NUMERICAL EVALUATION OF THE SEISMIC PERFORMANCE OF BRIDGES MADE OF UHPC AND TITANIUM ALLOY REINFORCING BARS

Conventional Reinforced concrete (RC) structures, typically engineered for a lifespan of 50 years, are susceptible to various deterioration issues. In particular, continuous deterioration can weaken the structural elements of bridges in coastal areas, potentially reducing their lifespan. To address this issue, bridge engineers have proposed the use of advanced materials like ultra-high-performance concrete, titanium alloy reinforcement, composite materials, and others. Recently, the combination of titanium alloy bars (TiABs) and ultra-high-performance concrete (UHPC), namely TARUHPC structures, has been proposed as a novel construction method to enhance the durability and longevity of RC bridges in seismic regions. However, the seismic performance of TARUHPC is not fully characterized yet. Thus, it is important to assess the seismic deformation capacity of TARUHPC bridges. This paper evaluates the seismic performance of TARUHPC piers via nonlinear Finite Element (FE) models. Fiber-based models with distributed plasticity were developed to evaluate three scenarios: (1) normal concrete with TiABs (NC-TI), (2) UHPC with conventional steel (U-TI), and (3) TARUHPC. The parameters of the models were fine-tuned through model updating based on previous experimental cyclic tests. After a detailed validation, the FE models were able to capture the ductility, stiffness degradation, residual deformation, energy dissipation, and failure modes observed in the test specimens. Moreover, a detailed parametric analysis is conducted to explore the influence of different design variables on the seismic performance of TARUHPC bridges. Finally, some important design recommendations are provided.