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Strengthening Continuous Steel Girder Bridges with Post-Installed Shear Connectors

Sponsor: Texas Department of Transportation
Principal Investigators: Michael Engelhardt, Todd Helwig, Eric Williamson, and Richard Klingner 
Research Assistants: Kerry Kreitman, Amir Reza Ghiami Azad, and Hemal Patel

Photo of concrete on steel girders

Many continuous steel bridges constructed prior to 1970 have a non-composite floor system consisting of a concrete deck over steel girders with no shear connectors.  This research is investigating a technique of strengthening such bridges by “post-installing” adhesive anchor shear connectors to create composite action between the existing deck and girders.  Small-scale fatigue testing on individual adhesive anchor connectors has indicated significantly better fatigue performance than conventional welded studs, allowing for partial-composite design to minimize the number of connectors needed.  Large-scale continuous two-span girders (84-foot and 104-foot long) strengthened with post-installed shear connectors performed very well at both fatigue and strength limit states, including under repeated large loads causing significant amounts of inelastic moment redistribution.  This technique is currently being used to strengthen an existing bridge in east Texas, originally constructed in the 1940s.

Photo of project