1.1. Preliminary slab thickness and joist dimensions
In this example deflection will be calculated and checked to satisfy project deflection limits. Minimum member thickness and depths from ACI 318-14 will be used for preliminary sizing.
a) One-way Slab
Using minimum thickness for solid one-way slabs in Table 7.3.1.1 for the solid slab spanning between the ribs.
End Spans: | ACI 318-14 (Table 7.3.1.1) | |
Interior Spans: | ACI 318-14 (Table 7.3.1.1) |
The minimum slab thickness for wide-module joists for 2-hour fire rating is 4.60 in.
IBC 2012 (Table 720.1(3))
Therefore, select a slab thickness of 5 in. for all spans.
b) One-way Joist
The wide-module joist systems do not meet the limitations of ACI 318-14, 9.8.1.1 through 9.8.1.4. Therefore, the structural members of this type of joist construction shall be designed with standard provisions for slabs and beams.
ACI 318-14 (9.8.1.8)
Using minimum thickness for non-prestressed beams in Table 9.3.1.1. For the ribs (part of the joists) supporting the solid slab.
End Spans: (governs) ACI 318-14 (Table 9.3.1.1) Interior Spans: ACI 318-14 (Table 9.3.1.1)
Therefore, select rib depth of 16 in. for a total joist depth of 21 in.
