Type
Solution Manual
Book Title
Design of Concrete Structures 15th Edition
ISBN 13
978-0073397948

### 978-0073397948 Chapter 21

July 6, 2020
21.1 Determine the required embedment, hef, for a 5/8 in. diameter hex head bolt away
from edges in 4000 psi cracked concrete with no supplemental reinforcement and carrying
a sustained dead load of 6000 lbs, Figure P21.1. Given: fy= 36 ksi, futa = 58 ksi,
ASe,N=0.226, and Abrg=0.454 in2. (
h
ef
=4 in.)
Given:
f'c4000 psi P6.0kip
futa 58000 psi
ASeN 0.226 in2Abrg 0.454 in2
ψcP 1.0 ≔ψcN 1.0
Nua =1.4 P 8.4 kip
Check steel capacity
3.5
7.5
21.2 An insert with four -1/2 in. diameter headed studs is embedded 4 in. into an uncracked concrete
panel well away from any edges, Figure P21..2 The material strength is f'c = 5000 psi and the stud
yield strength is fy = 51,000 psi. Determine the tensile design load for the insert. (Nu=21.7 kip)
f'c5000 psi fy51 ksi da0.50 in
futa =1.9 fy96.9 ksi n4
ψcN 1.2 ≔ϕ0.75 ≔kc24 in.5
hef 4in s4in λa1.0
Steel Strength
Solutions Chapter 21
21.3 An insert with four -1/2 in. diameter headed studs is embedded 4 in. into an uncracked
concrete panel with the center of the insert 6 in. from any edges, Figure P21.3. The material
strength is f'c = 5000 psi and the stud yield strength is fy = 51,000 psi. Determine the shear
ca1
f'c5000psi fya 51000psi futa 1.9fya 96900 psi
λ1.0 normal weight concrete
ϕ0.65 kc24 per Code
AVco
Check Pryout
kcp 2 Stud embedment >2"
Ncpg 30.6kip from Example 1
Solutions Chapter 21
21.4 An insert with four - 1/2 in. diameter headed studs is embedded 4 in. into an uncracked
concrete panel near a corner, Figure P21.4. The material strength is f'c = 5000 psi and the stud
yield strength is fy = 51,000 psi. Determine the tensile design load for the insert.
f'c5000psi fya 51000psi futa 1.9fya 96900 psi
2" 2"
16"
λ1.0 normal weight concrete
ϕ0.75 kc24
Pullout capacity Abrg
π
41in()
20.5in()
2

Np8Abrg f'c
23.6 kip
21.5 The attachment shown in Figure 21.5 carries a factored load of 18 kips loaded
concentrically on the attachment. Given that the four headed studs are 1/2 in. in diameter,
have a specified yield stress of 51 ksi, and are welded to a 3/8 in plate, determine hef for the
attachment. The concrete may be considered cracked, f'c= 4000 psi, and the attachment is
away from any edge.
f'c4000 psi fy51 ksi da0.50 in
futa =1.9 fy96.9 ksi n4
Nu18.0 kip ϕ0.75 ≔kc24 in.5
ψcN 1.0 ≔s4in λa1.0
hef ,‥2in 2.5 in 6in
Check steel capacity
Check pullout
2
21.6 The attachment shown in Figure P21.6 carries a factored load of 21.5 kips loaded
eccentricly 1/2 in. from the centerline of the attachment. Given that the four headed studs are
5/8 in diameter and have a specified yield stress of 51 ksi and are welded to a 3/8 in plate,
determine hef for the attachment. The concrete may be considered uncracked, f'c= 4000 psi,
and the attachment is away from any edge.
f'c4000 psi fy51 ksi
futa =1.9 fy96.9 ksi
Nu21.5 kip ϕ0.75 ≔kc24 in.5
ψcN 1.25 ≔s4in λa1.0
hef ,‥2in 2.5 in 6in
Calculate Nua
Check pullout
n2 Two most critically loaded studs
2
21.8 Determine the capacity of the attachment in Figure 21.18 adequate to carry a sustained
applied load using the bond stress Wcr = 1800 psi and tuncr = 2600 psi. The anchors have 10
threads per inch, are 3/4 in. diameter futa = 75000 psi steel embedded 8 inches into an exterior
concrete wall having a compressive strength of 4000 psi. The attachment is well away from
any edges, supplementary reinforcement is present and the anchors are considered category 2
- medium sensitivity and reliability. Comment on your solution.
The loads are sustained so only half the allowable bond stress from ACI 318 below is
permitted.
τcr 1800 psi τuncr 2600 psi nt10 ≔hef 8in
nV4≔nN2≔fya 55 ksi da0.75 in f'c4000 psi
ecc 3 in s18in s26in λa1.0 ≔ϕ0.65
ψecNa 1.0 ≔ψedNa 1.0 ≔ψcpNa 1.0
I
is based on category 2 and
supplemental reinforcement
being present.
\
values result from large edge distances and no eccentricity.
2