Seismic Vulnerability of Roman Aqueduct Bridge Structures: Numerical Modelling and Application to the Antioch-on-the-Orontes Aqueduct (Antakya, Türkiye)

Roman aqueduct bridges are widespread across the seismically active Mediterranean, yet their earthquake vulnerability remains insufficiently documented. This study evaluates the first-order seismic response of such structures and applies the approach to the Antioch-on-the-Orontes aqueduct at Harbiye (Antakya, Türkiye), a monument affected by multiple construction phases, repairs, and partial collapses. Linear static, modal, and time-history finite-element analyses were performed on idealized arch-and-pier configurations subjected to recorded ground motion. Variations in pier height, arch width, deck thickness, reinforcement, stiffness, Poisson’s ratio, and density were tested. The models consistently identify the arch springings and pier bases as recurrent stress-concentration zones. Vulnerability increases with pier height, arch width, deck thickness, lower stiffness, and greater structural mass, whereas buttresses, larger piers, and lower-density materials improve stability. In the Antioch models, the highest computed stresses coincide spatially with several observed damaged, collapsed, or repaired sectors. The reinforced construction stage shows reduced stress concentrations relative to the unrepaired configuration. These results support the interpretation that seismic shaking plausibly contributed to the monument’s structural evolution and demonstrate the value of simplified numerical modelling for archaeoseismological assessment of historical masonry infrastructure.