Full-Scale Structural Behavior and Nonlinear Finite Element Model Assessment of PSC Bridge Girders Decommissioned After more than 40 Years of Service

Full-scale test data for prestressed concrete (PSC) bridge girders after decades of service remain scarce, limiting assessment of aging bridges and numerical models. This study examined two 30 m PSC-I girders removed after 42 and 44 years of service using material tests and full-scale four-point bending tests. Specimen-specific three-dimensional finite element (FE) models were developed from the measured geometry, material properties, and tendon layouts. Cracking loads were 400 and 300 kN, and maximum recorded loads were 1043.9 and 843.7 kN for the Guro Overpass and Gunseong Bridge girders, respectively. Mean longitudinal concrete core strengths were 55.1 and 33.3 MPa. The models used the Concrete Damaged Plasticity (CDP) formulation. Because residual prestress was not measured directly, initial tendon stresses were assigned as specimen-specific analytical conditions considering the early cracking response. The models reproduced the nonlinear load–deflection response over the measured range. At the test-end deflections, computed loads exceeded the measured values by 6.5% and 5.7% for the Guro and Gunseong girders, respectively. Predicted damage zones were broadly consistent with observed crack initiation and propagation and with compressive damage in the top concrete. The numerical response continued beyond test termination because localized damage and some demolition-induced discontinuities were not modeled explicitly. The results provide full-scale reference data for long-term-service PSC girders and for further assessment and refinement of specimen-based nonlinear models.