<p>To improve the seismic behaviour and service durability of reinforced concrete bridge piers in corrosive environments, stainless materials are used in RC components of coastal bridges. In this work, a damage observation-informed seismic vulnerability assessment method of stainless steel-reinforced concrete bridge piers is proposed to address the limitations of conventional numerical limit state definitions. The method integrates experimental damage observations into fragility analysis, ensuring more accurate damage state thresholds. A stainless steel reinforced concrete bridge pier is presented as case study. Duplex stainless steel is selected to replace conventional carbon steel as reinforcement. A validated numerical model is used to simulate seismic responses under near-fault excitations. Results show that SS-reinforced piers generally exhibit lower fragility than CS-reinforced piers, though this advantage is influenced by reinforcement ratio and axial load. The presence of velocity pulses in near-fault motions significantly increases seismic vulnerability.</p>