1.0 TENSION
1.4 Side Face Blowout Failure Mode
Variables c a2
Variables ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
c a2
2.2 — Notation
c a1
= distance from the center of an anchor shaft to the edge of concrete in one direction , ………………… If tension is applied to the anchor , c a1 is the minimum edge distance . ………………… 17.6.4.1 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 ƒ ́c ( 17.6.4.1 )
17.6.4.1.1 If ca2 for the single headed anchor is less than 3ca1 , the value of Nsb shall be multiplied by the factor ( 1 + ca2 / ca1 )/ 4 , where 1.0 < ca2 / ca1 < 3.0 .
17.6.4 . 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 be calculated by :
N sbg
= 1 + s
6c a1
N sb
( 17.6.4 . 2 )
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 Table 17.9.2 ( a ) 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
, ƒ ́c and s .
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 .
( 17.6.4.1 ) without modification for a perpendicular edge distance .
Table 17.9.2 ( a ) — Minimum spacing and edge distance requirements
Anchor type
Spacing parameter Cast-in anchors
Minimum edge distance
Not torqued
Specified cover requirements for reinforcement according to 20.5.1.3
Torqued
6d a
114 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions