Compressive Buckling of Gusset Plates
Compressive Buckling of Gusset Plates
(OP)
I'm looking for design guidelines for the compressive buckling of gusset plates in braced connections. I've got a square steel tube welded to a single gusset plate that is connected to a beam/column joint or a column/baseplate. I know the Whitmore section defines the area of gusset plate to use for tensile yielding.
In the compression case, how does one set a K, and L and an r for kL/r and ultimately get phi x Fcr? Do I use the Whitmore section and use a length from the end of the brace to the corner of the gusset with a k = 0.65?
In the compression case, how does one set a K, and L and an r for kL/r and ultimately get phi x Fcr? Do I use the Whitmore section and use a length from the end of the brace to the corner of the gusset with a k = 0.65?






RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
We ended up with a 3/4" plate (this is a big warehouse with double tube X braces in NE Arkansas - Av = .26). Didn't look too bad but I just felt we were being a little too conservative since the gusset is really fixed at the beam/column side. So I was thinking of using k = 0.8 with the original L above. What do you think?
The other thought was - the gusset is really like a cantilever as the brace would be buckling out of plane before the gusset would...therefore k = 2.0 and we could use L = 1/2 the distance from end of brace to corner - which gets us back to the same design as using k = 1.0 and the full L.
RE: Compressive Buckling of Gusset Plates
Astaneh-Asl and AISC recommend a buckling length factor K of 1.2. Astaneh-Asl considers 1" strips of the gusset for compression but doesn't explicitly define whether to use the longest length (upper bound solution) or an average length. I believe it is common practice to use the average length of the Whitmore section for L.
RE: Compressive Buckling of Gusset Plates
Luis Felipe Rodríguez Martín
(whom I attest by experience was a grea teacher)
Servicio de Publicaciones del Colegio Oficial de Arquitectos de Madrid 1980
Imagine the straight gusset with base horizontal and point towards the right.
b is the base width
alfa is the angle atop the gusset
indicates as simplified procedure
bandwith=1/4 of total
length=7·b/[8·sin(alfa)]
slenderness=2.02·b/[t·sin(alfa)] better inferior to 100
K=2/3 is implied
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
I'm a rookie so you should probably take my advice with a grain of salt. However, you've answered a lot of my questions and this may be the only time in the near future where I have something to offer on one of your threads.
Here we go:
I dealt with this same problem a couple of weeks ago on a smaller scale. I basically ended up buying an entire book on steel connections just to get one little section that dealt with the buckling of gusset plates on the whitmore section (McGraw Hill Handbook of Steel Connections).
They have one example problem dealing with the buckling problem. In it, they use K=1.2 based on the assumption that the plate acts somewhat like a cantilever (Just like the recommendation above).
If you would like me to fax/email you a photocopy of the section dealing with this, please let me know. And thanks for all of your help over the last few weeks. Much appreciated.
Adam
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
For analysis, yes, you do not rely on moment resistance of the braces. However, for ductile detailing of braced frames, you sometimes do design the end connections to resist moments. It is required by code in some cases because it is beneficial to have a three-hinge mechanism to dissipate energy. I would recommend Tremblay's article "Seismic Behavior and Design of Concentrically Braced Steel Frames" (AISC Engineering Journal, Third Quarter, 2001) for further reading on braced frames.
trac,
If you are designing to U.S. codes, see the AISC Seismic Provisions (yellow book) and the Astaneh-Asl Steel Tips article I mentioned in a previous post for further information. You can download both of these free from www.aisc.org
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
RE: Compressive Buckling of Gusset Plates
I am interested to get these pages.
Is there a URL of Gusset design from the Mc-Grawhill book ?
Thanks
ganesh
RE: Compressive Buckling of Gusset Plates
Are you looking to get the book or do you just want me to fax you the pages?
The Book is:
Handbook of Structural Steel Connection Design & Details
Akbar R. Tamboli
McGraw-Hill Handbooks
ISBN: 0-07-061497-0
RE: Compressive Buckling of Gusset Plates
Thanks
k_anandaganesh@hotmail.com
RE: Compressive Buckling of Gusset Plates
I can't find Astaneh-Asl's article on the AISC website. Can someone provide a new link?
RE: Compressive Buckling of Gusset Plates
try www.steeltips.org