NCHRP VOBUG Nashville– 2010 NCHRP 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

NCHRP AASHTO Bridge – T-18 Update of NCHRP 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

NCHRP Background What is NCHRP 12-78? 3

NCHRP Background 4 NCHRP “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 Evaluation of Load Rating by LRFR

NCHRP 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

NCHRP Topics Preliminary Phase Vehicle/Bridge selection Gathering/Analyzing Importance of Virtis

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

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

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

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

NCHRP 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

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

NCHRP Preliminary Phase Analyze NBI Data NBI data used Software to analyze NBI DB Certain records ignored

NCHRP 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

NCHRP 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

NCHRP Preliminary Phase Analyze NBI Data 16 Software to breakdown data

NCHRP Preliminary Phase Analyze NBI Data 17 Software to breakdown data

NCHRP Preliminary Phase Analyze NBI Data ,000+ NBI Records Final 1500 Bridge Set

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

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

NCHRP 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

NCHRP Vehicle/Bridge Selection 22 Vehicle Selection SW region

NCHRP Vehicle/Bridge Selection 23 Vehicle Selection VehicleGVWLengthSchematic DE FL NM NC TX VehicleGVWLengthSchematic DE FL NM NC TX Routine Permit Vehicles

NCHRP Vehicle/Bridge Selection 24 Vehicle Selection Special Permit Vehicles VehicleGVWLengthSchematic OR IL WA

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

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

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

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

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

NCHRP Vehicle/Bridge Selection 30 Bridge Selection Bridge MaterialTotal # GirdersPercent % PS Multispan % PS Simple Span % RC Multispan % RC Simple Span % Steel Multispan % Steel Simple Span1, % Total3, %

NCHRP Vehicle/Bridge Selection 31 Bridge Selection Bridge TypeTotal # GirdersPercent % Multi-girder built up290.95% Multi-girder rolled beam1, % Multi-girder steel plate % PS box beam % PS I beam % Reinf Concrete slab % Reinf Concrete T beam % Total3, %

NCHRP 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

NCHRP Gathering/Analyzing Software used Process Manipulating data 33

NCHRP Gathering/Analyzing Virtis 6.1 BRASS LRFR and LFR Wyoming/ BridgeTech provided modifications for output 34 Software used

NCHRP 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

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

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

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

NCHRP Gathering/Analyzing Process Process 12-50

NCHRP Gathering/Analyzing 40 Manipulating data BRASS does not produce all results needed in format. Created application to read Virtis DB for user input data (e.g. span length, girder spacing, etc.) Combine user input/BRASS Process 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.

NCHRP Gathering/Analyzing 41 Manipulating 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

NCHRP Gathering/Analyzing 42 Manipulating 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

NCHRP Gathering/Analyzing 43 Manipulating data Angle of Skew Tributary Width (Girder Spacing) Year of Construction

NCHRP Gathering/Analyzing 44 Manipulating 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 With Report ID 85004

NCHRP 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