Shear transfer mechanism in slab-on-girder bridges

Headed shear connectors are commonly used to transfer longitudinal shear forces across the concrete steel interface in bridges. While the connectors are mainly meant to create composite action, they restrain the free shrinkage of concrete decks and as a result cause transverse cracking. A good understanding of the composite action and interaction between stud and its surrounding concrete is very beneficial for developing a remedy for the problem of deck cracking, which is the most significant part of bridge maintenance cost in the US. The aim of this work, therefore, is developing more insights into the shear transfer mechanism in welded shear studs to quantify its effect on bridge deck cracking. Preliminary results indicate that under gravity load shear studs uniformly contribute to transfer of shear stresses, although the end studs (farther from center) have slightly more contribution. However, under shrinkage load the end studs transfer majority of the load. Furthermore, it is determined that a wider shear stud spacing can be used without significant increase in deflections. An innovative concept to eliminate shrinkage deck cracking is briefly discussed.