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FHWA Webinar: Load Rating of Gusset Plates in Steel Truss Bridges by Other States Presented By: Anwar S. Ahmad, P.E. Assistant State Bridge Engineer Date: October 8, 2009. Presentation Outline. About VDOT

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Presentation Outline

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  1. FHWA Webinar: Load Rating of Gusset Plates in Steel Truss Bridges by Other StatesPresented By: Anwar S. Ahmad, P.E. Assistant State Bridge EngineerDate: October 8, 2009

  2. Presentation Outline • About VDOT • Chain of Events Since the I-35W Bridge collapse in Minnesota • VDOT’s Approach to Load Rating Gusset Plates

  3. About VDOT • VDOT maintains the 3rd largest state-owned road system in the U.S. • 57,867 miles of sate maintained roadway system • 20,918 Structures (Bridges and Large Culverts) • 19,390 Maintained by VDOT • 1,528 Maintained by Localities • 9 Districts and one Central Office

  4. Chain of Events Since the I-35W Bridge collapse in Minnesota • Worked with FHWA to identify all bridges with similar design type to the I-35W Bridge (Deck Truss Type) • Total of 11 bridges were identified • Both FHWA and VDOT reviewed the latest inspection reports of the 11 bridges and did not find anything out of the ordinary • All bridges were inspected within the last 2 years of the review date • Some were inspected as early as May 2007 • Assigned the inspections of all 11 bridges to the 3 engineering consulting firms • Inspection completed September 30, 2007

  5. Chain of Events Since the I-35W Bridge collapse in Minnesota • Identified all FCM bridges and reviewed the last inspection reports (305 total) • Re-inspected 36 of the 305 FCM structures for QA measures • Restricted permit vehicles from crossing truss bridges • Identified 113 truss bridges with gusset plates • Developed standard procedure for analyzing gusset plates in accordance with FHWA latest guidelines • Completed the load rating for 106 of the 113 truss bridges

  6. Chain of Events Since the I-35W Bridge collapse in Minnesota

  7. Chain of Events Since the I-35W Bridge collapse in Minnesota

  8. Chain of Events Since the I-35W Bridge collapse in Minnesota

  9. VDOT’s Approach to Load Rating Gusset Plates • VDOT decided to follow FHWA - LFR Guidelines • VDOT decided to develop examples in MathCAD • Analyze up to 5 members at a joint • Analyze gusset plates and member ends • Separate MathCAD sheet for splice plate

  10. VDOT’s Approach to Load Rating Gusset Plates Typical Connection

  11. VDOT’s Approach to Load Rating Gusset Plates MathCAD Calculations for Gusset Plates at Member Ends • Tension & Compression Check • Fastener Capacity • Block Shear Capacity • Tension / Compression Capacity (Whitmore Section)

  12. VDOT’s Approach to Load Rating Gusset Plates Tension and Compression Checks for Gusset Plate at Member Ends

  13. VDOT’s Approach to Load Rating Gusset Plates MathCAD Sample Calculations

  14. VDOT’s Approach to Load Rating Gusset Plates MathCAD Sample Calculations

  15. VDOT’s Approach to Load Rating Gusset Plates MathCAD Sample Calculations 1 = Inventory Rating 2= Operating Rating

  16. VDOT’s Approach to Load Rating Gusset Plates MathCAD Calculations for Members • Fastener Capacity Check • Block Shear Capacity Check

  17. VDOT’s Approach to Load Rating Gusset Plates • MathCAD Calculations For Gusset Plates at Sections A-A, B-B and C-C • Unsupported Length to Thickness Ratio • Gross and Net Section Shear Yielding Resistance

  18. VDOT’s Approach to Load Rating Gusset Plates Typical Connection

  19. VDOT’s Approach to Load Rating Gusset Plates MathCAD Sample Calculations

  20. VDOT’s Approach to Load Rating Gusset Plates MathCAD Sample Calculations

  21. VDOT’s Approach to Load Rating Gusset Plates • Gusset Plate Rating Summary • At each member

  22. VDOT’s Approach to Load Rating Gusset Plates • Truss Member Rating Summary • At each member

  23. VDOT’s Approach to Load Rating Gusset Plates • Final Summary • Controlling Gusset Plate • Controlling Truss Member

  24. VDOT’s Approach to Load Rating Gusset Plates

  25. VDOT’s Approach to Load Rating Gusset Plates Example of Gusset Plate Analysis can be found at the following weblink http://www.virginiadot.org/business/bridge-FRP.asp Thank you!

  26. FHWA Webinar: Load Rating of Gusset Plates in Steel Truss Bridges by Other StatesPresented By: Anwar S. Ahmad, P.E. Assistant State Bridge EngineerDate: October 8, 2009

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