Nonprestressed two-way joist systems (Waffle Slabs) per ACI 318-19 with ideCAD (v12)

Owned by nurgül Kaya (Unlicensed)
Last updated: Jul 31, 2024 by İsmail Hakki BESLER
1 min read

How does ideCAD design two-way joist systems (waffle slabs) according to ACI 318-19?

  • Minimum slab thickness over fillers is controlled and reported automatically.

  • If the minimum slab thickness condition is not provided, the programme gives warnings.

  • Minimum width of ribs condition is controlled and reported automatically.

Nonprestressed two-way joist systems are designed according to ACI 8.8.

General

  • Spaced ribs and a top slab are parts of waffle slabs.

  • Minimum width of ribs is 4 in.

  • The overall depth of ribs does not exceed 3.5 times the minimum width.

  • Clear spacing between ribs is a maximum 30 in.

  • At least one bottom bar in each joist is continued and anchored to develop fy at the face of supports.

  • Considering load concentrations, a reinforcement area perpendicular to the ribs is designed to provide slab moment strength requirements and is at least the shrinkage and temperature reinforcement area according to 24.4.

 

Joist systems with structural fillers

  • Minimum slab thickness over fillers is the greater of one-twelfth the clear distance between ribs and 1.5 in.

 

Joist systems with other fillers

  • Minimum slab thickness is the greater of one-twelfth the clear distance between ribs and 2 in., if fillers do not comply with 8.8.2.1 or removable forms are used.