State of The Practice and Art for Structural Health Monitoring of Bridge Substructures

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FOREWORD

This project was originally intended to show the merits of substructure health monitoring via a review of the few well-documented cases wherein a concerted effort to assess the long-term performance of foundations were in place. While these efforts were underway, the St. Anthony Falls Bridge, also known as the I-35W bridge, over the Mississippi River in Minneapolis, MN, collapsed in August 2007 in the middle of rush hour, killing 13 people. This incident revealed to engineers the United States’ failing infrastructure. As a result, the project was redirected to aid the Minnesota Department of Transportation and the Federal Highway Administration in providing an effective yet economical means to monitor the new substructure during construction and in future years. That which was intended to be a review of previously performed and available technologies became a demonstration of available technologies and how they play into the role of foundation health monitoring.

This final report provides an overview of the benefits of remote data acquisitions systems for both short- and long-term monitoring of highway bridges. It contains background information and presents capabilities of data collection systems for highway bridges and concludes with an evaluation of a recent case study where remote health monitoring was successfully implemented. Interested audiences of the report include bridge engineers, highway officials, and municipality officials.

Jorge E. Pagán-Ortiz
Director, Office of Infrastructure
Research and Development

 

Technical Report Documentation Page

1. Report No. FHWA-HRT-09-040	2. Government Accession No.		3 Recipient's Catalog No.
4. Title and Subtitle State of the Practice and Art for Structural Health Monitoring of Bridge Substructures			5. Report Date May 2014
			6. Performing Organization Code
7. Author(s) J. Collins, G. Mullins, C. Lewis, and D. Winters			8. Performing Organization Report No. G07-M-279
9. Performing Organization Name and Address Foundation and Geotechnical Engineering, LLC 712 East Alsobrook Street, Suite 3 Plant City, FL 33563 Under contract from: Engineering and Software Consultants, Inc. 14123 Robert Paris Court Chantilly, VA 20151			10. Work Unit No. (TRAIS)
			11. Contract or Grant No. DTFH61-07-00033
12. Sponsoring Agency Name and Address Federal Highway Administration 6300 Georgetown Pike McLean, VA 22101-2296			13. Type of Report and Period Covered Final Report
			14. Sponsoring Agency Code
15. Supplementary Notes The project began under the supervision of Carl Ealy (FHWA retired) and concluded under the supervision Mike Adams (FHWA, Turner-Fairbank Highway Research Center).
16. Abstract In an age of technological advances, the ability to monitor the performance of bridge foundations has evolved such that both short- and long-term data acquisition of embedded gauges is not only available but also cost effective. Case studies were documented that show the merits of using embedded gauges and low-cost data collection systems to provide increased quality assurance during construction as well as a means to monitor the health of the foundations while in service.
17. Key Words Data acquisition, Remote health monitoring, Embedded instrumentation, Bridge foundations		18. Distribution Statement No Restrictions
19. Security Classification (of this report) Unclassified	20. Security Classification (of this page) Unclassified		21. No. of Pages 97	22. Price

Form DOT F 1700.7

Reproduction of completed page authorized

 

SI* (Modern Metric) Conversion Factors

 

TABLE OF CONTENTS

• CHAPTER 1. INTRODUCTION
  • PROBLEM STATEMENT
  • SCOPE AND SIGNIFICANCE
  • REPORT ORGANIZATION
• CHAPTER 2. STATE OF THE PRACTICE
  • GENERAL MONITORING SYSTEMS
  • CASE STUDY
  • WIRELESS SENSORS FOR HEALTH MONITORING
  • FIBER OPTIC SENSORS FOR HEALTH MONITORING
  • CURRENT AND FUTURE POSSIBILITIES FOR HEALTH MONITORING
• CHAPTER 3. VOIDED SHAFT THERMAL MONITORING
  • TEST SPECIMEN INSTRUMENTATION
  • TEST SPECIMEN CONSTRUCTION
  • MONITORING SYSTEM INSTRUMENTATION AND PROCEDURE
  • RESULTS AND CONCLUSIONS
• CHAPTER 4. I-35W BRIDGE FOUNDATION MONITORING
  • PHASE I—THERMAL MONITORING
    • Construction and Instrumentation
    • Monitoring Setup and Procedure
    • System Results and Conclusions
  • PHASE II—CONSTRUCTION LOAD MONITORING
    • Construction and Instrumentation
    • Monitoring Setup and Procedure
    • System Performance
    • Construction Phase Monitoring Completion
  • PHASE III—LONG-TERM HEALTH MONITORING
    • Live Load Truck Tests
    • System Results and Conclusions
• CHAPTER 5. SUMMARY AND CONCLUSIONS
• REFERENCES

LIST OF FIGURES

Figure 1. Photo. Standard rotary dial gauges
Figure 2. Illustration. Pier EA-31 site map
Figure 3. Illustration. Pier EA-31 pile instrumentation layout
Figure 4. Graph. Pier EA-31 tip load in 3 of the 12 piles
Figure 5. Graph. Pier EA-31 average strain change pile 1
Figure 6. Graph. Pier EA-31 average strain change pile 7
Figure 7. Graph. Pier EA-31 average strain change pile 10
Figure 8. Photo. Wireless data collection and transmit setup
Figure 9. Photo. Train crossing bridge causing a strain event
Figure 10. Photo. Bascule Bridge on SR-401N in Port Canaveral, FL
Figure 11. Illustration. Locations and types of sensors on Bascule Bridge
Figure 12. Photo. FRP wrap installation on bridge superstructure
Figure 13. Photo. FOS installation on bridge superstructure
Figure 14. Photo. FOS installation over FRP wrap on bridge superstructure
Figure 15. Graph. Measurement of strain induced on bridge from varying events
Figure 16. Photo. East 12th Street bridge in Des Moines, IA
Figure 17. Photo. Host computer near East 12th Street bridge site
Figure 18. Illustration. Map of voided shaft testing site
Figure 19. Photo. Voided shaft reinforcement cage instrumentation
Figure 20. Photo. Voided shaft center casing center tube supports
Figure 21. Photo. Voided shaft TCs installed in center casing
Figure 22. Photo. Voided shaft TCs on outside of center casing
Figure 23. Photo. Voided shaft ground monitoring tube installation
Figure 24. Photo. Excavation for voided shaft
Figure 25. Photo. Picking of reinforcement cage for voided shaft
Figure 26. Photo. Placement of reinforcement cage for voided shaft
Figure 27. Photo. Hanging of reinforcement cage for voided shaft
Figure 28. Photo. Picking of central casing for voided shaft
Figure 29. Photo. Placement of central casing for voided shaft
Figure 30. Photo. Holding of central casing steady for voided shaft
Figure 31. Photo. Double tremie concrete placement of voided shaft
Figure 32. Photo. Voided shaft outer steel casing removal
Figure 33. Photo. Final voided shaft at ground level
Figure 34. Photo. Campbell Scientific, Inc.Ò CR1000 data logger
Figure 35. Photo. AM25T 25-channel multiplexer
Figure 36. Photo. Campbell Scientific, Inc.Ò Raven100 CDMA AirLink cellular modem
Figure 37. Photo. Campbell Scientific, Inc.Ò PS100 12-V power supply with rechargeable battery
Figure 38. Photo. Campbell Scientific, Inc.Ò ENC12x14 environmental enclosure
Figure 39. Photo. TC wire connection from AM25t 25-channel multiplexer to CR1000 data logger
Figure 40. Photo. Remote thermal monitoring system for voided shaft
Figure 41. Graph. Battery voltage of thermal monitoring system as of October 8, 2007
Figure 42. Graph. Battery voltage of thermal monitoring system as of December 14, 2007
Figure 43. Graph. TC data from voided shaft as of November 12, 2007
Figure 44. Graph. Final average TC data for all locations
Figure 45. Illustration. I-35W bridge over the Mississippi River
Figure 46. Illustration. Event schedule and overlap of I-35W bridge project phases
Figure 47. Photo. I-35W bridge shaft reinforcement cage construction
Figure 48. Illustration. I-35W bridge gauge levels on drilled shafts
Figure 49. Photo. Cable bundles in reinforcement cage for I-35W bridge
Figure 50. Photo. Top section of drilled shaft for I-35W bridge
Figure 51. Photo. Placement of reinforcement cage for I-35W bridge shaft
Figure 52. Photo. Conduits running from shafts to DAS boxes
Figure 53. Photo. Lower layer of pier footing reinforcement for I-35W bridge
Figure 54. Photo. Upper layer of pier footing reinforcement for I-35W bridge
Figure 55. Photo. Thermal monitoring DAS for I-35W bridge shafts
Figure 56. Photo. 35-W solar cell panel for I-35W bridge monitoring system
Figure 57. Photo. CC640 jobsite camera with perspective outlines
Figure 58. Photo. Sample camera shot from close-up camera on I-35W bridge
Figure 59. Graph. Data logger battery voltage from I-35W bridge monitoring system
Figure 60. Diagram. Concrete mix design for drilled shafts on I-35W bridge
Figure 61. Graph. I-35W bridge southbound pier 2 shaft 1 thermal data
Figure 62. Graph. I-35W bridge southbound pier 2 shaft 2 thermal data
Figure 63. Graph. I-35W bridge shaft 1 thermal data from TCs and thermistors
Figure 64. Graph. I-35W bridge shaft 2 thermal data from TCs and thermistors
Figure 65. Graph. Pier 2 southbound footing thermal data from TCs
Figure 66. Illustration. Detail of Geokon, Inc.TM 4911 sister bar strain gauges
Figure 67. Photo. VW gauge installed in shaft reinforcement cage
Figure 68. Photo. Coupled VW (blue cable) and RT (green cable) gauges
Figure 69. Photo. Reinforcement for first column pour for I-35W bridge columns
Figure 70. Photo. Reinforcement at midsection of columns for I-35W bridge
Figure 71. Photo. Longitudinal and horizontal column reinforcement
Figure 72. Photo. Coupled gauge installed in corner of column of I-35W bridge
Figure 73. Photo. Gauge wires tied and secured in column of I-35W bridge
Figure 74. Photo. Wires exiting through conduit
Figure 75. Photo. Wire connection to system 2
Figure 76. Photo. Construction load monitoring systems
Figure 77. Graph. Shaft construction loads and events
Figure 78. Photo. Pier footing concrete placement
Figure 79. Photo. Lift 1 column concrete placement
Figure 80. Photo. Interior column lift 2 formwork placement
Figure 81. Photo. Exterior column lift 2 formwork placement
Figure 82. Photo. New perspective from CC640 field camera
Figure 83. Graph. System 1 battery voltage over time
Figure 84. Graph. System 2 battery voltage over time
Figure 85. Graph. System 2 versus system 3 battery voltage
Figure 86. Illustration. Hover points on the main page of St. Anthony Falls Bridge health monitoring Web site
Figure 87. Illustration. Instrumentation scheme for the St. Anthony Falls Bridge health monitoring project
Figure 88. Graph. Pier 2 interior column strain
Figure 89. Graph. Pier 2 exterior column strain
Figure 90. Graph. Pier 2 shaft 2 all levels strain
Figure 91. Graph. Pier 2 shaft 1 all levels strain
Figure 92. Graph. Shaft 1 loads throughout the entire construction sequence
Figure 93. Graph. Shaft 2 loads throughout the entire construction sequence
Figure 94. Graph. Column loads compared with segment placement
Figure 95. Graph. Strains measured in the interior column of pier 2 southbound
Figure 96. Graph. Strains measured in the exterior column of pier 2 southbound
Figure 97. Photo. Temporary DAS system reconnected, reconfigured, and reattached in new location adjacent to the permanent DAS subpanel vault
Figure 98. Photo. Trucks (400-kip (181,436.95-kg) total load) staged at predetermined location
Figure 99. Graph. Column strains during 10-h truck tests (positive compression)
Figure 100. Graph. Truck load test results for both columns for one cycle of truck positions
Figure 101. Graph. Truck load test results for shaft 1 for one cycle of truck positions
Figure 102. Graph. Truck load test results for shaft 2 for one cycle of truck positions
Figure 103. Graph. Live load effects on the interior column over 4.5-day period
Figure 104. Graph. Live load effects on the exterior column over 4.5-day period
Figure 105. Graph. Live load effects on shaft 1 over 4.5-day period
Figure 106. Graph. Live load effects on shaft 2 over 4.5-day period
Figure 107. Graph. Diurnal temperature and truck load effects at the toe of shaft 2
Figure 108. Graph. Column gauge calibration from known truck loads

LIST OF TABLES

Table 1. Summary of gauge failures
Table 2. Summary of monitoring systems for I-35W bridge monitoring study