1. NCHRP 12-78 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 1

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

3. NCHRP 12-78 Background What is NCHRP 12-78? 3

4. NCHRP 12-78 Background 4 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. NCHRP 12-78 12-78 Objectives 5 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. NCHRP 12-78 Topics Preliminary Phase Vehicle/Bridge selection Gathering/Analyzing Importance of Virtis

7. NCHRP 12-78 Preliminary Phase Survey Collect Virtis Data Review/ Analyze NBI data 7

8. NCHRP 12-78 Preliminary Phase Survey 8 Surveys sent to all states Questions related to load rating procedures Solicit vehicle information and bridge data (Virtis)

9. NCHRP 12-78 Preliminary Phase Survey 9 Responses to survey (33 total) Manitoba

10. NCHRP 12-78 Preliminary Phase Collect Virtis Data 10 AASHTOWare Bridge Data Manitoba State # Bridges Alabama3139 Illinois3232 Michigan378 Missouri4644 New York5412 Oklahoma44 S. Dakota1135 Tennessee53 Total18038

11. NCHRP 12-78 Preliminary Phase Collect Virtis Data 11 Other sources Manitoba StateBridges Virginia20 LRFR Idaho100+ Auburn100 Bridges OregonBRASS 500 LRFR New YorkAdditional Wyoming20-7 Task 122 Bridges

12. NCHRP 12-78 Preliminary Phase Collect Virtis Data 12 18,000 + Virtis bridges 1500 from these 300 + vehicles 8 selected

13. NCHRP 12-78 Preliminary Phase Analyze NBI Data 13 2008 NBI data used Software to analyze NBI DB Certain records ignored

14. NCHRP 12-78 Preliminary Phase Analyze NBI Data 14 NBI Records Ignored NBI ItemRestriction/Items Ignored 5a – Record TypeIgnore values <> 1 31 – Design Load7- Pedestrian, 8-Railroad 41 – Structure Open/Posted/Closed D – Open, would be posted or closed except for temporary shoring, E – Open, temp structure, K – Closed 43A – Kind of Material and/or Design 0 – other, 8- Masonry, 9-Aluminum, Wrought Iron, Cast Iron

15. NCHRP 12-78 Preliminary Phase Analyze NBI Data 15 NBI Records Ignored NBI ItemRestriction/Items Ignored 43B – Type of Design/ConstructionOther, Frames, Arches, Suspension, Stayed Girder, Movables, Tunnel, Culvert, Mixed, Segmental 48 – Length of maximum span6.1 m (20 ft) < Span Length < 150 m (492 ft) 103 – Temporary Structure Designation Ignore values where Item 103 = T

16. NCHRP 12-78 Preliminary Phase Analyze NBI Data 16 Software to breakdown data

17. NCHRP 12-78 Preliminary Phase Analyze NBI Data 17 Software to breakdown data

18. NCHRP 12-78 Preliminary Phase Analyze NBI Data 18 400,000+ NBI Records Final 1500 Bridge Set

19. NCHRP 12-78 Vehicle/Bridge Selection Vehicle Selection – 300+ vehicles to 8 Bridge Selection – 18,000+ bridges to 1500 bridge Sample Bulk data change 19

20. NCHRP 12-78 Vehicle/Bridge Selection 20 Vehicle Selection States - ~ 300 vehicles Panel - divide into regions Select vehicles from regional groupings

21. NCHRP 12-78 Vehicle/Bridge Selection 21 Vehicle 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. NCHRP 12-78 Vehicle/Bridge Selection 22 Vehicle Selection SW region

23. NCHRP 12-78 Vehicle/Bridge Selection 23 Vehicle Selection VehicleGVWLengthSchematic DE-078041 FL-048067 NM-0455.222 NC-216121 TX-046920 VehicleGVWLengthSchematic DE-078041 FL-048067 NM-0455.222 NC-216121 TX-046920 Routine Permit Vehicles

24. NCHRP 12-78 Vehicle/Bridge Selection 24 Vehicle Selection Special Permit Vehicles VehicleGVWLengthSchematic OR-06150.573.5 IL-0112044 WA-0220770

25. NCHRP 12-78 Vehicle/Bridge Selection Eight (8) vehicles HL-93 (LRFR) HS-20 (LFR) Type 3, 3S2, 3-3 25 Vehicle Selection

26. NCHRP 12-78 Vehicle/Bridge Selection 26 Bridge Selection Virtis data Complex database 18000+ bridges How do we reduce to compare with NBI? Flatten data to compare with NBI

27. NCHRP 12-78 Vehicle/Bridge Selection 27 Bridge Selection Virtis Data Analysis Same Software for NBI analysis

28. NCHRP 12-78 Vehicle/Bridge Selection 28 Bridge Selection Graphic comparisons (Year built) Virtis NBI

29. NCHRP 12-78 Vehicle/Bridge Selection Virtis bridges selected by – Year – Span length – Bridge/Material Type – Bridge systems only (no line girders) 29 Bridge Selection

30. NCHRP 12-78 Vehicle/Bridge Selection 30 Bridge Selection Bridge MaterialTotal # GirdersPercent % PS Multispan2387.82% PS Simple Span84727.83% RC Multispan1053.45% RC Simple Span39412.95% Steel Multispan41813.74% Steel Simple Span1,04134.21% Total3,043100.00%

31. NCHRP 12-78 Vehicle/Bridge Selection 31 Bridge Selection Bridge TypeTotal # GirdersPercent % Multi-girder built up290.95% Multi-girder rolled beam1,05634.70% Multi-girder steel plate37412.29% PS box beam38112.52% PS I beam70423.14% Reinf Concrete slab2046.70% Reinf Concrete T beam2959.69% Total3,043100.00%

32. NCHRP 12-78 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 32 Bulk Data Change

33. NCHRP 12-78 Gathering/Analyzing Software used Process 12-50 Manipulating 12-50 data 33

34. NCHRP 12-78 Gathering/Analyzing Virtis 6.1 BRASS LRFR and LFR Wyoming/ BridgeTech provided modifications for 12-50 output 34 Software used

35. NCHRP 12-78 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) 35 Software used

36. NCHRP 12-78 Gathering/Analyzing 3043 x 12 x 2 = 73,032 BRASS runs 36 Software used

37. NCHRP 12-78 Gathering/Analyzing How do we review 73,032 BRASS runs? Process 12-50 37 Process 12-50

38. NCHRP 12-78 Gathering/Analyzing Process 12-50 -Developed under NCHRP 12-50 -See NCHRP Report 485 for details -BRASS uses Process 12-50 38 Process 12-50

39. NCHRP 12-78 Gathering/Analyzing Process 12-50 39 Process 12-50

40. NCHRP 12-78 Gathering/Analyzing 40 Manipulating 12-50 data 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. NCHRP 12-78 Gathering/Analyzing 41 Manipulating 12-50 data 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. NCHRP 12-78 Gathering/Analyzing 42 Manipulating 12-50 data Simple Span Steel Bridges – Design Vehicle – Moment Ratings for Interior, Composite girders (432 girders) LFR Inventory Rating for HS20 Loading LRFR Inventory Rating for HL-93 Loading

43. NCHRP 12-78 Gathering/Analyzing 43 Manipulating 12-50 data Angle of Skew Tributary Width (Girder Spacing) Year of Construction

44. NCHRP 12-78 Gathering/Analyzing 44 Manipulating 12-50 data New checks were noted for LRFR that have significant affect on rating – Longitudinal Steel Stress Rating near ends of concrete superstructure elements Without Report ID 85004 With Report ID 85004

45. NCHRP 12-78 Current Status 45 Panel has reviewed and provided comments on our ‘Findings’ report We are reviewing and replying to the comments Scheduled finish date: November, 2010