Civil Engineering Reference
In-Depth Information
Figure 2.14
c
.
The top 94.12 in.
2
of the beam of Figure 2.14 is stressed in compression to This area
can be shown to extend 9.23 in. down from the top of the beam. Its center of gravity (c.g.) is located
by taking moments at the top of the beam as follows:
0.85
f
6
3.23
2
(36)(3)
(58.12)
y
5.85 in.
94.12
d
y
21
5.85
15.15 in.
M
n
(240)(15.15)
3636 in.- k
303 ft- k
2.5
EXAMPLE PROBLEM USING SI UNITS
In Example 2.8, the nominal moment strength of a beam is computed using SI units. Ap-
pendix Tables B.1 to B.9 provide information concerning various concrete and steel
grades, as well as bar diameters, areas, and so on, all given in SI units.
EXAMPLE 2.8
c
Determine the nominal moment strength of the beam shown in Figure 2.15 if
f
28 MPa and
f
y
420 MPa.
430 mm
500 mm
3 #25 bars
70 mm
300 mm
(
A
s
= 1530
mm
2
from Appendix Table B.4.)
Figure 2.15
