2.0 SHEAR
2.1 Concrete Breakout Failure Mode
Variables c a2
Variables ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
c a2
17.7.2.1.1 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 an anchor group . 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 . ……………………………………..
17.7.2.2.2 For cast-in headed studs , headed bolts , or hooked bolts that are continuously welded to steel attachments basic concrete breakout strength in shear of a single anchor in cracked concrete , V b
, shall be the lesser of Eq . ( 17.7.2.2.1b ) and Eq . ( 17.7.2.2.2 ) provided that ( a ) through ( d ) are satisfied .
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 318-19 Section 17.7.2.2.2
• 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 .
|
V b
= 8
|
l e
0.2
d a
|
d λ a
( c a1 ) 1 . 5 ( 17.7.2.2.2 ) a ƒ ́c
|
The illustration below shows how the parameters c a1 and c a2 are considered with respect to one another . |
where l e is defined in 17.7.2.2.1 . |
|
|
|
( a ) Steel attachment thickness is the greater of 0.5d a and 3 / 8 in .
( b ) Anchor spacing s is at least 2.5 in . ( c ) Reinforcement is provided at the corners if c a2
≤ 1.5h ef
.
( d ) For anchor groups , the strength is calculated based on the strength of the row of anchors farthest from the edge
17.7.2.4.1 Modification factor for edge effects for single anchors or anchor groups loaded in shear ,
ψ ed , V
, shall be determined by ( a ) or ( b ) using the lesser value of c a2 .
………………………………………..
( b ) If c a2
< 1.5c a1 , then ψ ed , V
= 0.7 + 0.3 c a2 ( 17 . 7 . 2 . 4 . 1b )
1.5c a1
179 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions