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GUSSET PLATE EVALUATION
• Tom Macioce, P.E.• Chief Bridge Engineer
April 2009
PennDOT Load Rating of Gusset Plates
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PennDOT Load Rating of Gusset Plates Overview
• PennDOT Gusset Plate Evaluations• PennDOT Inspection Requirements• PennDOT Rating Spreadsheet• Target Dates• Summary
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PennDOT Truss Gusset Plate Evaluation
• Inventory - 320 steel trusses identified (174 state-owned, 146 locally-owned)
• PennDOT required all deck trusses (54) be re-inspected by August 30, 2007, and all non-SD deck truss bridges by November 30, 2007
• Cost - $2M for the re-inspection of deck trusses• Cost - $2M for rating of gusset plates
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PennDOT Truss Gusset Plate Evaluation
• PennDOT began development of gusset plate analysis spreadsheet in February 2008
• Permit load analysis approach– Heavy hauling permits evaluated using Bar 7– Assume reduced capacity of truss members framing into
gusset plates– Reduced member capacity approach will be used until
the gusset plate analysis option is incorporated into BAR7
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PennDOT Truss Gusset Plate Evaluation
• Spreadsheet development completed in accordance with FHWA technical advisories- October 2008
• Both LFD and ASD analysis methods supported• BAR 7 output file load data used in spreadsheet• Evaluates O.R. only• 3 man-days to analyze and check a truss bridge• 1.5 Hours per joint for a standard truss• 2.5 hour per joint for a complex truss• Additional hours required for field inspections
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PennDOT Truss Gusset Plate Evaluation
• Administration– Strike Off Letter (431-09-02) issued February 11, 2009
• Updates to Publication 238 Chapters 3 and 6 addressing gusset plate analysis.
• Developed Deck Truss Geometry Field Inspection Sheet
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PennDOT Inspection Requirements
• Revised inspection training September 2008• Issued policy February 2009 Strike-Off Letter
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PennDOT Inspection Requirements
Emphasis on-• Distortion or bowing• Corrosion documentation• Tack weld documentation• Slippage of connections• Repairs/retrofits (condition and performance)• NDE follow-up• Capture necessary field data to properly load
rate the gusset plate
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• Annotated data extraction from BAR 7
• Inspection– Forms– Digital Photo Measurements
PennDOT Rating Spreadsheet
BAR 7or
STAAD
ShopDrawings
Field Data
Analysis
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PennDOT Rating Spreadsheet
• Several months to develop • Tested on 7 bridges, primarily Interstate bridges• 5 engineers involved in verification
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Target Dates
• Important Milestones - • Strike Off Letter (431-09-04) issued March 10,
2009– State owned bridges analyzed by December 31, 2009– Local owned bridges analyzed by December 31, 2010.
• Revise BAR7 to include gusset plate analysis December 2009
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Status of Analysis
• Districts to provide monthly status reports for tracking progress
• State - 183– Completed 54– Under Analysis 98– Future Work Orders 31
• Local - 149– Completed 52– Under Analysis 11– Future Work Orders 86
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Issues
• Continuous chord members through gusset plate• Welded connections
– Plates are analyzed for shear– Weld strengths analyzed by supplemental hand
calculations• QA reviews of analysis is required• 1 bridge has required posting due to gusset plate
rating– Deck Truss– Bearing location – Section loss along top chord
• Leaking deck joint
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Summary
• Evaluation will provide additional level of bridge safety
• FHWA Technical Guidance is appropriate• Elected to perform rating as opposed to a
screening process• Revise BAR7 to include gusset plate analysis
December 2009
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Thank You