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7/25/2019 42 PRES OTEC 2004 AdvancedStrategies
1/50
Profs: Arthur Helmicki, Victor Hunt, James Swanson,
Douglas Nims
Students: Xiaoyi Wang, Scott J. Kangas, Divyachapan
Padur, Lei Lu i, Balram Chamaria
Advanced Strategies and Recent Results on Health
Monitoring and Condition Assessment of Bridges
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UCII Ohio bridge field test program
24 "Healthy" Steel Stinger Bridges
16 Tested to Date
10 "Low Rated" Steel Stringer Bridges
8 Tested to Date
District 8:
HAM-27(x2),HAM-126(x3),CLE-52(x3),BUT-732, PRE-725,PRE-503, CLI-132
District 7:
AUG-75,MOT-70(x2),MOT-75
District 12:
LAK-90(x2),CUY-77(x2)
District 3:
RIC-30(x3)
District 10:
ATH-356
District 5:
LIC-184,FAI-33
District 11:
TUS-212,TUS-751
District 6:
MAD-70(x2),MAD-40
RIC-30-1384 7001320 3
RIC-30-1438 7001479 3
RIC-30-1638 7001517 3
FAI-33-7.31 2301067 5
MAD-70-1555L 4902858 6
MAD-70-1555R 4902882 6
MOT-70-2210 5706270 7
MOT-75-0776 5706939 7
HAM-126-1279 3104850 8
HAM-126-1317 3105172 8
TUS-212-1509 7904533 11
TUS-751-0420 7906307 11
CUY-77-0645L 1806181 12
CUY-77-0645R 1806211 12
LAK-90-1641L 4304624 12
LAK-90-1641R 4304659 12
BUT-732-1043 903841 8
PRE-725-0880 6804209 8
CLE-52-0498L 1301535 8
CLE-52-0498R 1301594 8
HAM-27-1550L 3101746 8HAM-27-1550R 3101770 8
LIC-158-0164 4505379 5
MAD-40-0745 4901290 6
MOT-70-0553 5704952 7
AUG-75-0201 601926 7
CLE-52-0142 1301357 8
CLI-132-0083 1402587 8
PRE-503-1170 6803660 8
ATH-356-0459 504203 10
2 More to Test
8 More to Test
24 Bridge Project
Low Rated Bridge Project
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Project Goals and Tasks
Develop database of experimental resultsfor more diverse population of steel-stringer
bridgesField Test 24 "Healthy" Bridges
Field Test 10 "Low Rated" Bridges
Demonstrate practicality and usefulness of
field test toolsStreamline On-site Test Capabilities
Modal Impact Test (Global Information)Crawl Speed Truck-load Test (Local Information)
Develop Software Tools
Efficient FE model generation
Efficient calibration techniques
Efficient rating calculations
Investigate Bridge Condition on StatisticalBasis
Analytical vs. Experimental Flexibility
AF N SB RQPMLKJIH
GEDC
1
OT
U
2
34
5
A B C D E H I J K L M P Q R SF N T U
-0.012-0.011
-0.010-0.009
-0.008-0.007
-0.006-0.005
-0.004-0.003-0.002-0.0010.000
Deflection(in.)
Calibrated ModelImpact Test
- non-posted condition
- 0.7 - 0.8 span ratio
- built after 1950
- # of spans
- skew
- composite/noncomp.
- stub or integral abut.
- max. span length
- bridge width
- mainline route
- ADTT>2500
Field Test 40 (6+24+10) Bridges
x bridges in eachfamily
statistical database for family
90% or 95% conf. interval
Stress(ksi)fromTr
uckLoad
Truckload Response, West Lane Path
Front Axle Location (feet)
North
Pier
South
Pier
South
Abutment
North
Abutment
0 20 40 60 80 100 120 140 160 180 200-1.3
1.3
-1
-0.5
0
0.5
1
NorthSpan,Beam3 MiddleSpan,Beam3 SouthSpan,Beam3South Pier, Beam 3
NorthSpan,Beam4 Middle Span, Beam 4 South Span, Beam 4
Girder 1
Girder 2
Girder 3
Girder 4
Girder 5
BUT-732-1043SN
4 Spaces
@ 8'-4.5"
= 33'-6"PathTruck Load
60'-0" 75'-0" 60'-0"
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UCII Field-Test-Based Rating Strategy
BridgeRecord
Data
Truckload
Test Data
ModalTest
Data
UCIIPost-Processing
Algorithms
UCIIPost-Processing
Algorithms
Analyticaland
Engineering
Calculations
Rating
Calculations
FE Modeling
Simulation, Rating,Condition Assessment,
Statistics, etc
Analytically-Based
RatingsField-Test-Based Ratings
and Other Results
Material/Sample
Test Data
Capacity, Dead Load, and Live Load
Actual Live LoadStresses andUnit InfluenceLines
Flexibility, ModeShape, andFrequency
Estimates of Capacity,
Live Load, and Dead Load
Exist ing Rating
Approach
UCII Field-Test-Bas ed
Approach
Actual MaterialStrengths, Modulusof Elasticity, andother Properties
Model
Calibration
Nominal FEModel
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Bridge Modeler Software
3 Span Bridge:
2571 Joints
1928 shell elements
1633 frame elements
3D FE Model4 Span Bridge:
3755 Joints 2820 shell elements
2125 frame elements
Bridge Modeler
Some Other Bridges:
More Joints
More elements
No. of Nodes and Elements
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3D FE Modeling Strategy
Cross-Section of Super Structure
Rigid Links
Support Links
Supports
Steel Girders
Abuts/Piers
Concrete Deck
Elevation of Bridge
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Strain/Stress Responses - UIL
-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
Stress(ksi)
Span 1 Span 2 Span 3
Stress Response
Unit Axle Load
Velocity
Stress Responses - UIL
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Mode Shapes - Mode Types
B-111-OO
T-111-OO
F-111-OO
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Identifying Modes of Bridge
Complex Mode Indicator Function (CMIF) assimilates all accel responses into 1 plotEach line represents a unique impact location (6 impact pts = 6 lines)
Frequency, (Hz)
0 5 10 15 20 25 3010
-9
10-8
10
-7
10-6
Complex Mode Indicator Function Plot
LogMag
Drop Hammer Accelerometer
Bridge
-37
-34
-31
-28
-25
-22
-19
-16
-13
0 20 40 60 80 100 120 140 160 180 200
Frequency (Hz)
Time (sec)
-20
0
20
40
60
80
100
-0.029 0.971 1.97 2.97 3.97
Input Signal Output Response
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
-0.06 0.94 1.94 2.94 3.94 4.94 5.94 6.94 7.94
Time (sec)
1.E-03
1.E-02
1.E-01
1.E+00
0 10 20 30 40 50 60LogMagnitude(g/lbf)
Frequency (Hz)
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o a r er verage on r u on
1st 9 mode shapes have been found to be common to 3-span, 5-girder bridges
These 9 modes dominate dynamic behavior (providing approx 90% of response)
0 25 50 75 100 125 150 175 200
F-111-OO 4.97 Hz
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0 25 50 75 100 125 150 175 200
T-111-OO 5.54 Hz
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 25 50 75 100 125 150 175 200
F-121-OO 7.26 Hz
5
4
3
2
1
0
1
2
3
4
0 25 50 75 100 125 150 175 200
T-121-OO 8.21 Hz
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
0 25 50 75 100 125 150 175 200
F-111-II 8.62 Hz
0
0.1
0.2
0.3
0.4
0.5
0 25 50 75 100 125 150 175 200
T-111-II 9.39 Hz
0 25 50 75 100 125 150 175 200
B-111-OO 11.86 Hz
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0 25 50 75 100 125 150 175 200
B-121-OO 14.19 Hz
-0.45
-0.4
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
0 20 40 60 80 100 120 140 160 180 200
B-111-II 14.70 Hz
1 2 3 4 5 6 7 8 9
F-111-OO T-111-OO F-121-OO T-121-OO F-111-II T-111-II B-111-OO B-121-OO B-111-II8.78 2.89 2.41 2.50 45.46 16.71 2.09 1.40 11.74Contribution (%)
Mode #
Mode Type
Girder 3Girder 4
F - Flexural
T - Torsional
B - Butterfly
I - In Phase
O - Out of Phase
1 - 1 peak in Span
2 - 2 Peaks in Span
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2
Truckload Testing
Data acquisition system Moving load weighed dump truck Strain gage
Truckload test measures the static response of a bridge
Local behavior of a bridge can be identified
The stress response obtained from the tests is used for bridge rating
A loaded dump truck with known axle weights is run at crawl speed, instead of static
test
Truck runs are conducted on all the lanes of the bridge
Truckload tests are conducted with minimum disturbance to the traffic
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2
Calibration Diagram
-0.4
-0.2
0
0.2
0.4
0 50 100 150 200 250
Mode #3 (6.0536 Hz,2.2014
Test data: Modal + Truckload
Nominal modelCalibration program
Calibrated model
Before calibration During calibration After calibration
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4
Advantages of Automatic Calibration
Hours: The weeks
work of calibration is
shortened to within 48hours.
Parameters: More FE
parameters are
calibrated, provide a
better data-fit to thereality.
0
100
200
300
400
500
600
manual calibration computer calibration
Auto-Calibration Advantages
hours
parameters
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6
Objective Function
UILUILFreqFreqMACMACBGCIBGCI OFwOFwOFwOFwGOF +++=
Calibration Process Diagram
0
0.05
0.1
0.15
0.2
0.25
0.3
0 100 200 300 400
Calibration Iterations
O
bjectiveFunctio
ns'Values
Global OF
BGCI OF
MAC OF
Frequency OF
UIL OF
Calibration is started from nominal model Calibration is done, Tuned Model
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7
Calibration Parameters
All the parametersare set with limitationto have realisticvalues.
10-6 ~ 1061Moment of Inertia of Rigid Links (IRL), in4
27000~3100029000Modulus of Elasticity of Steel (ES), ksi
6~11From planThickness of Deck (TD), in
2000~60004750Modulus of Elasticity of Concrete (EC), ksi
10-4 ~ 1051Moment of Inertia of Support Links (ISL), in4
10-2 ~ 1053000Area of Support Links (ASL), in2
Calibration
Limitation
Nominal
Value
Parameters
Flexible Support
Composite Action
IRL
EC,TD
ASL,ISLES
G l I f ti f P t d B id
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General Information of Parameters and Bridges
Parameter Summary Parameter Value
Parameter NameNominal Value Calibration Limitations
Area of Support Links (ASL), in2 3000 10-2 105
Moment of Inertia of Support Links (ISL), in4 1 10-4 105
Modulus of Elasticity of Concrete (EC), ksi 4750 2000 6000Thickness of Concrete Deck (TD), in From bridge plan 6
11
Modulus of Elasticity of Steel (ES), ksi 29000 27000 31000
Moment of Inertia of Rigid Links (IRL), in4 1 10-6 106
Bridge IntroductionBridge Overall
Length (ft.)YearBuilt
No. ofSupports
No. ofGirders
Skew Angle(Deg.)
DeckThickness (in.)
BUT-732-1043 195 1952 4 5 0 8.5
PRE-725-0800 192 1968 4 5 -10 7.75
HAM-27-1550L 175.5 1970 4 5 -9 9
HAM-27-1550R 195 1970 4 5 -9 9
CLE-52-0498L 221 1965 4 6 0 8.75
CLE-52-0498R 221 1965 4 6 0 8.75RIC-30-1438 221.5 1971 5 6 0 8.5
A f S t Li k V ti l Stiff
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Areas of Support Links-Vertical Stiffness
Support Links(Elevation) Bearing Conditions
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
BUT PRE HAM-L HAM-R CLE-L CLE-R RIC
Bridge
Area(in^2)
Cal Support1 Cal Support2 Cal Support3 Cal Support4
Cal Support5 Nom Max Min
Distribution of Areas of Support Links
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Modulus of Elasticity of Concrete
Concrete Stripes (Plan) Road Surface Conditions
1000
2000
3000
4000
5000
6000
7000
BUT PRE HAM-L HAM-R CLE-L CLE-R RIC
Bridge
ModulusofElastic
ity(ksi.)
Cal Girder1 Cal Girder2 Cal Girder3 Cal Girder4 Cal Girder5
Cal Girder6 Nom Max Min
Distribution of Modulus of Elasticity of Concrete
M t f I ti f Ri id Li k C it A ti
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Moment of Inertia of Rigid Links-Composite Action
Steel Girders (Elevation) Composite Action Levels
0.0000001
0.00001
0.001
0.1
10
1000
100000
10000000
BUT PRE HAM-L HAM-R CLE-L CLE-R RIC
Bridge
M
omentofInertia(in^4)
Cal Girder1 Cal Girder2 Cal Girder3 Cal Girder4 Cal Girder5
Cal Girder6 Nom Max Min
Distribution of Moment of Inertia of Rigid Links
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Bridge Rating Statistics
BARS, Trucktest, FE Model Load Rating Comparison
0
0.5
1
1.5
2
2.5
3
Rating
BARS 1.05 0.95 1.4 1.2
TRUCK TEST 1.63 1.6 2.54 2.56
Nominal Model 1.73 1.65 2.52 2.38
Tuned Model 1.35 1.66 2.64 2.66
BUT 732 PRE 725 CLE 52L HAM 27L
HS20 Truckload Rating
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1.52 1.52
1.36
1.73
1.261.22
1.16
1.42
1.06
0.92
0.77
0.82
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0903841 6804209 1301535 3101746
Butler Preble Clermont Hamilton
DF, ASD DF, LRFD DF, UCII
Distribution Factors for Similar Stringer Bridges
Distrib
utionFactor,WheelLiveload,TwoLan
es
1.0
3
2.06.0
125.975.0,
+=
S
g
Lt
K
L
SSLRFDDF
5.5,
SASDDF =
BARSM
UCIIMASDDFUCIIDF
LL
LL
,
,,, =
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30.47
39.34
43.21
52.35
10.83
12 12.25
13
2.24
10.61
14.10
15.66
6
7 7
8
0
10
20
30
40
50
60
0903841 6804209 1301535 3101746
Butler Preble Clermont Hamilton
0
2
4
6
8
10
12
14
16
18
%Reduction LL Crossframe Spacing (feet) Effective Deck Width (feet) General Appraisal (0-9)
Relationship of Design and Condition Parametersto the Reduction of BARS Liveload
ParameterValue
,asgivenintheKeybelow
RecuctionofBARSLive
load(%)
Can we use Inspection to Scale BARS LL?
An Effect of Xframe spacing?
An Effect of Unintended Composite Action?
Where is the increasing difference from BARS LL coming from?
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CONCLUSIONS TO DATE
Impact and truck-load testing can be performed pract ical ly andeff ic ient lylane-by-lane "rapid" multi-reference impact testing
lane-by-lane truck tests
Modal and truck-load tests provide rel iable, accur ate, us efulinformation on
bridge condition
Calibrated 3D FE models can be readily obtained and help establish more
realistic load-rating and safe load-carrying capacity
Objective methods meant to complement inspection and load-rating
NOT REPLACENOT REPLACE
US Grant Bridge: SCI 23 0000US Grant Bridge: SCI-23-0000
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View of construction site as of November 12, 2003(taken from OH side)
Digital rendering of completed structure(viewed from KY)
US Grant Bridge: SCI-23-0000US Grant Bridge: SCI-23-0000
View of construction site as of November 7, 2003(taken from KY tower)
P t ti l B fitP t ti l B fit
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Potential BenefitsPotential Benefits
Formation of a team with theknowledge and expertise to
support ODOT's efforts toeffectively manage thesestructures.
Support inspection efforts
Provide hard data forrecommendations on actions takenthroughout bridge life-cycle:construction and service.
Development of a databaseof objective field informationon these structures.
Translate an understanding of USGrant behavior.
Better understanding ofmaintenance issues.
Track USG structural performance.
Deeper understanding of thegeneral behavior andperformance of cable stayedbridges in general.
EVENTS LOAD EFFECTS
DEAD LOADS
INTRINSIC
FORCES
LIVE LOADS
CAPACITY
REDUCTION
CONSTRUCTION
ERECTION
FABRICATION
ACCIDENT
FLOOD
DETERIORATION
EARTHQUAKE
SEASONAL SOILCONDITION
ENVIRONMENTALCHANGES
LONG-TERM CLIMATE
AMBIENT CONDITIONCHANGES
TRAFFIC
HYDROLOGICAL
Safety?
Serviceability?
Overall Monitor ArchitectureOverall Monitor Architecture
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WeatherStation
CR-10Network
VW Gages
Thermistors
Low Speed/EnvironmentalMonitor
Traffic Monitor
OPTIM
ResistiveGages
Accelerometers
Main cabinetw/PC
ResearchLabs/ODOT
Web/Phone/ModemRemote Connection
Vibration Monitor
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Criterion Stay Cable
WORST RATING 1S, 1N
MAX LOAD FORCE 1S, 1N
MAX DEAD STRESS 8N
SUMMARY PLAN FOR INSTRUMENTATION OF
STAY CABLES 1, 8, & 16
4B 16A16B
INSTRUMENTED SECTION
COAXIAL and OTHER CABLE
MAIN COMPUTER CABINET
CSAT3 WIND SENSOR
NEMA Cabinet, 2 x 3 x 6 feetwith 120VAC, 15A power,
analog phone, and air vents
Computer with modem
(1) Campbell Scientific:
CSAT3 Wind Sensor
CR10X-2M datalogger
MD9 Multidrop
ENC 16/18 EnclosurePS12LA Power Supply
CSAT3 Wind Sensor
Optim Electronics:
continuous 200 samples per second
stores data crossing pre-set thresholds
(1) 3415 MEGADAC system
(8) AD808, 8-channel cards
Campbell Scientific:
(1) CR10X-2M datalogger
(1) MD9 Multidrop
(1) ENC 16/18 Enclosure
(1) AVW1 Interface
1N16N16S1S
KEY
From Page 166
of Bridge Plans
STAY CABLE CONTAINMENT INSTRUMENTATION
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STAY CABLE CONTAINMENT INSTRUMENTATION
Geokon Model VCE-4200
(16) Geokon Vibrating Wiresampled every 15 minutes
STRAIN GAGE PAIR
PVC CONDUIT
DATA SYSTEM
Strain gage pairs installed with steel clampto the rebar cage of the concrete
containment.
Strain gage cables routed through rebarcage to the data system cabinet.
Data system cabinet is embedded within orattached upon the pylon wall.
Strain gage pairs installed in aT or cross pattern in order to
measure radial and longitudinalstrains and deformations in the
containment immediately
adjacent to the cradle sheathfor the stay cable
KEY
Campbell Scientific:
(1) AM416 Multiplexer
(1) AM ENC Enclosure
Data System
From Page 111
of Bridge Plans
SECTION INSTRUMENTATION PLAN (S ti l Vi )
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Stay Cable Instrumentation:
(2) PCB Piezotronics
Capacitive Accelerometers (3701)
Note: roved to various
instrumented sections
Concrete Embedment Sensors:
(4) MM Resistive Foil
sampled during semi-annual tests
or connected to Vibration Monitor
Concrete Embedment Sensors:
(4) Geokon Vibrating Wire
sampled every 15 minutes
SECTION INSTRUMENTATION PLAN (Sectional View)
Geokon Model VCE-4200
Micro Measurements ModelEGP-5-120
Steel Tag-Welded Sensors:
(8) TM Resistive Foil Strainsampled during semi-annual tests
or connected to Vibration Monitor
Steel Epoxied Sensors:
(8) Geokon Vibrating Wire
sampled every 15 minutes
Geokon Model VSM-4000
Texas Measurements AWC-8B
PCB Model 3701
Campbell Scientific:(1) AM416 Multiplexer
(1) AM ENC Enclosure
Optim Electronics:
(2) AD808FB/120
Data System
STRAIN GAGE PAIRS:
Steel Foil and VWG
Concrete Foil and VWG
ACCELEROMETER
PVC CONDUIT
DATA SYSTEM
KEY
Close-up Sectional View of
CIP Joint over Fascia Girder
Not Shown: Longitudinal PVC Conduit in Exterior Traffic BarrierFrom Page 106
of Bridge Plans
From Page 162
of Bridge Plans
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Load Factor Inventory Rating Factors
[using HNTB section properties]
0.1
1
10
100
1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000
Station (feet), KY Tower at 1487 feet, OH Tower at 2362 feet
Ptv LL Moment (composite section) Neg LL Moment (noncomposite section)
Potential Sections to be Instrumented
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EXAMPLE SENSOR PLAN FOR AMBIENT MONITORING
DYNAMIC MODE SHAPES
US Grant Bridge Superstructure
PCB Piezotronics
Capacitive Accelerometers (3701)
Sensors installed in both
the Y and Z coordinates to
observe vertical and lateral modes
**MODE 1 FREQ 0.2918 CYC/SEC
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EXAMPLE SENSOR PLAN FOR AMBIENT MONITORING
DYNAMIC MODE SHAPES
US Grant Bridge Superstructure
PCB Piezotronics
Capacitive Accelerometers (3701)
Sensors installed in both ? (as high up as possible)
the X and Y coordinates to
observe longitudinal & lateral modes at stay anchor
**MODE 1 FREQ 1.0 3.0 CYC/SEC (not accounting for sag)
m
T
Lf
2
1=
OH Tower InstrumentationOH Tower Instrumentation Environmentalloads
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At approxEL 600'
N
Erec
tion
loa
ds
View of tower rebar cage
OH Tower @ EL 600 Moment and Axial Forces During Erection (B&T)
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0
2000
4000
6000
8000
10000
12000
14000
16000
1 4 710
13
16
19
22
25
28
31
34
37
40
43
46
49
52
55
58
61
64
67
70
73
76
79
82
85
88
91
94
97
100
103
106
109
112
115
Erection Stage
AxialForce(kip)
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
Moment(1000kip-ft)
P M
Towerpour
SegmentErection
Temporary bent
Creep,
Shrinkage,etc.
Opening Day
Maumee River CrossingMaumee River Crossing
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Recent view of construction site
Digital rendering of completed structure
Maumee River CrossingMaumee River Crossing
Instrumented Segment in Storage in Casting Yard
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Segment SelectionSegment Span 27-4 Span 27-41 Span 28-3 Span 28-28
In-Service
Highpoints
All bottom RFs low, Top
temp. RF low, Top LL is close
to abs. max., Segment
between two longest stays.
Good LL response, Bottom
RFs are high. Top RFs are low.
Near the center of back-span.
Low RFs. Both 27-67 and 28-
3 are near the shortest stays.
RFs are lower than 28-34. Best
bottom LL response and Low top
RFs.
In-Construction
Highpoints
Low max. stress, Not very
responsive to construction until
phase 210+ (Day 559).
Low max. stress, Responsive to
construction after phase 24
(Day350), Responsive to pier
removal, Stresses uniform
throughout the length.
Good construction response,
Uniform stress throughout
segment length.
Responsive through the end of
construction, Peaks pronounced
and good magnitude, Uniform
stress.
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TYPICAL SEGMENT
INSTRUMENTATION LAYOUT
STRA IN G AGE PAI RS:
LONG ITUDINAL
LATER AL
ACCELE ROMETER
PV C CON DU IT
JUNCTIO N BO X
Strain gag e pairs installed in r ebar cage by URT at time o f casting
Strain gage cables r outed by URT through r ebar cage to the junction boxes.
Junction boxes installed by con tractor within the concrete Je rsey barr ie rs.
Con duit with 3" inner diameter installed by contr actor to connect the junction boxes.
Geoko n Mode l VCE -420 0
Mic ro Me asure ment s Mode lEGP -5-35 0
MM Res istive FoilS tr ain Gage:
sampled during semi-annual tests
or connec tedto Vibration Moni tor
Geokon Vibr ating WireS tr ain Gage:
sampled every 15minutes
Campbell Scientific :
(1) C R10X-2Mdatalogger
(1) MD 9Multidrop
(1) ENC 16/18 Enc losure
(1) PS12LA Power Supply
(1) AM416 M ultipl exer
(1) AVW1 Inter face
Ca mpbe ll Sci entif i c
Mod el CR -10X- 2M
Note : The fo ur such sege ments of t he MRC wil l be instr umented. The a bovediagram is sim ply a repr esentation of the instrum entation plan . All conduit a ndcables to be provided concurrent with section e rection, with installation to t heJersey bar rier concu rrent with ba rrier con struction and with installation of1 20VAC power concur rent with othe r bridge electrical wo rk.
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VIEWS OF EMBEDMENT GAGE
INSTALLATIONS
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VIEWS OF INSTRUMENTED
SEGMENTS
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1
2 2
1
Instrumentation plan
One vibrating wire and one sister bar at each location
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Delta frame Storage and vertical lifting position
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Delta frame Tensioning tendons layout
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Post-tensioning sequenceData Collection
Stage #1 DF2 tensioned (2pm)
Stage #2 DF3 tensioned (2:26pm)
Stage #3 DF1 tensioned (2:42pm)
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Strain gage readingsGage readings during t he process of tensioning
-80
-60
-40
-20
0
20
40
60
80
100
Time
1100
1115
1130
1145
1200
1215
1230
1245
1300
1315
1330
1345
1400
1415
1430
1445
1500
1515
1530
1545
1600
1615
1630
1645
Time (hrs)
Readings(micr
ostrains)
18BVNTO
18BSNTO
18BSNBI
18BVSTO
18BSSTO
18BVSBI
18BSSBI
Prestressing
begins
DF2 tensioned
DF3 tensioned
DF1 tensioned
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Modeling in BD2
2D dimensional stiffness method
Can model post-tensioning losses
Other losses like elastic shortening are also modeled
Good for staged loading
Time dependent properties like shrinkage and creep can also be
modeled, but not considered in this analysis as the process takesplace over a span of only one hour.
Duct properties used as provided by the consultant
Jacking forces and seating loss obtained by PT stressing log
Used for change in strains due to tensioning of tendons
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Modeling in BD2
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Test-Model CorrelationAssumptions:
Plane section remains plane
Homogeneous materials No cracks in the bottom chord
Strain gages not dislocated and measurement in the rightdirection
No affect in accuracy of gages due to temperature The gage represents its centerline strains
Linear noise can be separated by simple arithmetic's
Immediate force transfer
No effect of shrinkage, creep and temperature (over a shortperiod of 1 hr)
No effect of dead load deformations
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Comparison: Normalized strains
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Comparison: Normalized strains
Great match after
normalizing.
Analytical and
experimental resultsagree well at all three
stages.
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Conclusion
No crack in bottom chord Very good agreement between analytical
and experimental results
Eccentricity is an issue while using 2D
models
Losses and other design assumptions arefairly accurate