Composite joist floor systems are ideal for multi-story construction

Composite Joists

Create multi-story designs that are stronger, lighter, efficient

Composite joists
Composite joists create the longest spans possible for multi-story buildings

Composite joists (CJ-Series) create a stronger, stiffer, lighter and less expensive steel structure compared to other structural steel frame approaches. Considering all of its benefits, a composite joist floor system is ideal for multi-story construction.

Composite joists bond with the overlying concrete slab to create a unified load bearing system that deflects as a single unit. The two components are connected using field-applied shear studs that are attached through the composite steel deck to the joist top chord. The studs become embedded in the concrete after it is poured and cured. The concrete slab adds extra strength, allowing the joist top chord to be smaller and therefore reducing material because the joist alone does not support full design loads. Joists also can be spaced further apart, reducing steel, manufacturing, shipping and erection costs. Using a composite joist narrows the floor, creating more headroom, while allowing MEP routing options through the joist.

Composite Joist Chart
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  • Designed using Load and Resistance Factor Design (LRFD)
  • Stiffer floors for reduced live load deflections, vibration
  • Expanded span-to-depth ratio to 30 times the joist depth
  • Earlier erection equals earlier building occupancy
CJ-Series catalog

Weight tables, bridging tables and codes of standard practice for composite joists available in the Steel Joist Institute CJ-Series catalog.

Credit hour: Multi-story systems

Earn credit and gain an in-depth understanding of the role composite joists play in long-span composite floor systems.

Long-span composite systems

Composite deck combines the benefits of steel and concrete in one efficient floor system.

Case Study
Exterior of the Cauley Ferrari Dealership
Supporting 292,000 pounds for cars

What makes a second-floor showroom full of Ferraris possible? Just 28-inch composite joists coupled with composite deck.

Steel Joists Brochure Cover
Steel joists brochure

Get in-depth information about our composite steel joists, including BIM design, in our latest brochure.

Building a better steel experience