Advanced Analysis of FRP Reinforced Concrete Structures (ACI Spring 2024, New Orleans, LA) The study delves into modeling the interface between Fiber-Reinforced Polymer (FRP) and concrete, with a specific emphasis on simulating the gradual deterioration of bond strength. A model rooted in continuum damage mechanics is integrated with an empirically derived relationship to address interfacial shear failure. Material models are defined for the concrete, the externally bonded FRP reinforcement, and the adhesive layer. These material models are implemented in finite element simulations, replicating experimental setups widely used to investigate the FRP-concrete interface. Key results are reported and discussed. More precisely, the numerically obtained load-slip relationships for the interface and visualizations of the damaged zones in concrete are provided. The numerical results are in close agreement with existing experimental data. The finite element analyses suggest that concrete degradation is not limited to the areas near the adhesive joint. This implies that the adhesive joint could influence the overall behavior of the structural elements, even when debonding failures are prevented by anchorage devices.

Sustainable Building Solutions with UHPC – Case Studies (ACI Spring 2024, New Orleans, LA) The Delaware River and Bay Authority (DRBA) now has an ultra-high performance concrete (UHPC) overlay on the entire deck of one of its twin two-mile-long bridges known collectively as the Delaware Memorial Bridge. This is the first long-span bridge and the first suspension bridge with a complete UHPC overlay in the United States. Construction began in September 2022 and was carried out in three phases and completed in November 2023. The UHPC overlay was placed on over 51,000 square meters (550,000 square feet) of deck while keeping traffic flowing in both directions across the twin bridges. This project was preceded by a detailed lifecycle cost analysis followed by a small pilot project which helped guide project decision-making. The lifecycle cost analysis, which was focused on construction time and cost, showed a clear economic advantage to performing a UHPC overlay versus deck replacement or placing other overlay products. However, revisiting the comparative analysis from a sustainability perspective shows that the UHPC overlay is also the most sustainable solution. UHPC contains approximately twice as much cement as conventional concrete contains, and cement is known as a significant source of carbon dioxide emissions. However, deck replacement would require approximately three times as much concrete and a construction duration that is three times longer, which more than offset the higher carbon footprint of the UHPC material. Similarly, while other overlay materials may also have a lower carbon footprint, they would have to be replaced at least once, if not more, during the anticipated life span of the UHPC overlay. The presentation will provide a more detailed analysis of the sustainability of the UHPC overlay on the Delaware Memorial Bridge, while also briefly presenting how the full overlay project transpired and how the completed project is performing.