1.0 TENSION
1.4 Side Face Blowout Failure Mode
Equations N sb
= 160 c a1
Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering anchor group in tension
N sb
= 160c a1
A brg λ a f ́c
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 . 2 For multiple headed anchors with deep embedment close to an edge ( h ef > 2.5c a1
) and anchor spacing less than 6ca1 , 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 )
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 . PROFIS Engineering permits h ef
-values ranging between 4danchor and 25 ” to be input for the cast-in anchors in its portfolio . For the illustration below : N sbg
= [ 1 + ( s y1 + s y2
)/ 6c a1 ] N sb
PROFIS Engineering bearing area values ( A brg ) for the cast-in anchors in its portfolio .
MATERIAL SPECIFICATION
AWS D1.1 Type B Headed Stud
" ASTM F1554 Headed Bolt Gr . 36 , Gr . 55 , Gr . 105 "
Diameter ( d 0
) ( in )
Bearing area ( A brg in 2 ) welded headed stud
Bearing area ( A brg in 2 ) square head bolt
Bearing area ( A brg in 2 ) heavy square bolt
Bearing area ( A brg in 2 ) hex head bolt
Bearing area ( A brg in 2 ) heavy hex head bolt
0.500 |
0.589 |
0.625 |
0.920 |
0.750 |
0.785 |
0.875 |
0.884 |
0.500 |
0.464 |
0.569 |
0.291 |
0.467 |
0.625 |
0.693 |
0.822 |
0.454 |
0.671 |
0.750 |
0.824 |
1.210 |
0.654 |
0.911 |
0.875 |
1.121 |
1.465 |
0.891 |
1.188 |
1.000 |
1.465 |
1.855 |
1.163 |
1.501 |
1.125 |
1.854 |
2.291 |
1.472 |
1.851 |
1.250 |
2.228 |
2.773 |
1.817 |
2.237 |
1.375 |
2.769 |
3.300 |
2.199 |
2.659 |
1.500 |
3.295 |
3.873 |
2.617 |
3.118 |
1.750 |
|
|
|
4.144 |
2.000 |
|
|
|
5.316 |
Side-face blowout is a tension failure mode that can occur when anchors are installed at a “ deep ” embedment ( h ef
> 2.5c a1 ), near a fixed edge ( c a1
). In lieu of concrete breakout or pullout occurring , the applied tension load creates lateral bursting stresses at the head of the anchors which cause the concrete to “ blow out ” at the face of the fixed edge . The parameter h ef corresponds to the embedded portion of the anchor that is “ effective ” in transferring tension load from the anchor into the concrete . The parameter c a1 corresponds to the nearest fixed edge , where side-face blowout is assumed to occur .
Side-face blowout is a possible failure mode for cast-in anchors . Splitting failure , rather than side-face blowout , is a more common failure mode for post-installed anchors ; however , side-face blowout could possibly occur with undercut anchors . PROFIS Engineering does not consider side-face blowout for the HDA-P and HDA-T undercut anchors in its portfolio because it will not be a controlling tension failure mode for these anchors . PROFIS Engineering only performs side-face blowout calculations for the cast-in anchors in its portfolio .
When modeling a group of anchors in tension , the side-face blowout strength for a single anchor ( N sb
) is calculated , and modified by the factor ( 1 + s / 6c a1 ). PROFIS
Engineering designates this factor “ α group
”. The parameter “ s ” corresponds to the distance between the outer anchors ( e . g . s y1
+ s y2 in the illustration to the left ) along the fixed edge being considered for side-face blowout . PROFIS Engineering limits the value of “ s ” to “ 6c a1
”; which means that PROFIS Engineering permits
“ α group ” values in the range :
1.0 ≤ α group ≤ 2.0
The modification factor “ α corner ” is not used to calculate N sbg
.
The PROFIS Engineering cast-in anchor portfolio is as follows :
• AWS D1.1 Type B headed studs : ( 1 / 2 ” — 7 / 8 ” nominal diameter )
• ASTM F1554 hex head bolt , Gr . 36 , Gr . 55 , Gr . 105 : ( 1 / 2 ” — 1-1 / 2 ” nominal diameter )
• ASTM F1554 heavy hex head bolt , Gr . 36 , Gr . 55 , Gr . 105 : ( 1 / 2 ” — 2 ” nominal diameter )
• ASTM F1554 square head bolt , Gr . 36 , Gr . 55 , Gr . 105 : ( 1 / 2 ” — 1-1 / 2 ” nominal diameter )
• ASTM F1554 heavy square head bolt , Gr . 36 , Gr . 55 , Gr . 105 : ( 1 / 2 ” — 1-1 / 2 ” nominal diameter ) λ a is a modification factor for lightweight concrete .
ƒ ́c corresponds to the concrete compressive strength .
106 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions