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VOBUG Nashville– 2010 NCHRP 12-78 Evaluation of Load Rating by LRFR

VOBUG Nashville– 2010 NCHRP 12-78 Evaluation of Load Rating by LRFR. Mark Mlynarski, P.E. – Michael Baker Jr., Inc. Wagdy Wassef, Ph.D. P.E.- Modjeski and Masters, Inc. Andy Nowak, Ph.D., University of Nebraska.

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VOBUG Nashville– 2010 NCHRP 12-78 Evaluation of Load Rating by LRFR

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  1. VOBUG Nashville– 2010NCHRP 12-78Evaluation of Load Rating by LRFR Mark Mlynarski, P.E. – Michael Baker Jr., Inc. Wagdy Wassef, Ph.D. P.E.- Modjeski and Masters, Inc. Andy Nowak, Ph.D., University of Nebraska

  2. AASHTO Bridge – T-18Update of NCHRP 12-78Evaluation of Load Rating by LRFRPanel Members ArturD’Andrea, Louisianna MurugesuVinayagamoorthy, California Dr. Pe-Shen Yang, Arizona Dr. Firas Ibrahim, FHWA Waseem Dekelbab, NCHRP Matt Farrar, Idaho – Chair Tim Armbrecht, Illinois George Christian, New York George Conner, Alabama Becky Curtis, Michigan William R. Cox, ASBI

  3. Background What is NCHRP 12-78?

  4. Background • NCHRP 12-46 • “Guide Manual for Condition Evaluation and LRFR of Highway Bridges, 1st Edition and 2005 Interim” • HSCOBS wanted additional research to explain differences with LFR • NCHRP 20-7 (Task 122) (Mertz) • Flexural ratings/ small sample • NCHRP 12-78 -Evaluation of Load Rating by LRFR

  5. 12-78 Objectives • Recommend refinements to the LRFR methods in the AASHTO MBE • Explain changes in truck weight restrictions • Develop a comprehensive database (1500 bridges) – Virtis Database • Develop the proposed refinements

  6. Topics • Preliminary Phase • Vehicle/Bridge selection • Gathering/Analyzing Importance of Virtis

  7. Preliminary Phase Survey Collect Virtis Data Review/ Analyze NBI data

  8. Preliminary Phase • Surveys sent to all states • Questions related to load rating procedures • Solicit vehicle information and bridge data (Virtis) Survey

  9. Manitoba Preliminary Phase • Responses to survey (33 total) Survey

  10. Manitoba Preliminary Phase AASHTOWare Bridge Data Collect Virtis Data

  11. Manitoba Preliminary Phase Other sources Collect Virtis Data

  12. Preliminary Phase • 18,000 + Virtis bridges • 1500 from these • 300 + vehicles • 8 selected Collect Virtis Data

  13. Preliminary Phase • 2008 NBI data used • Software to analyze NBI DB • Certain records ignored Analyze NBI Data

  14. Preliminary Phase NBI Records Ignored Analyze NBI Data

  15. Preliminary Phase NBI Records Ignored Analyze NBI Data

  16. Preliminary Phase Software to breakdown data Analyze NBI Data

  17. Preliminary Phase Software to breakdown data Analyze NBI Data

  18. Preliminary Phase 400,000+ NBI Records Final 1500 Bridge Set Analyze NBI Data

  19. Vehicle/Bridge Selection • Vehicle Selection • 300+ vehicles to 8 • Bridge Selection • 18,000+ bridges to 1500 bridge Sample • Bulk data change

  20. Vehicle Selection Vehicle/Bridge Selection • States - ~ 300 vehicles • Panel - divide into regions • Select vehicles from regional groupings

  21. Vehicle Selection Vehicle/Bridge Selection Vehicles analyzed using a utility developed by M&M Computes LL moments and shears for SS beams and two spans (equal length) Ratio to HL-93 vehicle Vehicles grouped by region

  22. Vehicle Selection Vehicle/Bridge Selection SW region

  23. Vehicle Selection Vehicle/Bridge Selection Routine Permit Vehicles

  24. Vehicle Selection Vehicle/Bridge Selection Special Permit Vehicles

  25. Vehicle Selection Vehicle/Bridge Selection Eight (8) vehicles HL-93 (LRFR) HS-20 (LFR) Type 3, 3S2, 3-3

  26. Bridge Selection Vehicle/Bridge Selection Flatten data to compare with NBI Virtis data Complex database 18000+ bridges How do we reduce to compare with NBI?

  27. Bridge Selection Vehicle/Bridge Selection Virtis Data Analysis Same Software for NBI analysis

  28. Bridge Selection Vehicle/Bridge Selection NBI Virtis Graphic comparisons (Year built)

  29. Bridge Selection Vehicle/Bridge Selection • Virtis bridges selected by • Year • Span length • Bridge/Material Type • Bridge systems only (no line girders)

  30. Bridge Selection Vehicle/Bridge Selection

  31. Bridge Selection Vehicle/Bridge Selection

  32. Bulk Data Change Vehicle/Bridge Selection • Modifying Data in Virtis • Small application modify Virtis DB • Effective Flange width • Development length (P/S) • Shear analysis flag • Discard some bridges- choose others

  33. Gathering/Analyzing Software used Process 12-50 Manipulating 12-50 data

  34. Software used Gathering/Analyzing Virtis 6.1 BRASS LRFR and LFR Wyoming/ BridgeTech provided modifications for 12-50 output

  35. Software used Gathering/Analyzing Total number of BRASS runs 1500 bridges (3043 girders) 8 permit vehicles + 1 design + 3 AASHTO loads = 12 vehicles 2 methods (LRFR – LFR)

  36. Software used Gathering/Analyzing 3043 x 12 x 2 = 73,032 BRASS runs

  37. Process 12-50 Gathering/Analyzing How do we review 73,032 BRASS runs? Process 12-50

  38. Process 12-50 Gathering/Analyzing Process 12-50 • Developed under NCHRP 12-50 • See NCHRP Report 485 for details • BRASS uses Process 12-50

  39. Process 12-50 Gathering/Analyzing Process 12-50

  40. Manipulating 12-50 data Gathering/Analyzing • BRASS does not produce all results needed in 12-50 format. • Created application to read Virtis DB for user input data (e.g. span length, girder spacing, etc.) • Combine user input/BRASS Process 12-50 results into MS Access database • Process each girder into a single line of output using project developed software • Output imported to spreadsheet for further calculation/ plotting.

  41. Manipulating 12-50 data Gathering/Analyzing • Databases created for each vehicle for each set of bridges • Results used to: • Compare dead and live loads • Compare rating factors • Calculate reliability index • Determine if trends exist in data

  42. Manipulating 12-50 data LFR Inventory Rating for HS20 Loading LRFR Inventory Rating for HL-93 Loading Gathering/Analyzing • Simple Span Steel Bridges – Design Vehicle • Moment Ratings for Interior, Composite girders (432 girders)

  43. Manipulating 12-50 data Gathering/Analyzing Angle of Skew Year of Construction Tributary Width (Girder Spacing)

  44. Manipulating 12-50 data Gathering/Analyzing Without Report ID 85004 With Report ID 85004 • New checks were noted for LRFR that have significant affect on rating • Longitudinal Steel Stress Rating near ends of concrete superstructure elements

  45. Current Status • Panel has reviewed and provided comments on our ‘Findings’ report • We are reviewing and replying to the comments • Scheduled finish date: November, 2010

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