Experimental Behavior of Mechanical In-Flange Connectors

Prestressed double-Tee beams are used in multi-level parking structures and in some states bridges. Steel brackets, called in-flange connectors, are embedded in the flanges of the beams and are welded together on-site to facilitate system behavior. To date, placement, i.e. spacing, of these connectors has been based primarily on engineering judgment although some guidelines are available. This paper summarizes the results of seventy (70) monotonic and twentythree (23) reversed-cyclic tests on double-Tee in-flange connectors in an effort to provide comprehensive information on the relative performance of several different available connectors. Test results are reported for six different connectors manufactured by two different companies using seven different test protocols described herein. Each connector was imbedded in a 965x914x102 mm (38x36x4 in) concrete slab designed to be representative of the overhanging portion of the flange of a concrete double-Tee beam. The connectors were also tested using a slow reversed-cyclic displacement control protocol and the ability of each connector to dissipate/absorb energy is also discussed, along with the relationship to serviceability-related concrete damage, i.e. cracking and spalling.