Numerical Simulations of Abutment PRB Structures with Post-Tensioned Unbonded Prestressing Tendons for Highway Bridges under Horizontal Seismic Loads

Traditional sacrificial concrete retaining blocks (CRBs) play a significant role in reducing the excessive transverse displacements of bridge superstructures and protecting the substructures from severe damage during seismic events. However, rehabilitating these CRBs after earthquakes is very difficult. Thus, many previous studies proposed the prefabricated retaining blocks (PRBs) with the unbonded post-tensioned prestressing tendons (PTs), which has been proven to be effective in maintaining the same functionality as that of traditional sacrificial CRBs while also simplifying their postearthquake rehabilitation. However, the response mechanisms and influential parameters of the abutment PRB under the horizontal seismic loads are unclear, affecting its further application in practical bridge engineering. This study established the three-dimensional (3D) finite-element (FE) model of the abutment PRB designed by the previous researcher and validated the feasibility and effectiveness of studying its seismic behavior through the available experimental results. Additionally, comprehensive parametric studies were performed to examine the effects of the friction coefficients, initial tension forces, and tensile strength of PTs on the seismic behavior of the abutment PRB. Subsequently, to fully utilize the mechanical merits of ultrahigh-performance concrete (UHPC), this paper proposed the modified abutment UHPC-PRB structures and their hysteretic behavior and damage modes were compared with those of the original ones through numerical simulations and available test results in the literature. Finally, the results indicated that (1) the developed FE models could accurately simulate the seismic behavior of the abutment PRBs; (2) the friction effect between the PRB body and side surface of the abutment stem wall had significant impacts on the hysteretic behavior and energy-dissipation performance of the abutment PRBs; (3) the critical rotational load, horizontal loading strength, deformation ability, energy-dissipation ability, and self-resetting capacity of the abutment PRBs could be improved with the increase of the initial tension force and tensile strength of PTs; and (4) the proposed replaceable abutment UHPC-PRB structures exhibited superior seismic performance and outperformed mechanical merits compared to traditional sacrificial CRBs.