1. Preliminary Member Sizing

1.1. Slab Minimum Thickness - Deflection

ACI 318-14 (Table 8.3.1.1) 

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.

Using ACI 318-14 minimum slab thickness for two-way construction without interior beams in Table 8.3.1.1. 

Where l_n = length of clear span in the long direction = 216 – 16 = 200 in.

Try 7 in. slab for all panels (self-weight = 87.5 psf)

1.2. Slab Shear Strength - One Way Shear

Evaluate the average effective depth (Figure 2):

Where:

Figure 2 - Two-Way Flat Concrete Floor System

At an interior column:

Consider a 12-in. wide strip. The critical section for one-way shear is located at a distance d, from the face of support (see Figure 3).

Tributary area for one-way shear is:

where λ = 1 for normal weight concrete

Slab thickness of 7 in. is adequate for one-way shear.

Figure 3 - Critical Section for One-Way Shear

1.3. Slab Shear Strength - Two-Way Shear

Check the adequacy of slab thickness for punching shear (two-way shear) at an interior column (Figure 4):

Tributary area for two-way shear is:

Slab thickness of 7 in. is adequate for two-way shear.

Figure 4 - Critical Section for Two-Way

1.4. Column Dimensions - Axial Load

Check the adequacy of column dimensions for axial load:

Tributary area for interior column is:

Column dimensions of 16 in. x 16 in. are adequate for axial load.