Two-Way Slab Design Strength per ACI 318-19 with ideCAD

How does ideCAD calculate Two-Way slab design strength according to ACI 318-19?

Symbols

M_u = factored flexural moment at section, lb
M_n = nominal flexural strength at section, in.
M_sc = factored slab moment that is resisted by the column at a joint, in.-lb
f'_c = specified comprehensive strength of concrete, psi
A_c-sh = area of concrete used to determine shear stress, in²
A_g = gross area of concrete section, in²
b_w = web width or diameter of circular section, in.
d = distance from extreme compression fiber to centroid of longitudinal tension reinforcement, in.
h = overall thickness, height, or depth of member, in.
s = center-to-center spacing transverse reinforcement, in
γ_f = factor used to determine the fraction of M_sc transferred by slab flexure at slab-column connections

To design two-way slab under flexural moment, two-way slab design strength is provided ΦS_n ≥ U. Both flexural moment and shear strength are controlled according to 8.5.1.1.

ΦM_n ≥ M_u at all sections along the span in each direction

ΦM_n ≥ γ_fM_sc within b_slab 8.4.2.2.3 (flat slab)

Φv_n ≥ v_u at the critical sections defined 8.4.4.1 for two-way shear (flat slab)

Φ is automatically designed according to Strength Reduction Factors per ACI 318-19 with ideCAD.

Moment

M_n is determined according to 22.3 as nominal flexural strength M_n is calculated as shown below. Detailed information: Flexural Strength per ACI 318-19 with ideCAD

Open

Openings in slab systems

ACI 22.6.4.3 is provided when an opening is placed at least 4h from the face of a column, concentrated load or reaction area. Detailed information: Two-Way Shear Strength per ACI 318-19 with ideCAD .