DEVELOPMENT OF A HYBRID BRIDGE EVALUATION SYSTEM by ANDREAS JOHANN FELBER

297 Pages·2009·5.01 MB·English

DEVELOPMENT OF A HYBRID BRIDGE EVALUATION SYSTEM
by
ANDREAS JOHANN FELBER
B.A.Sc., The University ofBritish Columbia, 1988
M.A.Sc., The University ofToronto, 1990
A THESIS IN PARTIALFULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OFPHILOSOPHY
in
THE FACULTY OF GRADUATE STUDIES
Department of Civil Engineering
We accept this thesis as conforming
to the required standard
THE UNIVERSITY OF BRITISH COLUMBIA
December 1993
© Andreas Johann Felber, 1993
____________________________________
In presenting this thesis in partial fulfilment of the requirements for an advanced
degree at the University of British Columbia, I agree that the Library shall make it
freely available for reference and study. I further agree that permission for extensive
copying of this thesis for scholarly purposes may be granted by the head of my
department or by his or her representatives. It. is understood that copying or
publication of this thesis for financial gain shall not be allowed without my written
permission.
(Signature)
Department of /1/?/
The University of British Columbia
Vancouver, Canada
/93
/2
Date
DE-6 (2188)
11
Abstract
There is an increasing need to verify analytical dynamic models used for the seismic evaluation of
existing bridges. During a retrofit evaluation, analytical models are created to predict the bridge
response and damage levels due to seismic loading. These models should be verified so damage
levels can be determined more confidently. Currently experimental studies are only occasionally
performed on existing structures to verify analytical models because existing testing methods are
toocostly, require traffic shutdowns, and do not deliverresults quickly enough for routine use.
To overcome these limitations, the hybrid bridge evaluation system (HBES) was developed using
ambient vibration techniques to inexpensively and quickly determine the dynamic characteristics
ofalargevarietyofstructures. TheHBEScombinesstateoftheartvibrationmeasurementhardware
with a series of custom developed programs to expedite ambient vibration studies. In particular,
two new functions were developed and implemented as partofthe HBES software to interpret the
dataquickly. These functions made itpossible to analyse thedataobtained from ambient vibration
measurements in the field. This is a considerable advancement over traditional systems which
require several weeks ofdata analysis afterthe field workis completed. Sincepartialexperimental
results can be obtained with the HBES while some of the tests are still in progress, the quality of
the collectedinformation can be assessed before leaving the site. Afterreturning from the site, the
experimental results can be used to verify and tune analytical models.
A numberoftestswere conductedaspartofthisthesis whichdemonstrate theHBES’ performance.
The study ofthe Shipshaw Bridge data, which was analyzed in one day, demonstrated the unique
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speed of the system. The study of the Squamish Wharf demonstrated the system’s capability to
determine the dynamic characteristics of structures with very small ambient vibrations levels (+1-
0.02 mg). The complete study of the Colquitz River Bridge was used to evaluate the HBES’
components and their integration. This study confirmed the suitability of the hardware and
demonstratedthat the integratedprograms were capable ofexpeditiously acquiring, analyzing, and
interpreting large amounts of data. The experimentally obtained characteristics of the structure
were used to refine the structure’s analytical models. The HBES system can now be used as an
effective tool in the seismic evaluation ofbridges.
iv
Table of Contents
Page
Abstract ii
List ofTables vi
List ofFigures viii
Nomenclature xvi
Acknowledgements xviii
Dedication Xix
Chapter 1 Introduction 1
1.1 General Problem 1
1.2 Current Research 3
1.3 Objectives and Outline ofthis Thesis 4
1.4 Future Applications 5
Chapter 2 Review of Structural Dynamic Testing Concepts 7
2.1 Theoretical Background on Structural Dynamics 7
2.2 Forced Vibration Testing Methods 16
2.3 Ambient Vibration Testing Methods 21
Chapter 3 Development ofthe Hybrid Bridge Evaluation System 34
3.1 Vibration Measurementson the Second Narrows Bridge 35
3.2 HBES Hardware Description 41
3.3 HBES SoftwareDescription 49
3.4 Software and Hardware Interaction 67
V
Chapter4 Application ofthe Hybrid Bridge Evaluation System 71
4.1 Preliminary Verification ofthe HBES Software 71
.
4.2 Study ofthe Shipshaw Bridge Vibration Data 76
4.3 Study ofthe Colquitz River Bridge 87
4.4 Study ofthe Squamish Wharf 149
Chapter 5 Summary of the Features of the Hybrid Bridge evaluation System 156
. .
Conclusions 159
List ofReferences 162
Appendix A Measurement Hardware Selection and Specifications 170
.
Appendix B Program AVTEST User’s Manual 206
. .
Appendix C Program ULTRA User’s Manual 214
. .
Appendix D Program VISUAL User’s Manual 255
. .
Appendix E Program SUBSAP User’s Manual 265
. .
Appendix F Details ofIndividual Test Setups 269
. . .
Appendix G Index ofTerms and Abbreviations 276
vi
List of Tables
Page
Table 4.1: AnalyticalDerivedandNumericallyObtained Dynamic Characteristicsof
the Three Degree ofFreedom System Example 74
Table 4.2: SensorLocations for Shipshaw Bridge Tests 80
Table 4.3: Experimentally Determined and Analytically Derived Frequencies of the
Shipshaw Bridge 84
Table 4.4: Key Element Properties for the Base Model ofthe Colquitz River Bridge 91
Table 4.5: Experimentally Determined Modal Frequencies of the Colquitz River
Bridge 100
Table 4.6: Damping Estimates from the First Ten Cycles ofthe Transverse Pullback
Test ofthe Colquitz River Bridge 113
Table 4.7: DampingEstimatesfromtheFirstTenCyclesoftheLongitudinalPullback
Test ofthe Colquitz River Bridge 117
Table 4.8: Effective Moments of Inertia of Beam Elements for the Colquitz River
Bridge Model 127
Table 4.9: Experimentally Determined and Analytically Derived Frequencies of the
Colquitz River Bridge 140
Table 4.10: DifferenceBetweenExperimentallyDeterminedandAnalyticallyDerived
Frequencies ofthe Colquitz River Bridge 141
vii
Table 4.11: Experimentally Determined Frequencies of the Squamish Wharf 152
.
Table A.1: AmplificationLevels of the Kinemetrics Signal Conditioner 186
Table A.2: Configuration ofHardware Components forHardware Test 202
Table F.1: Sensor Locations for Vertical Ambient Vibration Survey at the Colquitz
River Bridge 270
Table F.2: SensorLocationsforTransverseAmbientVibration SurveyattheColquitz
River Bridge 271
Table P.3: Sensor Locations for Longitudinal Ambient Vibration Survey at the
Colquitz River Bridge 272
Table F.4: Sensor Locations for Transverse Pullback Tests at the Colquitz River
Bridge 273
Table F.5: Sensor Locations for Longitudinal Pullback Tests at the Colquitz River
Bridge 273
Table F.6: Sensor Locations for Ambient Vibration Tests at the Squamish Wharf 275
viii
List of Figures
Page
Fig. 2.1 Idealized Single Degree ofFreedom Model 8
Fig. 2.2 Absolute Value and Phase Angle of The Dimensionless Frequency
Response Function 12
Fig. 2.3 Three Degree ofFreedomExample 13
Fig. 2.4 Mode Shapes and Natural Frequencies of the Three Degree of Freedom
Example 16
Fig. 2.5 Acceleration Response of a Undamped SDOF System to Initial
Displacements 20
Fig. 2.6 RoofAccelerationResponseofaThreeDegreeofFreedomSystemSubject
to White Noise Excitation 25
Fig. 2.7 Acceleration PSD of Top Mass of Three DOF System Subject to White
Noise Excitation 26
Fig. 3.1: View ofthe Second Narrows Bridge 37
Fig. 3.2: Elevation View of the Second Narrows Bridge 37
Fig. 3.3: Typical Recording Setup for Ambient Vibration Measurements 42
Fig. 3.4: HBES Sensor Attached to a Steel Beam 43
Fig. 3.5: Ambient Vibration Measurement Hardware 43
Fig. 3.6: Quick Release Mechanism 48
ix
Fig. 3.7: Typical Release Force Time History of the QRM Developed at UBC 49
.
Fig. 3.8: Schematic ofData Reduction with ULTRA 52
Fig. 3.9: Transfer Function of Sample Data 56
Fig. 3.10: Phase Angle of SampleData 57
Fig. 3.11: Phase Window Function Corresponding to Sample Data 57
Fig. 3.12: Coherence Function ofSample Data 58
Fig. 3.13: Coherence Window Function Corresponding to Sample Data 58
Fig. 3.14: Potential Modal Ratio Function ofSample Data 59
Fig. 3.15: Schematic ofData Interpretation with Visual 62
Fig. 3.16: Relationship Between the Series, Signal, and Spectra Classes 66
Fig. 3.17: Interaction of AVTEST, ULTRA, VISUAL, and the Measurement
Hardware 68
Fig. 3.18: Interaction ofSUBSAP and SAP9O 70
Fig. 4.1: ANPSD for the Three Degree ofFreedom System Example 73
Fig. 4.2: View ofthe Shipshaw Bridge 77
Fig. 4.3: Sensor Locations for the Shipshaw Bridge 80
Fig. 4.4: Acceleration RecordforSensorNo.6Duringthe5thTestofthe Shipshaw
Bridge 81
Fig. 4.5: AccelerationRecordforSensorNo.3Duringthe2ndTestofthe Shipshaw
Bridge 81