Precast Concrete Deck-to-Girder Connection using UHPC

The method used in Nebraska for connecting precast concrete deck panels to concrete girders to create composite section is extending shear connectors (i.e., threaded rods) from the concrete girder into HSS-formed shear pockets in the deck panels, and then filling the pockets and haunch area using self-consolidating concrete (SCC). This method requires high level of quality control/quality assurance (QA/QC) in spacing the shear connectors during girder fabrication as well as shear pockets during panel fabrication to avoid any conflict between them during erection. It also requires shear connectors to achieve minimum embedment in the shear pockets to develop the design capacity, which necessitates adjusting connector’s height to compensate for girder camber. The main project objective is to develop and test a new UHPC connection between precast concrete deck panels and NU precast/prestressed concrete girders that eliminates any changes to girder design/production and any possible conflict between deck and girder reinforcement. Typical girder shear reinforcement will be used and positioned below the bottom mat of deck reinforcement, then, UHPC is placed through grouting holes to fill the trough and haunch areas (i.e., a hidden composite connection). The constructability and structural performance of the new connection will be evaluated analytically and experimentally using commercial and local UHPC mixtures (currently being developed under another NDOT project).