Experimental study on joint of spliced steel-PSC hybrid girder, Part I: Proposed parallel-perfobond-rib-type joint

The object of this study is to determine and propose a suitable joint type for spliced hybrid I-girder bridges consisting of steel girders at the mid-span and PSC (prestressed concrete) girders at the supports. Three joint types are experimentally tested on small-scale steel-PSC hybrid beams to determine the type offering the best combination of structural capacity and constructional convenience. One joint type, first suggested and trialed in the present study, is composed of multiple perfobond rib connectors attached in parallel to upper and lower plates located between the steel girder and the PSC girder. The two other types incorporate the stud connectors, which are widely used in connecting steel and concrete, but differ in the amount of reinforcement. The test results reveal that a joint consisting of parallel perfobond ribs and a joint consisting of studs with sufficient reinforcement show the similar beam strength and failure modes resulting from the failure of the PSC components. Notably, beams of the proposed joint type consisting of perfobond ribs, compared to those with studs, show higher stiffness and strength prior to reaching their ultimate strength, as well as lower strains in the joint. Indeed, with the parallel-perfobond-rib-type joint, advances in constructional convenience as well as structural capacity can be anticipated. Thus, it is concluded that the proposed joint type is a more suitable system for spliced steel-PSC hybrid girder bridges.