PROFIS ENGINEERING REPORT SHEAR LOAD
Concrete Breakout Failure Mode
Variables c a2
Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
c a2
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 Vc is the projected area of the failure surface on the side of the concrete member at its edge for a single anchor or a group of anchors . It shall be permitted to evaluate A Vc as the base of a truncated half-pyramid projected on the side face of the member where the top of the half-pyramid is given by the axis of the anchor row selected as critical . The value of c a1 shall be taken as the distance from the edge to this axis . ……………………………………..
17.5 . 2.3 For cast-in headed studs , headed bolts , or hooked bolts that are continuously welded to steel attachments having a minimum thickness equal to the greater of 3 / 8 in . and half of the anchor diameter , the basic concrete breakout strength in shear of a single anchor in cracked concrete , V b
, shall be the smaller of Eq . ( 17.5.2.2b ) and Eq . ( 17.5.2.3 )
The parameter “ c a2
” corresponds to a fixed edge distance perpendicular to the direction of the applied shear load . c a2 is considered when calculating the following parameters :
• Shear area of influence ( A Vc
)
• Basic concrete breakout strength in shear ( V b
) per the provisions of ACI 318-14
Section 17.5.2.3
• Modification for edge effects ( ψ ed , V
)
When modeling an application consisting of two fixed edges perpendicular to the direction of the applied shear load , PROFIS Engineering uses the smaller of these edge distances for the c a2
-value . The illustration below shows how the parameters c a1 and c a2 are considered with respect to one another .
|
V b
= 8
|
l e
0.2
|
d a λ a f ́c
|
( c a1 ) 1 . 5 ( 17.5.2.3 ) |
|
d a
|
|
|
where l e is defined in 17.5.2.2 provided that :
( a ) For groups of anchors , the strength is determined based on the strength of the row of anchors farthest from the edge
( b ) Anchor spacing s is not less than 2.5 in . ( c ) Reinforcement is provided at the corners if c a2
≤ 1.5h ef
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
176 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions