailing requirements for a SDC D can be made with the HSS sections. I can’t find any examples relating. This is relating to my little stair tower problem that I fell into (wishing I hadn’t now). The seismic issues just came up yesterday and do make a mess of the process considering the small scope and smaller time frame.
If there are any seismic Gurus out there, do you think a stair tower which consists of a moment frame can be considered a non-building structure? If so, can a person use the “all other structures” category with an R=1.25, and if so does that allow a design without all the seismic detailing issues?
Any help
Joe
Casey K. Hemmatyar
This is not because of HSS sections.
OSMF is only permitted in SDC A, B & C.
In SDC D one can only go with SMRF or if qualifies for footnote "h", may use ISMF.
Regards
Casey (Khashayar) Hemmatyar
<khemmatyar_AT_hotmail.com>
_________________________________________________________________________
From: Joseph R. Grill [mailto:jrg...@cableone.net]
Sent: Wednesday, August 13, 2008 9:28 PM
To: sea...@seaint.org
Subject: SDC D Ordinary Moment frame connection using HSS sections
Can HSS sections be used in an Ordinary Moment Frame in a SDC D. I can't see, in the seismic design manual, where it is specifically excluded, but I can't find any information for the HSS Beam to HSS column connection design. It seems that it can't be done since a full pen weld is difficult if not impossible to do for a HSS beam to HSS Column face. If there is an example out there I would love to see it. I am doing some work for a fabricator and they are expecting HSS sections due to what is seen in the construction documents. I have to let him know real soon if he will need to go to wide flange members.
Thanks for the help,
Joe Grill
Joseph R. Grill, PE
Verde Valley Engineering, PLLC
2220 Sky Drive
Clarkdale, AZ 86324
Ph. (928) 600-5459
Fax (928) 649-3659
email: VV...@cableone.net
Jason Christensen
Casey,
Footnote h to Table 12.2-1 refers to section 12.2.5.6 & 12.2.5.7 where both OMF and ISMF are permitted if the requirements are met. It even mentions that OMFs are allowed in the footnote h.
Jason
From: Casey K. Hemmatyar
[mailto:khemm...@gmail.com]
Sent: Thursday, August 14, 2008 9:32 AM
To: sea...@seaint.org
Acharya, Suresh
Mark D. Baker
Joe,
Section 11.1 of the Seismic Provisions for Structural Steel Buildings, AISC 341-05 says:
“While these provisions for OMF were primarily developed for use with wide flange shapes, with judgment, they may also be applied to other shapes such as channels, built-up sections, and hollow structural sections (HSS)”
In the situation where column meets beam and the column does not continue past beam, cut ends of column and beam at 45, backing can be installed for this joint.
Where column does run past beam, cut notch in column in a V shape (female end) and cut end of beam in a V shape (male end) to insert into the column notch. This joint also will be able to receive backing plates.
You are correct that when trying to join the beam to the column face, full pen welds are nearly impossible.
Regards,
Mark D. Baker
Baker Engineering
From: Joseph R. Grill
[mailto:jrg...@cableone.net]
Sent: Wednesday, August 13, 2008
9:28 PM
To: sea...@seaint.org
Subject: SDC D Ordinary Moment frame
connection using HSS sections
Can HSS sections be used in an Ordinary Moment Frame in a SDC D. I can’t see, in the seismic design manual, where it is specifically excluded, but I can’t find any information for the HSS Beam to HSS column connection design. It seems that it can’t be done since a full pen weld is difficult if not impossible to do for a HSS beam to HSS Column face. If there is an example out there I would love to see it. I am doing some work for a fabricator and they are expecting HSS sections due to what is seen in the construction documents. I have to let him know real soon if he will need to go to wide flange members.
Gordon Goodell
Mark,
If I’m understanding you correctly, cyclical tension force would be at a 45º angle to the weld, so the backing would have to be removed, which could not be accomplished. Also, there would be a significant stress increase at the point of the V.
This is a really good question. I’d be interested to know how others deal with it.
regards,
Gordon Goodell
Mark D. Baker wrote:
“In the situation where column meets beam and the column does not continue past beam, cut ends of column and beam at 45, backing can be installed for this joint.
Where column does run past beam, cut notch in column in a V shape (female end) and cut end of beam in a V shape (male end) to insert into the column notch. This joint also will be able to receive backing plates.
You are correct that when trying to join the beam to the column face, full pen welds are nearly impossible.”
Mark D. Baker
Gordon,
Hmmm, in the case of the V, rounding the point of V would aid in reducing stress concentration effects.
In the case of tension force at 45 to weld I also am interested in others comments. Could one convince himself that the tension force is resolved as simply as a couple in the plane of top and bottom of beam within column thereby staying out of weld? I guess I’d have to slow down and sketch a stress diagram through the joint to really think this through.
To further display my ignorance…..where is it written that backing must be removed when force is at 45 to weld?
MDB
From: Gordon Goodell
[mailto:Gordon...@harmonydesigninc.com]
Sent: Thursday, August 14, 2008
11:18 AM
To: sea...@seaint.org
Joseph R. Grill
Mark and Suresh,
I did see the note in Section 11.1. It’s been a long time since I’ve done one of these (pre IBC). In going through the seismic manual I saw the note, but couldn’t envision how to make the connection. Mark, your idea sounds great. However in reviewing other criteria for the OMF I don’t think I can comply with some of those, such as bracing as this is a frame within a stair tower with no floors or perpendicular framing at the horizontal beam locations.
The fabricator is open to a concentric braced frame. I’m looking at single diagonals in the bays (3 bays high x 1bay long). I think this works. I do, however have a question regarding this. I would think that the diagonals could be welded directly at the column beam intersections without gusset plates. I don’t see a requirement for the use of gussets. Am I correct there. The loads shouldn’t be very high.
Thanks for the idea.
Joe
From: Mark D. Baker
[mailto:shake...@verizon.net]
Sent: Thursday, August 14, 2008 9:01 AM
To: sea...@seaint.org
Acharya, Suresh
Gerard Madden, SE
Miter both ends @ 45 degrees. Put a plate (1" thick or so) with at least 1/2" wider on all sides than the 45 degree cross-section of the cut HSS. Full pen weld HSS to Plate (plate is at 45 deg.)
This seems to be the preferred way by steel fabricators.
Like others have said, it's acceptable to use OMF's in SDC 4 as long as it's low rise or mill building types and the gravity loads are small.
-gm
Gordon Goodell
Mark,
AWS D1.1, provision 5.10 requires removal of backing on welds that are transverse to the direction of stress, but not for welds that are parallel. Maybe at 45º half of the backing should be removed. Just kidding. It is a stress concentrator and inhibits ductile behaviour, and you would not want to leave the backing in a SMF, but maybe OK for an OMF with low force levels. But D1.1 applies to OMF. SMFs are governed by the seismic supplement, D1.8, which is more restrictive.
regards,
Gordon
Josh Comfort
I don’t have the latest version of AWS D1.1, but section 5.10 of the 2004 AWS D1.1 only talks about removal of backing plates for cyclically loaded structures and it states explicitly that backing plates need not be removed for statically loaded structures. While wind/seismic forces may be cyclic in the truest sense of the word, I’ve always taken the definition of cyclically loaded structures to mean bridges, cranes, machinery supports, etc. Anyone else have any insight on the definition of a “cyclically loaded structure”?
Dennis Wish
I haven’t heard back from Joe privately on this but I suggested that he consider the MiiTek SidePlate™ moment frame and give Hardy Frame (the MiiTek company) to see if their HSS moment frames can be used for this consideration. You can check this out on their website at http://www.hardyframe.com.
If Brian Wehmeier, PE (Hardy Frame / MiiTek) picks this up off the SEAINT List he might have some comments to offer that can help educate us all in the possible creative use of the SidePlate™ moment frame.
Dennis
Mark D. Baker
Thanks Gordon, great info.
Mark
Casey K. Hemmatyar
Regards
Casey (Khashayar) Hemmatyar
<khemmatyar_AT_hotmail.com>
___________________________________________________________________
From: Acharya, Suresh [mailto:Suresh....@ci.concord.ca.us]
Sent: Thursday, August 14, 2008 8:48 AM
To: 'sea...@seaint.org'
Subject: RE: SDC D Ordinary Moment frame connection using HSS sections
Casey,
Section 12.2.5.6 as referenced by footnote "h" allows OMF under certain limitations for structures in D or E. These limitations are very generous.
Regarding HSS, "User Note" in Section 11.1 of AISC-Seismic gives you a hint. HSS can be used.
Suresh Acharya, S.E.
From: Jason Christensen [mailto:ja...@wcaeng.com]
Sent: Thursday, August 14, 2008 8:35 AM
To: sea...@seaint.org
Subject: RE: SDC D Ordinary Moment frame connection using HSS sections
Casey,
From: Casey K. Hemmatyar [mailto:khemm...@gmail.com]
Sent: Thursday, August 14, 2008 9:32 AM
To: sea...@seaint.org
Subject: RE: SDC D Ordinary Moment frame connection using HSS sections
Joe:
No. OSMF is not permitted, period.
This is not because of HSS sections.
You may refer to Table 12.2-1; item C4.
OSMF is only permitted in SDC A, B & C.
In SDC D one can only go with SMRF or if qualifies for footnote "h", may use ISMF.
Regards
Casey (Khashayar) Hemmatyar
<khemmatyar_AT_hotmail.com>
_________________________________________________________________________
From: Joseph R. Grill [mailto:jrg...@cableone.net]
Sent: Wednesday, August 13, 2008 9:28 PM
To:
Subject: SDC D Ordinary Moment frame connection using HSS sections