This Design memorandum requires checking capacity of gusset plates of existing non-load-path redundant steel truss bridges as follows:

Bridge Rehabilitation:

As part of bridge rehabilitation, calculations shall demonstrate the adequacy of the gusset plates for any changes in loading conditions including increased dead or live load, or to account for structural modifications or other alterations that result in significant changes in stress level. A thorough survey of impacted gusset plates shall be made to determine section loss due to corrosion or prior modification.

Bridge Load Rating:

As part of the load rating, calculations shall demonstrate the adequacy of the gusset plates for any changes in loading conditions, such as section loss or increased dead or live load, to make permit or posting decisions, or to account for structural modifications or other alterations that result in significant changes in stress level.

Background:

On January 17, 2008 FHWA has issued Technical Advisory T 5140.29 – Gusset Plate Capacities on Steel Truss Bridges. The above memorandum reflects the FHWA’s Technical Advisory memorandum.

If you have any questions regarding these issues, please contact Nate Brown at 705-7219, Mohamad Al-Salman at 570-2567, or Bijan Khaleghi at 705-7181.

cc:   Mohammad Sheikhizadeh, Bridge Construction - 47354