Giải thích hệ số PBN - Example Continued

BridgeTech, Inc.
Example Continued
 
6 12
0.9
2 10 2 10
0.9
0.61 0.9 0.16
0.71
exterior
Lever Rule
Calibrated m Lever Rule m
Calibrated
P P
R P
g
g a g b
g
     
  
     
     

   

  
0.71
1.05 1.2 0.71
0.89
Calibrated
a

a
g g
mg
mg


 


Previous
Example
BridgeTech, Inc.
All effects are now separated an
understandable
  
1.05 1.2 0.71
0.89
a
a
mg
mg




Variability in
analysis
Effect of Multiple
Presence
Analysis

BridgeTech, Inc.
Skew
Adjustments for shear
No iteration
Commentary M&M 20-07 Study
Neglect decrease for moment
BridgeTech, Inc.
Curvature
No change
BridgeTech, Inc.
Type of Superstructure
Applicable Cross-Section
from Table 4.6.2.2.1-1 Correction Factor
Range of
Applicability
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-Section
a, e and also h, i, j
if sufficiently connected to
act as a unit
1.0 0.20tan  0 60
3.5 16.0
20 240
4
b
S

L
N
 
 
 

Precast concrete I and bulb tee
beams
K
1.0 0.09tan 
0 60
3.5 16.0
20 240
4
b
S
L
N
 
 
 

Cast-in-Place Concrete Multicell
Box
D
12.0
1.0 0.25 tan
70
L
d

 
  
 
 
0 60
6.0 13.0
20 240
35 110
3
c
S
L
d
N
 
 
 
 

Concrete Deck on Spread Concrete
Box Beams
B, c
12.0
1.0 tan
6
Ld
S
 
0 60
6.0 11.5

20 140
18 65
3
b
S
L
d
N
 
 
 
 

Concrete Box Beams Used in
Multibeam Decks
f, g
12.0
1.0 tan
90
L
d
 
0 60
20 120
17 60
35 60
5 20
b
L
d

b
N
 
 
 
 
 
BridgeTech, Inc.
Push-the-limits bridges
W
SS
Overhang
1'-9"
Overhang
S
s
t
1'-9"
Bridge
No.
Girder
Spacing,
S
(ft)
Recommended
minimum slab
thickness
(AASHTO STD
Table 8.9.2)
Slab

Thickness,
t
s
(in)
Span
Length, L
(ft)
Total
Bridge
Width, W
(ft)
No.of
girders
Overhang
(ft)
1 12 8.80 9.00 240 44 4 4
2 12 8.80 9.00 260 44 4 4
3 12 8.80 9.00 280 44 4 4
4 12 8.80 9.00 300 44 4 4
5 12 8.80 9.00 200 44 4 4
6 14 9.60 9.75 200 48 4 3
7 16 10.40 10.50 200 54 4 3
8 18 11.20 11.25 200 60 4 3
9 20 12.00 12.00 200 68 4 4
10 12 8.80 9.00 160 58 5 5
11 12 8.80 9.00 160 53 4 8.5