Design guide for considering concrete breakout in shear using ACI 318 anchoring-to-concrete provisions October 2025 | Page 150

PROFIS ENGINEERING

Nominal Concrete Breakout Strength in Shear( V cbg)

Check shear towards to the x- edge from Col 1,3.

V b = 7 l e d a

0.2 d a λ a f ′ c c a1

1.5

CASE 3 c a1 is taken from anchor 3 and V ua, col 1, 3 = 1.0V ua, x

ACI 318-19 Eq.( 17.7.2.2.1a)

l e = MIN h e f | 8d a = 4.0in h ef = 4.0 in CONTROLS d a = 0.625 in 8d a = 5.0 in normal weight concrete: λ = 1.0 → λ a = 1.0 ACI 318-19 Table 17.2.4.1

V b = [( 7)( 4.0 in / 0.625 in) 0. 2( 0.625 in) 0. 5 ]( 1.0)( 3000 psi) 0. 5( 6.0 in) 1. 5

= 6458 lb V b = 9λ a f ′ c c a1

1.5 f’ c = 3000 psi

ACI 318-19 Eq.( 17.7.2.2.1b)

c a1, row 12 = 6 in

V cbg =

V b =( 9)( 1.0)( 3000 psi) 0. 5( 6.0 in) 1. 5 = 7245 lb check: design V b = MIN { 6458 lb; 7245 lb } = 6458 lb Shear towards the y- edge

A Vc A Vc0 ψ ec, V ψ ed, V ψ c, V ψ h, V ψ parallel, V V b

V cbg, row 12 =( 154.8 in 2 / 162 in 2)( 0.981)( 1.0)( 1.0)( 1.23)( 1.0)( 6458 lb)

V cbg =

A Vc A Vc0

= 7446 lb Shear parallel to y- edge

ψ ec, V ψ ed, V ψ c, V ψ h, V ψ parallel, V V b

V cbg, row 12 =( 154.8 in 2 / 162 in 2)( 0.981)( 1.0)( 1.0)( 1.23)( 2.0)( 6458 lb)

= 14,892 lb ψ parallel, V = 2.0

V b = 6458 lb

Nominal Concrete Pryout Strength in Shear( V cpg) ACI 318-19 Section 17.7.3

There are 4 anchors in tension and 4 anchors in shear → calculate V cpg using N cbg for 4 anchors.

NOTE:

Pryout is a shear load. Calculate N cbg for pryout using shear eccentricity values.

V cpg = k cp N cbg

h ef = 4.0 in → k cp = 2.0 for h ef ≥ 2.5 in V cpg =( 2.0)( 20,448 lb) = 40,896 lb reference page 147: N cbg = 19,584 lb ψ ec, N = 0.952 N cbg, modified = N cbg / ψ ec, N = 20,571 lb e c, x = 0.015 in ψ ec, Vx = 0.998 e c, y = 0.023 in ψ ec, Vy = 0.996 N cbg, pryout = N cbg, modified)( ψ ec, Vx)( ψ ec, Vy) = 20,448 lb

ACI 318-19 Eq.( 17.7.3.1b)

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