04

4. Determination of Design Moment and Shear

The factored moment and shear can be determined using the ACI 318 simplified method if the requirements are satisfied:

ACI 318-14 (6.5.1)

✓ Members are prismatic.

✓ Loads are uniformly distributed.

✓ L ≤ 3D (80 psf ≤ 3 × 107.50 = 322.50 psf)

✓ There are at least two spans.

✓ The longer of two adjacent spans does not exceed the shorter by more than 20 percent.

Thus, the approximate coefficients can be used. The factored moments and shears are determined and summarized in the following tables.

ACI 318-14 (Table 6.5.2 and Table 6.5.3)

Note that a unit strip of 1 ft is considered for the analysis and design of the one-way slab system covered in the Design Example.

Table 1 - One-Way Slab Design Moment Values
Location		Design Moment Value
End Spans	Exterior Support Negative^*
	Mid-span^*
	Interior Support Negative^†
Interior Spans	Mid-span Positive^**
	Support Negative^**
^*
^**
^†		ACI 318-14 (Table 6.5.2)

Table 2 - One-Way Slab Design Shear Values
Location	Design Shear Value
End Span at Face of First Interior Support
At Face of all other Supports	(For Exterior Spans)
At Face of all other Supports	(For Interior Spans)