PROFIS ENGINEERING REPORT SHEAR LOAD
Concrete Breakout Failure Mode
Calculations ψ ed , V
Calculations 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ψ ed , V
17.5 . 2.6 The modification factor for edge effect for a single anchor or group of anchors loaded in shear , ψ ed , V
, shall be calculated as follows using the smaller value of c a2 .
If c a2
≥ 1.5c a1 , then ψ ed , V
= 1.0 ( 17.5.2.6a )
If c a2
< 1.5c a1 , then ψ ed , V
= 0.7 + 0.3 c a2 ( 17 . 5 . 2 . 6b )
1.5c a1
17.5 . 2.1 The nominal concrete breakout strength in shear , V cb of a single anchor or V cbg of a group of anchors , shall not exceed : ( a ) For shear force perpendicular to the edge on a single anchor
V cb
=
A vc ψed , V ψ c , y ψ h , V
V b
( 17.5.2.1a )
A vc0 ψ ed , V is a modification factor that is used to account for fixed edge distances perpendicular to the direction of the applied shear load that are less than
1.5c a1
. Shear concrete breakout failure calculations are predicated on the fixed edge distance in the direction of the applied shear load ( c a1
). Edge distances perpendicular to the direction of the applied shear load are designated ca2 . If c a2 is less than 1.5c a1
, ψ ed , V is calculated per Eq . ( 17.5.2.6b ).
If more than one fixed edge perpendicular to the direction of the applied shear load exists , the smallest of these edge distances is used to calculate ψ ed , V
. For the application in the illustration below , if c a2 , x- < c a2
, x +: ψ ed , V
= 0.7 + 0.3 ( c a2 , x-
/ 1.5c a1 )
Per Section 17.5.2.4 , when anchoring into a narrow section , the checks noted in ( a ) through ( c ) should also be made to determine if a modified c a1
-value should be used for the shear concrete breakout calculations . For the application below , h a is greater than 1.5c a1 , so no modified c a1
-value would be calculated .
( b ) For shear force perpendicular to the edge on a group of anchors
V cbg
= A vc ψ ec , V ψ ed , V ψ c , V ψ h , V
V b
( 17.5.2.1b )
A vc0
( c ) For shear force parallel to an edge V cb or V cbg shall be permitted to be twice the value of the shear force determined from Eq . ( 17.5.2.1a ) or ( 17.5.2.1b ), respectively , with the shear force assumed to act perpendicular to the edge and with ψ ed , V taken equal to 1.0
( d ) For anchors located at a corner , the limiting nominal concrete breakout strength shall be determined for each edge , and the minimum value shall be used
17.5 . 2.4 Where anchors are located in narrow sections of limited thickness such that both edge distances c a2 and thickness ha are less than 1.5c a1 , the value of ca1 used for A Vc in accordance with 17.5.2.1 as well as for the equations in 17.5.2.1 through 17.5.2.8 shall not exceed the largest of :
( a ) c a2 / 1.5 , where c a2 is the largest edge distance
( b ) h a
/ 1.5
( c ) s / 3 , where s is the maximum spacing perpendicular to direction of shear , between anchors within a group
192 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions