A Thesis entitled Ice Prevention and Weather Monitoring on Cable-Stayed Bridges by Nutthavit Likitkumchorn Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Mechanical Engineering ________________________________________ Dr. Terry Ng, Committee Chair ________________________________________ Dr. Douglas K. Nims, Committee Member ________________________________________ Dr. Victor J. Hunt, Committee Member ________________________________________ Dr. Patricia R. Komuniecki, Dean College of Graduate Studies The University of Toledo August 2014 Copyright 2014, Nutthavit Likitkumchorn This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Ice Prevention and Weather Monitoring on Cable-Stayed Bridges by Nutthavit Likitkumchorn Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Mechanical Engineering The University of Toledo August 2014 The Veteran’s Glass City Skyway (VGCS) is a large cable-stayed bridge with a single pylon. Since the bridge has gone into service in 2007, five major icing events have occurred causing a high risk to traveling public and lanes and/or bridge closures. Several studies have been conducted to help the Ohio Department of Transportation (ODOT) in developing ice hazard mitigation strategies. This thesis addresses four aspects of the strategies including the development of (1) an ice presence-and-state sensor, (2) a suitable thickness measurement device for this project, (3) anti and de-icing strategies using internal heating, and (4) anti-icing strategy using superhydrophobic coatings. An “ice presence-and-state sensor” (UT icing sensor) based on electric impendence was successfully developed. The sensor is rugged and compact, and can be mounted directly on the stay. Once mounted, it has the ability to identify the presence of, ice, slush (wet snow), or water. Currently the sensor is ready for deployment for actual application on the VGCS bridge. Additionally, an “UT laser thickness sensor” was found to be suitable for detecting a full profile of ice or snow thickness on a stay. None of the anti/deicing strategies tested was found to be a solution for VGCS icing problems. The internal heating method failed to prevent ice from accumulating on the iii specimen in windy condition. Though it can, in theory, melt the accumulated ice to avoid shedding, the cost of implementing the method will likely to be very high. The super- hydrophobic coatings tested also failed to prevent ice accumulation. Contrary to initially assumed, the ice accumulation rate is actually higher on a coated specimen than one that is uncoated. iv Acknowledgements First of all, I would like to express deepest gratitude and appreciation to both my advisors Dr. Douglas K. Nims, a faculty member in The Department of Civil Engineering and Dr. Terry Ng, a faculty member in The Department of Mechanical Engineering for their full support, expert guidance, and encouragement throughout my study and research. I also would like to thank Dr. Hunt for having served on my committee. His thoughtful questions and comments were valued greatly. Thanks also go to my colleagues from the University of Toledo Mr. Ahmed Abdelaal, Mr. Clinton Mirto, and Mr. Ali Arbabzadegan for helping me performing the experiments and guided me with their experience. I really appreciated it. I would like to thank the University of Cincinnati graduate students and professors for their efforts in development of dashboard and installation of bridge sensors. This project was sponsored by the Ohio Department of Transportation. The author gratefully acknowledges their financial support this study. Finally, I wish to express my sincere thanks to my family for their unconditional love and support for the past years and giving me the opportunities to study abroad. I would not have been able to complete this thesis without their love and encouragement. v Table of Contents Abstract .............................................................................................................................. iii Acknowledgements ..............................................................................................................v Table of Contents ............................................................................................................... vi List of Tables .....................................................................................................................x List of Figures .................................................................................................................... xi List of Abbreviations ....................................................................................................... xix List of Symbols ..................................................................................................................xx 1 Introduction … .........................................................................................................1 1.1 Statement of Problem .........................................................................................1 1.2 General Bridge Information ...............................................................................3 1.3 Objective…. .......................................................................................................5 1.4 Organization .......................................................................................................6 2 Literature Review….................................................................................................7 2.1 Introduction to Icing ..........................................................................................7 2.1.1 In-Cloud Icing .....................................................................................7 2.1.2 Precipitation ........................................................................................9 2.1.3 Frost ..................................................................................................11 2.2 History of Icing Events on VGCS ...................................................................12 2.3 Anti-Icing and De-Icing ...................................................................................15 vi 2.3.1 Heating ..............................................................................................15 2.3.2 Superhydrophobic Coating ...............................................................16 2.4 Available Sensors.............................................................................................17 2.4.1 Dielectric Leaf Wetness Sensor ........................................................18 2.4.2 Ultrasonic Ranging Sensor ...............................................................20 2.4.2.1 SR50AT .............................................................................21 2.4.2.2 AGKU1500GI ....................................................................23 3 Ice Presence and State Sensor Development .........................................................27 3.1 Introduction ......................................................................................................27 3.2 Ice Presence and State Sensor Laboratory Test ...............................................28 3.2.1 Sensors and Data Acquisition System ..............................................29 3.2.2 Design of Experiment .......................................................................32 3.2.3 Laboratory Test Results ....................................................................37 3.2.3.1 UT Icing Sensor with 1-mm Electrode Spacing ................37 3.2.3.2 UT Icing Sensor with 7-mm Electrode Spacing ................44 3.3 UT Icing Sensor on Full Scale Experiments ....................................................48 3.3.1 Specimens and Data Acquisition System Setup ...............................50 3.3.2 Full Scale Outdoor Test ....................................................................56 3.3.3 Full Scale Experimental Result .........................................................58 3.3.3.1 Icing Experiments ..............................................................59 3.3.3.2 Wet Snow Experiments......................................................62 3.3.3.2.1 Dry Snow Event ..................................................63 3.3.3.2.2 Wet Snow on Top of Specimen ..........................67 vii 3.3.3.2.3 Wet Snow on East Side of Specimen ..................72 3.4 Conclusion and Next Steps ..............................................................................75 4 Thickness Measurement.........................................................................................76 4.1 Devices Setup and Initial Test .........................................................................77 4.1.1 AGKU1500GI ...................................................................................77 4.1.2 SR50AT ............................................................................................82 4.1.3 UT Laser Thickness Sensor ..............................................................85 4.2 Full Scale Experiment and Result ....................................................................88 4.3 Sensor Selection ...............................................................................................92 5 Thermal Experiments .............................................................................................94