ICC ESR-3027 for Kwik HUS-EZ Screw Anchors in Concrete

ESR-3027
|
Most Widely Accepted and Trusted Page 18 of 20
Given: Two
1
/
2
″ diameter KH-EZ
with static tension load
h
nom
= 4.25 inches
h
ef
= 3.22 inches
Normal Weight Concrete: f’
c
=
3,000 psi
No supplementary reinforcement
(Cond. B)
No eccentricity, 60% live load, 40%
dead load.
Assume cracked concrete since no
other information is available.
h
min
=6.375 in.
c
min
=1.75 in.
s
min
=3 in.
Needed: Allowable stress design
(ASD)
tension capacity
Calculation per ACI 318-19 Chapter 17, ACI 318-14 Chapter 17,
ACI 318-11 Appendix D and this report
ACI 318-19
Ref.
ACI 318-14
Ref.
ACI 318-11
Ref.
ESR
Reference
Step 1: Calculate steel capacity:
ϕN
s
=nϕN
sa
=2
󰇛
0.65
󰇜󰇛
18,120
󰇜
=23,556 lbs.
17.6.1.2 17.4.1.2 D.5.1.2 Table 3
Step 2: Verify minimum member thickness, spacing and edge
distance:
h
min
=6.375 in. ≤12 in. →ok
c
min
=1.75 in. ≤4 in. →ok
s
min
=3 in. ≤6 in. →ok
17.9 17.7 D.8 Table 1
Step 3: Calculate concrete breakout strength of anchor group in
tension:
N
cbg
=
A
Nc
A
Nco
Ψ
ec,N
Ψ
ed,N
Ψ
c,N
Ψ
cp,N
N
b
17.6.2.1 17.4.2.1 D.5.2.1 4.1.3
Step 3a: Calculate A
Nc
and A
Nco
:
A
Nc
=
󰇛
1.5h
ef
+4
󰇜󰇛
3h
ef
+6
󰇜
=
󰇛
8.83
󰇜󰇛
15.66
󰇜
=138.3 in.
2
A
Nco
=9(h
ef
)
2
=9(3.22)
2
=93.32 in.
2
17.6.2.1 17.4.2.1 D.5.2.1 Table 3
Step 3b: Determine Ψ
ec,N
→e
n
'
=0→Ψ
ec,N
=1.0
17.6.2.3.1 17.4.2.4 D.5.2.4 ----
Step 3c: Calculate Ψ
ed,N
→Ψ
ed,N
=0.7+0.3 󰇡
4
4.83
󰇢=0.948
17.6.2.4.1 17.4.2.5 D.5.2.5 Table 3
Step 3d: Determine Ψ
cp,N
→ Ψ
cp,N
=1.0 because concrete is
cracked.
17.6.3.3 17.4.3.6 D.5.3.6 ----
Step 3e: Calculate N
b
:
N
b
=k
cr
𝜆


f
c
'
󰇛
h
ef
󰇜
1.5
=17(1.0)

3,000(3.22)
1.5
=5,380 lbs
(λ
a
=1.0 for normal weight concrete)
17.6.2.2 17.4.2.2 D.5.2.2 Table 3
Step 3f: Calculate 𝜙𝑁

:
ϕN
cbg
=
󰇛
0.65
󰇜
󰇡
138.3
93.32
󰇢
󰇛
1.0
󰇜󰇛
0.948
󰇜󰇛
1.0
󰇜󰇛
1.0
󰇜󰇛
5,380
󰇜
=4,914 lbs
17.6.2.1
17.5.3 (c)
17.4.2.1
17.3.3 (c)
D.5.2.1
D.4.3 (c)
4.1.3
Table 3
Step 4: Check Pullout Strength → per Table 2 does not control ---- ---- ---- Table 3
Step 5: Controlling Strength:
Lesser of nϕN
sa
and ϕN
cbg
→ 4,914 lbs
17.5.2.2 17.3.1.2 D.4.1.2 Table 3
Step 6: Convert to ASD based on 1.6 (0.60)+1.2(0.40)=1.44
60% Live Load and 40% Dead Load:
T
allowable,ASD
=
4,914
1.44
=3,412 lbs
--- --- --- 4.2.1
FIGURE 13—EXAMPLE CALCULATION