PROFIS Design Guide: US-EN Summer 2021 | Page 59

Concrete Breakout Failure Mode

Variables c _{a , min}

Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering

c _{a , min}

17.4 . 2.1 …….. A _Nc is the projected concrete failure area of a single anchor or group of anchors that shall be approximated as the base of the rectilinear geometrical figure that results from projecting the failure surface outward 1.5h _ef from the centerlines of the anchor , or in the case of a group of anchors , from a line through a row of adjacent anchors ……..

17.4 . 2.1 …….. A _Nc0 is the projected concrete failure area of a single anchor with an edge distance greater than 1.5h _ef .

A _Nc0

= 9h _ef

2

( 17.4.2.1c )

17.4 . 2.5 The modification factor for edge effects for single anchors or anchor groups loaded in tension , ψ _{ed , N}

, shall be calculated as If c _{a , min}

≥ 1.5h _ef , then ψ _{ed , N}

= 1.0 ( 17.4.2.5a )

If c _{a , min} < 1.5h _ef

, then ψ _{ed , N} = 1.0 c a , min ( 17 . 4 . 2 . 5a )

17.4 . 2.7 The modification factor for post-installed anchors designed for uncracked concrete in accordance with 17.4 . 2.6 without supplementary reinforcement to control splitting , ψ _{cp , N}

, shall be calculated as follows using the critical distance cac as defined in 17.7.6

c _Na

If c _{a , min} ≥ c _ac

, then ψ _{cp , N} = 1.0 ( 17.4.2.7a ) c _{a , min} is defined as the “ minimum distance from the center of an anchor shaft to the edge of concrete .” When one or more fixed edges are modeled in PROFIS Engineering , the report will show the smallest fixed edge as “ c _{a , min}

” in the Variables section . Excerpted ACI 318-14 anchoring-to-concrete provisions and equations that include

c _{a , min} for calculating concrete breakout strength in tension are shown to the left . Reference the parameters A _Nc and A _Nc0 in the Equations section of the PROFIS Engineering report for more information on the following parameters :

c _a1

:

c _a2

:

Distance from the center of an anchor shaft to the edge of concrete in one direction ( e . g . the x + direction ). For tension calculations , c _a1 is the smallest fixed edge distance

Distance from the center of an anchor shaft to the edge of concrete in a direction perpendicular to c _a1

( e . g . the y + direction )

Reference the parameters ψ _{ed , N} and ψ _{cp , N} in the Equations and Calculations sections of the PROFIS Engineering report for more information on how c _{a , min} is used to calculate these parameters .

but ψ _{cp , N} determined from Eq . ( 17.4.2.7b ) shall not be taken less than 1.5h _ef

/ c _ac , where the critical distance c _ac is defined in 17.7.6 .

59 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions