A guitar-shaped concert venue with a roofline that resembles the rolling hills of Nashville. A manufacturing facility with a grand, curved ceiling called “industrial art.” An outdoor gymnasium with curved joist girders left exposed for an architecturally interesting roof system.
These are the visions of architects who think outside the box. The steel building systems that bring them to life come from suppliers who can support architects and innovate along the way. Specialty steel joists and joist girders are among the primary steel building components used to create stunning, one-of-a-kind structures.
Special profile joists primarily consist of gable, scissor, bowstring and barrel (arch) joists and their variations. Together these joists enable more than 40,000 special profile steel joist design possibilities.
“Designers and architects are not limited to the specialty joists commonly offered,” says Alex Therien, market development manager for New Millennium Building Systems. “Most joists are a derivation of the four profiles—you can use your imagination to execute a custom design vision.”
The exposed joist framing system for the Harvey E. Najim Family YMCA’s 6,500-square-foot outdoor gym features joist girders with curved bottom chords to meet structural and aesthetic requirements.
It took a lot of imagination—and hard work—to create an outdoor “Air-nasium” at Harvey E. Najim Family YMCA in San Antonio, Texas, that features joist girders with curved bottom chords. Marmon Mok Architecture used specialty arch joists to achieve the unique look.
“The original concept called for joist girders with a curved bottom chord to be part of the moment frame, but we could not make that work given the aesthetic constraints. So we needed to come up with an alternative,” says Joe Voigt, sales engineer at New Millennium Building Systems. “[Engineer of record] Thomas Hamer and I spent several weeks together trying different design approaches until we found something that worked.”
What worked is this: An atypical design in which the joists run the same direction as the curved bottom chord special girders. Typically, joists bear on girders perpendicularly and the deck sits on the joists. For this structure, beams went straight down the middle of the bay and connected to the webs of the girders, with the joists bearing on the beams so that the top of the girder and the top of the joist were at the same elevation. The deck then connected to the top of the girders and the joists.
“Beams connecting to the center span of the girder web members and special joists bearing on those beams met the design intent of the architect and did so economically,” Hamer said. “The joist girders support the metal deck, large concentrated loads at mid-span, and wind loads while still providing an economical and aesthetically pleasing framing system.”
“Joists aren’t typically fabricated to be aesthetically pleasing,” Voigt says. “But with collaboration on the front end of a project between the design team and the manufacturer, the end result can be both practical and stunning with a much lower price tag versus conventional alternatives.”
The curved ceiling-roof assemblies inside the Tool-Flo manufacturing bays feature 18 total 110-foot bow-string girders (9 per bay) and dovetail roof deck.
About three hours east of the YMCA in San Antonio is the brand-new headquarters for Tool-Flo, a manufacturer of cutting tools and tool holders. Designed by architect Rob Hiroshi Noma of KBD Group, the $12.3 million, 118,000-square-foot facility features two manufacturing bays with soaring, curved ceilings. Noma created the aesthetically pleasing look with 110-foot bow-string girders on concrete tilt walls and a dovetail roof deck left exposed for its clean, lineal plank appearance.
“The most important part of this project is that curved roof profile,” Voigt says. “It just gives the space an awe-inspiring feel.”
Each manufacturing bay features nine of the 110-foot bow-string girders. Because of their length, the 18 girders were delivered to the job site in two parts for a total of 36 total pieces. The two pieces of each girder were connected on the ground using a field-bolted splice and then lifted into position.
“The goal was to build an aesthetically pleasing manufacturing facility that reflects Tool-Flo’s philosophy, first-class operation and culture,” Voigt says.
New Millennium manufactures a full range of special profile steel joists, including bowstring, arched, scissor, gable, double- and single-pitched steel joists. Steel joists can be furnished as a single piece up to 15 feet deep and 125 feet long. Field splices can increase lengths and depths in cases that call for it.
With more than 40,000 specialty joist designs, the architectural possibilities are nearly endless. To simplify and expedite design, the New Millennium specialty joist design guide is offered online as an interactive PDF. In addition, an online special profile steel joist tool allows for digital exploration of a full palette of joist options, including gable, bowstring, scissor and arch steel joists.
This outdoor "air-nasium" features a unique design element in which the joists run in the same direction as the curved bottom chord special girders. Typically, joists bear on girders perpendicularly and the deck sits on the joists. For this structure, beams went straight down the middle of the bay and connected to the webs of the girders, with the joists bearing on the beams so that the top of the girder and the top of the joist were at the same elevation. The deck then connected to the top of the girders and the joists.
An expanding car dealership wanted to make a branded statement with the architecture of its new location in Downers Grove, Ill. With the help of New Millennium Building Systems, it will get a visually striking, curved structure to deliver its message. The Ford brand wall uses barrel joists cladded in plywood connected with a custom truss system to bridge the members.
Building a better steel experience
