Fatigue Response in Bridge Deck Connection Composed of Field-Cast Ultra-High-Performance Concrete

The use of prefabricated concrete bridge deck components can offer many advantages over conventional cast-in-place construction techniques. However, completing the overall bridge system requires the installation of connecting elements. The state of the practice for these connecting elements has been deficient in resilience, durability, and ease of construction. An ongoing research effort at FHWA, in conjunction with partners from the New York State and Iowa Departments of Transportation, is focused on engaging the advantageous properties of ultra-high-performance concrete (UHPC) to develop a new type of detail applicable to deck-level connections between prefabricated modular bridge components. This physical testing program investigated the structural performance of a field-cast UHPC connection under repeated truck wheel loading. The connection—150 mm (5.9 in.) thick and 152 mm (6 in.) wide—was designed as a noncontact lap splice with straight 16M (No. 5) steel reinforcement. After more than 11 million structural-loading cycles at progressively increasing load levels, individual bars within the connection began to fail in metal fatigue. The stress range in the reinforcement at initial fatigue failure was conservatively estimated at 197 MPa (28.6 ksi). No debonding or slippage of reinforcement was observed. The performance of this connection detail demonstrated the types of details that can be developed and deployed with field-cast UHPC.