2.0 SHEAR
2.1 Concrete Breakout Failure Mode
Equations V b
= 9λ a
Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
|
V b
= 9λ a
|
( c ƒ ́c a1
) 1 . 5
|
17.7.2 . 2.1 Basic concrete breakout strength of a single anchor in shear in cracked concrete , V b , |
|
|
shall not exceed the lesser of ( a ) and ( b ): |
( a ) V b = 7 l e
0.2 d a d λ a
( c a1 ) 1 . 5 ( 17.7.2.2.1a ) a ƒ ́c
……………………………………………………………
( b ) V b = 9λ a ƒ ́c ( c a1 ) 1 . 5 ( 17.7.2.2.1b )
V b corresponds to concrete breakout in shear for a single anchor without any geometry influences .
ACI 318-19 Chapter 2 defines the parameter V b as the “ basic concrete breakout strength in shear of a single anchor in cracked concrete ”. V b calculated using Eq . ( 17.7.2.2.1a ) can be considered relevant for anchors that are not rigidly attached to the fixture , i . e . an annular space exists between the anchor element and the hole in the fixture through which the anchors are located . V b calculated using Eq . ( 17.7.2.2.1b ) is a limiting value . PROFIS Engineering calculates V b using both equations , and shows the controlling equation in the Equations section of the report , and the V b
-value calculated using the controlling equation in the
Calculations section .
Consider a single anchor installed near a fixed edge with a shear load acting on the anchor towards that edge . Assuming there are no fixed edges perpendicular to the direction of the applied shear load , and the concrete has an “ infinite ” thickness ; if concrete breakout occurs , it could be defined by the calculated capacity V b using either Eq . ( 17.7.2.2.1a ) or Eq . ( 17.7.2.2.1b ). V b is calculated using both equations and the smaller calculated value is used to calculate the nominal concrete breakout strength in shear ( V cb or V cbg ). Geometry influences are considered via the parameters A vc , ψ ed , V and ψ h , V
. Reference the Design Guide sections for these parameters for more information .
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
λ a
: lightweight concrete modification factor ƒ ́c : concrete compressive strength
c a1
: edge distance in the direction of the shear load
Reference the Calculations section of the PROFIS Engineering report for more information on the following parameters :
V b calculated per Eq . ( 17.7.2.2.1a )
V b calculated per Eq . ( 17.7.2.2.1b ).
174 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions