Cellular Beams in HDG Steel Parking Structures
What are cellular beams and why are they growing in popularity for parking garages?
In recent decades, the construction of new parking structures has increasingly utilized steel. Steel structures afford more options for member shape and façade design, meaning the designer can create a structure that is pleasing to the eye and attractive to the community. Using slender, strong steel beams means garages can have better lighting, contributing to an open, safer ambiance for users. Also, the slender steel elements will take up less usable space within the structure, maximizing available space for vehicles.
Cellular beams are meant to extend the low-weight-high-strength benefits of steel even further. Distinguishable by circular holes in their web, cellular beams achieve a lighter weight than traditional I-beams without reducing structural integrity. This is accomplished by cutting a standard I-beam in half down the web while integrating half-circle shapes into the cutline. The two pieces are then welded together offset, aligning the series of half circles into full circular holes spanning the length of the web. (See figure 1). The web openings in cellular beams then provide a convenient place for running conduits, ductwork, and internal lines. Web openings can be placed in customized locations to account for structural load capacity or to accommodate electrical or plumbing layouts.
Note: Cellular beams have round openings (circular pattern) while castellated beams have hexagonal openings (hexagonal pattern) spanning the web. Both are achieved by a cutting and rewelding process. When specifying hot-dip galvanizing, the cellular beam design is recommended to avoid stress concentrations at sharp hexagonal corners, therefore minimizing the risk of liquid metal-assisted cracking (LMAC).
Steel parking structures can see further benefits by using hot-dip galvanizing to protect steel elements. A hot-dip galvanized steel parking structure can experience steel’s benefits virtually free from maintenance or corrosion-related concerns. See AGA’s publications, Parking for the Future: A Collection of Hot-Dip Galvanized Parking Garages and Hot-Dip Galvanized Parking Structures for examples.
In summary, cellular beams are becoming increasingly popular in steel parking structure designs thanks to their ability to maximize space, reduce weight, and enhance the overall aesthetic quality of the structure. As cellular beams are readily hot-dip galvanized, parking structures can also benefit from long-lasting and low-cost corrosion protection in comparison to other building and coating options.
Additional information on cellular beams can be found in AISC publications Parking: Conventional Steel Framing Study and Steel Parking Structures: A 25-Year Perspective
AGA Project Gallery Examples Featuring Cellular or Castellated Beams
Lowes Company Headquarters Parking Deck
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