Civil Engineering Reference
In-Depth Information
Use 500 mm
800 mm section (
d
680 mm)
Beam wt
(500)(800)
10
6
(23.5)
9.4 kN/m
10 kN/m assumed OK
A
s
(0.01415)(500)(680)
4811 mm
2
Use six #32 bars in two rows (4914 mm
2
).
One row could be used here.
A
s
f
y
0.85
f
(4914)(420)
(0.85)(28)(500)
173 mm
a
c
b
c
a
1
173
0.85
204 mm
t
680
204
204
(0.003)
0.0070
0.005
0.90
Note:
Can more easily be checked with
values.
b
min
267 mm from Appendix Table B.5
500 mm OK
The final section is shown in Figure 4.11.
Note:
This problem can be solved more quickly by making use of the Appendix tables. In
Table B.9 with
f
y
420 MPa,
c
f
28 MPa, and
0.01415.
M
u
bd
2
5.201
(105)(10)
6
(0.9)(5.201)
M
u
(5.201)
bd
2
2.2432
10
8
mm
3
640 mm
800 mm
6 #32
80 mm
80 mm
8
mm
8
mm
2 @
170mm
= 340mm
500 mm
Figure 4.11
