ABSTRACT
The dynamic behavior of railway bridges is significantly influenced by their infrastructure system, particularly the asset foundation. Practical solutions for assessing the responses of foundations to imposed loads must balance low computational cost with high precision and accuracy. Among these solutions, techniques involving Winkler springs and specific impedance functions, which account for the effect of lateral confinement of the soil using in situ Standard Penetration Test (SPT) results stand out. This study analyzes the structural behavior of isolated reinforced concrete piles used in a Brazilian railway bridge system subjected to horizontal loads. A soil-structure-interaction approach was used to determine the stiffness values of Winkler springs, combined with a P-delta nonlinear geometric analysis, nodal displacement control, and line search algorithm. Load-displacement curves were obtained for two scenarios: intact foundations and foundations with induced damage, simulating defects in the foundation elements and the soil surrounding the steel piles. The minimum resilience of the foundation was determined based on the loss of performance that resulted from the displacement increment observed in the damaged foundations. Additionally, the probable vibration modes and natural frequencies of the railway infrastructure were analyzed based on the modal participation factors. The results obtained allowed us to conclude that the vibration modes and natural frequencies are more affected by damage to the foundations and that the resilience levels using the performance lost due to the damage were similar for displacements or natural frequencies.
