42 PRES OTEC 2004 AdvancedStrategies

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


2/50

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


3/50

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"


4/50

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


5/50

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


6/50

3D FE Modeling Strategy

Cross-Section of Super Structure

Rigid Links

Support Links

Supports

Steel Girders

Abuts/Piers

Concrete Deck

Elevation of Bridge


7/50

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


8/50

Mode Shapes - Mode Types

B-111-OO

T-111-OO

F-111-OO


9/50

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)


10/50

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


11/50

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


12/50

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


13/50

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


14/50

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


15/50

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


16/50

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


17/50

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


18/50

Modulus of Elasticity of Concrete

Concrete Stripes (Plan) Road Surface Conditions

1000

2000

3000

4000

5000

6000

7000


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


19/50

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


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


20/50

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


21/50

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

,

,,, =


22/50

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?


23/50

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


24/50

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


25/50

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


26/50

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


27/50

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


28/50

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 )


29/50

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


30/50

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


31/50

EXAMPLE SENSOR PLAN FOR AMBIENT MONITORING

DYNAMIC MODE SHAPES

US Grant Bridge Superstructure

PCB Piezotronics


Sensors installed in both

the Y and Z coordinates to

observe vertical and lateral modes

**MODE 1 FREQ 0.2918 CYC/SEC


32/50

EXAMPLE SENSOR PLAN FOR AMBIENT MONITORING

DYNAMIC MODE SHAPES

US Grant Bridge Superstructure

PCB Piezotronics


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


33/50

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)


34/50

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


35/50

Recent view of construction site

Digital rendering of completed structure

Maumee River CrossingMaumee River Crossing

Instrumented Segment in Storage in Casting Yard


36/50

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.


37/50

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.


38/50

VIEWS OF EMBEDMENT GAGE

INSTALLATIONS


39/50

VIEWS OF INSTRUMENTED

SEGMENTS


40/50

1

2 2

1

Instrumentation plan

One vibrating wire and one sister bar at each location


41/50

Delta frame Storage and vertical lifting position


42/50

Delta frame Tensioning tendons layout


43/50

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

42 PRES OTEC 2004 AdvancedStrategies

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