gusset

Late medieval shirt with gussets in the seams at shoulder, underarm, and hem.

A gusset is a device, often triangular, used to reinforce a connection between two components. Gussets are used in engineering, sewing and armour.

In engineering

In engineering, a gusset is a structure designed to reinforce a joint where two or more disconnected parts meet, such as two steel beams. It is a plate that is placed on the exterior of the separate parts, such that an equal amount of area on the plate covers each part. It is then fastened using glue, rivets, bolts, welding, etc.

Use in wooden structures

If building a structure out of wood, a much stronger structure is yielded by connecting the joints with gussets as opposed to gluing the ends of the beams of wood together.

Metal gusset plates (image here[1]) are used with lightweight wooden trusses. They may vary in size, but 18-gauge steel plates with 3/8" prongs is the standard.

For firefighters, lightweight truss systems are particularly dangerous. Metal gusset plate connectors fail quickly when exposed to heat and fire. When the bottom chord or webbing fails due to fire damage or the gusset plate pulls out of the wood from the heat, the truss will fail. Since lightweight construction depends on the sum of all members for structural integrity, the potential for total building collapse is high.

Use in bridges

Gusset plates are also used in bridge construction, to attach two or more girders together, but in some bridge designs, five or more girders may connect via a gusset plate assembly. Gusset plates came under scrutiny, as disclosed in an August 9, 2007 article in the New York Times, in regard to the August 1st, 2007 collapse of the Interstate 35W Mississippi River bridge in Minneapolis, Minnesota. [2] The 35W bridge, completed in 1967, used riveted gusset plates (rivets in steelwork have since been replaced by bolts[3]). The investigations of the bridge collapse have not been completed at the time of this writing, but the concern over the gusset plates will likely be investigated.

Image of a structure with gussets here[4]; close-up of a gusset attached with a combination of rivets and bolts, here[5].

Designing for Gusset Plates

An online resource found: "Seismic Behavior and Design of Gusset Plates", which "presents information and tips on seismic behavior and design of gusset plates used in steel concentrically braced frames"[6].

Industry References

American Institute of Steel Construction[7]

Structural failure

• The failure of a gusset plate was implicated in the November 15, 1988 collapse of the original Green Bank radio telescope, located in Green Bank, West Virginia. The telescope collapsed due to the sudden loss of a gusset plate in the box girder assembly, which was a key component for the structural integrity of the telescope.[8]
• A twin set of bridges east of Cleveland, Ohio, were closed due to structural failure in May, 1996. The structural failure involved corroded gusset plates. The bridge had been built in 1960. (Grand Gusset Failure, by Arthur A. Huckelbridge, Jr., P.E., Member, ASCE, (Assoc. Prof. of Civ. Engrg., Case Western Reserve University, Cleveland, OH), Dean A. Palmer, P.E., Fellow, ASCE, (Chairman, Richland Engineering Limited, Mansfield, OH), and Richard E. Snyder, P.E., Member, ASCE, (Pres., Bridge Weighing Systems, Inc., Novelty, OH), Civil Engineering, ASCE, Vol. 67, No. 9, September 1997, pp. 50-52. [9]
• A 2006 Canadian Journal of Civil Engineering paper describes limitations in gusset plate failure analysis, including limitations of previous mathematical models. (Tension and shear block failure of bolted gusset plates, Authors Huns, Bino B.S.; Grondin, Gilbert Y.; Driver, Robert G., Canadian Journal of Civil Engineering, Volume 33, Number 4, 1 April 2006 , pp. 395-408(14))[10]
• A 2006 analysis of "gusset-plate welded connections in structural steel hollow sections and very high strength tubes" finds that "existing design rules are inadequate". (Engineering Structures, Volume 29, Issue 4, April 2007, Pages 469-482, Authors T.W. Ling, X.L. Zhao, R. Al-Mahaidi, and J.a. Packer).[11]

In sewing

In sewing, a gusset is a triangular or square piece of fabric inserted into a seam to add breadth or reduce stress. Gussets were used at the shoulders, underarms, and hems of traditional shirts and chemises made of rectangular lengths of linen to shape the garments to the body.^[1]

Gussets are used in manufacturing of modern tights or pantyhose to add breadth at the crotch seam; these gussets are often made of breathable fabrics for hygiene.

In armor

Gusset is also an alternate spelling of gousset, a component of late Medieval armor.

Notes

1. ^ Burnham, Dorothy, Cut My Cote, Royal Ontario Museum, 1973.

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