Structural Concrete - Hassoun

902 Chapter 22 Prestressed Concrete Bridge Design
Table 22.13
Distribution of Live Load per Lane for Moment in Interior Beams
Type of Superstructure
Wood deck on wood or
steel beams
Concrete deck on wood
beams
Concrete deck, filled
grid, partially filled
grid, or unfilled grid
deck composite with
reinforced concrete
slab on steel or
concrete beams;
concrete T-beams,
T- and double
T-sections
Cast-in-place concrete
multicell box
Concrete deck on
concrete spread box
beams
Concrete beams used in
multibeam decks
Applicable
Cross Section
from Table 22.11
a, l See 22.12
l
Distribution Factors
One design lane loaded:
S/12.0
Two or more design lanes loaded:
S/10.0
Range of
Applicability
S ≤ 6.0
3.5 ≤ S ≤ 16.0
7.0 ≤ S ≤ 13.0
6.0 ≤ S ≤ 18.0
a, e, k, and also One design lane loaded:
i, j if
( )
sufficiently
S 0.4 ( ) S 0.3
( ) 0.1 4.5 ≤ t
Kg
s ≤ 12.0
0.06 +
20 ≤ L ≤ 240
connected to
14 L 12.0Lts
3 N b ≥ 4
act as unit Two or more design lanes loaded: 10,000 ≤ K g ≤
( ) 7,000,000
( S 0.6 ( ) 0.1
S
0.2 Kg
0.075 +
9.5)
L 12.0Lts
3
Use lesser of the values obtained from the N b = 3
equation above with N b = 3 or the lever rule
d
One design lane loaded:
( S 0.6 ( ) S 0.2
( ) 0.1 Kg
0.075 +
9.5)
L 12.0Lts
3
(
1.75 +
3.6) S ( ) 1 0.35
( ) 0.45 60 ≤ L ≤ 240
1 N c ≥ 3
L N c If N c > 8use
Two or more design lanes loaded:
N c = 8
b, c One design lane loaded:
( ) S 0.6 ( ) Sd 0.125
9.6.35 12.0L 2
( ) S 0.35 ( ) Sd 0.25
20 ≤ L ≤ 140
18 ≤ d ≤ 65
3.0 12.0L 2 N b ≥ 3
Two or more design lanes loaded:
Use lever rule S > 18.0
f
One design lane loaded:
35 ≤ b ≤ 60
( ) b 0.5 ( )
I 0.125
20 ≤ L ≤ 120
k
5 ≤ N
33.3L 12.0L 2 b ≤ 20
where k = 2.5(N b ) −0.2 ≥ 1.5
g if sufficiently Two or more design lanes loaded:
connected to ( ) bS 0.6 ( ) b 0.2 ( I
act as a unit k
305 12.0L J
) 0.06
(continued)