PROFIS Design Guide - AC 318-19 July 2022 | Page 196

2.1 Concrete Breakout Failure Mode

Calculations ψ _hV

Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering

17.7.2.1 Nominal concrete breakout strength in shear , V _cb of a single anchor or V _cbg of an anchor group satisfying 17.5.1.3.1 , shall be calculated in accordance with ( a ) through ( d ): ( a ) For shear force perpendicular to the edge on a single anchor

V _cb

=

A _{Vc ψed , V} ψ _{c , V} ψ _{h , V}

V _b

( 17.7.2.1a )

A _Vc0

( b ) For shear force perpendicular to the edge on an anchor group

V _cbg

= ^A Vc ψ _{ec , V} ψ _{ed , V} ψ _{c , V} ψ _{h , V}

V _b

( 17.7.2.1b )

A _Vc0

………………………………………….. ψ _{h , V} is a modification factor that is used to account for a concrete member thickness ha that is less than a projected distance of 1.5c _a1 down from the surface of the concrete . The parameter ca1 corresponds to the distance of an anchor , in the direction of the applied shear load , to the fixed edge for which concrete breakout in shear is being calculated . ψ _{h , V} is always ≥ 1.0 per the provisions of

Section 17.7.2.6.1 .

ACI anchoring-to-concrete provisions do not set a maximum limit on the value for ca1 . Minimum edge distance values ( c _min

) are given in ACI 318-19 Table 17.9.2 ( a ) and in post-installed anchor approvals .

PROFIS Engineering always uses a c _a1

-value corresponding to the distance from the anchor row nearest the fixed edge where concrete breakout is assumed to occur unless AWS D1.1 headed studs are being modeled . AWS D1.1 headed studs are rigidly attached to a fixture so a c _a1

-value corresponding to the distance from the anchor row farthest from the fixed edge where concrete breakout is assumed to occur can be used to model this type of anchor .

The figures below illustrate conditions for calculating ψ _{h , V} . h _a

> 1.5c _a1 h _a

< 1.5c _a1 ψ _{h , V}

= 1.0 ψ _{h , V} =

1.5c _a1

h _a

Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :

c _a1

: fixed edge distance in the direction of the applied shearload

h _a

: concrete thickness

Reference the Equations section of the PROFIS Engineering report for more information on ψ _{h , V}

.

196 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions