Traffic Monitoring Using FBG Sensors

1. Hands-On Sensor Course April 22, 2004 Marley Kunzler Blue Road Research 376 NE 219th Avenue Gresham, OR 97030 (503) 667-7772 * Traffic Monitoring Using FBG Sensors

2. Outline 1. Functionality of the Dynamic FBG System 2. Background on Project 3. Results from Testing 4. Summary & Future Work

3. Functionality of the Dynamic FBG System Light is launched through the core of a fiber optical strand to the grating

4. Functionality of the Dynamic FBG System As the fiber undergoes tension & compression, the grating spacing changes

5. Functionality of the Dynamic FBG System The grating’s reflection is spectrally demodulated

6. 1998 - Horsetail Falls CFRP Strengthening

7. FBG Traffic Sensor Advantages

8. Overview Leading up to First Freeway Install • In July, 1999 Oregon Dept. of Transportation contracted Blue Road Research to develop a traffic sensor (based on fiber optic sensor technology) which is more durable, reliable and cost\installation effective than traditional sensing methods. • The primary focus of the contract: a sensor for vehicle classification and counting, (flexibility for other traffic sensing applications). • After preliminary testing on a concrete and asphalt testpad, sensors were installed in the Interstate 84 freeway East of Portland, Oregon on August 1, 2001.

9. Blue Road Research Goals: • Create and Demonstrate a Fiber Optic Traffic Sensing System • Count and Classify Traffic Using Fiber Optic System • Test Ruggedness of Sensors for Freeway Use • Determine Optimal Installation Procedures • Develop an Enhanced Traffic Sensor Product Line

10. Final Layout (Top-View)

11. Final Layout (Sensors Area) Sensing Area Junction Box Fiber Backbone Line Bicycle path On Ramp 207th Overpass Sensors are approx. 7 feet apart in left wheel lane. n l m k Sensor 5 (diagonal) monitors temperature. j

12. Grooving 205th Avenue to Enable Fiber Optic Installation & Remote Monitoring

13. Trenching the Fiber Optic Cableto the Freeway Site

14. Cutting Grooves for Sensor Placement in the Freeway Lanes

15. Installation of the Traffic SensorsInto Portland Cement Concrete

16. Filling the Sensor Grooves with Bituminous Hot Melt (~375° F)

17. Roadside Junction Box at Ground Level

18. Installation of the Traffic System Network Buried Fiber Lines

19. Data Collected from Semi Trailer

20. Data Collected from Semi Trailer Relative Amplitude vs. Time

21. Car Profile

22. Conclusions & Future Work Costs prohibitive for traffic classifier, but not Weigh-in-Motion (WIM) Development under NSF of up to 12 channel self-tuning readout system suitable for freeway Pursuing funding for WIM research

23. Modal Analysis of Bridges Using Fiber Bragg Grating Sensors • Background • Long gage length fiber Bragg grating sensors • Modal Analysis • Full scale field test, 2002 • Current work • Blue Road Research multiplexed FBG system • Laboratory Experiments • Fairview Model Bridge • Broadway Bridge work • Summary Session 6, Page 64

24. Acknowledgements • National Science Foundation • STTR Grant No. DMI-0131967 • Caltrans • Support of full scale field test • Oregon DOT • Continuing support of civil structures research ODOT • Multnomah County Bridge Section • Support of upcoming bridge system deployment Session 6, Page 65

25. Long Gage Length Fiber Bragg Grating Sensors: Packaging One meter gage length Aluminum bulkheads for anchor points Rugged housing Session 6, Page 66

26. Modal Analysis (1 Degree of Freedom) c k f Max Re (G(w)) Re (G(w)) x m wa wb w Min Re (G(w)) Im (G(w)) wn w I Session 6, Page 67

27. Modal Analysis (1 Degree of Freedom) w Max Re (G(w)) Re (G(w)) w wa wb Min Re (G(w)) Im (G(w)) wn I Tongue, Benson H. Principles of Vibration. Oxford University Press: Oxford. 1996. 101. Session 6, Page 68

28. Modal Analysis (multi-DoF) Mode 1 Mode 2 Mode 3 Re (G(w)) w Im (G(w)) w F Sensor Session 6, Page 69

29. Modal Analysis (multi-DoF) Im (G(w)) I First Mode Shape w I7 I1 I6 I2 I5 I3 I4 x y F1 F2 F3 F4 F5 F6 F7 x Sensor Session 6, Page 70

30. Experimental Validation of the Approach: 2002 Carbon Splice Test • 30’ composite wrapped concrete beam with splice at midspan • Test performed by UCSD, FHWA, CALTRANS • Blue Road Research and UCSD • Placed optical sensors on the beam • Performed dynamic tests Session 6, Page 71

31. Carbon Splice Test: I-5 Gilman Bridge Session 6, Page 72

32. Carbon Splice Test: Mode Shapes Session 6, Page 73

33. Carbon Splice Test: Modal Vectors Session 6, Page 74

34. Conclusions from Splice Test • Strong agreement between accelerometer and FOS data • Validates use of Long Gage FOS in system identification • Clear changes in modal characteristics with damage • Suggests that this method will work for detecting structural damage in bridges Session 6, Page 75

35. Current Work • Algorithm refinement by UCSD • Enable location and quantification of damage through system identification • Hardware development for sensor data acquisition • Acquire data from eight sensors simultaneously with sub-microstrain resolution • Full scale deployment on the Broadway Bridge in Portland, Oregon • in planning with Multnomah County Bridge Section Session 6, Page 76

36. Laboratory Tests: Instrumented I-Beam Session 6, Page 77

37. Laboratory Tests: Parked and Sweeping Etalon Parked Sweeping Session 6, Page 78

38. Laboratory Tests: Parked Etalon Session 6, Page 79

39. Field Tests: BRR Fairview Bridge • Environmental Effects • Temperature • Wind • Performance • Modal Analysis with controlled damage • Quasi-static loading • 20’x4’ steel truss • Concrete and composite deck • Sensors installed in concrete • Sensors planned for installation on structure and in composite section Session 6, Page 80

40. Blue Road Research Health Monitoring and Seismic Damage Assessment System Session 6, Page 81

41. Cable Routing from Readout Unit to Sensors Multi-Strand cable, running from Readout Unit to Bridge Eight strings of 5 sensors Junction Box-Mounted on bridge Session 6, Page 82