Civil Engineering Reference
In-Depth Information
In Problems 4.23 and 4.24 design rectangular sections for the beams and loads shown in the accompanying illustrations.
Beam weights are not included in the given loads.
f
y
60,000 psi and
4000 psi. Live loads are to be placed where
they will cause the most severe conditions at the sections being considered. Select beam size for the largest moment
(positive or negative) and then select the steel required for maximum positive moment and for maximum negative mo-
ment. Finally, sketch the beam and show approximate bar locations.
c
f
Problem 4.23
(
One ans.:
12 in.
28 in. with three #10 bars negative reinf. and three #9 bars positive reinf.)
D =
2 k/ft,
L =
4 k/ft
18'
9'
0.18
f'
c
f
y
Use
=
ρ
Problem 4.24
D
= 3 k/ft,
L
= 2 k/ft
10'
24'
10'
0.18
f'
c
f
y
=
Use
ρ
In Problems 4.25 and 4.26 design interior one-way slabs
for the situations shown. Concrete weight
150 lb/ft
3
,
f
y
60,000 psi and
4000 psi. Do not use the ACI
Code's minimum thickness for deflections. Steel percent-
ages are given in the figures.
Problem 4.26
c
f
4.27
Repeat Problem 4.26 using the ACI Code's mini-
mum thickness requirement for cases where deflections
are not computed. Do not use the
given in Problem 4.26.
(
Ans.
Problem 4.25
(
One ans.
5 in. slab with #6 @ 10 in. main
reinf.)
14
2
in. slab with #6 @ 10 in. main reinf.)
c
4.28
Using
3000 psi,
f
y
60,000 psi, and
max
, de-
termine the depth of a simple beam to support itself for a
200-ft simple span. Neglect cover in calculations and as-
sume
0.5
b
.
f
