Superload Move
April 06, 2013
Prasad Nallapaneni & Jonathan Mallard
Structure and Bridge, VDOT
Superload - Route
2
Superload- Details
Total Distance :
Approximately 96 Miles
Number of Structures: 62 (61 VDOT)
Bridges: 25
Culverts: 37
VDOT Structures:
Analyzed in-house: 47
Third Party Analysis: 16
3
Superload - Detials
Analysis Method:
In house: LFR/LRFR –
»VIRTIS if available
»Compared Simple span moments
with HS20 ratings
Third Party: LRFR -16 Bridges
Verified hand calculations
/ LFR analysis
Structures Jumped: 5 (five)
4
Superload - Permit
5
Superload - Permit
6
Superload - Jump
7
Superload - Restrictions
8
Superload - Crabs
9
Superload
10
Superload
11
Superload
Attempt Made:
• Run few bridges in 6.5 with Non
Standard Gage Vehicle
• Compare with calculations received
from Third Party and in-house STAAD
runs
12
Superload
Bridge Fed ID: 24505
13
Superload
Bridge Fed ID: 24505
Wheel Configuration: Straight
Dead Load
Moment (K ft)
Capacity (K Ft)
Rating Factor
Live Load (K ft)
BrR Model
Hand
Clacs
1550
1519
6271
2.01
6221
2.09
2355
2246
% Diff
Reason
Model has slightly higher
Superimposed loads
0.80%
Round of error
-4.22%
May be round off error in
Distribution Factor. No
4.83%
detail output in BrR for
Live Load.
2.04%
14
Superload
Bridge Fed ID: 25334
15
Superload
Bridge Fed ID: 25334
Wheel Configuration: Straight
Dead Load
Moment (K ft)
Capacity (K Ft)
Rating Factor
Live Load (K ft)
BrR Model
Hand
Clacs
% Diff
5701
5691
0.18%
15475
1.11
15463
1.19
0.08%
-6.48%
8233
May be round off error in
Distribution Factor. No
6.95%
detail output in BrR for
Live Load.
8805
Reason
Round Off
Round Off
16
Superload
Bridge 24231
17
Superload
Bridge Fed ID: 24231
Wheel Configuration: Straight
Dead Load
Moment (K ft)
Capacity (K Ft)
Rating Factor
Live Load (K ft)
BrR Model
Hand
Clacs
% Diff
320
320
0.0%
1828
2.07
1828
2.19
0.08%
-5.6%
688
May be round off error in
Distribution Factor. No
5.93%
detail output in BrR for
Live Load.
729
Reason
18
Superload
Difficulties Faced
• Installation issues with 64 vs. 32 bit
• Long time run process
• Memory issues
• Run only from bridge explorer
• Not able to get a detailed LL output.
19
Superload
20
Superload
http://www.youtube.com/watch?v=Dmacnt
5GaHw
http://www.youtube.com/watch?v=v8_3uy
ecXSc
21
Field Operations
Field Surveys
• LIDAR survey was taken before and after on 5 long
span structures.
• Calculated LL deflections from vehicle were up to 6”
• Survey showed before and after elevations of the
bridge deck surface and the bottoms of the girders
were within the tolerance of the method used.
• Any post move deflection was undetectable from a
survey perspective.
22
Field Operations
Structure 10720, Lee County
• Originally designated to be ‘jumped’
• Field review of route raised concerns about limited
hospital access for an extended period.
• Detour length = 50 miles.
• Hauler’s consultants recommended removing a 20 kip
counterweight from each of the tractors.
• Tractors effectiveness was limited due to traction
loss.
23
Field Operations
Structure 24362, Norton
• Rated by private consultant. Substructure controlled
at pier due to uneven span arrangement
• Travel restrictions were issued.
• During transport, hydraulic line broke while crossing
the structure. Lead tractor was over critical pier.
• After line replacement, vehicle initiated movement
from rear tractor, which was not on bridge.
24
Field Operations
Structure 22454, Norton
• Simple Span Plate Girder with partial depth welded
diaphragms
• First diaphragm on girder 4 cracked at the base.
• Retrofitted by drilling, arrested by next inspection
cycle.
25
26