|
V b
= 8
|
l e
0.2
d a
|
d a λ a f ́c
|
( c a1
) 1 . 5
|
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 )
( a ) V b = 8
l e
0.2
where l e is defined in 17.5.2.2 provided that :
d a
d a λ a f ́c
( c a1 ) 1 . 5 ( 17.5.2.3a )
( 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
17.5.2.2 The basic concrete breakout strength in shear of a single anchor in cracked concrete , V b
, shall be the smaller of ( a ) and ( b ):
where le is the load-bearing length of the anchor for shear :
l e
= h ef for anchors with a constant stiffness over the full length of embedded section , such as headed studs and post-installed anchors with one tubular shell over the full length of the embedment depth ;
l e
= 2d a for torque-controlled expansion anchors with a distance sleeve separated from expansion sleeve , and le ≤ 8da in all cases .
V b corresponds to concrete breakout in shear for a single anchor without any geometry influences .
|
ACI 318-14 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 . ( 17.5.2.3 ) is only relevant for anchors that are rigidly attached to the fixture , e . g . a welded head stud . V b calculated using Eq . ( 17.5.2.2b ) is a limiting value .
V b calculated using Eq . ( 17.5.2.2a ) is not relevant to anchors rigidly attached to a fixture . PROFIS Engineering only calculates V b using Eq . ( 17.5.2.3 ) for the AWS
D1.1 headed studs in its anchor portfolio . The V b -value calculated using Eq .
( 17.5.2.3 ) is checked against the V b
-value calculated using Eq . ( 15.5.2.2b ) and the smaller value is used to calculate the nominal concrete breakout strength in shear ( V cb or V cbg ). The controlling V b
-equation is shown in the Equations section of the report , and the V b
-value calculated using the controlling equation is shown 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 . ( 17.5.2.3 ) or Eq . ( 17.5.2.2b ). Vb 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 .
ACI 318 anchoring-to-concrete provisions define the parameter l e as the “ load bearing length of anchor for shear ”. This “ length ” corresponds to the embedded portion of an anchor element that is effective in transferring shear load into a concrete member . The cast-in anchor elements in the PROFIS Engineering portfolio have a constant stiffness over their embedded depth ; therefore , the
l e
-value calculated by PROFIS Engineering for these anchors equals the smaller of the effective embedment depth ( h ef
) and eight times the nominal diameter of the anchor element ( d a
).
|
|
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters : |
||||||
|
l e
:
d a
:
λ a
:
f ́c :
c a1
:
h a
:
|
Load bearing length of anchor in shear
Anchor element diameter
Lightweight concrete modification factor
Concrete compressive strength
Edge distance in the direction of the shear load
Concrete thickness
|
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Reference the Calculations section of the PROFIS Engineering report for more information on the following parameters : | ||||||
V b calculated per Eq . ( 17.5.2.2b ) | ||||||
V b calculated per Eq . ( 17.5.2.3 ). |