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
 Chain of Events Since the I-35W Bridge collapse in Minnesota
 VDOT’s Approach to Load Rating Gusset Plates
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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)
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19,390 Maintained by VDOT
1,528 Maintained by Localities
 9 Districts and one Central Office
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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
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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
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Chain of Events Since the I-35W Bridge collapse in Minnesota
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Chain of Events Since the I-35W Bridge collapse in Minnesota
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Chain of Events Since the I-35W Bridge collapse in Minnesota
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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
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VDOT’s Approach to Load Rating Gusset Plates
Typical Connection
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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)
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VDOT’s Approach to Load Rating Gusset Plates
Tension and Compression Checks for Gusset
Plate at Member Ends
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VDOT’s Approach to Load Rating Gusset Plates
MathCAD Sample Calculations
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VDOT’s Approach to Load Rating Gusset Plates
MathCAD Sample Calculations
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VDOT’s Approach to Load Rating Gusset Plates
MathCAD Sample Calculations
1 = Inventory Rating
2= Operating Rating
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VDOT’s Approach to Load Rating Gusset Plates
MathCAD Calculations for Members
 Fastener Capacity Check
 Block Shear Capacity Check
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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
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VDOT’s Approach to Load Rating Gusset Plates
Typical Connection
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VDOT’s Approach to Load Rating Gusset Plates
MathCAD Sample Calculations
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VDOT’s Approach to Load Rating Gusset Plates
MathCAD Sample Calculations
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VDOT’s Approach to Load Rating Gusset Plates
 Gusset Plate Rating Summary
 At each member
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VDOT’s Approach to Load Rating Gusset Plates
 Truss Member Rating Summary
 At each member
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VDOT’s Approach to Load Rating Gusset Plates
 Final Summary
 Controlling Gusset Plate
 Controlling Truss Member
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VDOT’s Approach to Load Rating Gusset Plates
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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!
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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