Cellular steel floors are an integrated system of parallel steel beams that serve as both load-bearing members and a continuous deck spanning between main supporting girders, beams, or walls 1935-Miami-Dade-Building-Code_p325_344 (p. 331). The city-of-miami amended its building code to provide specific requirements for this construction method, replacing vague general specifications for steel joists.
Material and Construction Requirements
- Steel Grade: The steel used must meet the requirements of astm-a24542t (A.S.T.M. “Tentative Specifications for Light Gauge Structural Quality Flat Hot-Rolled Carbon Steel”), Grades A, B, or C 1935-Miami-Dade-Building-Code_p325_344 (p. 331).
- Thickness: The minimum thickness for the steel is U.S. Standard Gauge No. 18 1935-Miami-Dade-Building-Code_p325_344 (p. 331).
- Analysis and Testing: Floor assemblies must admit of rational analysis and be tested and certified by a recognized testing agency to substantiate stress values 1935-Miami-Dade-Building-Code_p325_344 (p. 331).
Structural Limits
- Flexural Stress: Values shall not exceed 60 percent of the yield point specified for the permitted grade of steel 1935-Miami-Dade-Building-Code_p325_344 (p. 331-332).
- Deflection: When plastered ceilings are suspended from the units, the maximum permissible deflection due to full live load after plaster application shall not exceed 1/360 of the span 1935-Miami-Dade-Building-Code_p325_344 (p. 332).
Fire Protection
When used in fire-resistive construction, cellular steel floors must include:
- A minimum of two inches of concrete fill on top.
- A fire-resistive ceiling suspended from the underside, meeting national-board-of-fire-underwriters specifications for fire ratings 1935-Miami-Dade-Building-Code_p325_344 (p. 331).
These standards relate to broader floor-construction-standards and structural-steel-design within the building code.