I Use of Sensors in Monitoring Civil Structures By Bassam William Daher B.E., Civil Engineering (2002) Lebanese American University Submitted to the Department of Civil and Environmental Engineering In Partial Fulfillment of the Requirements for the Degree of Master of Science in Civil and Environmental Engineering at the Massachusetts Institute of Technology September 2004 D Bassam William Daher. All rights reserved. The author grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part. Signature of A uthor.............. ...............---... Department of Civil and Environmental Engineering Xugust 10, 2004 Certified by.. .......-...-. .-. - Nathaniel D. Osgood Senior Lecturer in Civil and Environmental Engieering Thesis Supervisor C ertified by .... - - -...... ...........-..--- Ruaidhri M. O'Connor Assistant Professor in Civil and Environmental Engieering Thesis Reader Accepted by............ ... ----------- Heidi Nepf Chairman, Department Committee on Graduate Students MASSACHUSETTS INSTMJE OF TWCHNOLOGY SEP 17 2004 I I IPPADICO BARKER Use of Sensors in Monitoring Civil Structures By Bassam William Daher Submitted to the Department of Civil and Environmental Engineering On August 10, 2004 in Partial Fulfillment of the Requirements for the Degree of Master of Science in Civil and Environmental Engineering ABSTRACT This thesis surveys the use of sensors and sensor networks in monitoring civil structures, with particular emphasis on the monitoring of bridges and highways using fiber optic sensors. Following a brief review of the most widespread form of civil infrastructure inspection -- visual inspection -- the thesis describes the anatomy, mechanisms, and types of fiber optic sensors and characterizes the tradeoffs involved in choosing between fiber-optic and conventional sensor technologies. The thesis then presents a survey of contributions to this field, followed by a discussion of deployed applications of fiber- optic sensors, many of them in North America. The latter portion of the thesis first briefly discusses the emerging technology of wireless sensor networks and then presents an abbreviated case study comparing the costs and time required to deploy a fiber optic system to traditional visual inspection on the same structure. The case study suggests that the fiber optic sensors are a cost-effective technology, particularly when indirect savings are considered. The thesis concludes with some comments on the prospects and challenges for sensor technologies in civil infrastructure monitoring. Thesis Supervisor: Nathaniel D. Osgood Title: Senior Lecturer in Civil and Environmental Engineering 2 Dedication To my parents Amal and William for all their seen, unseen and unforeseen heroic sacrifices. May God protect you and bless you forever. To my Grandmother Teta Nabiha Daou Haddad,b eing your first grandson to enter GraduateS chool. Your love and prayers are always with me and accompany me. 3 Do to others as you would have them do to you. For if you love those who love you, what credit is that to you? Even sinners love those who love them. And if you do good to those who do good to you, what credit is that to you? Even sinners do the same. If you lend money to those from whom you expect repayment, what credit (is) that to you? Even sinners lend to sinners, and get back the same amount. But rather, love your enemies and do good to them, and lend expecting nothing back; then your reward will be great and you will be children of the Most High, for he himself is kind to the ungrateful and the wicked. Be merciful, just as (also) your Fatheri s merciful. Luke 6: 31-36 4 Acknowledgements First and foremost my gratitude is to the LORD my GOD for all the uncountable blessings that he continues to overwhelm me with from the first day I saw light. His greatest blessing will always be my parents Amal & William to whom I express my deepest gratitude, and whose continuous sacrifice, love, care, moral and financial support made my MIT dream a reality. I am also most grateful to my wonderful sister Salam and to my precious uncle Nabil, whose continuous advice and moral support have always strengthened my will. I am indebted to Dr. Nathaniel Osgood, my thesis advisor for all the trust, time, patience and effort he spent to make me finish my thesis on time. I would like to specially thank Dr. Ruaidhri O'Connor, my thesis reader for his valuable comments and confidence. I can never forget the continuous support and faith of Dr. Gebran Karam, my professor, advisor, mentor and friend forever. I would like also to thank all the people who helped provide me additional information in this thesis and particularly: Dr. Aftab Mufti and his assistant Mr. Chad Klowak from ISIS Canada, Dr. Dryver Huston from University of Vermont, Dr. Brent Phares from Iowa 5 State University, Mr. Ahmad Abu-Hawash from Iowa DOT, Mr. Tom Graver from Micron Optics Inc. , Mr. Dave Fletcher from IDERS, and Ms. Marina Colotti from SMARTEC. 6 Table of Contents 1. IN TR OD U C T IO N .................................................................................................. 12 1.1 INTRODUCTION TO STRUCTURAL HEALTH MONITORING (SHM)... 13 1.1.1 Purpose for Monitoring......................................................................... 13 1.1.2 Economic Importance ........................................................................... 14 1.1.3 Safety and Failure of Bridges ............................................................... 14 1.1.4 Steel C orrosion....................................................................................... 15 1.1.5 Smart Structures and Fiber Optic Sensors (FOS) .................................. 15 1.2 CURRENT PRACTICE................................................................................ 16 1.2.1 V isual Inspection .................................................................................... 16 1.2.2 Visual Inspection and Shortcomings .................................................... 17 1.2.3 FHWA-NDEVC Study 2001 ................................................................. 17 1.2.4 R esults of T he Study.............................................................................. 18 1.3 Conventional Sensor Technology .................................................................. 19 1.3.1 B ackground ........................................................................................... 19 1.3.2 Conventional Strain Sensors .................................................................. 20 1.4 STRUCTURAL HEALTH MONTORING USING FOS ............................. 23 2 FIBER OPTIC SENSORS: BACKGROUND....................................................... 25 2.1 IN TR O D U C TIO N ......................................................................................... 25 2.2 ANATOMY OF AN OPTICAL FIBER ....................................................... 25 2.3 M EC H A N ISM ................................................................................................ 26 2.4 STRUCTURAL MONITORING MEASURANDS...................................... 27 2.5 CLASSIFICATION of FOS .......................................................................... 29 2.5.1 Transduction Mechanism....................................................................... 30 2.5.2 A pplication ............................................................................................. .32 2.5.3 Purpose of U se ...................................................................................... 35 2.5.4 Intrinsic vs. E xtrinsic ............................................................................. 36 2.5.5 Intensiometric vs. Interferometric......................................................... 38 2.6 MAJOR FOS TYPES .................................................................................... 39 2.6.1 SOFO Displacement Sensors................................................................ 39 2.6.2 Microbend Displacement Sensors......................................................... 40 2.6.3 Bragg Grating Strain and Temperature Sensors .................................... 41 2.6.4 Fabry-Perot Strain Sensors .................................................................... 44 2.6.5 Raman-Distributed Temperature Sensors ............................................. 45 2.6.6 Brillouin Distributed Temperature Sensors ........................................... 45 2.6.7 Hydrogel-Distributed Humidity Sensors ............................................... 46 2.6.8 Mach-Zender Interferometer.................................................................. 47 2.6.9 Michelson Interferometer....................................................................... 47 2.7 COMPONENT COST AND AVAILABILITY ........................................... 50 2.7.1 Microbend Sensitive Optical Fiber ....................................................... 50 2.7.2 Fiber E talons ......................................................................................... 50 2 .7 .3 F B G ...................................................................................................... . 50 2.7.4 Michelson Interferometer....................................................................... 50 3 FIBER OPTIC SENSORS CHARACTERISTICS................................................ 53 7 3.1 DESIRABLE CHARACTERISTICS ........................................................... 53 3.2 A D V A N TA G ES ........................................................................................... 54 3.3 L IM ITA T ION S .............................................................................................. 57 3.3.1 C odes and Standards ............................................................................. 57 3.3.2 Difficulties With Large Structures......................................................... 58 3.3.3 R eliability Issues for FO S ....................................................................... 59 3.3.4 Practical C onsiderations......................................................................... 62 4 PREVIOUS and RECENT WORK ...................................................................... 64 R E C E N T W O R K ....................................................................................................... 75 5 DEPLOYED APPLICATIONS ............................................................................. 77 5.1 THE BEDDINGTON TRAIL BRIDGE, CALGARY.................................. 77 5.2 THE TAYLOR BRIDGE, WINNIPEG MANITOBA .................................. 79 5.3 THE CROWCHILD TRAIL BRIDGE, CALGARY..................................... 81 5.4 HALL'S HARBOUR WHARF, NOVA SCOTIA ........................................ 82 5.5 JOFFRE BRIDGE, QUEBEC....................................................................... 83 5.6 PIPELINE, FT MCMURRAY, ALBERTA .................................................. 83 5.7 COMMODORE BARRY BRIDGE, PA-NJ ................................................. 85 5.8 BENICIA-MARTINEZ BRIDGE, CALIFORNIA ...................................... 85 5.9 LUZZONE DAM-SWITZERLAND ............................................................. 86 5.10 STORK BRIDGE-SWITZERLAND.............................................................. 87 5.11 THE VERSOIX BRIDGE, SWITZERLAND ............................................... 87 5.12 INTERSTATE 89-WINOOSKI RIVER BRIDGE, VERMONT .................. 88 5.13 STAFFORD BUILDING, UNIVERSITY OF VERMONT.......................... 89 5.14 WINOOSKI ONE HYDROELECTRIC DAM, VERMONT........................ 93 5.15 MIDDLEBURY RAILWAY BRIDGE ......................................................... 94 5.16 1-10 BRIDGE IN LA CRUCES , NEW MEXICO................... 95 6 W IRELESS SEN SO RS ........................................................................................ 98 6.1 A N A T O M Y .................................................................................................. 99 6.2 THE PATH TOWARD PROACTIVE COMPUTING................................... 104 6.3 EXAMPLE OF A WIRELESS STRAIN SENSING NODE.......................... 106 6.3.1 Batteries and Alternative Power Sources................................................ 107 6.4 THE PROMISE OF WIRELESS SENSORS IN SHM .................................. 108 6.5 Case Study: Wireless Modular Health Monitoring System (WiMMS)..... 110 6.5.1 System D escription ................................................................................. 1 10 6.5.2 Hardware Design of a WiMMS sensing Unit ......................................... 111 6.5.3 Power Consumption of a WiMMS Sensing Unit.................................... 113 6.5.4 Wireless Communication Channel ......................................................... 114 6.5.5 Lab and Field V alidation ........................................................................ 116 6.5.6 Power Efficiency with Embedded Algorithms ....................................... 117 7 CA SE ST U D Y ........................................................................................................ 119 7.1 EAST 12TH STREET BRIDGE OVER 1-235, DES MOINES, IA................. 119 7.2 BRID G E D ESCRIPTION ............................................................................... 119 7.3 O B JEC T IV E S ................................................................................................. 120 7.4 DESCRIPTION OF THE FOS MONITORING SYSTEM............................ 120 7.5 COST OF THE FOS SYSTEM ...................................................................... 123 7.6 COST OF THE ROUTINE INSPECTION..................................................... 123 8 7.7 COM PA RISON & CON CLU SION ............................................................... 124 8 CON CLUSIO N S ..................................................................................................... 127 8.1 SUM M A RY .................................................................................................... 127 8.2 FUTU RE DEV ELOPM ENTS ........................................................................ 128 8.3 W IRELESS vs. FOS SEN SORS..................................................................... 129 8.3.1 W ireless vs. FO S Tradeoffs .................................................................... 129 8.3.2 Do m ains of Application.......................................................................... 132 8.3.3 Prospects for a hybrid System ................................................................. 132 8.4 Conclusions and Recom m endations ............................................................... 133 9 GLO SSA RY ........................................................................................................... 138 10 REFEREN CES ................................................................................................... 141 9 Table of Figures Figure 1: Schematic diagram of a foil strain gage (www.sensorland.com).................. 22 Figure 2: Schematic diagram of a Wheatstone Bridge (www.omega.com) ................. 23 Figure 3: schematic diagram of an optical fiber (Leung, 2000) ................................... 26 Figure 4: Basis for light transmission in optical fibers (Ansari, 1997)......................... 27 Figure 5: Classification Diagram (Ansari, 1997)......................................................... 29 Figure 6: Optical fiber intensity sensor (Ansari, 1995) ............................................... 30 Figure 7: Fiber optic interferometric sensors (Ansari, 1995) ........................................ 32 Figure 8 : Schematic depiction of localized (top),distributed (middle), and multiplexed (bottom ) FOS (M erzbacher et al,1996).................................................................. 35 Figure 9 : Schematic diagrams of (a) lFPI, (b) EFPI, (c) ILFE (Merzbacher et al., 1996) ................................................................................................................................... 3 8 Figure 10: SOFO strain sensor (Leung, 2001).............................................................. 40 Figure 11: Strain induced shift in wavelength for an FBG (Ansari, 1997).................. 42 Figure 12 : Fabry-Perot sensor system and geometry (Claus et al. ,1993)................... 44 Figure 13: A distributed water/moisture sensor (Leung, 2001).................................... 46 Figure 14 : Detection of air bubbles in fresh concrete by an optical fiber (Ansari, 1997)66 Figure 15: Effect of bubble size and spacing on the amplitude of the reflected signal (A n sari, 1997) ...................................................................................................... . 66 Figure 16: Fiber Optic CTOD sensor for Concrete (Ansari & Navalurkar, 1993)..... 67 Figure 17: Fabry Perot sensor system and geometry (Claus et al., 1993) ..................... 71 Figure 18 : Distributed sensor for concrete wall anchoring system (Zimmermann & C lau s, 19 9 3 ) .............................................................................................................. 7 2 Figure 19: The crack sensing concept (Leung , 1997).................................................. 74 Figure 20: Bragg grating laser sensor locations in the Beddington Trail Bridge (Measures et al. , 19 9 5 ) ............................................................................................................... 7 8 Figure 21: Beddington Trail Bridge (Top), a four channel Bragg grating demodulation system used (Bottom) (Measures et al. ,1995).................................................. 79 Figure 22 : Sensors locations in the Taylor Bridge (Mufti et al.,2003)........................ 80 Figure 23: FRP reinforcement, FOS and remote monitoring system of Crowchild Trail bridge (M ufti et al. 2003)....................................................................................... 81 Figure 24: Installed sensors in Hall's Harbor Wharf (Mufti et al., 2003)..................... 82 Figure 25 : Remote monitoring system for Hall's Wharf (Mufti et al., 2003).............. 83 Figure 26: FOS snake configuration, pipe in Ft McMurray, Alberta (Mufti et al. 2003) 84 Figure 27 : Architecture for health monitoring system for the Commodore Barry Bridge (Pines & A tkan , 2002) ......................................................................................... 86 Figure 28 : Stafford Building at the University of Vermont (Huston et al.,1994)........ 90 Figure 29 : Electrical conduit box for gracefully exiting the forms (Fuhr et al., 1992) ... 91 Figure 30: Vertical rebar attachment of optical fibers and conduit box (Fuhr et al., 1992). ................................................................................................................................... 9 2 Figure 31 : Configuration after the concrete pouring (Fuhr et al., 1992) ...................... 92 Figure 32: The Middlebury railway bridge (Huston et al. ,1994)................................. 94 Figure 33: Smart Dust mote major components: power system, sensors, and integrated circuits (W arneke et al., 200 1)................................................................................ 102 10