Civil Engineering Reference
In-Depth Information
2.61
2.04
Overstress
1.85
1.69
1.54
1.40
a
b
c
40 at 5"
24 at 7"
19 at 9"
2 at 270
"
= 540
"
FIGURE E7.7
Shear flow and resistance along the span.
386, 516 in.
4
provides a very stiff structure.
The deflections are estimated as (see Chapter 5)
The section
I
g
=
0.104
M
LL
+
I
L
2
EI
2
0.104
(
7314
)(
12
)
[
90
(
12
)
]
Δ
LL+I
=
=
=
0.95 in.
29,000
(
386,516
)
0.104
M
DL1
L
2
EI
g1
0.104
M
DL2
L
2
EI
g2
Δ
DL
=
+
2
2
0.104
(
1430
)(
12
)
[
90
(
12
)
]
0.104
(
1070
)(
12
)
[
90
(
12
)
]
=
+
29,000
(
223,444
)
29,000
(
299,065
)
0.50
,
=
0.32
+
0.18
=
no camber is required.
TABLE E7.17
Deflection Criteria,
Required Gross Moment of
Inertia,
I
g
, (in.
4
)
L
/
Δ
LL+I
500
170,180
640 (AREMA, 2008)
217,832
800
272,290
1000
340,362
