1.0 TENSION
1.4 Side Face Blowout Failure Mode
Variables λ a
Variables ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
λ a
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 )
17.2.4.1 Modification factor λ a for lightweight concrete shall be in accordance with Table 17.2.4.1 . It shall be permitted to use an alternate value of λ a if tests are performed and evaluated in accordance with ACI 355.2 or ACI 355.4 . Table 17.2.4.1 — Modification factor λ a for lightweight concrete
Cast-in and undercut anchor concrete failure
Case λ a
[ 1 ]
1.0 λ λ a is a modification factor for lightweight concrete . Generally speaking , ACI 318 applies a multiplier to the parameter √ƒ ́c to “ account for the properties of lightweight concrete ”, and designates this parameter “ λ ”. The parameter “ λ a
“ is a modification of “ λ ” that specifically “ accounts for the properties of lightweight concrete ” with respect to anchoring-to-concrete calculations , hence the subscript “ a ” in “ λ a
”. Per Section 17.2.4.1 , the modification factor λ , determined per the provisions of Section 19.2.4 , is multiplied by an additional factor that is specific to the type of anchor being used , to obtain the parameter λ a
. PROFIS Engineering uses the λ-value that has been input , to calculate a λ a
-value for the anchor being modeled . PROFIS Engineering users can input a λ-value based on the properties of the lightweight concrete being used in the application . Any λ-value between 0.75 and 1.0 can be input .
Expansion , screw , and adhesive anchor concrete failure Adhesive anchor bond failure per Eq . ( 17.6.5.2.1 )
[ 1 ] λ shall be in accordance with 19.2.4
0.8 λ 0.6 λ
PROFIS Engineering only performs side-face blowout calculations for the cast-in anchors in its portfolio . The parameter λ a is included in Eq . ( 17.6.4.1 ) to calculate the nominal side-face blowout strength for a single anchor ( N sb
). Per Section 17.2.4.1 , if lightweight concrete conditions are being modeled , PROFIS Engineering will use ( λ a
= 1.0 λ ) to calculate N sb with Eq . ( 17.6.4.1 ).
19.2.4 Lightweight concrete 19.2.4.1 Except as required in Table 25.4.2.5 , the value of λ shall be determined using Table 19.2.4.1 ( a ) based on the equilibrium density , w c
, of the concrete mixture used in design , or Table 19.2.4.1 ( b ) based on the composition of the aggregate in the concrete mixture assumed in the design .
Reference the Variables section of the report for more information on the parameters c a1
, c a2 , A brg
, ƒ ́c and s .
Reference the Calculations section of the report for more information on the parameters N sb
.
Table 19.2.4.1 ( a ) — Values of λ for lightweight concrete based on equilibrium density
w c lb / ft 3 λ
≤ 100 |
0.75 |
( a ) |
100 ≤ w c ≤ 135 |
0.0075 w c ≤ 1.0 |
( b ) |
> 135 |
1.0 |
( c ) |
Table 19.2.4.1 ( b ) — Values of λ for lightweight concrete based on composition of aggregates |
Concrete |
Composition of Aggregates |
λ |
All-lightweight
Lightweight , fine blend
Sand-lightweight
Sand-lightweight , course blend
Normal weight
Fine : ASTM C330 Course : ASTM C330
Fine : Combination of ASTM C330 and C33 Course : ASTM C330
Fine : ASTM C33 Course : ASTM C330
Fine : ASTM C33 Course : Combination of ASTM C330 and C33
Fine : ASTM C33 Course : ASTM C33
0.75
0.75 to 0.85 [ 1 ]
0.85
0.85 to 1 [ 2 ]
1
[ 1 ] Linear interpolation from 0.75 to 0.85 is permitted based on the absolute volume of normal weight fine aggregate as a fraction of the total absolute volume of fine aggregate .
[ 2 ] Linear interpolation from 0.85 to is permitted based on the absolute volume of normal weight course aggregate as a fraction of the total absolute volume of course aggregate .
117 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions