Composite Joists
Build efficient multi-story steel structures with superior strength-to-weight ratios
Massive 82-inch-deep composite joists spanning an impressive 116 feet, topped with a composite cellular acoustical deck.
Engineered for longer spans and leaner floors
Composite Joists (CJ-Series) are a superior alternative to conventional structural steel framing. The increased strength-to-weight ratios, enhanced stiffness, and cost-effectiveness make composite joist floor systems ideal for multi-story steel construction projects.
CJ-Series steel joists reduce steel tonnage
Composite joists function integrally with the concrete slab above to form a unified load-resisting system. This composite behavior is achieved through the installation of shear studs, which are welded through the steel deck to the top chord of the steel joist. Once the concrete is poured and cured, the studs become embedded in the slab, allowing it to act compositely with the steel joist and share in resisting applied loads.
This combination significantly reduces the demand on the steel joist alone, allowing for a smaller top chord section and reducing overall steel tonnage. Additionally, composite joists can be spaced further apart, reducing material, fabrication, shipping, and installation costs. The resulting shallower floor depth increases headroom and offers greater flexibility for routing mechanical, electrical, and plumbing (MEP) systems through the joist web openings.
Versatile integration with supporting structures
In addition to system-wide benefits, composite joists offer versatile integration with supporting structures. The figures below illustrate two common connection types: the standard seat connection (Figure 1), which bears on the supporting beam, and the flush-framed connection (Figure 2), which aligns the joist’s top chord with the support for a more streamlined floor profile. These options provide flexibility to meet varying design and construction requirements.
Composite Joist with Standard Seat Connection
Composite Joist with Flush Framed Connection
Benefits of composite joists
- Achieve extended spans with fewer steel joists and columns (Span-to-depth ratio up to 30:1 vs. 24:1 for non-composite)
- Maximize usable space by minimizing floor system depth
- Open-web joist configuration allows easy routing of mechanical, electrical, and plumbing systems
- Lower costs associated with materials, fabrication, and erection
- Stiffer floors reduce deflections and improve vibration characteristics
- Faster erection translates to quicker building enclosure and earlier occupancy
- Compatible with multiple types of framing, including structural steel, ICF, masonry, and more
Featured Projects
