Horizontal Shear Transfer for Full-Depth Precast Concrete Bridge Deck Panels

Full-depth precast deck panels are a promising alternative to the conventional cast-in-place concrete deck. They afford reduced construction time and fewer burdens on the motoring public. In order to provide designers guidance on the design of full-depth precast slab systems with their full composite strength, the horizontal shear resistance provided at the slab-to-beam interface must be quantified through further investigation. Currently, all design equations, both in the AASHTO Specifications and the ACI code, are based upon research for cast-in-place slabs. The introduction of a grouted interface between the slab and beam can result in different shear resistances than those predicted by current equations.

A total of 29 push off tests were performed to quantify peak and post-peak shear stresses at the failure interface. The different series of tests investigated the surface treatment of the bottom of the slab, the type and amount of shear connector and a viable alternative pocket detail.

Based on the research performed changes to the principles of the shear friction theory as presented in the AASHTO LRFD specifications are proposed. The proposal is to break the current equation into two equation that separate coulomb friction and cohesion. Along with these changes, values for the coefficient of friction and cohesion for the precast deck panel system are proposed.