Development and Evaluation of a Removable and Portable Strain Sensor for Short-term Live ...

259 Pages·2006·15 MB·English

Development and Evaluation of a Removable and Portable Strain
Sensor for Short-term Live Loading of Bridge Structures

By
Carl L. Schneeman, B.S.C.E.

A Thesis submitted to the Faculty of the Graduate School, Marquette University, in
Partial Fulfillment of the Requirement for the Degree of
Master of Science

Milwaukee, Wisconsin
2006
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Preface
Historically, bridges have been constructed in many different ways. As economic
conditions change, so do the materials and methods used in construction. To evaluate the
use of new materials for these structures, research and development is conduced to
determine their adequacy in modern construction. However, long-term results are
required for analysis of bridges, as they are constructed to remain in service for extended
periods of time. Additionally, a fundamental understanding and proper selection of the
tools used in bridge monitoring is required.
This thesis presents a detailed discussion of the state of bridge monitoring,
development and operation of a removable strain sensor to be used in collecting data on
bridge structures, and guidelines for a future load test of a bridge in northern Wisconsin.
Observations and conclusions of the study are made as well, with recommendations for
future work on this topic.
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Acknowledgements
I would like to thank the many people who have helped in numerous ways
throughout my tenure at Marquette. Without their support and help none of this work
would have been possible.
The members of my advisory committee have been wonderful. Dr. Chris Foley
has been a tireless and selfless mentor to me. Never before have I worked with an
individual so passionate and dedicated. His constant drive to teach others has benefited
me countless ways. Drs. Stephen Heinrich and Baolin Wan both were extremely helpful
in my classes and during my thesis work.
The many people working for the laboratories of Marquette need to be
recognized. Dave Newman has been an instrumental person for me. His frequent
questions, new challenges, and often used humor have helped shape my education in so
many positive ways. Our students are fortunate to have such a wealth of experience to
learn from. Tom Silman’s help and guidance requires thanks also. Without his tireless
flexibility my late hours in the machine shop would not have been possible.
Additionally, John Boudnik’s willingness to help at any time is much appreciated.
To those in the working world who have shown me what being a professional
means. Many thanks are directed to John Pluta at MSI General, who was the first to truly
show me how to be an engineer. The generosity of Victory Steel of Milwaukee and
Construction Supply & Errection of Germantown, WI are to be commended – their
willingness to aid the university is instrumental to our successes.
Thanks are also due to so many people who have pushed me to go beyond what is
required. People like Andy Basta, Nick Hornyak, Kristine Martin, Panchito Ojeda, Brian
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Porter, and Danny Stadig, have been a mainstay for me. Their support, suggestions and
assistance in all aspects of life have left are truly valued.
Many thanks are due to my girlfriend, Meg Taylor. She has been a pillar of
stability for me, constantly supporting me in my endeavors.
Finally, my family has also been wonderful. My parents, Chris and Cathy, and
siblings, Pat, Dan, Matt and Lucy, have always provided me with endless support. How
they have sustained my many engineering lectures and overly-scientific explanations of
daily occurrences is amazing.
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Table of Contents
1. Introduction and Summary of Work
1.0 Introduction……………………………………………………………………. 1
1.1 The De Neveu Creek IBRC Bridge…………………………………………… 3
1.2 Objective of Thesis…………………………………………………………… 6
1.3 Scope of Thesis………………………………………………………………... 7
2. Literature Review and Synthesis
2.0 Introduction …………………………………………………………………… 8
2.1 Instrumentation Guidelines…………………………………………………… 8
2.2 The De Neveu Creek IBRC Bridge …………………………………………... 13
2.2.1. FRP Reinforcement in the De Neveu Bridge…………………………... 15
2.2.2. Development and Testing of the FRP-grillage Reinforced Deck ……... 17
2.3 Load Testing of the De Neveu Creek Bridge ………………………………… 20
2.3.1. Strain Gage Instrumentation of the Bridge ……………………………. 21
2.3.2. In-Situ Load Test of B-20-148 FRP Bridge …………………………… 23
2.3.3. In-Situ Load Test of B-20-149 Conventional Bridge …………………. 26
2.3.4. Results of B-148 and B-149 Load Tests ………………………………. 27
2.4 Ohio Bridge HAM-126-0881 ………………………………………………… 31
2.4.1. Data Acquisition System Employed …………………………………... 32
2.4.2. Load Testing and Results ……………………………………………… 34
2.5 South Carolina Route S655 …………………………………………………... 37
2.5.1. GFRP Panels …………………………………………………………... 38
2.5.2. Instrumentation and Load Testing …………………………………….. 40
2.6 Fairground Road Bridge ……………………………………………………… 44
2.6.1. Study of Composite Action and Strain Measurements ……………….. 45
2.6.2. Load Testing and Results………………………………………………. 46
2.7 The Bridge Street Bridge……………………………………………………… 50
2.7.1. Materials Used ………………………………………………………… 51
2.7.2. Instrumentation ………………………………………………………... 52
2.7.3. Load Test and Results …………………………………………………. 53
2.8 Synthesis of Literature ………………………………………………………... 55
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3. Data Acquisition and Strain Measurement
3.0 Introduction …………………………………………………………………… 59
3.1 Signal Processing ……………………………………………………………... 59
3.1.1. Analog to Digital Conversion ………………………………………… 60
3.1.2. Sampling Rates………………………………………………………… 63
3.1.3. Signal Amplification…………………………………………………… 64
3.1.4. Signal Filtering………………………………………………………… 69
3.2 Measurement with Electrical Resistance Strain Gages ………………………. 75
3.3 Strain Gage Measurement Errors …………………………………………….. 83
3.4 String Potentiometers and Linear Position Sensors …………………………... 90
3.5 DASYLab Data Acquisition Software ……………………………………….. 93
3.5.1. Installation of ADC Modules …………………………………………. 96
3.5.2. Installation of Digital Filtering ………………………………………... 99
3.5.3. The Black Box Module ………………………………………………... 102
3.5.4. Offset Adjustment of Signals………………………………………….. 104
3.5.5. Establishment of Calibration Modules …………………………………108
3.5.6. Continuous Unit Conversion ………………………………………….. 113
3.5.7. Duplicating the Black Box for use with Transducers ………………… 115
3.5.8. Configuring the Black Box for Use with Different Channels…………. 117
4. Development and Testing of a Portable Strain Sensor
4.0 Introduction …………………………………………………………………… 123
4.1 Quarter Bridge Circuit Selection ……………………………………………... 124
4.2 Material Experimentation and Selection ……………………………………... 127
4.3 Description of Portable Strain Sensor ………………………………………… 130
4.4 Anchorage of the Sensor ……………………………………………………… 133
4.5 Laboratory Validation…………………………………………………………. 135
4.5.1. Torque Level Tests ……………………………………………………. 140
4.5.2. Evaluation of Washer Presence………………………………………... 142
4.5.3. Excitation Voltage Evaluation…………………………………………. 143
4.6 Finite Element Analysis ………………………………………………………. 144
4.6.1. Finite Element Model of Test Beam …………………………………... 145
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4.6.2. Finite Element Model of Strain Sensor ……………………………….. 149
4.7 Calibration of Individual Strain Sensors for Field Implementation ………….. 163
4.7.1. Calibration Method and Equipment Used………………………………163
4.7.2. Data Recorded during Load Tests …………………………………….. 166
4.7.3. Individual Calibration Factors…………………………………………. 169
5. Proposed Load Test
5.0 Introduction …………………………………………………………………… 171
5.1 Load Test Objectives and Instruments………………………………………... 171
5.2 Permanently Installed Equipment……………………………………………... 177
5.2.1. Lead Wiring for Instruments…………………………………………… 177
5.2.2. Enclosure Box and Screw Terminals…………………………………... 180
5.2.3. Installation of Strain Sensors…………………………………………... 184
5.3 Load Test Vehicles and Test Configuration…………………………………... 187
5.3.1. Load Test Objectives…………………………………………………... 188
5.3.2. Load Test Configurations……………………………………………… 189
5.4 Data Acquisition System……………………………………………………… 193
5.4.1. Signal Conditioning Modules………………………………………….. 196
5.4.2. Connection to Strain Gage Modules…………………………………… 198
5.4.3. Acquisition Software…………………………………………………... 200
5.4.4. Error Correction in Readings…………………………………………... 201
6. Summary and Conclusions
6.0 Summary……………………………………………………………………… 203
6.1 Conclusions…………………………………………………………………… 204
6.2 Recommendations for Future Research………………………………………. 206

References……………………………………………………………………………… 210
Appendix A…………………………………………………………………………….. 214
Appendix B……………………………………………………………………………..235
Appendix C……………………………………………………………………………..241
Appendix D……………………………………………………………………………..244
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List of Figures
Figure 1.1.1 – Wisconsin Highways 151 before (left) the bypass and after (right) 4
Figure 1.1.2 – The De Neveu Creek Bridge 5
Figure 2.2.1 – The De Neveu Creek Bridge, WI B-20-148 14
Figure 2.2.2 – Cross section of the De Neveu Creek Bridge 15
Figure 2.2.3 – Assembled FRP grillage 15
Figure 2.2.4 – Cross sections of FRP materials used 16
Figure 2.2.5 – Simple-span slab tests 19
Figure 2.2.6 – Restrained end slab tests 19
Figure 2.3.1 – Layout of surveying prisms and strain gages 21
Figure 2.3.2 – Strain gage locations 22
Figure 2.3.3 – Strain gage locations 22
Figure 2.3.4 – Stopped vehicle locations for live-load testing of B-20-148 FRP 25
Figure 2.3.5 – Stopped vehicle locations for live-load testing of
B-20-149 Conventional 27
Figure 2.3.6 – Deflection plot of mid-span girder response in bridge B-20-148 FRP 28
Figure 2.3.7 – Deflection plot of mid-span girder response in bridge B-20-149
Conventional 29
Figure 2.4.1 – Schematic of Ohio Bridge HAM-126-0881 32
Figure 2.4.2 – Static live-load Cases A through L 35
Figure 2.4.3 – Method for calculating internal moments in stingers 37
Figure 2.5.1 – Individual Duraspan® deck panels 39
Figure 2.5.2 – Section of bridge deck and integral grout-filled shear pockets 39
Figure 2.5.3 – Instrument layout of S655 Bridge 41
Figure 2.5.4 – Live-load test cases for S655 Bridge 42
Figure 2.6.1 – Instrumentation layout of the Fairground Road Bridge 46
Figure 2.6.2 – Bridge Diagnostics Strain Transducer 46
Figure 2.6.2 – Method used to locate the neutral axis of stringers 48
Figure 2.6.3 – Comparison of composite nature stress profiles through a typical deck
section 48
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Figure 2.6.4 – Top flange tensile “spike” observed in stringers during live load
testing 49
Figure 2.7.1 – Bridge Street Bridge cross section 51
Figure 2.7.2 – Strain gage location in instrumented spans of Structure B 52
Figure 2.7.3 – Long-term instrumented spans of Structure B 53
Figure 2.7.4 – Live-load test cases for Bridge Street Bridge 54
Figure 3.1.1 – Layout of a typical data acquisition system 60
Figure 3.1.2 – Application of the Nyquist Theorem 63
Figure 3.1.3 – Block diagram of an IOTech DBK43A 66
Figure 3.1.4 – Signal path of the “OFFSET” trimpot 67
Figure 3.1.5 – Signal path during adjustment of the input amplifier gain 68
Figure 3.1.6 – Signal path during adjustment of the scaling amplifier gain 69
Figure 3.1.7 – Typical low-pass frequency response 70
Figure 3.1.8 – Butterworth low-pass filter response 71
Figure 3.1.9 – Chebyshev low-pass filter response 71
Figure 3.1.10 – Comparison of filtered (b & c) and unfiltered data (a) 72
Figure 3.1.11 – (a) standard wave composed of AC and DC signals, (b) AC
Coupled wave 73
Figure 3.2.1 – Typical strain gage 76
Figure 3.2.2 – The Wheatstone bridge 76
Figure 3.2.3 – Typical configurations of the Wheatstone bridge 77
Figure 3.2.4 – Diagram of variables used in calculations 78
Figure 3.2.5 – Simulated strain via shunt calibration 80
Figure 3.3.1 – Quarter bridge strain gage configurations 84
Figure 3.3.2 – Nonlinearity errors for tensile strains in bridge circuits 89
Figure 3.4.1 – Circuit diagram of a typical three-wire transducer 91
Figure 3.4.2 – 30-inch String Potentiometer 92
Figure 3.4.3 – 4-inch Linear Position Sensor 92
Figure 3.4.4 – Linear calibration of sensors 93
Figure 3.5.1 – Data acquisition worksheet 94
Figure 3.5.2 – Logical map of software configuration 95
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Figure 3.5.3 – Hardware configuration window 97
Figure 3.5.4 – Hardware configuration window on the main worksheet 98
Figure 3.5.5 – Expansion of analog inputs in the DBK43A module 99
Figure 3.5.6 – Defining global variables 100
Figure 3.5.7 – Defining filtration properties for each channel within the filter
module dialog box 101
Figure 3.5.8 – ADC and filter modules connected on the worksheet 101
Figure 3.5.9 – Locating a new black box on the main worksheet (left) and opening
the black box (right) 102
Figure 3.5.10 – Modules installed in the black box 104
Figure 3.5.11 – Offset adjust modules and digital meter in black box 105
Figure 3.5.12 – Specification of the Switch module operation 106
Figure 3.5.13 – Specification of the Action module operation 107
Figure 3.5.14 – Specification of the Digital Meter module operation 108
Figure 3.5.15 – Linear scaling from shunt calibration 109
Figure 3.5.16 – Locating the Linear Scaling/Unit Conversion module on the black
box workshet 10
Figure 3.5.17 – Flow chart depicting the signal path while acquiring simulated
strain voltages from shunt calibration 111
Figure 3.5.18 – Storing global variables for calibration 112
Figure 3.5.19 – Setting linear scaling values for individual strain gages 114
Figure 3.5.20 – Signal path of completed black box worksheet for linear scaling 114
Figure 3.5.21 – Saving the active black box for future applications 115
Figure 3.5.22 – Flow of dialog boxes while saving a black box for future use 116
Figure 3.5.23 – Modified black box for DBK65 transducer channels 117
Figure 3.5.24 – Modifications of the black box for DBK65 transducer channels 119
Figure 3.5.25 – Signal path from the black boxes to the Write Data module 120
Figure 3.5.26 – Specifying data recording options 120
Figure 3.5.27 – Overview of completed worksheet 122
Figure 4.1.1 – Quarter bridge circuit used during laboratory experimentation
with the DaqBook 2000 system 126