Design of UHPC Structural Connection Elements for Precast Bridge Decks

The utilization of Ultra-High-Performance Concrete (UHPC) for connecting bridge elements in accelerated bridge construction has become increasingly prevalent. Among their various applications, connecting bridge decks using UHPC stands out due to its ability to leverage key properties, including enhanced shear strength, tensile strength, compressive strength, and fatigue resistance. This study focuses on extensive testing and material modeling using an approach to use the flexural test results of small beams for back-calculation and validation of material constitutive response and using these properties in the context of a hybrid reinforcement strategy for typical UHPC bridge deck connection elements. Experimental programs were conducted using a 4-point bend test at both the materials and structural levels. After the assessment of the material data obtained from closed-loop tests, the results were evaluated using an actual-size reinforced concrete section tested under flexure. Results reveal multiple cracking mechanisms induced by the fibers, with the fibers exhibiting substantial capacity to withstand loads at large deflections. The analysis was used to characterize the contribution of the matrix, fiber, and reinforcement rates, thus providing insight into the tension-stiffening behavior of Hybrid section composites.