PART 3 TENSION LOAD
Side-Face Blowout Failure
Variables c a2
Variables ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
c a2
2.2 – Notation
c a2
= distance from center of an anchor shaft to the edge of concrete in the direction perpendicular to c a1
, in . 17.4.4.1 For a single headed anchor with deep embedment close to an edge ( h ef
> 2.5c a1 ), the nominal side-face blowout strength , N sb , shall not exceed
N sb
= 160c a1
A brg λ a f ́c ( 17.4.4.1 )
If c a2 for the single headed anchor is less than 3c a1
, the value of N sb shall be multiplied by the factor ( 1 + c a2
/ c a1 )/ 4 , where 1.0 ≤ c a2
/ c a1
≤ 3.0 . 17.4.4.2 For multiple headed anchors with deep embedment close to an edge ( h ef
> 2.5c a1 ) and anchor spacing less than 6c a1 , the nominal strength of those anchors susceptible to a side-face blowout failure N sbg shall not exceed
When calculating nominal side-face blowout strength ( N sb or N sbg
), the parameter
“ c a1
” corresponds to the distance from the center of the anchor ( s ) to the nearest fixed edge where side-face blowout is assumed to occur . When two or more fixed edges are present , the parameter c a2 corresponds to the fixed edge perpendicular to c a1 such that c a1
< c a2
.
PROFIS Engineering only performs side-face blowout calculations for the cast-in anchors in its portfolio . The software uses the minimum edge distance requirements given in Section 17.7.2 for these anchors .
The illustration to the left shows how the parameters c a1 and c a2 are utilized for side-face blowout calculations .
Reference the Variables section of the report for more information on the parameters c a1
, A brg , λ a
, f ́c and s .
|
N sbg
= 1 +
|
s
6c a1
|
N sb
( 17.4.4.2 )
|
Reference the Calculations section of the report for more information on the parameter N sb
.
|
where s is the distance between the outer anchors along the edge , and N sb is obtained from Eq .
( 17.4.4.1 ) without modification for a perpendicular edge distance .
17.7.2 Unless determined in accordance with 17.7.4 , minimum edge distances for cast-in anchors that will not be torqued shall be based on specified cover requirements for reinforcement in 20.6.1 . For cast-in anchors that will be torqued , the minimum edge distances shall be 6d a
.
Illustration showing the parameters c a1 and c a2 that are used in side-face blowout calculations . single anchor
anchor group
111 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions